Jump to content




Welcome to Unexplained Mysteries! Please sign in or create an account to start posting and to access a host of extra features.


- - - - -

Exploration Of Venus


  • Please log in to reply
68 replies to this topic

#1    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 31 March 2006 - 03:59 PM

Venus Express is a European Space Agency mission to Earth's nearest planetary neighbour. On 9th November 2005 it was launched from the Baikonour Cosmodrome in Kazakhstan aboard a Russian Soyuz-Fregat launcher. It was constructed using the Mars Express design (ESA's successful Mars orbiter). This made it cheaper and quicker to build than is usual for planetary probes. Venus Express will enter Venus orbit on 11th April 2006.

The latest update from ESA is reproduced below:

Venus within ESA probe reach

user posted image
An artist's impression of the first firing test of the Venus Express spacecraft main engine,
being performed in space during the night of 16/17 February 2006. The burn started at
01:27 CET and lasted about three seconds.

Credits: ESA


31 March 2006
PR 12-2006. After its five-month, 400-million-kilometre journey inside our Solar System following its lift-off on 9 November 2005, ESA’s Venus Express spacecraft will finally arrive on 11 April at its destination: planet Venus.

Venus Express mission controllers at the ESA Space Operations Centre (ESOC) in Darmstadt, Germany, are making intensive preparations for orbit insertion.
This comprises a series of telecommands, engine burns and manoeuvres designed to slow the spacecraft down from a velocity of 29000 km per hour relative to Venus, just before the first burn, to an entry velocity some 15% slower, allowing the spacecraft to be captured into orbit around the planet.

The spacecraft will have to ignite its main engine for 50 minutes in order to achieve deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of onboard propellant will be used for this manoeuvre. The spacecraft’s solar arrays will be positioned so as to reduce the possibility of excessive mechanical load during engine ignition.  

Over the subsequent days, a series of additional burns will be done to lower the orbit apocentre and to control the pericentre. The aim is to end up in a 24-hour orbit around Venus early in May.

ESA TV will cover this event live from ESOC in Darmstadt. The live transmission will be carried free-to-air. For broadcasters, complete details of the various satellite feeds are listed at http://television.esa.int
.


The event will be covered on the web at venus.esa.int. The website will feature regular updates, including video coverage of the press conference and podcast from the control room at ESA’s Space Operations Centre.

Source: ESA - News

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#2    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 07 April 2006 - 10:07 AM

ESA’s Venus Express to reach final destination

user posted image
Venus Express will make unprecedented studies of the largely unkown phenomena taking place in the Venusian atmosphere. Its suit of instruments will also dig into the interaction between the solar wind and the planetary environment. Finally, the mission will gather glimpses about the planet's surface, so dense that it is striclty coupled with the atmosphere.

Credits: ESA - AOES Medialab


7 April 2006
ESA INFO 02-2006. It was on 9 November last year that ESA's Venus Express spacecraft lifted off from the desert of Kazakhstan onboard a Soyuz-Fregat rocket. Now, after having travelled 400 million kilometres in only about five months, the spacecraft is about to reach its final destination. The rendezvous is due to take place on 11 April.


First step: catching Venus

To begin to explore our Earth’s hot and hazy sister planet, Venus Express must complete a critical first step, the most challenging one following launch. This involves a set of complex operations and manoeuvres that will inject the spacecraft into orbit. The Venus Orbit Insertion (VOI) manoeuvre allows the spacecraft to reduce its speed relative to Venus, so that it can be captured by the planet’s gravitation. The manoeuvre is a critical one which must proceed at precisely the right place and time.
The VOI phase officially started on 4 April and will not be completed until 13 April. It is split into three main sub-phases. The first consists in preparing or initialising the spacecraft for the actual capture manoeuvre so as to avoid the risk of the spacecraft going into safe mode, should parameters unrelated to VOI go off-range.

The capture manoeuvre itself consists of a main-engine burn lasting about 50 minutes on the morning of 11 April starting at 09:17 (Central European Summer Time). This is the second main VOI sub-phase.

The final sub-phase will be restoring all spacecraft functions, notably resuming communications with Earth and uplinking the commands to be executed during the preliminary ‘capture’ orbit.

Orbital capture is controlled by an automatic sequence of predefined commands, uploaded to the spacecraft four days prior to VOI. This sequence is the minimum set needed to perform the main-engine burn.

All spacecraft operations are controlled and commanded by the ground control team located at ESA’s European Spacecraft Operations Centre (ESOC) in Darmstadt, Germany.  

Timeline of major VOI events (some times subject to change)

user posted image
Artist's impression of the Venus Express orbit insertion, to take place on 11 April 2006. In this phase of the mission, the most challenging since launch, the spacecraft's main engine will have to burn for about 50 minutes, to reduce its speed with respect to Venus so that the spacecraft can be captured by the planet's gravitation.

Credits: ESA - AOES Medialab


4 April, spacecraft transmitter connected to low gain antenna is switched on. During its interplanetary cruise and during the scientific part of the mission to come, Venus Express communicates with Earth by means of its two high gain antennas. However, during the orbit capture phase (11 April), these two antennas become unusable because of the spacecraft’s required orientation at that time.

The low gain antenna, carrying a feeble but instantly recognisable signal, will be transmitting throughout all VOI manoeuvres. This will allow ground controllers to monitor the velocity change during the burn, using NASA’s Deep Space Network’s 70-metre antenna near Madrid, Spain. No other means of communication with the Earth is possible during the capture burn.

5 and 9 April, targeting control manoeuvres. Two time slots are available to adjust course if needed. Given the high accuracy of the course correction performed end of March, Venus Express is currently on the right trajectory for a successful capture into orbit and it is therefore unlikely that either of these two extra slots will be required.

10 to 11 April, final preparations for VOI manoeuvre. 24 to 12 hours before VOI, spacecraft controllers will command Venus Express into its final configuration for the burn. Over the final 12 hours, they will monitor its status, ready to deal with any contingencies requiring last-minute trajectory correction or any revising of the main-engine burn duration.

11 April, 08:03 (CEST), ‘slew’ manoeuvre. This manoeuvre lasts about half an hour and rotates Venus Express so that the main engine faces the direction of motion. Thanks to this, the burn will slow down (rather than accelerate) the spacecraft.

11 April, 09:17 (CEST), main-engine burn starts. A few minutes after firing of the spacecraft thrusters to make sure the propellant settles in the feed lines to the main engine, the latter will begin its 50-minute long burn, ending at 10:07.

user posted image
Artist's impression of the Venus Express orbit insertion burn (the firing of its engine to slow down enough to be captured by the gravity of Venus and enter orbit).

Credits: ESA - AOES Medialab


This thrust will reduce the initial velocity of 29 000 kilometres per hour (in relation to Venus) by 15 percent, allowing capture. Venus Express will settle into its preliminary, elongated nine-day orbit. On capture, it will be at about 120 million kilometres from the Earth and, at its nearest point, within 400 km of the surface of Venus.

During the burn, at 09:45 (CEST), Venus Express will disappear behind the planet and will not be visible from Earth. This is known as its ‘occultation’ period. The spacecraft will re-emerge from behind Venus’s disc some ten minutes later. So, even with the low gain antenna’s signal, it will only be visible during the first half of the burn and the last six minutes. Receiving the spacecraft signal after the occultation period will be the first positive sign of successful orbit insertion.

11 April, h 11:13 (CEST), re-establish communication with Earth. At the end of the burn, Venus Express still has to perform a few automatic operations. These re-orient the solar panels towards the sun and one of the high gain antennas (the smaller High Gain Antenna 2) towards Earth. If everything goes as expected, at 11:13 the spacecraft should be able to establish its first communication link with ESA’s Cebreros ground station near Madrid. Over the next few hours, it will send much-awaited information about its state of health. Information about its actual trajectory will be available from ESOC’s flight dynamics team around 12:30 (CEST).

12 to 13 April 2006, full reactivation starts. During the 24 hours following orbital capture, time will be devoted to reactivating all spacecraft functions, including all internal monitoring capacity. By the morning of the 13th, the larger ‘High Gain Antenna 1, hitherto unused, will be oriented and fed by the transmitter to communicate with Earth. The two high gain antennas, located on different sides of the spacecraft, will be used alternately during the mission, to avoid exposure to the sun of critical equipment on the outside.
  

Reaching final orbit

user posted image
This artist's impression shows the trajectory of ESA's Venus Express to its final destination, planet Venus. In the first week of March 2006, the spacecraft crossed the path of the planet around the Sun. The trajectory took it inside the orbit of Venus to ‘anticipate’ the celestial motion of the planet and finally to catch up with it on 11 April 2006. Once at Venus, the spacecraft will have travelled 400 million kilometres. The injection into orbit will put the spacecraft into a first, elongated orbit lasting about 9 days. On 7 May 2006, after a series of manoeuvres and 16 ever smaller loops around the planet, Venus Express will reach its final operational orbit, lasting 24 hours.

Credits: ESA - C.Carreau


A series of further manoeuvres and many more days will be required to settle Venus Express into its final orbit. The preliminary nine-day orbit is elliptical, ranging from 350 000 kilometres at its furthest point from the planet (apocentre) to less than 400 kilometres at its closest (pericentre).

During this period, Venus Express will also have to perform seven burns (two with the main engine, five with its banks of thrusters) to gradually reduce the apocentre of the following orbits. Final orbit will be reached on 7 May after 16 loops around the planet. It will be a polar orbit, ranging from 66 000 to 250 kilometres from Venus and with a pericentre located at above latitude 80°North.

On 22 April, Venus Express will start its in-orbit commissioning phase. Its instruments will be switched on one by one for detailed checking until 13 May, then operated all together or in groups. This allows simultaneous observation of phenomena to be tested, to be ready for the nominal science phase beginning on 4 June.

  
Observations in capture orbit

user posted image
This artist's impression shows Venus Express over the 'double-eye' atmospheric vortex at the planet's North pole. In fact two enormous atmospheric vortices, with very complex shapes and behaviour, rotate vertically over both poles of Venus, recycling the atmosphere downwards. The vortex at the North pole, the only one previously studied in some detail, completes a full rotation in only three days. Venus Express' observations will help understand how the stormy atmospheric circulation on Venus work.

The preliminary nine-day polar orbit will be a great opportunity to perform scientific observations. These will proceed only if other critical operations of the spacecraft do not take priority, and in any case not before 30 hours after VOI. The first opportunity to gather scientific data will be on 12-13 April.

During this preliminary orbit phase, the complete disc of Venus will be fully visible for the spacecraft’s imaging instruments, an opportunity that will not occur during the nominal mission, when the range of distances from the planet will be smaller. Such observations will mainly cover the southern hemisphere, which was inadequately studied on previous missions.

In particular, the geometry of the capture orbit makes it possible to observe the dynamics of the Venusian atmosphere continuously and thoroughly from a greater distance, over a duration even longer than the full rotation cycle of the atmosphere at the cloud tops (the still-unexplained four-day ‘super rotation’). Indeed, atmospheric study is one of the mission’s prime goals.

For instance, from distances greater than 200 000 kilometres, the visible/near-infrared mapping spectrometer (VIRTIS) will be able to take snapshots of the entire planetary disc and atmosphere. During the nominal science phase, images of the atmosphere will need to be built up in mosaics.

The analyser of space plasma and energetic atoms (ASPERA) will have an unprecedented opportunity to study from great distances the unperturbed solar wind and to gather data on the atmospheric escape processes on a planet which has no magnetic protection.

In the capture orbit, all the instruments (except the VeRA radio science experiment and PFS spectrometer) may perform observations for a few hours a day on selected dates.

  
…and plenty of science to come

user posted image
Venus is a planet with no intrinsic magnetic field and so, differently from Earth, it has no shield to protect it from the continuous attack of the capricious and violent solar wind. ESA's Venus Express will study how much of the atmosphere of the planet escaped under the bombardment of the solar wind and how much it combined with the surface material.

Credits: ESA - C.Carreau


Venus Express is designed to carry out scientific observations over two Venusian days, corresponding to 486 Earth days. The mission could be extended to double the nominal duration.

Notwithstanding the intense previous exploration (Venus is the third most visited celestial body in our solar system after the Moon and Mars), a plethora of mysteries still surround this planet. Venus Express’s unique instruments for planetary investigation are tailored to taking advantage of clues from previous missions and investigating the planet’s oddities with unprecedented precision.

The instruments onboard, the spacecraft’s ‘eyes’, include a combination of spectrometers (the PFS planetary fourier spectrometer and the SpicaV/SOIR ultraviolet and infrared atmospheric spectrometer), spectro-imagers (VIRTIS ultraviolet /visible/near-infrared mapping spectrometer) and imagers (VMC Venus monitoring Camera).

user posted image
Through the Venus Radio Science Experiment on board Venus Express - using the powerful radio link bewteen the spacecraft and Earth - scientists will investigate the conditions of the ionosphere of the planet (upper atmospheric layer), and study the local conditions of the solar wind. The experiment will also allow the study of the physical properties of mid atmospheric layers and the roughness and electrical properties of the surface.

Credits: ESA - AOES Medialab


They are extremely sensitive in a wide range of electromagnetic wavelengths from ultraviolet to infrared and will allow detailed study of the Venusian atmosphere and its interaction with the surface. Also onboard are the MAG magnetometer, the ASPERA analyser of space plasma & energetic atoms and the VeRA radio science experiment, to study all interaction between the atmosphere and the ever-blowing solar wind.

Venus Express will take advantage, for the first time ever, of the so-called ‘infrared windows’, which are narrow atmospheric bands in the infrared part of the spectrum. Through these, precious information about the lower layers of the atmosphere and even the surface can be gathered.

The Venus Express mission will help find answers to several unsolved questions. How does the complex atmospheric dynamics and cloud system work? What causes the fast “super-rotation” of the atmosphere at the cloud top? And what is the origin of the double vortex at the north pole?

Venus Express will also investigate the processes that determine the chemistry of the noxious Venusian atmosphere, which can be as hot as 500°C at the surface and is mainly composed of carbon dioxide, with clouds of sulphuric acid drops. It will study what role the greatest greenhouse effect in the solar system plays in the overall evolution of the Venusian climate. It will also help us to ascertain whether Venus provides a possible preview of a future Earth.

Lastly, through combined analysis of the dense atmosphere and surface, Venus Express will help us to understand the planet’s geology and ascertain there are signs of present volcanic or seismic activity.

  
“Venus Express to ground control”

user posted image
The Cebreros Deep Space 35m antenna.

Credits: ESA


During the course of the nominal mission, Venus Express will communicate with Earth via ESA’s Cebreros ground station near Madrid. ESA’s New Norcia station in Australia will be used to support the VeRA radio science experiment.


Source: ESA - News

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#3    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 11 April 2006 - 09:26 AM

Venus Express main engine burn starts

11 April 2006
At 09:17 CEST today (07:17 GMT), Venus Express started its main engine burn. The burn, to last 50 minutes, will slow down the spacecraft and allow the capture into orbit around Venus. The main engine burn started a few minutes after the firing of the spacecraft thrusters, to make sure the propellant settles in the feed lines to the main engine.

This thrust is aimed at reducing the initial velocity of 29 000 kilometres per hour (in relation to Venus) by 15 percent, to allow capture by the planet’s gravity. Thanks to this burn, Venus Express will settle into its preliminary, elongated nine-day orbit.
Only the spacecraft low-gain antenna, carrying a feeble but instantly recognisable signal, is transmitting throughout all VOI manoeuvres. This allows ground controllers to monitor the velocity change during the burn, using NASA’s Deep Space Network’s 70-metre antenna near Madrid, Spain. No other means of communication with the Earth is possible during the capture burn.

During the burn, at 09:45 CEST, Venus Express will disappear behind the planet and will not be visible from Earth. This is known as its ‘occultation’ period, in which the only signal coming from the spacecraft – the carrier signal from the low gain antenna - will become unavailable for ten minutes.


Source: ESA - News

------------------------------------


Venus Express main engine burn ended

11 April 2006
Ground controllers at ESA’s European Spacecraft Operations Centre (ESOC) confirmed the end of the Venus Express main engine burn at 10:07 (CEST) today (08:07 GMT).

A few more automatic operations should now follow to reorient the spacecraft towards the Sun (so-called ‘sun acquisition mode’) and then have one of the spacecraft’s high gain antennas (the HGA 2) oriented towards Earth, ready to establish the first communication link with ground control.


Source: ESA - News

------------------------------------


Venus Express 'talks' to Earth

user posted image
Venus Express communicates with Earth

11 April 2006
At 11:12 CEST Venus Express re-established communication with Earth for the first time after the start of the orbit insertion manoeuvres.

After the end of the main engine burn, Venus Express still had to perform a few automatic operations. These included re-orienting the solar panels towards the Sun and one of its high gain antennas (the smaller High Gain Antenna 2) towards Earth.
It is through this antenna that the spacecraft established the first communication link with Earth and started to send back information about its health status. The spacecraft data are sent to ESA’s European Spacecraft Operations Centre (ESOC) via ESA’s Cebreros ground station near Madrid. The data downlink lasts for a few hours.

Information about Venus Express’ actual trajectory will be available from ESOC’s flight dynamics team around 12:30 CEST.


Source: ESA - News

Edited by Waspie_Dwarf, 11 April 2006 - 12:22 PM.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#4    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 11 April 2006 - 09:51 AM

Europe scores new planetary success: Venus Express enters orbit around the Hothouse Planet

user posted image
Artist's impression of the Venus Express orbit insertion on 11 April 2006. In this phase of the mission, the most challenging since launch, the spacecraft's main engine burns for about 50 minutes, to reduce its speed with respect to Venus to allow the the spacecraft to be captured by the planet's gravitation.

Credits: ESA - AOES Medialab


11 April 2006
ESA PR 13-2006. This morning, at the end of a 153-day and 400-million km cruise into the inner Solar System beginning with its launch on 9 November 2005, ESA’s Venus Express space probe fired its main engine at 09:17 CEST for a 50-minute burn, which brought it into orbit around Venus.

With this firing, the probe reduced its relative velocity toward the planet from 29,000 to about 25,000 km/h and was captured by its gravity field. This orbit insertion manoeuvre was a complete success.
During the next four weeks, the Venus Express probe will perform a series of manoeuvres to reach the scheduled operational orbit for its scientific mission. It will move from its current highly elongated 9-day orbit to a 24-hour polar orbit, culminating at 66,000 kilometres. From this vantage point, the orbiter will conduct an in-depth observation of the structure, chemistry and dynamics of the atmosphere of Venus for at least two Venusian days (486 Earth days).  
  
Enigmatic atmosphere

user posted image
The Venus Express mission mainly focusses on studying the peculiar atmosphere of Venus, with a precision never achieved before. In doing so, it will make the first ever use of the so called 'infrared windows', which are narrow bands in the atmospheric spectrum, discovered in the 1980s thanks to ground observations. Looking through these 'windows' Venus Express will be able to gather precious information about the lower layers of the atmosphere and even the surface.

Credits: ESA - AOES Medialab


From previous missions to Venus as well as observations directly from Earth, we already know that our neighbouring planet is shrouded in a thick atmosphere where extremes of temperature and pressure conditions are common. This atmosphere creates a greenhouse effect of tremendous proportions as it spins around the planet in four days in an unexplained 'super-rotation' phenomenon.

The mission of Venus Express will be to carry out a detailed characterisation of this atmosphere, using state-of-the-art sensors in order to answer the questions and solve the mysteries left behind by the first wave of explorers. It will also be the first Venus orbiter to conduct optical observations of the surface through 'visibility windows' discovered in the infrared spectrum.

The commissioning of the onboard scientific instruments will begin shortly and the first raw data are expected within days. The overall science payload is planned to be fully operational within two months.

Europe explores the Solar System

user posted image
ESA can now add Venus to its range of Solar System studies

Credits: ESA


With this latest success, ESA is adding another celestial body to its range of Solar System studies. ESA also operates Mars Express around Mars, SMART-1 around the Moon and is NASA’s partner on the Cassini orbiter around Saturn. In addition, ESA is also operating the Rosetta probe en route to comet 67P/Churyumov-Gerasimenko. It should reach its target and become the first spacecraft ever to enter orbit around a comet nucleus by 2014. Meanwhile, ESA also plans to complete the survey of our celestial neighbours with the launch of the BepiColombo mission to Mercury in 2013.

“With the arrival of Venus Express, ESA is the only space agency to have science operations under way around four planets: Venus, the Moon, Mars and Saturn” underlines Professor David Southwood, the Director of ESA’s science programmes. “We are really proud to deliver such a capability to the international science community.”

“To better understand our own planet, we need to explore other worlds in particular those with an atmosphere,” said Jean-Jacques Dordain, ESA Director General. “We’ve been on Titan and we already are around Mars. By observing Venus and its complex atmospheric system, we will be able to better understand the mechanisms that steers the evolution of a large planetary atmosphere and the change of climates. In the end, it will help us to get better models of what is actually going on in our own atmosphere, for the benefit of all Earth citizens.”
  
State-of-the-art science package

user posted image
This image is an artistic interpretation of a possible volcano on Venus. In fact, from previous missions to the planet, Venus appears to be among the most geologically active planets in the solar system. Venus Express is able to detect gaseous markers in the lower layers of the atmosphere and variations in its temperature, possible signs of volcanic activity. Local variations in atmospheric temperature and pressure may also indicate the presence of seismic activity.

Credits: ESA - AOES Medialab


Venus Express was developed for ESA by a European industrial team led by EADS Astrium incorporating 25 main contractors from 14 European countries. Its design is derived from that of its highly successful predecessor, Mars Express, and its payload accommodates seven instruments including upgraded versions of three instruments developed for Mars Express and two for Rosetta.

The PFS spectrometer will determine the temperature and composition profile of the atmosphere at very high resolution. It will also monitor the surface temperature and search for hot spots from possible volcanic activity. The UV/infrared SpicaV/SOIR spectrometer and the VeRa radioscience experiment will probe the atmosphere by observing the occultation of distant starts or the fading of radio signals on the planetary limb. SpicaV/SOIR will be particularly looking for traces of water molecules, molecular oxygen and sulphur compounds, which are suspected to exist in the atmosphere of Venus. The Virtis spectrometer will map the different layers of the atmosphere and provide imagery of the cloud systems at multiple wavelengths to characterise the atmospheric dynamics.

user posted image
Venus is a planet with no intrinsic magnetic field and so, differently from Earth, it has no shield to protect it from the continuous attack of the capricious and violent solar wind. ESA's Venus Express will study how much of the atmosphere of the planet escaped under the bombardment of the solar wind and how much it combined with the surface material.

Credits: ESA - C. Carreau

  
On the outer edge of the atmosphere, the Aspera instrument and a magnetometer will investigate the interaction with the solar wind and plasma it generates in an open environment without the protection of a magnetosphere like the one we have around Earth.

The VMC wide-angle multi-channel camera will provide imagery in four wavelengths, including one of the 'infrared windows' which will make imaging of the surface possible through the cloud layer. It will provide global images and will assist in the identification of phenomena detected by the other instruments.


Source: ESA - News

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#5    Bella-Angelique

Bella-Angelique

    Caprica Six Cylon

  • Member
  • 7,174 posts
  • Joined:02 Feb 2006
  • Gender:Female
  • Location:USA

  • There is more to learn

Posted 11 April 2006 - 09:56 AM

I would like to see some Venus dome pictures.

Posted Image

#6    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 11 April 2006 - 10:17 AM

Quote


I would like to see some Venus dome pictures.


The domes seem to be volcanic in origin. This image is a radar image made by the US Magellan probe:

user posted image

Venus Express will concentrate on on the atmosphere of Venus but will also be able to take infrared images of the surface. This will be the first time that the surface of venus has been seen directly.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#7    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 11 April 2006 - 03:50 PM

Venus Express’ initial orbit matches expectations

user posted image
Venus Express flight control team

11 April 2006
At about 13:30 CEST ground controllers at ESA’s European Spacecraft Operations Centre (ESOC) confirmed that the geometry of the initial orbit of Venus Express is matching expectations.

The ground team were able to confirm this by analysing the data that the spacecraft has been sending down to Earth after the first communication link was established at 11:12 CEST today.
ESA’s Cebreros ground station sent the spacecraft High-Gain antenna (HGA 2) receiver a sequence of tones. The time needed for the spacecraft to receive and then mirror these tones back to Earth, together with the precise measurements of the radio signal frequency change, provides point-by-point positioning and velocity of the spacecraft, and hence its trajectory.

The capture orbit is a long ellipse ranging from 350 000 kilometres at its furthest point from the planet (the apocentre) to less than 400 kilometres at its closest (the pericentre, which is almost over the planet’s North pole). The spacecraft will take nine days to travel this orbit, during which a few slots for preliminary scientific observations will be available.

A series of further engine and thrusters burns will then be needed to gradually reduce the apocentre during the following 16 orbital loops around the planet.

The final polar 24-hour orbit will be reached on 7 May 2006, and will range from 66 000 to 250 kilometres above Venus.

A period of commissioning for the spacecraft and its instruments will then precede the official start of Venus Express scientific operations on 4 June this year.


Source: ESA - News

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#8    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 13 April 2006 - 04:20 PM

Unexpected detail in first-ever Venus south pole images

user posted image
Composite, false-colour view of Venus south pole captured by VIRTIS 12 April 2006 onboard Venus Express.

Credits: ESA/INAF-IASF, Rome, Italy, and Observatoire de Paris, France


13 April 2006
ESA's Venus Express has returned the first-ever images of the hothouse planet’s south pole from a distance of 206 452 kilometres, showing surprisingly clear structures and unexpected detail. The images were taken 12 April during the spacecraft’s initial capture orbit after successful arrival on 11 April 2006.

Engineers have lost no time in switching on several of the instruments and yesterday the VMC (Venus Monitoring Camera) and VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) imaged, for the first time in space history, the southern hemisphere of Venus as the spacecraft passed below the planet in an elliptical arc.
Scientists are especially intrigued by the dark vortex shown almost directly over the south pole, a previously suspected but until now unconfirmed structure that corresponds to a similar cloud structure over the north pole. “Just one day after arrival, we are already experiencing the hot, dynamic environment of Venus,” said Dr Hakan Svedhem, Venus Express project scientist. “We will see much more detail at an unprecedented level as we get over 100 times better resolution as we get closer to Venus, and we expect to see these spiral structures evolve very quickly.”

The initial, low-quality images were taken from an extreme distance of 206 452 kms from the planet, yet caught scientists’ attention, particularly with the surprisingly clear structures and unexpected details shown in the VIRTIS spectrometer images.  

The false-colour VIRTIS composite image shows Venus’s day side at left and night side at right, and corresponds to a scale of 50 kms per pixel.

The day half is itself a composite of images taken via wavelength filters and chiefly shows sunlight reflected from the tops of clouds, down to a height of about 65 km above the planet’s surface.


Dynamic spiral cloud structures

The more spectacular night half, shown in reddish false colour, was taken via an IR filter at a wavelength of 1.7 microns, and chiefly shows dynamic spiral cloud structures in the lower atmosphere, around 55 km altitude. The darker regions correspond to thicker cloud cover, while the brighter regions correspond to thinner cloud cover, allowing hot thermal radiation from lower down to be imaged.

user posted image
False-colour view imaged in ultraviolet of Venus south pole captured by VMC 12 April 2006 onboard Venus Express.

Credits: ESA/MPS, Katlenburg-Lindau, Germany


The smaller VMC image shows Venus at a scale of 150 kms per pixel and is also shown in false colour. It was recorded in ultraviolet.
Venus Express fired its main engine to enter Venus orbit on 11 April 2006 and is now in the first 9-day capture orbit taking it to apocentre (maximum height) at 350 000 kilometres below the south pole. It will swing back up to pass pericentre (minimum height) at an altitude of 250 kilometres over the planet’s north pole.


Towards the 24-hour final orbit

In the first capture orbit, Venus Express will have 5 additional opportunities for gathering data until reaching pericentre. These observations represent a great opportunity because, at apocentre, the full disc of Venus is fully visible for the spacecraft’s imagers. Such opportunities will not occur again during the nominal mission, starting on 4 June 2006, when the range of distances from the planet will be much smaller.

user posted image
View imaged in ultraviolet of Venus south pole captured by VMC 12 April 2006 onboard Venus Express.
  
In addition to VMC and VIRTIS, the spacecraft’s MAG (Venus Express Magnetometer) has been switched on for initial verification and is operating nominally. Together with the ASPERA (Analyser of Space Plasma and Energetic Atoms), the two instruments are expected to gather information about the unperturbed solar wind and the atmospheric escape processes on Venus, a planet with no magnetic protection.

A series of further engine and thruster burns are planned to gradually reduce the apocentre during the following 16 orbital loops around the planet and the spacecraft is due to attain its final 24-hour polar orbit on 7 May, ranging from 66 000 to 250 kilometres above Venus.


Source: ESA - News

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#9    Bella-Angelique

Bella-Angelique

    Caprica Six Cylon

  • Member
  • 7,174 posts
  • Joined:02 Feb 2006
  • Gender:Female
  • Location:USA

  • There is more to learn

Posted 14 April 2006 - 12:11 PM

Quote


The domes seem to be volcanic in origin.


Thanks. The domes are the most interesting visual of Venus to me. I am glad the new probe is getting a lot of nice new Venus pics.

Posted Image

#10    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 14 April 2006 - 12:40 PM

Quote


Thanks. The domes are the most interesting visual of Venus to me. I am glad the new probe is getting a lot of nice new Venus pics.


thumbsup.gif Glad to be of service.


"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#11    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 09 May 2006 - 10:42 AM

Venus Express has reached final orbit

user posted image
Venus Express will make unprecedented studies of the largely unkown phenomena taking place in the Venusian atmosphere. Its suit of instruments will also dig into the interaction between the solar wind and the planetary environment. Finally, the mission will gather glimpses about the planet's surface, striclty coupled with the dense atmosphere.

Credits: ESA - AOES Medialab


9 May 2006
Less than one month after insertion into orbit, and after sixteen loops around the planet Venus, ESA’s Venus Express spacecraft has reached its final operational orbit on 7 May 2006.

Already at 21:49 CEST on 6th May, when the spacecraft communicated to Earth through ESA’s ground station at New Norcia (Australia), the Venus Express ground control team at ESA’s European Spacecraft Operations Centre (ESOC) in Darmstadt (Germany) received advanced confirmation that final orbit was to be successfully achieved about 18 hours later.
Launched on 9 November 2005, Venus Express arrived to destination on 11 April 2006, after a five-month interplanetary journey to the inner solar system. The initial orbit – or ‘capture orbit’ – was an ellipse ranging from 330 000 kilometres at its furthest point from Venus surface (apocentre) to less than 400 kilometres at its closest (pericentre).

user posted image
This artist's impression shows the trajectory of ESA's Venus Express to its final destination, planet Venus. In the first week of March 2006, the spacecraft crossed the path of the planet around the Sun. The trajectory took it inside the orbit of Venus to ‘anticipate’ the celestial motion of the planet and finally to catch up with it on 11 April 2006. Once at Venus, the spacecraft will have travelled 400 million kilometres. The injection into orbit will put the spacecraft into a first, elongated orbit lasting about 9 days. On 7 May 2006, after a series of manoeuvres and 16 ever smaller loops around the planet, Venus Express will reach its final operational orbit, lasting 24 hours.

Credits: ESA - C. Carreau


As of the 9-day capture orbit, Venus Express had to perform a series of further manoeuvres to gradually reduce the apocentre and the pericentre altitudes over the planet. This was achieved by means of the spacecraft main engine – which had to be fired twice during this period (on 20 and 23 April 2006) - and through the banks of Venus Express’ thrusters – ignited five times (on 15, 26 and 30 April, 3 and 6 May 2006).

"Firing at apocentre allows the spacecraft to control the altitude of the next pericentre, while firing at the pericentre controls the altitude of the following apocentre," says Andrea Accomazzo, Spacecraft Operations Manager at ESOC. "It is through this series of operations that we reached the final orbit last Sunday, about one orbital revolution after the last ‘pericentre change manoeuvre’ on Saturday 6 May".


Venus Express entered its target orbit at apocentre on 7 May 2006 at 15:31 (CEST), when the spacecraft was at 151 million kilometres from Earth. Now the spacecraft is running on an ellipse substantially closer to the planet than during the initial orbit. The orbit now ranges between 66 000 and 250 kilometres over the Venus and it is polar. The pericentre is located almost above the North pole (80º North latitude), and it takes 24 hours for the spacecraft to travel around the planet.

user posted image
This artist's impression shows Venus Express focussing on studying the peculiar atmosphere of Venus, with a precision never achieved before. In doing so, the mission will make the first ever use of the so called 'infrared windows', which are narrow bands in the atmospheric spectrum, discovered in the 1980s thanks to ground observations. Looking through these 'windows' Venus Express will be able to gather precious information about the lower layers of the atmosphere and even the surface.

Credits: ESA - AOES Medialab


"This is the orbit designed to perform the best possible observations of Venus, given the scientific objectives of the mission. These include global observations of the Venusian atmosphere, of the surface characteristics and of the interaction of the planetary environment with the solar wind," says Håkan Svedhem, Venus Express Project Scientist. "It allows detailed high resolution observations near pericentre and the North Pole, and it lets us study the very little explored region around the South Pole for long durations at a medium scale," he concluded.

Until beginning of June, Venus Express will continue its ‘orbit commissioning phase’, started on 22 April this year. "The spacecraft instruments are now being switched on one by one for detailed checking, which we will continue until mid May. Then we will operate them all together or in groups" said Don McCoy, Venus Express Project Manager. "This allows simultaneous observations of phenomena to be tested, to be ready when Venus Express’ nominal science phase begins on 4 June 2006," he concluded.


Source: ESA - News

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#12    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 27 June 2006 - 03:02 PM

Double vortex at Venus South Pole unveiled!

user posted image
This video is composed by six sequences of images (in false colour) taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express spacecraft between 12 and 19 April 2006, during the first orbit, or ‘capture orbit’, around the planet.
The sequences (taken at 5 microns) were obtained during six different time slots and at different distances from Venus:
  • 12 April: from 210 000 kilometres
  • 13 April: from 280 000 kilometres
  • 14 April: from 315 000 kilometres
  • 16 April: from 315 000 kilometres
  • 17 April: from 270 000 kilometres
  • 19 April: from 190 000 kilometres

The planet’s globe, imaged at different angles, was mapped onto an electronic mock-up of Venus, so to have the South Pole always plotted at the centre of each single image.
Around the South pole it is possible to see a peculiar double-eye vortex structure, never clearly seen by any other Venusian mission before. The movie shows the rotation and the shape variation of the double vortex over time. It is also possible to see the rotation of the ‘terminator’, the line separating the day side – visible in yellow - from the night side.

The images also show the presence of a collar of cold air around the vortex structure (dark blue), possibly due to the recycling of cold air downwards.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA



27 June 2006
ESA’s Venus Express data undoubtedly confirm for the first time the presence of a huge 'double-eye' atmospheric vortex at the planet's south pole. This striking result comes from analysis of the data gathered by the spacecraft during the first orbit around the planet.

On 11 April this year, Venus Express was captured into a first elongated orbit around Venus, which lasted 9 days, and ranged between 350 000 and 400 kilometres from Venus' surface. This orbit represented for the Venus Express scientists a unique opportunity to observe the planet from large distances. This made it possible to obtain first clues about the Venusian atmospheric dynamics on a global scale, before the spacecraft got closer and started observing the planet in greater detail.

user posted image
This composite image shows six infrared views of Venus as seen by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express spacecraft between 12 and 19 April 2006, during the first orbit, or ‘capture orbit’, around the planet.
The images (taken at 5 microns) were obtained at six different time slots and at different distances from Venus (top left: 12 April, from 210 000 kilometres; centre left: 13 April, from 280 000 kilometres; bottom left: 14 April, from 315 000 kilometres; top right: 16 April, from 315 000 kilometres; centre right: 17 April, from 270 000 kilometres; bottom right: 19 April, from 190 000 kilometres), while the spacecraft moved along a long ellipse around the planet. The separate images can be downloaded here [COB_01.TIF, COB_02.TIF, COB_03.TIF, COB_0.TIF, COB_05.TIF, COB_06.TIF].

The infrared radiation coming from Venus was converted in this reddish colour scheme. Thermal radiation comes from the lower atmosphere, (just above the cloud top, located at about 60 kilometres altitude). Solar radiation reflected by the upper atmospheric layers (roughly between 60 and 80 kilometres altitude) and thermal radiation from the layers below contribute to the brightest part of the image.

The south polar vortex structure is visible from different view points close to the centre of the images, mostly in the dark side.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


During this first orbit – called the 'capture orbit' – some of the Venus Express instruments were used to perform the first observations at different distances from Venus, for a few hours per time on six different slots between 12 and 19 April 2006.
Amazing infrared, visible and ultraviolet images of the Venusian globe already reveal several atmospheric features of great interest. The most striking of these is a huge, double-eye atmospheric vortex over the south pole, not dissimilar from the equivalent structure present at the north pole – the only one previously studied in some detail.

user posted image
These two images of Venus’s south pole were taken by NASA’s Mariner 10 (during a Venus fly-by on its way to Mercury) and Pioneer Venus missions during the early 1970s and 1980s, respectively. The images provided the first glimpses about a stormy atmospheric behaviour at the south pole of the planet.

Credits: NASA

  
Only glimpses of the stormy atmospheric behaviour at the south pole were obtained by previous missions (Pioneer Venus and Mariner 10), but such a double-eye structure was never clearly seen before now.
  
High velocity winds are known to spin westwards around the planet, and to take only four days to complete a rotation. This 'super-rotation', combined with the natural recycling of hot air in the atmosphere, would induce the formation of a vortex structure over each pole. But why two vortexes?

user posted image
These six different infrared images (in false colour) were taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express spacecraft between 12 and 19 April 2006, during the first orbit, or ‘capture orbit’, around the planet.
The images (taken at 5 microns) were obtained at six different time slots and different distances from Venus (top left: 12 April, from 210 000 kilometres; top centre: 13 April, from 280 000 kilometres; top right: 14 April, from 315 000 kilometres; bottom left:16 April, from 315 000 kilometres; bottom centre: 17 April, from 270 000 kilometres; bottom right: 19 April, from 190 000 kilometres), while the spacecraft moved along a long ellipse around the planet. The separate images can be downloaded here [ COB_01_geo.TIF, COB_02_geo.TIF, COB_03_geo.TIF, COB_04_geo.TIF, COB_05_geo.TIF, COB_06_geo.TIF].

The planet’s globe, imaged at different angles, was mapped onto an electronic mock-up of Venus, so to have the south pole always plotted at the centre of each single image.

Around the south pole it is possible to see a peculiar double-eye vortex structure, never clearly seen by any other mission to Venus before. The sequence shows the rotation and variation of the double vortex over time. It is also possible to see the rotation of the ‘terminator’, the line separating the day side – visible in yellow - from the night side.

The images also show the presence of a collar of cold air around the vortex structure (dark blue), possibly due to the recycling of cold air downwards.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


"We still know very little about the mechanisms by which the super-rotation and the polar vortexes are linked," said Håkan Svedhem, ESA’s Venus Express Project Scientist. "Also, we are still not able to explain why the global atmospheric circulation of the planet results in a double and not single vortex formation at the poles. However the mission is just at the beginning and it's doing fine; we expect this and many other long-standing mysteries to be addressed and possibly solved by Venus Express," he added. Atmospheric vortexes are very complex structures that are very difficult to model, even on Earth.

Thanks to these first pictures, it has also been possible to observe the presence of a collar of cold air around the vortex structure, possibly due to the recycling of cold air downwards.

user posted image
This visible/ultraviolet image of Venus (380 nanometres) was taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express spacecraft on 19 April 2006, during the first orbit (capture orbit) around the planet, from a distance of about 190 000 kilometres.
In the day side (blue part) it is possible to see interesting atmospheric stripe-like structures. Spotted for the first time by Mariner 10 in the 1970s, they may be due to the presence of dust and aerosols in the atmosphere, but their true nature is still unexplained.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

  
Views of the southern hemisphere of Venus in visible and ultraviolet light show interesting atmospheric stripe-like structures. Spotted for the first time by Mariner 10 in the 1970s, they may be due to the presence of dust and aerosols in the atmosphere, but their true nature is still unexplained. "Venus Express has the tools to investigate these structures in detail," added Svedhem. "Studies have already begun to dig into the properties of the complex wind fields on Venus, to understand the atmospheric dynamics on local and global scales."

Venus Express also made use for the first time ever from orbit of the so-called 'infrared windows' present in the atmosphere of Venus – if observed at certain wavelengths, it is possible to detect thermal radiation leaking from the deepest atmospheric layers, revealing what lies beneath the dense cloud curtain situated at about 60 kilometres altitude.

user posted image
This sequence of images was taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express spacecraft between 12 and 19 April 2006, during the first orbit (capture orbit) around the planet.
The images were obtained at six different time slots and different distances from the planet (top left: 12 April, from 210 000 kilometres; top centre: 13 April, from 280 000 kilometres; top right: 14 April, from 315 000 kilometres; bottom left:16 April, from 315 000 kilometres; bottom centre: 17 April, from 270 000 kilometres; bottom right: 19 April, from 190 000 kilometres), while the spacecraft moved along a long ellipse around Venus. The separate images can be downloaded here [ VOI_1_12_04_2006_b, VOI_2_13_04_2006_b, VOI_3_14_04_2006_b, VOI_4_16_04_2006_b, VOI_5_17_04_2006_b, VOI_6_19_04_2006].

Each image is the composite of the day side of Venus (left, in blue, taken in visible light at 380 nanometres) and the night side (right, in a red colour scheme, taken in infrared light at 1.7 microns).

The visible part shows solar radiation reflected by the atmosphere. The infrared part shows complex cloud structures, revealed by the thermal radiation coming up from different atmospheric depths. Venus Express can resolve these structures by use (for the first time from orbit) of the so so-called ‘infrared windows’ present in the atmosphere of Venus. In fact, if observed at certain wavelengths, it is possible to detect thermal radiation leaking from the deepest atmospheric layers, revealing what lies beneath the dense cloud curtain situated at about 60 kilometres altitude.

In the colour scheme of the presented infrared images, the brighter the colour, the more radiation comes up from the lower layers.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


The first infrared images making use of the ‘windows’ show complex cloud structures, all revealed by the thermal radiation coming up from different atmospheric depths. In the colour scheme shown in the image at right, the brighter the colour (that is, the more radiation comes up from the lower layers), the less cloudy is the observed area.

During capture orbit, preliminary data about the chemical composition of the atmosphere were also retrieved. Venus’ atmosphere is mainly composed of carbon dioxide (CO2). The incoming solar radiation dissociates this molecule into carbon monoxide (CO) and oxygen in the upper atmospheric layers. In fact, Venus Express has already spotted the presence of an oxygen (O2) airglow high in the atmosphere. However, Venus Express has revealed the presence of carbon monoxide as low as the cloud-layer top.

Scientists will continue the data analysis and retrieval to understand the phenomenon, which is very important to clarify the complex chemical processes and cycles at work in the atmosphere of Venus under the influence of solar radiation.

user posted image
This false colour image of planet Venus was taken by the Venus Monitoring Camera (VMC) on board ESA’s Venus Express spacecraft on 19 April 2006, during the first orbit, or ‘capture orbit’, around the planet.
From a distance of about 190 000 kilometres, it was already possible to see the complex atmosphere that surrounds the planet.

Credits: ESA/MPS, Katlenburg-Lindau, Germany

  
Since 7 May 2006 Venus Express has been circling the planet in its final 24-hour orbit, ranging between 66 000 and 250 kilometres from Venus - therefore at much closer distances with respect to the capture orbit. Venus Express scientists are now analysing the new data coming in, which already show what seems to be exciting new features. “We have never seen Venus in such great detail so far. We are eagerly waiting for these new data to be available,” concluded Svedhem.


Source: ESA - Venus Express

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#13    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 12 July 2006 - 10:17 PM

Flying over the cloudy world – science updates from Venus Express

user posted image
This false-colour movie was built with ultraviolet images taken by the Venus Monitoring Camera (VMC) on board ESA’s Venus Express spacecraft on 22 May 2006. The spacecraft was flying over the northern hemisphere approaching the planet, over distances ranging between about 39 100 and 22 600 kilometres from the surface.
The images were taken at 365 nanometres, starting respectively 03:30 and 01:45 hours before reaching the pericentre (point of closest approach of the spacecraft to Venus). The complex atmosphere that surrounds the planet is clearly visible.

The true-colour (grey-scale) version of this movie can be downloaded here.

Credits: ESA/MPS, Katlenburg-Lindau, Germany



12 July 2006
On 20 April 2006, after its first 9-day, elongated orbit around Venus, ESA’s Venus Express started to get closer to the planet, until it reached its final 24-hour long orbit on 7 May. During this time, and up to today, the spacecraft has been working relentlessly: the new data coming in are already providing first glimpses on planetary features never seen before.

If taking the first ever clear images of the double-eye vortex at Venus’ south pole - imaged by Venus Express during its very first orbit - was already a first in the history of planetary exploration and a very pleasant surprise for the scientists, nobody could expect that the vortex had a structure even more complicated than possibly foreseen.
Infrared images taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board the spacecraft not only provided the first clear view of the vortex, but also gave a much closer insight into it when Venus Express flew over the south pole at the end of May this year.

user posted image
This triple image provides a close-up view of the double-eyed vortex at Venus south pole, as seen by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express. The images were taken on 29 May 2006, from a distance of about 64 000 kilometres from the planet. All the separate images can be downloaded here:
- South polar_vortex close up_1_b.gif
- South polar_vortex close up_1_b.tif
- South polar_vortex close up_3_b.tif
- South polar_vortex close up_2_b.tif

The vortex is imaged at different infrared wavelengths, corresponding to different atmospheric depths. The left image (taken at 5.05 microns) correspond to an atmospheric altitude of about 59 kilometres, just about the Venusian cloud deck. The central image (taken at 4.65 microns) corresponds to an atmospheric altitude of about 60 kilometres. The right image (taken at 4.08 microns) corresponds to an altitude of about 65 kilometres, just in the upper clouds. The images were taken with a 20º inclination with respect to vertical pointing.

The brighter the colour, the more radiation is reaching out from the hot layers below. The brightest spot correspond to the centre of the vortex, where radiation from the deeper layers become clearly visible , like looking through a hole.

The dark circular structures surrounding the brighter area belong to the big vortex structure (bottom of the images) - as large as a big portion of Europe (2500 kilometres across) - and are part of the planet atmospheric super-rotation. The left image also clearly shows a complex structure, where many more small structures are visible.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


VIRTIS is an instrument that can operate at different wavelengths. Each infrared wavelength provides a view of the Venusian atmosphere at a different altitude, like a 'cross-section'. "When we looked at this gigantic vortex at different depths, we realised how much its shape is varying over altitude," said Pierre Drossart, VIRTIS co-Principal Investigator, from the Observatoire de Paris, France. "It is like if we were looking at different structures, rather than a single one. And the new data we have just started gathering and analysing reveal even stronger differences".

user posted image
This movie, built with infrared images taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express, provides a close-up view of the double-eyed vortex at Venus south pole. The images (ranging from 4.5 to 5.1 microns) were taken on 29 May 2006, from a distance of about 64 000 kilometres from the planet.
Thanks to the use of different wavelengths, VIRTIS probed the atmosphere at different depths, ranging from 70 kilometres to about 60 kilometres altitude. It is interesting to see how the images contrast and the details increase while approaching the 60 kilometres altitude.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


The reason why the morphology of the vortex varies so extensively along a 'vertical' line is still unexplained. "This is why we are organizing a campaign to observe the south polar vortex, fully dedicated to solve this unexpected puzzle," said Giuseppe Piccioni, VIRTIS co-Principal Investigator. "First we want to understand how the structure is organized - actually, with VIRTIS we are building a true 3D view of the vortex. Then we hope to be able to better understand what are the driving forces that shape it".

Tracking clouds and winds

While Venus Express was flying over the planet, many other details from the thick atmosphere have also started to emerge. Both the Venus Monitoring Camera (VMC) and the VIRTIS instruments started to monitor the cloud system and to track its complex dynamics, while the SpicaV/SOIR spectrometers started retrieving information on the atmospheric chemistry and temperature.

Ultraviolet images from the VMC camera show the complex morphology of the cloud deck, characterised by very thin, low-contrast stripe-features, possibly due to the presence of strong winds that produce elongated structures. Set of periodic 'wave' patterns in the clouds, possibly due to the local variation of temperature and pressure, or to a kind of tidal forces in action at Venus, can also be seen.

user posted image
This mosaic is composed of ultraviolet images taken by the Venus Monitoring Camera (VMC) on board ESA’s Venus Express spacecraft on 24 April 2006, when the spacecraft was flying over the northern hemisphere, at distances ranging between 7505 and 1570 kilometres over the surface.
The original images (taken at a wavelength of 365 nanometres) were projected on geographical coordinates. While flying over the cloud deck at high speed (from left to right), Venus Express got closer to the deck itself and obtained ever more detailed images (see right-hand side).

The sequence allows a first qualitative analysis of the cloud structures. Low-contrast stripe-features are visible, possibly due to the presence of strong winds that produce elongated structures. Set of periodic ‘wave’ patterns in the clouds, possibly due to the local variation of temperature and pressure, or to a kind of tidal forces in action at Venus, can also be seen.

The mysterious ‘UV absorbers’, ultraviolet markings on the cloud top, are visible as darker features in this mosaic. They are so called because they absorb almost half of the solar energy received by the planet. The mysterious substance that causes this absorption still represents a true puzzle for the scientists.

Differently from Earth and other planets, Venus absorbs only the ultraviolet radiation coming from the sun, while it scatters most of the rest of the solar radiation. This is the reason why Venus appears so bright in the sky (high ‘albedo’).

Credits: ESA/MPS, Katlenburg-Lindau, Germany


One of the most important confirmations from the first set of data being analysed by the scientists is the detection of the so called 'UV absorbers'- ultraviolet markings on the cloud top, also visible as darker features in the VMC mosaic image. They are so called because they absorb almost half of the solar energy received by the planet. The mysterious substance that causes this absorption still represents a true puzzle for the scientists.

"Understanding what is the origin of these ultraviolet markings and what makes their absorbing power so high is one of the major objectives of Venus Express," said Wojciech J. Markiewicz, VMC Principal Investigator, from the Max Planck Institute for Solar System Research in Lindau, Germany. "We now have confirmation that we can actually see them, so we can start working to understand what their source is. Because of their amazing absorbing power, they are very important to understand the overall radiative and thermal balance of the planet, and also the atmospheric dynamics".

user posted image
This spectacular night image is an infrared view taken at 1.7 microns, as seen by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express on 12 April 2006, during the first orbit around the planet (capture orbit).
The image, covering an area situated between 20º and 90 º south, show clouds being clearly pushed by winds. Using a set of images of the same area acquired at different times, it is possible to make a direct measurement of the wind speed.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


Tracking cloud motion and starting to characterise the wind speed is an exercise that the Venus Express scientists have already started. A spectacular night view of the mid to low atmospheric layers over low latitudes (between 20º and 90 º south) by VIRTIS, show clouds being clearly pushed by winds.

"We can now make a first qualitative assessment of the wind fields and circulation, which is comfortably matching with previous measurement from the Galileo mission over the north pole," continued Giuseppe Piccioni. "We are now collecting more data from different atmospheric depths, to be able to provide the first precise numbers, possibly in the near future".

user posted image
These infrared images were taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express on 25 April 2006, while the spacecraft was flying over low planetary latitudes (between 15º and 60º south).
The two images on the left panel (taken at 2.3 and 1.7 microns, respectively) show a fine atmospheric structure below the Venusian cloud deck, at about 35 and 20 kilometres altitude, respectively.

The right panel is the result of the projection on geographical coordinates of the second image of the left panel. The images at the top where taken from a distance of about 6000 kilometres from the surface, allowing VIRTIS to generate the high resolution details visible at the top of the panel. While Venus Express continued flying over the planet it got farer from the surface – up to 20 000 kilometres distance – allowing VIRTIS to obtain a wider view, but in lower resolution.

Stripe-like features are visible at the bottom of all images. They could be indicative of a wave-like atmospheric motion (due to tidal forces?), but their nature is still unexplained. The separate images can be downloaded here: [Cloud_tracking_infrared_b_H.tif, Cloud_tracking_infrared_c_H.tif, Wind_tracking_b_H.tif]

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


"We are also collecting the first information on the minor chemical components of the atmosphere, such as carbon monoxide," added Pierre Drossart. "With VIRTIS we can see in the atmosphere of the southern hemisphere deeper than any other previous mission, and we started gathering data on the yet unknown chemistry of the lower atmospheric layers, to build a global picture. Studying the variation of minor chemical compounds over different latitudes and depths is also a very useful tracer for the atmospheric global motion."

Surprise at the atmospheric 'top'

user posted image
This ultraviolet image of the Venus southern hemisphere was taken by the Venus Monitoring Camera (VMC) on board ESA’s Venus Express spacecraft on 15 May 2006, when the spacecraft was flying at about 66500 kilometres distance from the planet.
In this image (taken at 365 nanometres) the South Pole is near the terminator, just above the centre of the image. The complex atmosphere that surrounds the planet is clearly visible. Near the pole we see spiralling clouds surrounding the polar vortex, away from the pole we see cloud features of the upper cloud deck at approximately 70 kilometres altitude.

Credits: ESA/MPS, Katlenburg-Lindau, Germany


When looking at the higher atmospheric layers with Venus Express, the scientists were taken once more by surprise. It is in fact know that the Venusian cloud deck is about 20 kilometres thick and it extends up to about 65 kilometres altitude over the planet. The first 'stellar occultation' measurements ever done at the Venus thanks to the SpicaV spectrometer, revealed that on the night side the cloud deck actually extends up to 90 kilometres altitude in the form of a fully opaque haze, and then continues as a more transparent haze up to 105 kilometres.

Stellar occultation is a technique that allows to determine the composition of a planet's atmosphere by looking at the 'sunset' of a pointed star through the atmosphere itself. "On Earth the atmosphere becomes perfectly clear already above 20 kilometres altitude," said Jean-Loup Bertaux, SpicaV/SOIR Principal Investigator, from the Service d'Aéronomie of CNRS, France.

"We were truly amazed to see how unexpectedly higher the haze at Venus can get. Actually, on Earth as well as on Venus, at around 20 kilometres it is sometimes possible to see droplets of sulphuric acid. On Earth they come from volcanic eruptions. It makes us wonder if on Venus, where differently from Earth the droplets form very thick clouds, their origin is volcanic too."

The haze phenomenon may be due to water condensation in ice crystals on the night side, but it is too early to rule out other explanations. "Now we need to gather and study more data to understand this phenomenon in the high atmosphere - an area that, before SpicaV, was still virtually unexplored," he concluded.

Bertaux also expressed his satisfaction for the atmospheric detection of 'heavy water' - a molecule similar to water but with higher mass – thanks to the SOIR spectrometer. "The detection of heavy water in the atmosphere of a planet, and its percentage with respect to normal water, is very important to understand how much water was present on the planet in the past, and how much of it escaped," added Bertaux.

"The amount of water vapour present today in the atmosphere of Venus would be enough to cover the planet with a 3-centimetre deep liquid layer. If we find out that heavy water – a trace of the original water – is massively present in the top atmospheric layers where it can more easily escape, than the amount of water in the past may have well corresponded to a layer up to a few hundred metres deep," Bertaux concluded.

user posted image
These two plots where built with data retrieved from ASPERA, the Analyzer of Space Plasma and Energetic Atoms on board ESA’s Venus Express, on 30 May 2006, when the spacecraft was flying through different domains of the interaction region between Venus and the solar wind.
The X axis of the plots provides the different position at which the ions (charged atoms) hit the ASPERA detectors. The Y axis provides the energy of the detected ions. The white lines correspond to different ion masses.

The left plot shows the heated solar wind (protons and ‘alfa-particles’) which just passed the Venus bow shock (the region in space separating the unperturbed solar wind from the area where the solar wind interacts with the planetary environment). The right plot shows massive escape of the planetary oxygen ions detected inside the solar wind void which results from the interaction with Venus.

Credits: ESA/ASPERA/Swedish Institute of Space Physics (Kiruna)


Studying the atmospheric escape process at Venus is actually one of the major objective of another Venus Express instrument – ASPERA (Analyzer of Space Plasma and Energetic Atoms). The instrument already detected the massive escape of oxygen and tracked trajectories of other planetary ions such as singly-charged helium.

"This early detection confirms the strong interaction between the solar environment and the atmosphere of Venus - a planet without a planetary magnetic field to protect it from the incoming solar wind," said Stanislav Barabash, ASPERA Principal Investigator, from the Swedish Institute of Space Physics in Kiruna, Sweden. "The study of this interaction will provide important clues on the complex set of mechanisms by which atmospheric gases get lost in space, and on the influence that this may have had on Venus’ climate over geological time scales", he concluded.

The status of the spacecraft

user posted image
During the course of its mission, Venus Express communicates with Earth by means of its two high gain antennas, located on two different sides of the spacecraft. Routinely, Venus Express will downlink scientific data for about eight hours once a day, when the spacecraft is around its furthest point from the planet (apocentre) along its 24-hour orbit.

Credits: ESA - AOES Medialab


On 4 July 2006 Venus Express passed an important exam. An ESA board declared the conclusion of the spacecraft in-orbit commissioning phase and declared that the spacecraft has met the requisites to officially enter the operational phase of its scientific mission.

The Venus commissioning phase, started on 7 May when Venus Express reached its final 24-hour orbit around the planet, and concluded on 4 June this year, is a series of operations aimed at validating the performance of the spacecraft and its systems in the Venus environment, of the scientific instruments, and of all ground systems and operations.

The spacecraft and instruments are showing an overall good performance. However, one of the instruments on board - the Planetary Fourier Spectrometer (PFS) – showed a malfunctioning, that could not be fixed yet in the series of attempts performed so far in space. The PFS scanner - the mirror needed by the instrument for pointing - is currently blocked in a close position, preventing the instrument spectrometer from 'seeing' its targets.

The commissioning review board endorsed a series of activities and further in-orbit tests to be conducted in the next months, as well as a series of independent investigations to examine the origin of the problem. In the meantime, other instruments will cover some of the PFS objectives.

PFS is designed to measure the chemical composition and temperature of the atmosphere of Venus. It is also able to measure surface temperature, and so search for signs of volcanic activity.


Source: ESA - Venus Express

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#14    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 13 October 2006 - 01:54 PM

Complex meteorology at Venus

user posted image
The false-colour view is the composite of three infrared images acquired by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA's Venus Express on 22 July 2006, at a time interval of about 30 minutes from each other and from a distance of about 65 000 kilometres over the planet's surface. Venus was in the night side.
The image, taken at a wavelength of 1.7-micrometre, shows the thermal radiation emitted from about 15-20 kilometres altitude. The brighter the colour (towards white), the more radiation comes from the surface, so the less cloudy the region in the line of sight between the view and the spacecraft is.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


13 October 2006
On 20 April 2006, after its first 9-day, elongated orbit around Venus, ESA’s Venus Express In its relentless probing of Venus's atmosphere, ESA's Venus Express keeps revealing new details of the Venusian cloud system. Meteorology at Venus is a complex matter, scientists say.

New night-side infrared images gathered by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) in July 2006, clearly show new details of a complex cloud system.
The first (false colour) view - the composite of three infrared images acquired by VIRTIS, was taken on 22 July when the spacecraft was flying around the apocentre of its orbit (point of maximum distance from the planet surface) at about 65 000 kilometres altitude. Venus was in the night side.

Using its capability to observe at 1.7-micrometre wavelenght, VIRTIS could probe at about 15-20 kilometres altitude, below the thick cloud deck situated at about 60 kilometres from the surface. The thermal radiation coming from the oven-hot surface of Venus is represented by the intensity of the colours: the brighter the colour (towards white), the more radiation comes from the surface, so the less cloudy the region in the line of sight between the view and the spacecraft is.

The edge of the images, taken at a time interval of about 30 minutes from each other, do not precisely match. This is due to the fact that clouds on Venus move very rapidly and constantly vary their shape. Venus’s atmosphere is certainly the most dynamic among the terrestrial planets that have one, taking only four days to completely rotate around the planet.

"Clouds at Venus present repetitive patterns and recurrent features, but they are very variable in position both on short and long time scales," said Giuseppe Piccioni who, with Pierre Drossart, is the instrument co-Principal Investigator. "This makes meteorology a very complex matter for this planet."

Since the thermal radiation from the surface of Venus is in practice modulated by the presence of the clouds, taking the negative of the image it is possible to see directly the clouds structure on the night side, and so study its morphology and dynamics.  

user posted image
This picture of the Venusian atmosphere is the 'negative' of a night-side infrared image acquired by the VIRTIS instrument on board ESA's Venus Express on 29 July 2006, from a distance of about 65 000 kilometres from the surface.
At the centre of the image, taken at 2.3-micrometre wavelength, it is possible to see a large cloud extending toward the bottom-right part of the view. The cloud is about 2000 kilometres long and 500 kilometres wide. It presents the peculiar elongated shape of clouds at Venus, which is due to high-speed winds.

The very cloudy region visible at the top-right of the image is situated beyond 60º South latitude, and represents the transition to the region where the atmosphere is dominated by the effects of the powerful South double polar vortex.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


This was done for this other night-side image, acquired by VIRTIS on 29 July around apocentre from a distance of about 65 000 kilometres from the surface.

The 2.3-micrometre wavelength used for this image brought the 'view' again down below the cloud deck. The large cloud visible in the centre of the image and extending toward the bottom-right part is about 2000 kilometres long and 500 kilometres wide.

This cloud presents the familiar and peculiar shape of clouds at Venus. They are usually elongated due to the very high-speed winds – reaching up the formidable velocity of 360 kilometres per hour and being caused by the 'super-rotation' of the atmosphere.

The very cloudy region visible at the top-right of the image is situated beyond 60º South latitude, and represents the transition to the region where the atmosphere is dominated by the effects of the powerful South double polar vortex.


Source: ESA - Venus Express

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button

#15    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 34,219 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 09 November 2006 - 02:04 PM

Happy birthday, Venus Express!

IPB Image
This night-side, false-colour image was taken by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express on 23 September 2006, when the spacecraft was flying at about 60 000 kilometres over the planet around the point of furthest distance from the surface (apocentre). It was taken at 1.7-micrometre wavelength, and shows an area close to the South pole (out of the field of view beyond the top left of the image).

The bright big spot on the left of the image corresponds to an area where the cloud deck is thinner. Such regions, similar to large holes, allow the thermal radiation from below the clouds layer to increase significantly with respect to the surrounding areas, and make it possible to probe very deep in the atmosphere with a limited attenuation from the clouds.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


9 November 2006
One year after its launch on 9 November 2005 and a few months into its science phase, ESA's Venus Express keeps working well and continues to gather lots of data about the hot and noxious atmosphere of the planet. Newly released images show additional details of the thick cloud deck that surrounds Venus.

It was 11 April 2006 when, after a delicate manoeuvre, Venus Express entered into orbit around Venus, and started a series of gradually smaller loops around the planet to reach its 24-hour science orbit (spanning between 66 000 over the South pole and 250 kilometres over the North pole) on 7 May 2006.  

IPB Image
This artist's impression shows Venus Express focussing on studying the peculiar atmosphere of Venus, with a precision never achieved before. In doing so, the mission will make the first ever use of the so called 'infrared windows', which are narrow bands in the atmospheric spectrum, discovered in the 1980s thanks to ground observations. Looking through these 'windows' Venus Express will be able to gather precious information about the lower layers of the atmosphere and even the surface.

Credits: ESA - AOES Medialab


"From that time onwards this unique spacecraft, equipped with the most advanced instruments ever used for atmospheric investigations at Venus, has started gathering views and information on the thick atmosphere, its cloud system and its dynamics – during experiment tests in the beginning, and on a nominal basis after 4 June 2006," said Håkan Svedhem, Venus Express Project Scientist.

From the very first images of the approaching planet and from the South Pole views obtained on 12 April - the first of this area taken in the infrared in the history of Venus’ exploration - scientists immediately obtained novel glimpses about an extraordinarily complex weather system.

This is ruled by huge and still largely unexplained forces at work in the atmosphere, causing hurricane-force winds and generating the amazing double-eyed vortices over both poles.

IPB Image
This movie, built with infrared images taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express, provides a close-up view of the double-eyed vortex at Venus south pole. The images (ranging from 4.5 to 5.1 microns) were taken on 29 May 2006, from a distance of about 64 000 kilometres from the planet.

Thanks to the use of different wavelengths, VIRTIS probed the atmosphere at different depths, ranging from 70 kilometres to about 60 kilometres altitude. It is interesting to see how the images contrast and the details increase while approaching the 60 kilometres altitude.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


It was indeed this European spacecraft to entirely reveal for the first time the double vortex over the planet's South pole, with its 3D structure so much differentiated over different altitudes and similarly shaped (but mirrored) to that present over the North pole.

Newly released images, obtained in July and September 2006 by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express, show new details of the cloud structure. This thick layer of clouds, located around 60 kilometres altitude over the surface, blocks part of the thermal radiation coming from below.

However, VIRTIS is designed to catch the only radiation that can pass through the lower atmopshere and the cloud deck, making use of the so called 'infrared windows'. Through these 'windows', thermal (infrared) radiation at specific wavelengths can cross the lower atmosphere and escape towards space. By doing so, it carries information about the lower atmospheric layers and the surface that VIRTIS can collect from orbit.

The first, false-colour night-side image (see top of the article), was taken at a 1.7-micrometre wavelength on 23 September 2006, when the spacecraft was flying at about 60 000 kilometres over the planet around the point of furthest distance from the surface (apocentre). It shows an area close to the South pole (out of the field of view beyond the top left of the image).

"The bright big spot on the left of the image corresponds to an area where the cloud deck is thinner," said Giuseppe Piccioni, VIRTIS co-Principal Investigator. "Such regions, similar to large holes, allow the thermal radiation from below the clouds layer to increase significantly with respect to the surrounding areas, and make it possible to probe very deep in the atmosphere with a limited attenuation from the clouds."

The atmospheric layers below the cloud deck, and the fact that they are blocking almost all thermal radiation coming from the surface, are the main responsible for the tremendous green-house effect at work on the planet – the most powerful found in the Solar System. It maintains the surface temperature as high as 450°C!

IPB Image
This night-side image of the southern hemisphere of Venus was taken by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express on 29 July 2006, from a distance of about 64 000 kilometres over the surface (around the orbit apocentre), at a wavelength of 1.7 micrometres. The South pole is visible on the top left of the image.

This image provides a remarkable example of a wave structure, running from the bottom to the top-right, each ‘wave’ extending about 150 kilometres. This peculiar cloud feature is often seen at a latitude of about 55º South.

The picture also shows a part of the polar vortex (top left). Regions of thinner clouds are also present in this image. They are visible as bright spots (top left corner), as they allow more thermal radiation to escape towards deep space from the hotter regions below.

The region between the black stripe around the pole and the wave structure contains the so called ‘cold collar’, a region in which the temperature of the clouds is lower than that of the surrounding area.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA


The second, night-side image of the southern hemisphere was taken by VIRTIS on 29 July 2006 from a distance of about 64 000 kilometres over the surface (around the orbit apocentre) at a wavelength of 1.7 micrometres. The South pole is visible on the top left of the image.

This image provides a remarkable example of a wave structure, running from the bottom to the top-right, each 'wave' extending about 150 kilometres. This peculiar cloud feature is often seen at a latitude of about 55º South.

"Despite the fact that the cloud structure is very variable and dynamic at Venus, recurrent patterns and structures tend to appear in the same locations," said Pierre Drossart, VIRTIS co-Principal Investigator. "They are mostly visible in the infrared, sometimes very easily, some other times less. When they are very faint and hidden, we need to play with the intensity of the images."

The picture also shows a part of the polar vortex (top left). Regions of thinner clouds are present also in this image. They are visible as bright spots (top left corner), as they allow more thermal radiation to escape towards deep space from the hotter regions below.

The region between the black stripe around the pole and the wave structure contains the so called 'cold collar', a region in which the temperature of the clouds is lower than that of the surrounding area. Similar cold-collar structures are present at both poles. The cold collar over the South pole cannot be clearly seen in this image (1.7 micrometre wavelenght), but it was was imaged by VIRTIS at 5 micrometres in April 2006.


In the meantime, VIRTIS and the other instruments on board Venus Express keep observing the mysterious atmosphere of Venus. Well done so far and…happy anniversary, Venus Express!


Source: ESA - Venus Express

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users