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Rosetta warms up for Mars swing-by

Rosetta’s 11-year expedition began in March 2004, with an Ariane-5 launch
from Kourou in French Guiana. The three-tonne spacecraft was first inserted into a
parking orbit around Earth, before being sent on its way towards the outer Solar System.

Mars Fly-by (February 2007): Rosetta flies past Mars at a distance of about 250 kilometres,
obtaining some science observations. An eclipse of the Earth by Mars lasts for about 25
minutes, causing a communications blackout.

Credits: ESA/AOES Medialab

29 November 2006
This month the team working on ESA's Rosetta mission have been particularly busy. Activities are underway to set the spacecraft's trajectory and prepare the on-board instruments ready for the next major mission milestone: the swing-by of planet Mars in February 2007.

Since its launch in March 2004, Rosetta has been bouncing around the inner solar system on a trajectory that will eventually lead it to its final destination in the first half of 2014 – comet 67P Churyumov-Gerasimenko. As the three-tonne spacecraft could not be set by its launcher onto a trajectory that would take it directly to the comet, a series of four planetary gravity-assisted manoeuvres were introduced into the mission design.

Swing-bys allow a spacecraft to gain energy in a 'natural' way by exploiting the gravitational energy of massive planetary bodies such as planets, similar to the way in which a slingshot is used to release a stone.


Earth fly-bys: March 2005, September 2007 and September 2009
To gain speed through a series of gravitational 'kicks', Rosetta flies past the Earth three
times during its journey. The fly-by distance is between 300 and 14 000 km. Manoeuvres
to correct Rosetta's orbit take place before and after each fly-by.

Credits: ESA/AOES Medialab

The Mars swing-by in February next year is the second of these manoeuvres for Rosetta, as the first Earth swing-by took place in March 2005. After next February's Mars swing-by, the next Earth swing-by will take place on 13 November 2007.

To aim Rosetta precisely at Mars, two deep-space manoeuvres were carried out on 29 September and 13 November of this year. Rosetta will make its closest approach to Mars on 25 February when it will be just 250 km above its surface.

Close vicinity to the planet is essential for the spacecraft to make the most efficient use of the swing-by, however, this also makes the manoeuvre complex. This is why mission controllers at ESA's European Space Operations Centre (ESOC) in Germany are carefully monitoring the spacecraft's path in space and preparing to perform trajectory correction manoeuvres 16 and 7 days before Rosetta makes its closest approach to Mars.

Rosetta's close vicinity to Mars will also provide an excellent opportunity to take a close look at the planet. Using the on-board instruments both on the orbiter and the Philae lander, the Rosetta scientists will be able to calibrate their instruments and complement ESA's Mars Express data by carrying out a 'mini' observation campaign in the weeks around the Mars swing-by. Science operations will start at the beginning of January 2007 and be 'formally' concluded at the end of March.


Looking at Mars

In preparation for the Mars' observation, earlier this week mission controllers at ESOC commenced a full series of instrument checks. These operations, which included switching on the instruments and checking their pointing performance, will last about a month.


The Orbiter's scientific payload includes 11 experiments, in addition to the Lander.
Scientific consortia from institutes across Europe and the United States have provided
these state-of-the-art instruments. All of them are located on the side of the spacecraft
that will permanently face the comet during the main scientific phase of the mission.

Credits: ESA/AOES Medialab

Between 2 and 3 January 2007 Rosetta will 'warm-up' its on-board camera OSIRIS to take a look at the asteroid 21-Lutetia that lies between the orbits of Mars and Jupiter in the Asteroid Belt. The purpose of this 36-hour observation campaign is to understand the rotation direction of the asteroid. This valuable information will enable scientists to characterise this target so that Rosetta can study it in greater detail in July 2010, when the spacecraft will pass within about 2000 km of the asteroid.

Rosetta will be able to observe Mars from about 20 hours before it makes its closest approach to about a few weeks after. Before making its close approach to Mars, priority will be given to spacecraft operations. If the in-flight tests planned for 7 January reveal that the spacecraft's illumination and thermal conditions are not favourable for its own navigational security, then all the science operations that are to be carried out before it makes its close approach will have to be cancelled.

In any event, just around the time of closest approach, the orbiter's instruments will be switched off for about three hours, and the spacecraft will be put in eclipse mode. This is to prepare the spacecraft for a period of eclipse that will last for 25 minutes and take place as Rosetta goes behind Mars and enters its shadow. During this eclipse period the solar arrays will not 'see' the Sun and will not be able to produce any power.


Rosetta’s 10 year expedition began in March 2004, with an Ariane-5 launch from
Kourou in French Guiana. The three-tonne spacecraft was first be inserted into a
parking orbit, before being sent on its way towards the outer Solar System.
Once a suitable landing site is chosen, the Lander is released from a height of about 1 km.
Touch-down takes place at walking speed – less than 1 m/s. Once it is anchored to the
nucleus, the Lander sends back high-resolution pictures and other information on the
nature of the comet’s ices and organics in the crust. The data are relayed to the Orbiter,
which stores them for downlinking to Earth during the next ground station contact.

Credits: ESA/AOES Medialab

However, a few scientific instruments on the Philae lander will still be operating and taking measurements during the eclipse as the lander has its own independent power system. This is because once the lander is on the surface of the comet, ready to carry out its mission, it has to survive autonomously without the orbiter's support.

Rosetta will use its imaging system and imaging spectrometers to gather data about the surface and atmosphere of Mars and its chemical composition. It will also collect data about the atmosphere's interaction with the solar wind and the Martian radiation environment, and it will image the two natural satellites of Mars: Phobos and Deimos.

During the Mars swing-by, Rosetta's velocity and trajectory will also be accurately measured to check if any anomalous spacecraft acceleration can be observed.

Source: ESA - News

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Lutetia asteroid in Rosetta’s spotlight

Rosetta images asteroid Lutetia.

Credits: ESA/MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

(Please note: this is a screen capture of an animation. Please click on the image or the
source link for the animation)

26 January 2007
Earlier this month ESA's Rosetta had a first look at asteroid 21-Lutetia, one of the targets of its long mission. The onboard camera OSIRIS imaged the asteroid passing through its field of view during the spacecraft's gradual approach to Mars. The planet will be reached on 25 February 2007 for the mission's next gravity assist.

During its long trek to final destination (comet 67P Churyumov-Gerasimenko), Rosetta is planned to study two asteroids – 2867-Steins and 21-Lutetia, both lying in the asteroid belt between the orbits of Mars and Jupiter. Asteroids, as well as comets, carry important information about the origin of the Solar System – a better understanding of which is one of the primary goals of Rosetta.

The two asteroids will be visited at close range in September 2008 and July 2010, respectively, but the Rosetta scientists have already taken the opportunity to collect preliminary data about them. This opportunity will help scientists to better prepare for the broader observation campaigns of the two asteroids to come at later stage.

Steins was imaged by Rosetta on March 11, while Lutetia was first imaged by Rosetta during a 36-hour observation campaign on 2 and 3 January 2007, when the spacecraft was flying at about 245 million kilometres from the asteroid. OSIRIS, the Optical, Spectroscopic, and Infrared Remote Imaging System mounted onboard the Rosetta orbiter, was switched on for this remote sensing observation.

Lutetia can be seen as the near-stationary spot visible at the centre of the animated sequence presented in this article. The scattered light spots seen in the movie are cosmic rays events, that is high-energy cosmic radiation hitting the detectors of the OSIRIS camera.

Little is known about Lutetia and Steins. Actually, very little is known about asteroids in general. Out of the many millions of asteroids that populate the Solar System, only a few have been observed so far from near-by.

According to what we know so far, Steins and Lutetia have rather different properties. Steins is relatively small, with a diameter of a few kilometres. Lutetia is a much bigger object, about 100 kilometres in diameter.

The Lutetia observation this month were aimed at pre-characterizing the rotation direction of the asteroid. This can be done by the study of the so-called 'light curve' of the asteroid – by analysing how the light emitted by the observed object changes intensity for the observer, one can deduce in what direction the object rotates. Scientists are now busy in analysing the OSIRIS data to build the light curve of Lutetia.


This view of Mars (visible towards the top of the image) and of the Milky Way was
taken by the OSRIS camera on board the Rosetta orbiter on 3 December 2006, during
the last series of instrument check-outs. In this image Mars is heavily overexposed and
therefore surrounded by a halo of scattered light.

OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) will continue to
image Mars during the next major mission phase: the swing-by of planet Mars at the
end of February 2007. Rosetta will use its imaging system and imaging spectrometers
to gather data about the surface and atmosphere of the Red Planet, including its chemical
composition. It will also collect data about the interaction of the atmosphere with the solar
wind and about the Martian radiation environment. It will also image the two natural
satellites of Mars, Phobos and Deimos.

Credits: ESA/MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Having concluded the Lutetia observations, Rosetta is now getting ready for the next mission milestone: the swing-by of planet Mars. At the end of February, the gravitational energy of the Red Planet will be used by the spacecraft to get accelerated and then pushed, like a stone in a sling-shot, on a trajectory towards Earth for the following gravity assist manoeuvre in November 2007.

In the meantime Rosetta continues to provide new emotions as this incredible spacecraft, travelling through the Solar System as a cosmic 'billiard ball', collects data and images of the objects on its way.


Note

Asteroid 2867-Steins will be visited again by Rosetta on 5 September 2008 from a distance of just over 1700 kilometres. This encounter will take place at a relatively low speed of about 9 kilometres per second during Rosetta's first excursion into the asteroid belt. On 10 July 2010 Rosetta will pay its second visit to asteroid 21-Lutetia, passing within about 3000 kilometres of it, at a speed of about 15 kilometres per second.

Rosetta will gather unprecedented data as it flies by these primordial rocks. Its onboard instruments will provide information on the mass and density of the asteroids, thus telling us more about their composition, and will also measure their subsurface temperature and look for gas and dust around them.

Source: ESA - News

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Rosetta correctly lined up for critical Mars swingby

15 February 2007
ESA mission controllers have confirmed Rosetta is on track for a critical 250-km Mars swingby on 25 February. Engineers have started final preparations for the delicate operation, which includes an eclipse, a signal blackout, precise navigation and complex ground tracking.

Rosetta is scheduled to make its closest approach to Mars at 02:57 CET on Sunday, 25 February, using the Red Planet as a gravitational brake to reduce speed and alter trajectory as part of the spacecraft's complex, 10-year, 7.1-thousand-million-kilometre journey to comet 67P/Churyumov-Gerasimenko.

"Last Friday's engine firing went well. On Tuesday, we confirmed the spacecraft is on nominal track for the swingby. There is currently no need for additional engine burns, so the next manoeuvre slot, planned for the weekend, has been cancelled," said Paolo Ferri, Rosetta Flight Director, speaking at ESOC, ESA's Space Operations Centre in Darmstadt, Germany.

Communications blackout, eclipse as Rosetta passes behind Mars


Artist's impression of Rosetta at Mars

Credits: ESA - C.Carreau

Later today, the Flight Control Team is scheduled to begin charging Rosetta's batteries for the planned 25-minute eclipse during the swingby. During the eclipse, Rosetta's solar panels will be shadowed from sunlight by Mars, and all but essential systems will be turned off or placed into low-power modes.

Rosetta's original trajectory and engineering design did not include an eclipse, but unavoidable launch delays forced the trajectory to be replanned. Mission controllers working on Rosetta have spent months carefully planning and testing a low-power configuration which will allow the spacecraft to safely operate on batteries.

Further, ground controllers expect to lose contact with Rosetta for a tense 15-minute occultation, or blackout, starting at 03:14 CET on 25 February, as Rosetta passes behind Mars with respect to ground stations on Earth.

At closest approach, Rosetta will skim by Mars in a spectacular passage, a mere 250 km above the Red Planet. At this time, ESA's Mars Express will be some 11 042 kms away from Rosetta, while NASA's Mars Reconnaissance Orbiter will be about 7172 kms distant.

ESA-NASA cooperation for deep-space tracking

The intensive swing-by activities at ESOC have included a comprehensive tracking campaign to carefully plot Rosetta's position and trajectory.

Ranging and Doppler measurements from DSA 1, ESA's deep-space tracking station at New Norcia, Australia, have been augmented by data from NASA's DSN deep-space network. Both networks are using Delta DOR (Delta Differential One-Way Ranging) technology to precisely locate and track the spacecraft.

Delta DOR uses two widely separated ground antennas to simultaneously track a spacecraft and measure the time difference between signals arriving at the two stations. ESA first used the sophisticated technique to track Venus Express in 2006.

Source: ESA - Rosetta

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Timeline: Mars swingby at 36 000 km per hour

23 February 2007
The timeline for Rosetta's speedy swingby of Mars on 25 February includes a series of slew manoeuvres, an occultation and signal blackout, an eclipse and some excellent opportunities for scientific observations.

Rosetta's Mars swingby kicks off today with a series of complex slew manoeuvres to enable instrument calibration. The spacecraft has been correctly lined up on the proper trajectory since a series of engine firings in the past several weeks.

Rosetta is expected to pass the Red Planet at 250 km altitude and 36 191 km/hour with respect to Mars at closest approach. The swingby should reduce Rosetta's velocity with respect to the Sun by 7887 km/hour, and the spacecraft should depart Mars travelling at 78 779 km/hour relative to the Sun.


Timeline of major activities

Note: Times shown are ground event times in Central European Time, equivalent to UTC (Coordinated Universal Time) + 1 hour. Spacecraft event time is 17 mins 33 secs earlier.


23 February

17:32 First of a series of slew manoeuvres to perform instrument calibrations
19:30 Flight Control Team in ESOC's Main Control Room (MCR) around the clock

24 February

~14:00 Webcam in MCR switched on (access via ESA portal)
18:35 Additional slew manoeuvres to perform Mars observations with onboard instruments
22:30 End of observations until after Mars swingby


In this artist's representation, Rosetta's track past Mars on 25 February 2007 is shown
as viewed from Earth. The track is based on actual estimated flight dynamics data. Closest
approach - 250 km altitude - is expected at 01:57:59.0 UTC, 25 February, +/- 1.3 seconds.

The pre- and post-Mars swingby velocities relative to the Sun are the sums (added
vectorially) of Mars velocity relative to the Sun (91 454 km/hr) and Rosetta's velocity
relative to Mars. This gives a pre-Mars swingby velocity of 86 666 km/hr relative to the
Sun and a post-Mars swingby velocity of 78 779 km/hr relative to the Sun. The swingby
should therefore reduce Rosetta's velocity relative to the Sun by 7887 km/hr.

Credits: ESA

25 February



ESA/NASA interagency cooperation supports Rosetta


ESA's first 35-metre deep-space ground station is situated at New Norcia, 140 kilometres
north of Perth in Australia. The 630 tonne antenna will be used to track Rosetta and
Mars Express, the latter to be launched in 2003, as well as other missions in deep space.
The ground station was officially opened on 5 March 2003 by the Premier of Western
Australia, Hon Dr Geoff Gallop.

Credits: ESA

Increased ground tracking support has been scheduled throughout the swingby period.

In addition to ESA's 35m deep-space station at New Norcia, NASA's Deep Space Network (DSN) stations at Goldstone, Canberra and Madrid will participate.

The two agencies often work together and regularly share tracking station resources.



Source: ESA - Rosetta

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Spectacular view approaching Mars

Rosetta swingby update - 22:00 CET

Mars as seen by Rosetta's navigation camera (NAVCAM) during
approach 24 February 2007. The image was taken at 19:32 CET from
a distance of 237 477 km.

Credits: ESA

24 February 2007
Earlier today, on its approach to Mars, Rosetta's navigation camera (NAVCAM) captured a spectacular image of the Red Planet, just a few hours before the spacecraft's second planetary swingby on its incredible 10-year journey to comet 67P/Churyumov-Gerasimenko.

Rosetta's NAVCAM captured the black & white image of Mars at 19:32 CET from a distance of 237 477 km.

The navigation camera, together with other orbiter instruments including the OSIRIS camera, the VIRTIS imaging spectrometer and the RPC instrument, started collecting pre-close-approach data around 19:20 CET.


This observation slot began at the end of a specially dedicated ‘slew’ manoeuvre (see animations), which started at 18:35 CET and that changed the orientation of the spacecraft in order to allow these observations.

Spectacular view of Mars

In the upper left of the black & white image, it is possible to identify the Elysium Mons region centred at approximately 147° East. Mars' equator runs horizontally approximately across the middle of the image.

Just northeast of the 'double finger' feature, visible in the lower half of the disk, is Aeolis Mensae mountain, located at 140° East.

The small double feature visible in the upper-right quadrant is the Cerberus Fossae ridge.

Rosetta switches to 'eclipse mode'

At 23:30 CET, the pre-approach observations of Mars will stop and the spacecraft will be put into 'eclipse mode' until 03:50 CET.

This configuration is needed to avoid having Rosetta enter 'safe mode' due to lack of solar power while swinging behind Mars.

The occurrence of a safe mode would require several hours to reconfigure normal operations and would cause the mission to miss the opportunity to make observations of Mars and its satellite Phobos from up close, just after closest approach.

During the ‘eclipse’ phase, however, the Philae Lander instruments will be activated and will collect data, as they can rely on their own batteries.

Source: ESA - News

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Rosetta swingby update - 03:13 CET

25 February 2007
At 03:13 CET today, Rosetta disappeared as planned behind planet Mars in the course of its critical planetary swingby manoeuvre, and, as anticipated, communication with the spacecraft was lost.

During this communication blackout, or occultation, planned to last until 03:28 CET, the spacecraft will have achieved closest approach with the Red Planet, at an estimated distance of some 250 kilometres from the surface.

The actual distance from the planet will only be confirmed tomorrow morning, when ground station ranging and distance data are processed and the exact spacecraft trajectory reconstructed.


Between 03:15 and 03:40 CET, Rosetta will be in actual eclipse – its solar arrays will not be illuminated by the Sun. During this phase, the spacecraft will have to live on the power generated by its on-board batteries, until the Sun rises over Mars' horizon and sunlight again hits the solar arrays.


Mission controllers at ESA's European Space Operations Centre (ESOC, Germany) will be able to definitively confirm the actual result of the swingby manoeuvre when the first house-keeping data is received on the ground, expected to happen at 03:58 CET.

Source: ESA - News

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Rosetta comet-chaser takes a close look at planet Mars

25 February 2007
ESA PR 07-2007. There was considerable relief today at ESA's Space Operations Centre (ESOC) in Darmstadt, Germany. In the early hours, spacecraft controllers, flight dynamics experts, engineers and scientists were able to see a spacecraft playing 'cosmic billiards'.

Between 03:13 and 03:40 CET, ESA's comet chaser, Rosetta, swung-by Mars at a distance of only 250 kilometres, changed direction and then sped away from the Red Planet on a brand new path, continuing on a journey that will ultimately take it beyond Jupiter's orbit.

Its final destination is comet Churyumov-Gerasimenko, which it will reach only in 2014, after travelling some 6000 million kilometres in 10 years (its epic voyage began on 2 March 2004 with a launch by an Ariane 5 rocket). Rosetta will next be heading for the Sun, and its journey will require two more swing-bys around the Earth, in November this year and November 2009.

Once at its destination, Rosetta will first deposit, from a height of about one kilometre, a small but very complex lander on the comet’s nucleus. This lander, a sort of miniature chemical laboratory packed with sophisticated instruments, will analyse the surface and provide information on the nucleus. The Rosetta probe will then chase the comet for one year and observe its nucleus as it continues on its trip towards the inner Solar System at a speed of 135,000 km per hour.

There is still a long way to go, but so far everything seems to be going exactly according to plan. ESA's Director of Science, David Southwood, witnessing the Mars swing-by at ESOC with scientists involved in the mission and the operations teams, said: "Interplanetary expeditions rely on very complex communication links. ESA’s mission operations centre here in Darmstadt is doing a great job. I and all the scientists involved in the mission are grateful to the experts who are taking such good care of 'our baby'. And this is only the beginning. The true excitement of targeting and releasing the lander on the comet’s nucleus is yet to come. Today we have reached another milestone on the way to finding an answer to questions such as whether life on Earth began with the help of comets."

During the approach to Mars, instruments onboard Rosetta - as well as on its lander - were switched on at predefined times to observe the environment and take imagery of the Red Planet. In September 2008 and July 2010, when it is deep inside the asteroid belt between Mars and Jupiter, Rosetta will also observe the asteroids Stein and Lutetia close up.

Source: ESA - News

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Rosetta successfully swings-by Mars – next target: Earth

Two-colour composite of Mars seen by the OSIRIS narrow-angle camera on 24 February
at 19:28 CET from a distance of about 240 000 km. Image resolution is about 5 km.
The greenish regions are clouds above the red surface of Mars.

Credits: ESA © 2007 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

25 February 2007
At 03:57 CET today, mission controllers at ESOC, ESA's Space Operations Centre in Germany, confirmed Rosetta's successful swingby of Mars, a key milestone in the 7.1-thousand-million km journey of this unique spacecraft to its target comet in 2014.

The gravitational energy of Mars helped Rosetta change direction, while the spacecraft was decelerated with respect to the Sun by an estimated 7887 km/hour. The spacecraft is now on the correct track towards Earth - its next destination planet whose gravitational energy Rosetta will exploit in November this year to gain acceleration and continue on its trek.

Presented in this article is one two-colour composite image of Mars collected by Rosetta's Optical, Spectroscopic and Imaging system (OSIRIS) instrument before closest approach to the planet, and before the orbiter instruments where switched off for the spacecraft's Mars eclipse period.

The OSIRIS narrow-angle camera took this image at 19:28 CET, 24 February. It shows Mars from a distance of 240 000 kms and at a resolution of about 5 kms per pixel. The greenish regions are clouds above the Red Planet's surface.

Source: ESA - News

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Rosetta lander measures Mars' magnetic environment around close approach

Rosetta represented during closest approach to Mars.

Credits: ESA - C. Carreau

25 February 2007
In addition to acquiring incredible images of Mars during the planetary swingby earlier today, Rosetta and its lander Philae continue returning data from the Red Planet. The ROMAP instrument on board Philae measured the intensity of the peculiar magnetic field of Mars around closest approach.

Philae's ROMAP (Rosetta Lander Magnetometer and Plasma Monitor) instrument aims ultimately to study the local magnetic field of Comet 67P/Churyumov-Gerasimenko and examine the intensity of the magnetic interaction between the comet and the solar wind in three spatial dimensions ('3D').

The cometary magnetic environment is similar to that of Mars. Mars doesn't have a global planetary magnetic field protecting it from the solar wind. Its complex and 'disturbed' magnetic environment is – in very simplified terms - the result of the combination of the weak magnetosphere surrounding the planet, under continuous attack from the solar wind, with the local magnetic spots (anomalies) that characterise the planet's crust.


This graph, drawn thanks to data collected by the ROMAP
instrument on board Rosetta's Philae lander, shows how the magnetic environment of
Mars becomes complex when the solar wind, initially proceeding unperturbed at
supersonic speed (left of the image), encounters the boundary region of the
magnetosphere (bow shock), gets decelerated to subsonic speed and becomes
turbulent.

The data were collected around closest approach to the Red Planet during the Mars
swingby on 25 February 2007.

Time is ploted on the horizontal axis versus intensity of the magnetic field on the
vertical axis.

Credits: ROMAP / Philae / ESA Rosetta

The graph presented in this article plots time on the horizontal axis versus intensity of the magnetic field on the vertical axis.

It shows how the magnetic environment of Mars becomes complex when the solar wind, initially proceeding unperturbed at supersonic speed (left of the image), encounters the boundary region of the magnetosphere (bow shock), gets decelerated to subsonic speed and becomes turbulent. The turbulence continues in the ‘tail’ of the planet’s magnetosphere (right of the image).


These measurements are very important as they show how well the ROMAP instrument is performing. This data set is also almost unique, as the trajectory that Rosetta followed during the Mars swingby is very different from those usually followed by other spacecraft orbiting Mars: only the Russian probe Phobos-2 provided a similar insight into the plasma environment around Mars from this special viewpoint in space.

Source: ESA - Rosetta

This post has been edited by Waspie_Dwarf: 19 October 2007 - 01:20 PM

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Beautiful new images from Rosetta’s approach to Mars: OSIRIS UPDATE

Image of Mars seen by OSIRIS: A cloudy day on Mars.

25 February 2007
This series of beautiful images taken by Rosetta’s Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS), shows planet Mars in the pre-close-approach phase.

In the lead image above, an orange (red), green and near-UV colour filter composite image of Mars is shown; the UV channel (the blue color) has been enhanced. The enhanced UV signal clearly shows the presence of the cloud system covering most of the Martian disk.


Near-IR, green and near-UV colour view of Mars

The above-image composite is based on near-infrared, green and near-ultra-violet colour information obtained by the OSIRIS Narrow Angle Camera. At the southern part of the planet, the southern spring polar cap is clearly seen.

At this time of the Martian year, a large fraction of Mars' atmosphere is evaporating from the southern polar cap and will migrate to the northern polar cap during nothern winter. Over most of the Martian disk one can see large cloud systems.



True-colour image of Mars seen by OSIRIS

The first true-colour image (above) was generated using the OSIRIS orange (red), green and blue colour filters.



OSIRIS ultraviolet image of Mars

The ultraviolet image above was taken on 24 February 2007 with the OSIRIS wide-angle camera through the 'OH' colour filter, intended for the indirect detection of water when observing comet 67/P Churyumov-Gerasimenko.

Clouds are visible at the North polar cap of Mars and at the morning 'limb' (border or outermost edge of a celestial body). A high-altitude cloud is also visible and shown in the inset.

Atmospheric structures can be seen in the next pair of images taken by the OSIRIS narrow-angle camera. The images have been produced through a special combination of the green and red colour filters, emphasising the brightness difference. This image processing step enhances the structures in the atmosphere, either dust or clouds.



OSIRIS image of atmospheric structures of Mars



OSIRIS image of atmospheric structures of Mars


“If Mars were about the size of an apple and you were William Tell standing on Earth about half a mile (or 8 football fields) away and shot an arrow (Rosetta) toward the apple, you would miss the apple by 2.5 millimetres.”

J. Parker, Rosetta ALICE team, describing today's Mars swingby

The last OSIRIS image presented in this article is an annotated version of the two-colour composite of Mars seen by the OSIRIS narrow-angle camera on 24 February at 19:28 CET from a distance of about 240 000 km, with an image resolution of about 5 km per pixel.

This is better, for example, than previous views of the planet obtained by the Hubble Space Telescope. The greenish regions are clouds above the red surface of Mars.

All images were acquired on 24 February at 19:28 CET from a distance of about 240 000 km; image resolution is about 5 km/pixel.



Annotated image of Mars seen by OSIRIS.

Source: ESA - Rosetta

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Stunning view of Rosetta skimming past Mars

Stunning image taken by the CIVA imaging instrument on Rosetta's Philae lander just 4
minutes before closest approach at a distance of some 1000 km from Mars.

A portion of the spacecraft and one of its solar arrays are visible in nice detail. Beneath,
an area close to the Syrtis region is visible on the planet’s disk.

Credits: CIVA / Philae / ESA Rosetta

25 February 2007
This stunning view, showing portions of the Rosetta spacecraft with Mars in the background, was taken by the Rosetta Lander Imaging System (CIVA) on board Rosetta’s Philae lander just four minutes before the spacecraft reached closest approach to the Red Planet earlier this morning.

While the Rosetta orbiter instruments were switched off as planned during several hours around closest approach, which occurred at 03:15 CET today, some of the lander instruments were operational and collected data from Mars.

This incredible CIVA image was taken about 1000 kilometres from the planet’s surface. A portion of the spacecraft and one of its solar arrays are visible in nice detail. Beneath, an area close to the Syrtis region is visible on the planet’s disk.


Philae lander in first autonomous operation

This is the first time that the Philae lander operated in a totally autonomous mode, completely relying on the power of its own batteries. This will be the case when the lander will have touched down on comet 67P Churyumov-Gerasimenko in 2014 and will have to perform its scientific measurements independently from the Rosetta orbiter.

A sequence of observations from today's Mars close approach were run successfully, providing an important test for the science observations of the comet nucleus to come. In addition to CIVA, the ROMAP instrument was also switched on, collecting data about the magnetic environment of Mars. The data sets acquired by both instruments are unique, as the presented image summarises for CIVA.

The Philae lander still has still a long route ahead to ensure success for its highly challenging venture, which requires a safe landing on an unknown icy body, and performing a very complex programmed sequence of operations in a highly constrained environment.

A number of updates and validation of some systems and instruments are still required, which should be implemented during the upcoming cruise phase and the Earth swingby in November 2007.

Source: ESA - Rosetta

This post has been edited by Waspie_Dwarf: 25 February 2007 - 10:40 PM

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Rosetta teams up with New Horizons

Although the main mission of NASA's New Horizons is to explore the Pluto system and
the Kuiper Belt of icy, rocky objects, the spacecraft first flew by the solar system's larges
planet, Jupiter, on 28 February 2007 — just a little over a year after launch. In this artist's
rendering, New Horizons soars past Jupiter as the volcanic moon Io passes between the
spacecraft and planet.

Credits: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

2 March 2007
ESA and NASA are mounting a joint campaign to observe Jupiter over the next few weeks with two different spacecraft. Rosetta will watch the big picture from its current position near Mars, whilst New Horizons will take close-up data as it speeds past the largest planet in our Solar System on its journey to Pluto.

The co-ordinated observational campaign of Jupiter using Rosetta and New Horizons began this week. Jupiter remains a fascinating world of scientific mystery. "This is an excellent opportunity to test both spacecraft and to collect valuable science data," says Gerhard Schwhem, Rosetta's Mission Manager.

"We couldn't pass up this opportunity to study Jupiter's meteorology, rings, aurorae, satellites, and magnetosphere," says Alan Stern, Southwest Research Institute, Colorado, and New Horizon’s Principal Investigator.


A drawing of space near Jupiter, showing a portion of the radiation belts (in red), the Io
torus (green) and the Europa torus (blue). The blue and green belts come from the
atmospheres of the moons Europa and Io.

In a coordinated observation campaign started at the end of February 2007, ESA's Rosetta
and NASA's New Horizon spacecraft are studying Jupiter's space environment, while
travelling on their way to their respective destinations - comet 67P/Churyumov-Gerasimenko
and the Pluto system.

The picture comes from measurements taken by the Cassini spacecraft.

Credits: NASA

One of Rosetta's targets will be the doughnut-shaped ring of electrically charged gas that circles Jupiter. Known as the Io torus, it lies in Io’s orbit and is at its most dense near the volcanic moon, Io.

The best theory for its formation is that Io's volcanoes throw sulphur and sulphur dioxide into space during their eruptions. In space, the atoms and molecules are stripped of their electrons, electrically charging them and turning them in ions. These become trapped by Jupiter's powerful magnetic field and are pulled around every ten hours by the Jupiter’s rotation. The result is that the Io torus circles Jupiter at Io’s orbital radius.


This image of Jupiter is produced from a 2x2 mosaic of photos taken by the New Horizons
Long Range Reconnaissance Imager (LORRI), and assembled by the LORRI team at the
Johns Hopkins University Applied Physics Laboratory.

The telescopic camera snapped the images during a 3-minute, 35-second span on February
10, when the spacecraft was 29 million kilometres from Jupiter. At this distance, Jupiter's
diameter was 1,015 LORRI pixels - nearly filling the imager's entire (1,024-by-1,024 pixel)
field of view. Features as small as 290 kilometers are visible.

Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The idea for the joint observations came from Stern. As well as leading New Horizons, he is also the principal investigator for Rosetta’s ALICE instrument.

ALICE is the ultraviolet imaging spectrometer. Designed to analyse gases being given off by Rosetta's target comet, it will allow scientists to deduce the production rates of water vapour, carbon monoxide and carbon dioxide. For the current campaign, it will be the key instrument used to observe Jupiter. Joining the observations will be VIRTIS (the Visible and Infrared Thermal Imaging Spectrometer) and OSIRIS (the Optical, Spectroscopic, and Infrared Remote Imaging System).


Artist's impression of Rosetta at Mars

Credits: ESA - C.Carreau

Rosetta will study Jupiter for between 6 and 8 days in total, spread over the next few weeks. Each time Rosetta opens its eyes to look at Jupiter, it will do so for several hours at a time, collecting as much light from the faraway planet as possible. "Rosetta will give us the big picture context in which to see the up-close data from New Horizons," says Stern. During this time, New Horizons will be riding the long tail of magnetism that stretches out behind Jupiter and funnels charged particles away.

Rosetta's ALICE was the prototype for the ultraviolet imaging instrument flying on New Horizons. At Pluto, New Horizons' ALICE will be used to study the tiny world's tenuous atmosphere.

ESA's Rosetta was launched on 2 March 2004 and is currently circling the inner solar system using close fly-bys of the Earth and Mars planets to alter its orbit and eventually swing it out towards Jupiter's orbit, where it will rendezvous with comet Churyumov-Gerasimenko in 2014.

Such ventures add value to the science that can come out of the Rosetta mission. "I am sure that this is fascinating science," says Schwhem.

Source: ESA - Rosetta

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OSIRIS camera on Rosetta obtains ‘light curve’ of asteroid Steins

Four images of Asteroid (2867) Steins taken by the OSIRIS Narrow Angle Camera. The second, third, and fourth image, from bottom to top, were taken approximately 5, 10, and 15 hours after the first image, respectively. For the whole duration of the observation Steins stayed within the circle, demonstrating the excellent tracking capability of Rosetta.

Credits: ESA ©2006 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

20 March 2007
During the very first observations of Rosetta’s flyby target 2867-Steins in March 2006 the onboard camera OSIRIS obtained the most accurate ‘light curve’ of this asteroid so far.

OSIRIS observed Steins from a distance of 159 million kilometres and, from there, it obtained images and important clues about its characteristics.

Although ESA’s Rosetta is still far away from its destination comet 67P/Churyumov-Gerasimenko and its flyby targets 2867-Steins and 21-Lutetia, scientists have already started to collect preliminary data about these two largely unexplored asteroids. Advanced knowledge of the asteroids’ properties (like size and rotation period) is essential for the preparation of the planned asteroid observation campaigns in September 2008 and July 2010, respectively.

Brightness variation of the asteroid measured continuously over one day. The maximum in the light curve is about 23 percent brighter than the minimum.

Credits: Stefano Mottola (DLR), OSIRIS team

“Lutetia was imaged by Rosetta on 2 and 3 January 2007, whereas Steins was already observed during a 24-hour observation campaign on 11 March 2006. Both observations were aimed at pre-characterizing the rotation direction of the asteroid. This can be done by the study of the so-called 'light curve' of the asteroid from different locations – by analysing how the light emitted by the observed object changes intensity for different observers, one can deduce in what direction the object rotates” explains Michael Küppers from the Max-Planck-Institute for Solar System Research. The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) on board Rosetta is up to this ambitious task. On its interplanetary cruise it provided an observing geometry of Steins that cannot be obtained from Earth.

Although the brightness of the Steins asteroid during the measurement period was comparable to that of a candle seen at a distance of ~2000 kilometres, OSIRIS was able to measure brightness variations of the asteroid with an accuracy of better than two percent of its total brightness.

The observations show that Steins rotates with a spin period of slightly more than six hours, in agreement with previous earth-based observations. The asymmetry of the light curve suggests an irregular shape of Steins. However, OSIRIS found no evidence for a ‘tumbling’ motion of the asteroid or the presence of a satellite. Work is ongoing to construct the orientation of the spin axis of Steins from a combination of the OSIRIS observations with ground-based data.

Basically, asteroids are elemental components of the solar system, orbiting the sun for thousand of millions of years. For scientists, these minor bodies of rock or stone are much more than only boulders. Asteroids as well as comets carry important information about the origin of the Solar System – a better understanding of which is one of the primary goals of Rosetta. Rosetta will gather valuable data as it flies by these primordial rocks.

Rosetta’s instruments will provide information on the mass and density of the asteroids, thus telling us more about their composition, and will also measure their subsurface temperature and look for gas and dust around them.


Note

Asteroid 2867-Steins will be visited again by Rosetta on 5 September 2008 from a distance of just over 1700 kilometres. This encounter will take place at a relatively low speed of about 9 kilometres per second during Rosetta's first excursion into the asteroid belt. On 10 July 2010 Rosetta will pay its second visit to asteroid 21-Lutetia, passing within about 3000 kilometres of it, at a speed of about 15 kilometres per second.

This article is based on the paper “Determination of the light curve of the Rosetta target asteroid (2867) Steins by the OSIRIS cameras onboard Rosetta,” by M. Küppers et al published in: Astronomy & Astrophysics, Vol. 462-1 (January IV 2007, A&A 462, p. L13).

Source: ESA - Rosetta

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Rosetta and New Horizons watch Jupiter in joint campaign

30 March 2007

This image of Jupiter is produced from a 2x2 mosaic of photos taken by the New Horizons Long Range Reconnaissance Imager (LORRI), and assembled by the LORRI team at the Johns Hopkins University Applied Physics Laboratory.

The telescopic camera snapped the images during a 3-minute, 35-second span on February 10, when the spacecraft was 29 million kilometres from Jupiter. At this distance, Jupiter's diameter was 1,015 LORRI pixels - nearly filling the imager's entire (1,024-by-1,024 pixel) field of view. Features as small as 290 kilometers are visible.

Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

ESA’s Rosetta and NASA’s New Horizons are working together in their joint campaign to observe Jupiter. A preliminary analysis of the data from Rosetta’s Alice ultraviolet spectrometer indicates that the data quality is excellent and that good science is expected to follow.

New Horizons made its closest approach to Jupiter on 28 February 2007. Its principal objective was to use the gravity of the giant planet to slingshot it onwards to its rendezvous with Pluto, planned for 2015. However, as Alan Stern, Southwest Research Institute, San Antonio, Texas (USA), and New Horizon’s Principal Investigator says, “We couldn’t pass up this opportunity to study Jupiter’s meteorology, rings, aurorae, satellites, and magnetosphere.”

This image of a plume erupting from Tvashtar, a volcano on Io was taken by the Long Range Reconnaissance Imager (LORRI) on New Horizons at 11:04 Universal Time on February 28, 2007. Five hours after the spacecraft's closest approach to Jupiter, the picture was taken from a distance of 2.5 million kilometres.

The image was centred at 85 degrees west longitude, in the 11 o'clock direction near Io's north pole. The plume depicted is about 290 kilometres high. Seen at first by the Hubble Space Telescope, and then two weeks later on February 26 2007 by New Horizons itself, this image is much clearer. This is due to longer exposure; there is an excellent view of the night-side illuminated by Jupiter.

The filamentary structure seen in the plume is similar to that seen in the 1979 Voyager images of the plume produced by Io’s volcano Pele. This is the first time that these mysterious structures have been seen so clearly.

Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

A plume on Io erupting from the volcano Tvashtar
Rosetta, just after having swung by Mars and while on its way to comet 67P-Churyumov Gerasimenko, played an important role in this research, providing global observations of Jupiter’s aurora and the Io plasma torus that can be correlated with New Horizons’ detailed in-situ measurements.

Rosetta’s observation of Jupiter began on the same day as the New Horizons swingby. Because Rosetta is presently close to Mars and Jupiter is still far away, to some of the instruments the giant planet is just a pinprick of light. Nevertheless, Rosetta’s Alice instrument splits this light into a spectrum, in which the separate contributing regions can be distinguished.

A drawing of space near Jupiter, showing a portion of the radiation belts (in red), the Io torus (green) and the Europa torus (blue). The blue and green belts come from the atmospheres of the moons Europa and Io.

In a coordinated observation campaign started at the end of February 2007, ESA's Rosetta and NASA's New Horizon spacecraft are studying Jupiter's space environment, while travelling on their way to their respective destinations - comet 67P/Churyumov-Gerasimenko and the Pluto system.

The picture comes from measurements taken by the Cassini spacecraft.

Credits: NASA

“We have now clearly separated the three components that make up the spectrum,” says Alice team member Andrew Steffl, Southwest Research Institute. The first component is simply sunlight, reflecting off Jupiter’s cloud tops. The second part of the spectrum is composed of ultraviolet emission given off by particles ejected in volcanic eruptions by Jupiter’s moon Io. The third is light from Jupiter’s aurorae, caused by particles striking the planet’s atmosphere, some from the Sun, some ejected from Io.


Alice is an ultraviolet imaging spectrometer, designed to analyse the composition and density of gas molecules, and an almost identical Alice UVS instrument is on New Horizons. Rosetta’s Alice will measure the rates at which water vapour, carbon monoxide and carbon dioxide are given off by comet Churyumov-Gerasimenko, after the rendezvous in 2014. New Horizons’ Alice instrument will study the tenuous atmosphere at Pluto in mid-2015.

“New Horizons cannot observe Jupiter using its Alice instrument at the moment,” says Joel Parker, also at the Southwest Research Institute, and Alice Project Manager. This is because New Horizons’ Alice would have to be pointed back at Jupiter, towards the Sun. If bright sunlight fell into the instrument, it could damage the sensitive optics. Hence the scientists will not take the risk.

This ultraviolet image of Jupiter was taken with the Hubble Space Telescope Imaging Spectrograph (STIS) on 26 November 1998. The bright emissions above the dark blue background are auroral lights, similar to those seen above the Earth's polar regions. The aurorae are curtains of light resulting from high energy electrons following the planet's magnetic field into the upper atmosphere, where collisions with atmospheric atoms and molecules produce the observed light.

Credits: NASA, ESA & John T. Clarke (Univ. of Michigan)

Instead, other instruments on New Horizons can detect the actual particles that are trapped in Jupiter’s magnetic field, but to better understand this data, spectra of Jupiter’s aurora and the Io torus are also needed. This is where Rosetta’s Alice makes its important contribution.

Some of the things the team will be looking for are solar wind events. These are gusts in the number of electrically charged particles that the Sun gives out. When they strike the magnetic field of Jupiter, they can cause the aurora to shine more brightly. Rosetta’s Alice will see this, too, and the team can then look for changes in the particles detected by New Horizons. “This is a really nice synergy between the two projects,” says Parker.

Rosetta’s observations are set to continue until 8 May, and when complete, will include some 400 hours worth of observations. Using Rosetta’s Alice is proving to be invaluable to the team in their preparations for the 2014 comet rendezvous. “Every time we use the instrument, we learn more about how to get the most out of it when we arrive at the comet,” says Parker.

Source: ESA - News

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Boosting the accuracy of Rosetta's Earth approach

19 October 2007

Earth swingbys: March 2005, November 2007 and September 2009
To gain speed through a series of gravitational 'kicks', Rosetta swings past Earth three times during its journey. The swingby distance will be between 300 and 14 000 km. Manoeuvres to correct Rosetta's orbit take place before and after each swingby.

Credits: ESA/AOES Medialab

Yesterday, 18 October at 18:06 CEST, the thrusters of ESA’s comet chaser, Rosetta, were fired in a planned, 42-second trajectory correction manoeuvre designed to 'fine tune' the spacecraft's approach to Earth. Rosetta is now approaching Earth for its second planetary swing-by of 2007.

After passing Mars in April 2007, Rosetta is now approaching Earth for the second time - the third of four planetary swing-bys that provide fuel-saving gravitational assists enabling the spacecraft to ultimately reach and cross the orbit of comet 64P/Churyumov-Gerasimenko in 2014.

Rosetta's closest approach is predicted for 21:57 CET at a height of 5301 km over the Pacific Ocean and a speed of 45 000 km/h relative to the Earth. The third and last Earth swing-by will take place in November 2009.


Rosetta lines up

Stunning image taken by the CIVA imaging instrument on Rosetta's Philae lander just 4 minutes before closest approach at a distance of some 1000 km from Mars.

A portion of the spacecraft and one of its solar arrays are visible in nice detail. Beneath, the Mawrth Vallis region is visible on the planet’s disk. Mawrth Vallis is particularly relevant as it is one of the areas on the Martian surface where the OMEGA instrument on board ESA's Mars Express detected the presence of hydrated clay minerals - a sign that water may have flown abudantly on that region in the very early history of Mars.

Credits: CIVA / Philae / ESA Rosetta

"We have a target trajectory for Earth swing-by and regular orbit determinations allow us to decide when to do a correction manoeuvre. Brief burns now allow us to optimise the orbit and make the swing-by more accurate, saving us a lot of precious fuel later on," said Andrea Accommazzo, Rosetta Spacecraft Operations Manager at ESOC. He confirmed that yesterday's manoeuvre results were as expected.

A second trajectory correction slot, on 1 November, may also be used depending on results of an orbit determination scheduled for 30 October.

ESA’s comet chaser

Rosetta’s 11-year expedition begins with an Ariane-5 launch from Kourou in French Guiana. The three-tonne spacecraft will first be inserted into a parking orbit around Earth, before being sent on its way towards the outer Solar System.

Deep space hibernation to comet rendezvous (July 2011 – January 2014): after a large deep-space manoeuvre, the spacecraft goes into hibernation. During this period, Rosetta records its maximum distances from the Sun (about 800 million kilometres) and Earth (about 1 thousand million kilometres). The spacecraft is reactivated prior to the comet-rendezvous manoeuvre, during which the thrusters fire for several hours to slow the relative drift rate of the spacecraft and comet to about 25 metres per second.

Credits: ESA/AOES Medialab

Rosetta will be ESA’s first spacecraft to undertake long-term exploration of a comet at close quarters. The mission consists of a large orbiter, designed to operate for a decade at large distances from the Sun, and a small lander, Philae. Each of these carries a large suite of scientific experiments designed to complete the most detailed study of a comet ever attempted.

After entering orbit around Comet 67P/Churyumov-Gerasimenko in 2014, the spacecraft will release the lander onto the icy nucleus. It will then spend the next two years orbiting the comet as it heads towards the Sun. On the way to Comet Churyumov-Gerasimenko, Rosetta has received gravity assists from Earth and Mars, and will fly past two main-belt asteroids – Steins (September 2008), and Lutetia (July 2010).


A more technical version of this article is available at the ESA Spacecraft Operations pages.


For more information:

Andrea Accomazzo, ESA Rosetta Spacecraft Operations Manager
Email: Andrea.Accomazzo @ esa.int

Gerhard Schwehm, ESA Rosetta Mission Manager
Email: Gerhard.Schwehm @ esa.int

Source: ESA - Rosetta