[Waspie_Dwarf]

Rosetta closes in on Earth – a second time

8 November 2007

This is an artist’s rendition of Rosetta’s closest approach to Earth during its second swing-by of our planet on 13 November this year. The image shows the fly-by configuration as seen from above.

This month’s Earth swing-by is Rosetta’s third major step on its 10-year journey to comet 67/P-Churyumov-Gerasimenko. A trajectory correction manoeuvre successfully performed last month prepared ESA’s comet chaser for the upcoming encounter, and now Rosetta is right on track.

In swinging by Earth, the spacecraft will have gained the right amount of energy from Earth’s gravity to save precious fuel for later on.

Closest approach will take place on 13 November 2007 at 21:57 CET, at which time Rosetta will speed past at 45 000 km/h (about 12.5 km/s) relative to Earth. At this time, Rosetta will be 5301km above the Pacific Ocean, south-west of Chile, at 63° 46’ south and 74° 35’ west.

During this Earth swing-by, a few experiments both on the orbiter and the Philae lander will be activated for calibration, scientific measurements and imaging. Rosetta will first point to Earth and then to the Moon for the observations.

Credits: ESA (Image by C. Carreau)

ESA’s comet chaser, Rosetta, is on its way to its second close encounter with Earth on 13 November. The spacecraft’s operators are leaving no stones unturned to make sure Earth’s gravity gives it the exact boost it needs en route to its destination.

This month’s Earth swing-by is Rosetta’s third major step on its 10-year journey to 67/P Churyumov-Gerasimenko. The trajectory correction manoeuvre successfully performed last month prepared ESA’s Comet Chaser for the upcoming encounter. The spacecraft is now right on track to gain the right amount of energy from Earth’s gravity and save fuel later on.

Closest approach will take place on 13 November 2007 at 21:57 CET, at which time Rosetta will speed past at 45 000 km/h (about 12.5 km/s) relative to Earth. At this time, Rosetta will be 5301km above the Pacific Ocean, south-west of Chile, at 63° 46’ South and 74° 35’ West.

Why swing by Earth?

Rosetta swung by Mars on 25 February 2007.

Credits: ESA (Image by C. Carreau)

Swing-bys make use of the gravitational attraction of planets to modify a spacecraft’s trajectory and to gain the orbital energy needed to reach the final target.

The first Earth swing-by took place on 4 March 2005. On 25 February 2007 Rosetta made its closest approach to Mars, to use its gravity. The swing-by this month will be followed by the third and last swing-by, using Earth’s gravity, on 13 November 2009.

While the gravity-assist manoeuvre at Mars was needed to slow the spacecraft down and head back towards the inner solar system, the second Earth swing by will help Rosetta gain enough energy to reach the outer Solar System through the asteroid belt and observe asteroid Steins, one of its scientific targets. Rosetta will then head back to Earth for the last planned swing-by in November 2009.

The increased energy from this Earth swing-by will help Rosetta cross the asteroid belt for a second time, observe Lutetia (its second target asteroid) and finally rendezvous with comet 67/P Churyumov-Gerasimenko. The rendezvous will take place about 4 astronomical units or 600 million km from the Sun, in 2014.


Intense activity coming up...

During this Earth swing-by, the highest priority will be given to spacecraft operations, as the manoeuvre is critical for the success of the overall mission. In addition, during the incoming and outgoing tracks of the swing-by, Rosetta will be under unfavourable solar illumination and thus temperature conditions. This is why only very limited slots will be available for the instruments to be used safely.

Despite this, a few experiments both on the orbiter and the Philae lander will be activated for calibration, scientific measurements and imaging. The observations are scheduled during and around the time of closest approach, from 7 Nov, 01:00 CET, to 20 Nov, 15:00 CET.

Rosetta will first point to Earth to make observations of the atmosphere and the magnetosphere, including a search for shooting stars from space. It will image urban regions in Asia, Africa and Europe and then point to the Moon and obtain spectra of the illuminated Moon. Flying away after closest approach, Rosetta will image the Earth-Moon system from a distance.

Rosetta will be controlled from ESA’s Spacecraft Operations Centre (ESOC) in Darmstadt, Germany

For more detail about Rosetta’s spacecraft and scientific operations, please read the Rosetta second Earth swing-by Q&A.

For the swing-by, the ESA Web portal is hosting a Rosetta swing-by blog providing frequent updates, news and information direct from the Rosetta Dedicated Control Room at ESOC.


Timeline of major activities

This artist’s impression shows the orbits of Earth (blue) and Rosetta (white) as the comet chaser swings by our planet. Rosetta is on its way to its second close encounter with Earth on 13 November.

This month’s Earth swing-by is Rosetta’s third major step on its 10-year journey to comet 67/P Churyumov-Gerasimenko. A trajectory correction manoeuvre successfully performed last month prepared ESA’s comet chaser for the upcoming encounter, and now Rosetta is right on track.

In swinging by Earth, the spacecraft will gain the right amount of energy from Earth’s gravity and precious save fuel for later on.
Closest approach will take place on 13 November 2007 at 21:57 CET, at which time Rosetta will speed past at 45 000 km/h (about 12.5 km/s) relative to Earth. At this time, Rosetta will be 5301km above the Pacific Ocean, south-west of Chile, at 63° 46’ south and 74° 35’ west.

The first Earth swing-by took place on 4 March 2005. On 25 February 2007 Rosetta made its closest approach to Mars, to use its gravity. The swing-by this month will be followed by the third and last swing-by, using Earth’s gravity, on 13 November 2009.

This second Earth swing by will help Rosetta gain enough energy to reach the outer Solar System through the asteroid belt and observe asteroid Steins, one of its science targets.

Credits: ESA (Image by C.Carreau)

Times shown are ground event times in Central European Time, equivalent to UTC (Coordinated Universal Time) + 1 hour




For more information:

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

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

Rita Schulz, ESA Rosetta Project Scientist
Email: Rita.Schulz @ esa.int

Source: ESA - News

[Waspie_Dwarf]

Rosetta right on track for Earth swing-by

12 November 2007

This is an artist’s rendition of Rosetta’s closest approach to Earth during its second swing-by of our planet on 13 November this year. The image shows the fly-by configuration as seen from below. This month’s Earth swing-by is Rosetta’s third major step on its 10-year journey to comet 67/P-Churyumov-Gerasimenko. A trajectory correction manoeuvre successfully performed last month prepared ESA’s comet chaser for the upcoming encounter, and now Rosetta is right on track. In swinging by Earth, the spacecraft will have gained the right amount of energy from Earth’s gravity to save precious fuel for later on. Closest approach will take place on 13 November 2007 at 21:57 CET, at which time Rosetta will speed past at 45 000 km/h (about 12.5 km/s) relative to Earth. At this time, Rosetta will be 5301km above the Pacific Ocean, south-west of Chile, at 63° 46’ south and 74° 35’ west. During this Earth swing-by, a few experiments both on the orbiter and the Philae lander will be activated for calibration, scientific measurements and imaging. Rosetta will first point to Earth and then to the Moon for the observations.

Credits: ESA - C. Carreau

Preparations for Rosetta’s Earth swing-by scheduled for tomorrow, 21:57 CET, are well underway. The manoeuvre executed on 18 October 2007 has been accurate enough to not require any additional trajectory corrections today.

This means that the most critical operational procedures for the success of the swing-by are now over. However, the operations teams are constantly on the watch to make sure that nothing disturbs the spacecraft’s velocity and direction and that its stability is maintained throughout the observations.

The core observations will start only in the afternoon tomorrow, but the instruments are already being prepared for the delicate procedures. The spacecraft has been pointed to certain areas in the sky for calibration and this will continue for about 48 hours. During the swing-by, Rosetta will first point to Earth and will observe the Earth-Moon system as a whole afterwards.

Source: ESA - Space Science - News

This post has been edited by Waspie_Dwarf: 12 November 2007 - 09:19 PM
Reason for edit:: corrected source link.

[Waspie_Dwarf]

Rosetta on its way

13 November 2007

Rosetta, on its way to the upcoming Earth swing-by, was seen last night from the Starkenburg observatory in Heppenheim, Germany.

Credits: Starkenburg-Sternwarte (animation by A. Accomazzo)

Rosetta, on its way to the upcoming Earth swing-by, was seen last night from the Starkenburg observatory in Heppenheim, Germany.

The image was taken by Matthias Busch, Andreas Drefke, Albert Heller and Rainer Kresken. The picture was taken with a 450-mm Newtonian telescope equipped with a CCD camera.

Source: ESA - Rosetta

[Waspie_Dwarf]

Rosetta swing-by a success

13 November 2007
An important milestone has just been accomplished as Rosetta successfully swung by Earth at 21:57 CET. The spacecraft will now be catapulted towards the outer Solar System with its newly-gained energy before coming back to Earth for another boost.

As mission operators waited for the fully automated manoeuvre to be carried out, Rosetta flew directly above 63° 46’ south and 74° 35’ west, at 21:57 CET (above the Pacific ocean, south-west of Chile). Rosetta whizzed past 5295 km overhead, at a velocity of 45 000 km/h (12.5 km/s).

Europe’s comet chaser has now flown a little over 3 thousand million km of its 7.1 thousand-million-km journey on its way to its destination comet 67/P Churyumov-Gerasimenko. This was the third planetary swing-by for Rosetta and its second swing-by of Earth.


Science close to Earth

This is an artist’s rendition of Rosetta’s closest approach to Earth during its second swing-by of our planet on 13 November this year. The image shows the fly-by configuration as seen from below. This month’s Earth swing-by is Rosetta’s third major step on its 10-year journey to comet 67/P-Churyumov-Gerasimenko. A trajectory correction manoeuvre successfully performed last month prepared ESA’s comet chaser for the upcoming encounter, and now Rosetta is right on track. In swinging by Earth, the spacecraft will have gained the right amount of energy from Earth’s gravity to save precious fuel for later on. Closest approach will take place on 13 November 2007 at 21:57 CET, at which time Rosetta will speed past at 45 000 km/h (about 12.5 km/s) relative to Earth. At this time, Rosetta will be 5301km above the Pacific Ocean, south-west of Chile, at 63° 46’ south and 74° 35’ west. During this Earth swing-by, a few experiments both on the orbiter and the Philae lander will be activated for calibration, scientific measurements and imaging. Rosetta will first point to Earth and then to the Moon for the observations.

Credits: ESA - C. Carreau

Around closest approach, Rosetta took a good look at Earth for observations of its atmosphere and magnetosphere, imaged urban regions, and looked for meteors from space. Shortly before midnight, Rosetta will turn to observe the Moon until about 11:00 CET tomorrow, 14 November. Following this, on 15, 16, 18 and 20 November, Rosetta will observe the Earth-Moon system from a distance, on its outbound trajectory.

Scientists are now eagerly awaiting some of the first data to become available during the course of the night.

Rosetta will be back in our neighbourhood, and will swing by Earth for the last time in November 2009. But before that, as it crosses the asteroid belt, Rosetta will grab the opportunity to study asteroid Steins during a fly-by in September 2008.

Tune in early tomorrow morning: we will be publishing pictures and results as soon as they become available, throughout the day on 14 November.


For more information:

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

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

Rita Schulz, ESA Rosetta Project Scientist
Email: Rita.Schulz @ esa.int

Source: ESA - News

[Waspie_Dwarf]

Images of Earth and Moon captured by Rosetta

14 November 2007

This is a composite of two images taken by Rosetta’s navigation camera (NAVCAM) right after Rosetta’s closest approach to Earth. The pictures were taken at 21:55 and 21:56 CET on 13 November, as Rosetta’s second Earth swing-by concluded, while the spacecraft was flying at a height of about 5500 km from the surface.

Credits: ESA

Images taken right after Rosetta’s second Earth swing-by last night are now available. The comet chaser’s navigation camera (NAVCAM) took pictures of regions in the Antarctic and snapshots of Earth and the Moon.

The NAVCAM is one of the subsystems on the Rosetta orbiter used for optical navigation. The pictures were all taken immediately after Rosetta’s closest approach to Earth, between 21:55 CET on 13 November and 00:10 on 14 November while Rosetta was flying at heights of between 5500 to 6250 km from Earth’s surface.

This image was taken by Rosetta’s navigation camera (NAVCAM) right after Rosetta’s closest approach to Earth. The picture was taken at 21:55 CET on 13 November, as Rosetta’s second Earth swing-by concluded, while the spacecraft was flying at a height of about 5500 km from the surface.

Credits: ESA

This image was taken by Rosetta’s navigation camera (NAVCAM) right after Rosetta’s closest approach to Earth. The picture was taken at 21:56 CET on 13 November, as Rosetta’s second Earth swing-by concluded, while the spacecraft was flying at a height of about 5500 km from the surface.

Credits: ESA

Rosetta’s navigation camera (NAVCAM) took this shot of Earth right after Rosetta’s closest approach to our planet. The picture was taken at 22:56 CET on 13 November, as Rosetta’s second Earth swing-by concluded, while the spacecraft was flying at a height of about 6250 km from the surface.

Credits: ESA

This picture of the Moon was taken by Rosetta’s navigation camera (NAVCAM) right after the comet chaser’s closest approach to our planet. The picture was taken at 00:10 CET on 14 November, as Rosetta’s second Earth swing-by concluded, while the spacecraft was flying at a height of about 6250 km from the surface.

Credits: ESA

This image was taken by Rosetta’s navigation camera (NAVCAM) right after Rosetta’s closest approach to Earth. The picture was taken at 21:58 CET on 13 November, as Rosetta’s second Earth swing-by concluded, while the spacecraft was flying at a height of about 5343 km directly above 78.74° west and 63.12° south.

Credits: ESA

This image was taken by Rosetta’s navigation camera (NAVCAM) right after Rosetta’s closest approach to Earth. The picture was taken at 21:54 CET on 13 November, as Rosetta’s second Earth swing-by concluded, while the spacecraft was flying at a height of about 5415 km directly above 44.35° west and 64.49° south.

Credits: ESA

Source: ESA - News

[Waspie_Dwarf]

Cities at night: Extraordinary Rosetta images

14 November 2007

The Optical Spectroscopic and Infrared Remote Imaging System (OSIRIS) camera on board Rosetta observed Earth during its swing-by last night.

This image was taken with the OSIRIS Wide Angle Camera (WAC) at 19:45 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time, Rosetta was about 80000 km above the Indian Ocean where the local time approached midnight (the angle between Sun, Earth and Rosetta was about 160°).

Islands of artificial lights created by human habitation are sparsely distributed over the part of the globe seen in the picture.

The image was taken with a five-second exposure of the WAC with the red filter.

Credits: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

ESA's Rosetta has returned extraordinary images captured 13 November 2007 as the comet-chasing spacecraft completed a critical Earth swing-by at 45 000 kilometres per hour.

The images - captured by Rosetta's OSIRIS instrument - comprise a view of the Earth's night side including urban regions in Asia, Africa and Europe, and a view of the Earth's limb over Antarctica.

The first image was taken with the OSIRIS Wide Angle Camera (WAC) at 19:45 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time, Rosetta was about 80 000 km above the Indian Ocean where the local time approached midnight (the angle between Sun, Earth and Rosetta was about 160°).

Islands of artificial lights created by human habitation are sparsely distributed over the part of the globe seen in the picture.

Scroll down for an annotated version.


Earth's limb high over Antarctica

The Optical Spectroscopic and Infrared Remote Imaging System (OSIRIS) camera on board Rosetta observed Earth during its swing-by last night.

This image was taken with the Wide Angle Camera (WAC) at 20:05 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time Rosetta was about 75000 km from Earth. A sun-illuminated crescent can be seen around Antarctica. The image is a colour composite combining images obtained at various wavelengths.

Credits: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

This image was taken with the Wide Angle Camera (WAC) at 20:05 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time Rosetta was about 75000 km from Earth. A sun-illuminated crescent can be seen around Antarctica. The image is a colour composite combining images obtained at various wavelengths.

The Optical Spectroscopic and Infrared Remote Imaging System (OSIRIS) camera on board Rosetta observed Earth during its swing-by last night.

This image was taken with the OSIRIS Wide Angle Camera (WAC) at 19:45 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time, Rosetta was about 80000 km above the Indian Ocean where the local time approached midnight (the angle between Sun, Earth and Rosetta was about 160°).

Islands of artificial lights created by human habitation are sparsely distributed over the part of the globe seen in the picture.

The image was taken with a five-second exposure of the WAC with the red filter.

Credits: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

This is an annotated version of the first image, showing various geographical and population features.


The images were captured between 19:45 and 20:05 CET, about two hours prior to Rosetta's gravity-assist passage past Earth, as the spacecraft flew 75 000 to 80 000 km over Earth's surface.


OSIRIS

The image series was captured by the spacecraft's OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) instrument, which includes a wide-angle camera and a narrow-angle camera to obtain high-resolution images of the destination comet's nucleus and the asteroids that Rosetta passes on its voyage to Comet 67P/Churyumov-Gerasimenko.


OSIRIS will also help in identifying the best landing sites for the on-board lander. The Principal Investigator is H.U. Keller, of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany.

Source: ESA - News

[Waspie_Dwarf]

Rosetta: OSIRIS’ view of Earth by night

15 November 2007
This striking composite of Earth by night shows the illuminated crescent over Antarctica and cities of the northern hemisphere. The images were acquired with the OSIRIS Wide Angle Camera (WAC) during Rosetta’s second Earth swing-by on 13 November.

This image showing islands of light created by human habitation was taken with the OSIRIS WAC at 19:45 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time, Rosetta was about 80 000 km above the Indian Ocean where the local time approached midnight (the angle between Sun, Earth and Rosetta was about 160°). The image was taken with a five-second exposure of the WAC with the red filter.

This image showing Earth’s illuminated crescent was taken with the WAC at 20:05 CET as Rosetta was about 75 000 km from Earth. The crescent seen is around Antarctica. The image is a colour composite combining images obtained at various wavelengths.

Source: ESA - News

[Waspie_Dwarf]

The Moon and Europe - Rosetta OSIRIS images

This picture of the Moon was taken with the OSIRIS Narrow Angle Camera (NAC) at 07:36 CET on 13 November. This was about nine hours after Rosetta's closest approach to Earth.

OSIRIS has been designed to image faint objects, so a neutral density filter was placed in the optical path to reduce the sensitivity of the camera to one fiftieth. The above image was acquired through the far-focus red filter of the camera (750 nanometres).

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

16 November 2007
As Rosetta closed in on Earth, swung by and then left on its course again, several instruments on the spacecraft were busy taking snaps. As it swung away, the OSIRIS camera also caught glimpses of the Moon.

The Moon was imaged with the OSIRIS Narrow Angle Camera (NAC) at 07:36 CET, about nine hours after Rosetta's closest approach to Earth.

OSIRIS has been designed to image faint objects, so a neutral density filter was placed in the optical path to reduce the sensitivity of the camera to one-fiftieth. The above image was acquired through the far-focus red filter of the camera (750 nanometres).


The below image of Earth is targeted roughly at Greece. It was taken with the OSIRIS Wide Angle Camera (WAC) during the swing-by.

This image of Earth, targeted roughly at Greece, was taken with the OSIRIS Wide Angle Camera (WAC) during the Earth swing-by.

It shows major urban areas of Europe illuminated at night.

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

Major urban areas of Europe can be seen illuminated at night.

Source: ESA - Rosetta

[Waspie_Dwarf]

Rosetta: Earth’s true colours

After its closest approach to Earth, Rosetta looked back and took a number of images using the OSIRIS Narrow Angle Camera (NAC). This particular image was acquired 15 November 2007 at 03:30 CET.

The image is a colour composite of the NAC Orange, Green and Blue filters.

At the bottom, the continent of Australia can be seen clearly.

Credits: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

20 November 2007
True colour images of Earth as seen by Rosetta’s OSIRIS camera are now available. The pictures were taken on 13 November during the swing-by, and on 15 November, as Rosetta left on its way to the outer Solar System, after the swing-by.

After its closest approach to Earth, Rosetta looked back and took a number of images using the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) Narrow Angle Camera (NAC). This particular image was acquired 15 November 2007 at 03:30 CET.

The image above is a colour composite of the NAC orange, green and blue filters.

At the bottom, the continent of Australia can be seen clearly.

During the swing-by, OSIRIS observed Earth’s night-side.

This image shows a simulated view of Earth as seen from Rosetta's position.

During the swing-by, the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS)on board Rosetta observed Earth’s night-side.

This image shows a simulated view of Earth as seen from the position of Rosetta, just before the spacecraft's closest approach to Earth. It was acquired on 13 November 2007 at 20:30 CET using the WAC with a red filter.

Credits: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

The same view was seen by the OSIRIS Wide Angle Camera (WAC). It is shown in false colour to emphasise city lights seen at night.

This image was acquired on 13 November 2007 at 20:30 CET using the WAC with a red filter.

During the swing-by, the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS)on board Rosetta observed Earth’s night-side.

The is a picture taken with the OSIRIS Wide Angle Camera (WAC), showing the same view seen in the OSIRIS Narrow Angle Camera (NAC) image. It is shown in false colour to emphasise city lights seen at night.

This image was acquired on 13 November 2007 at 20:30 CET using the WAC with a red filter.

Credits: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDAA

Source: ESA - Rosetta

[Waspie_Dwarf]

Rosetta awakes from hibernation for asteroid encounter

3 July 2008

On its way to comet 67/P Churyumov-Gerasimenko, Rosetta is targeting two asteroids for study: (2867) Steins, on 5 September 2008, and (21) Lutetia on 10 June 2010.

Credits: ESA/AOES Medialab

Spacecraft controllers have just awoken Rosetta from hibernation to prepare for its encounter with asteroid (2867) Steins on 5 September. ESA’s comet chaser will study the relatively rare asteroid as it flies by on its way to comet 67/P Churyumov-Gerasimenko.

Launched in March 2004, Rosetta will reach its final destination only in 2014, after travelling a total of about 6500 million km. The distance between the spacecraft and the Sun as it approaches the comet will be about 600 million or 4 AU (1 AU or 1 Astronomical Unit is equal to 150 million km, the mean distance between Earth and the Sun).

Rosetta has swung by Earth twice and Mars once, performing gravity-assist manoeuvres, that gave it the necessary boost to continue on its journey. The third and last Earth swing-by is scheduled for November 2009. The spacecraft will also fly by two asteroids and study them on the way: (2867) Steins in September this year and (21) Lutetia in June 2010. As it closes in on (2867) Steins in September, Rosetta will have travelled about 3700 million km and will be 2.1 AU from the Sun.

After its last planetary swing-by on 13 November last year, Rosetta headed towards the asteroid belt located between the orbits of Mars and Jupiter. On 27 March 2008, the spacecraft switched to its near-Sun hibernation mode for a period of three months. During this phase, a few subsystems were put into a dormant state to optimise their lifetime (as this is only the beginning of the mission’s science phase).

Next stop, Steins

This is an artist’s rendition of Rosetta’s closest approach to Earth during its second swing-by of our planet on 13 November 2007. The image shows the fly-by configuration as seen from above.

The second Earth swing-by in November 2007 was Rosetta’s third major step on its 10-year journey to comet 67/P Churyumov-Gerasimenko. In swinging by Earth, the spacecraft gained the right amount of energy from Earth’s gravity to save precious fuel for later on.

Closest approach during the second Earth swing-by took place on 13 November 2007 at 21:57 CET, when Rosetta will sped past at 45 000 km/h (about 12.5 km/s) relative to Earth. At this time, Rosetta was 5301km above the Pacific Ocean, south-west of Chile, at 63° 46’ south and 74° 35’ west.

During this Earth swing-by, a few experiments both on the orbiter and the Philae lander were activated for calibration, science measurements and imaging. Rosetta first pointed towards Earth and then to the Moon for the observations.

Credits: ESA (Image by C. Carreau)

Rosetta will be closest to (2867) Steins at 20:58 CEST on 5 September, at a distance of 800 km. The spacecraft will zoom past at a relative speed of 8.6 km/s.

In preparation for the fly-by, all the instruments will be checked and tested through the month of July. Between 4 August and 4 September, spacecraft operators will conduct an optical navigation campaign: Steins will be tracked by the on-board cameras and the observations will be used to refine the knowledge of its orbit which has been derived only from ground-based measurements so far.


Asteroids are samples of the Solar System’s material at different stages of evolution, and studying them helps scientists understand the origin and evolution of Earth and of our planetary neighbourhood.

(2867) Steins is a relatively rare type of asteroid. Based on ground-based observations it has been classified as an E-type asteroid, composed mainly of silicates and basalts, but its properties are not known in detail. For these reasons, it has been selected as one of the two asteroids that Rosetta will study, from among those that were within reach of the mission. The knowledge gained from the measurements will add to our knowledge of the composition and evolution of E-type asteroids and will also supplement and help interpret future ground-based data on asteroids.

Making most of the fly-by

Rosetta’s 12-year expedition began in February 2004, with an Ariane-5 launch from Kourou in French Guiana. The three-tonne spacecraft was inserted into a parking orbit before being sent on its way towards the outer Solar System.

Rosetta’s deep space odyssey will comprise lengthy periods of inactivity, punctuated by relatively short spells of intense activity – the encounters with Mars, Earth and asteroids.

Ensuring that the spacecraft survives the hazards of travelling through deep space for more than 12 years is therefore one of the great challenges of the mission.

Credits: ESA/AOES Medialab

The observations will be used to characterise the asteroid and its environment and to test Rosetta’s instruments, most of which will be active during the fly-by.


The science objectives of the fly-by observations are as follows:

• To characterise the asteroid by studying its physical and chemical properties
• To study its kinematic properties (its rotation, for example)
• To study the asteroid’s surface and to perform comparative studies with surfaces of other asteroids in order to understand differences between asteroid types
• To study the interaction between the solar wind and the asteroid
• To study the asteroid’s environment, including the presence of natural satellites, the magnetic and electrical properties of the immediate environment, and gas or dust orbiting the asteroid

The fly-by will push Rosetta to its design limits, especially owing to the fast rotation of the spacecraft around the time of closest approach. The manoeuvre is necessary to ensure that the asteroid will stay in the field of view of the instruments. In view of this, a full in-flight simulation of the fly-by was performed on 24 March 2008. The tests were successful, confirming the spacecraft’s robustness.


Major journey milestones

Launch 2 March 2004
First Earth swing-by 4 March 2005
Mars swing-by 25 February 2007
Second Earth swing-by 13 November 2007
Steins fly-by 5 September 2008
3rd Earth swing-by 13 November 2009
Lutetia fly-by 10 June 2010
Comet rendezvous manoeuvres 22 May 2014
Lander delivery 10 November 2014
Escorting the comet until Dec 2015
End of mission December 2015

For more information:

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

Rita Schulz, ESA Rosetta Project Scientist
Email: Rita.Schulz @ esa.int

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

Source: ESA - Rosetta

[Waspie_Dwarf]

Intense preparations for Rosetta's asteroid visit

24 July 2008

An artist's impression of the Rosetta spacecraft scheduled for launch in 2004. Rosetta will rendezvous with a comet in 2014.

Engineers at ESA's European Space Operations Centre in Germany are working to a tight deadline as ESA's comet-chasing spacecraft Rosetta swings steadily closer to a spectacular asteroid fly-by on 5 September 2008.

Preparations for the fly-by of asteroid Steins are ongoing - and intensifying - for the men and women of the Rosetta Flight Control Team based at ESOC, where spacecraft operations are controlled from the Rosetta Dedicated Control Room (DCR).

The 5-person team of Spacecraft Operations Engineers is led by veteran Spacecraft Operations Manager (SOM) Andrea Accomazzo, and is directly supported by a pool of Spacecraft Controllers (referred to locally as 'spacons') who are shared between ESA's three deep-space missions, Rosetta, Mars Express and Venus Express. The Flight Control Team is in turn supported by several extended teams of specialists based at ESOC, including experts from Flight Dynamics, Software Support, Mission Analysis and Ground Station Operations.

Rosetta will pass by Steins at a relative speed of 8.6 km/s and will make her closest approach to (2867) Steins at 20:58 CEST, 5 September, at a distance of 800 km.

ESOC engineers work closely with Science Operations Centre

ASylvain Lodiot, Rosetta Spacecraft Operations Engineer

Credits: ESA

Before then, a series of demanding activities must take place in the right order and on schedule. Between 9 July and 3 August, ESOC engineers will work closely with the Rosetta Science Operations Centre (SOC), at ESA's European Space Astronomy Centre, near Madrid, Spain, to check-out and verify the spacecraft's 11 instruments.

The Flight Control Team will conduct simulations on 7, 14 and 21 August to confirm and practise procedures and reactions to any unforeseen problems that may occur.

"We will practise placing Rosetta's cameras into their proper tracking mode and, as we get closer to Steins, we will actually start tracking the asteroid, and use the data to refine our estimates of Steins' orbit and how to adjust Rosetta's trajectory," said Sylvain Lodiot, an engineer assigned to Rosetta.

A series of Trajectory Correction Manoeuvres (TCM) - in which the probe's thrusters can be fired to align its trajectory relative to Steins - are possible on 14 and 28 August as well as 2, 4, and 5 September. The last TCM slots come just 36 and 12 hours before closest approach; the tight telecommand uplink windows for these must be tested and practiced.


Timing for mission control activities becomes crucial

Shortly before the fly-by, the team will have to upload command sets to Rosetta for the fly-by itself; this must also be exercised during the simulations.

As the spacecraft closes on Steins, the timing of mission control activities will become much more critical.

The team have adopted an innovative strategy of defining 'payload break points' - basically, a series of default payload configurations at a given point in time - that can be used to recover payload operations if any anomalies arise.

"We have break points set to the times of the Trajectory Control Manoeuvres and one set just 2 hours prior to closest approach. This work has involved a lot of cooperation between us, the science and flight dynamics teams," said Lodiot.

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

Rosetta above Mars - seen by the Philae lander during Mars fly-by, February 2007
Intense science observations will begin some 2 hours prior to closest approach and run until about 2 hours after. Images gathered by OSIRIS and VIRTIS will be among the first to be downloaded after fly-by, and should be available on 6 September if all goes nominally.

Rosetta's Philae lander will also be activated for the fly-by, under control by the Philae lander control room at the German Aerospace Center (DLR) establishment in Cologne. During this phase of the mission, the control room will support three experiments, ROMAP, MUPUS, and SESAME (see links at right for more details on instruments on board Rosetta and Philae).


Close ESA/NASA cooperation for telecommunications

Ground station coverage is a critical factor in the coming weeks, as the spacecraft begins to generate data gathered from pre-approach asteroid tracking, as data is generated during fly-by and for ranging and navigation calculations throughout. On 5 September, when Rosetta and Steins are about 360 million kms from Earth, the one-way radio communication time delay will be 1200 seconds, or 20 minutes.

The Canberra Deep Space Communication Complex features a number of antennas that are required daily to receive from, and transmit information to a wide variety of spacecraft.

Credits: NASA

The Canberra Deep Space Communication Complex, Australia
Beginning in August, Rosetta has been assigned two passes per week via ESA's ESTRACK deep space station at New Norcia, Australia, plus three passes per week via NASA's DSN network, with various stations being assigned from the Agency's deep space complexes at Goldstone, USA, Madrid, Spain, and Canberra, Australia.

The number of passes provided from both ESA and NASA stations will steadily increase, with ESA's second 35m deep space antenna at Cebreros, Spain, joining in September.

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

"Toward the end of August, we have communication slots with Rosetta every day of the week, and around fly-by, we will be in more or less continuous contact with the spacecraft via New Norcia, Cebreros and Goldstone," said Lodiot.

During the critical days of 4 and 5 September, the Rosetta control team will split into 'Blue' and 'Red' halves, with each sharing responsibly for full-time operations in the Dedicated Control Room.


Blue Team will cover from the evening of 4 September until early on 5 September, when the final critical TCM may be necessary, while Red Team will cover the the day of 5 September; everyone will be present for the actual fly-by at 20:58 CEST.


"Although the focus is on the core Flight Control Team, we couldn't function at all without support from the rest of ESOC or from our colleagues on ESA's science teams. In particular, the Flight Dynamics teams at ESOC are instrumental," said Operations Manager Accomazzo. "They are the ones who calculate where the spacecraft is and tell us where to go."

Source: ESA - Rosetta

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Rosetta starts tracking asteroid Steins

4 August 2008

Asteroid (2867) Steins - artist's impression

Credits: ESA

Heading toward its first target-asteroid, (2867) Steins, ESA's Rosetta spacecraft has started using its cameras to visually track the asteroid and eventually determine its orbit with more accuracy.

Rosetta started the optical navigation campaign on 4 August 2008, at a distance of about 24 million km from Steins; the campaign will continue until 4 September, when the spacecraft will be approximately 950 000 km from the asteroid.

"The orbit of Steins, with which Rosetta will rendezvous on 5 September, closing to a distance of 800 km, is only known thanks to ground observations, but not yet with the accuracy we would like for the close fly-by," said Gerhard Schwehm, Rosetta Mission Manager based at ESA's European Space Astronomy Centre (ESAC), near Madrid, Spain.


“We will be able to use the first data set for the trajectory correction manoeuvre planned for mid-August.”

Optical tracking to better understand Steins' orbit

The purpose of the tracking campaign is to reduce the error in our knowledge of Steins' orbit from about 100 km to only within 2 km (in the direction perpendicular to the flight direction of the asteroid, called 'cross-track'), so as to allow Rosetta an optimal approach to this celestial body.

Both Rosetta's navigation cameras and the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) imaging system will be used to track Steins.

"For the first three weeks of the campaign, however, only the powerful eyes of OSIRIS will actually be able to spot the asteroid, which will look only like a dot in the sky," said Andrea Accomazzo, Rosetta Spacecraft Operations Manager at ESA's European Space Operations Centre (ESOC), Darmstadt, Germany.

The Rosetta orbiter - spacecraft design

Rosetta resembles a large aluminium box whose dimensions are 2.8 x 2.1 x 2.0 metres. The scientific instruments are mounted on the 'top' of the box – the Payload Support Module – while the subsystems are on the 'base' or Bus Support Module.

Credits: ESA/AOES Medialab

"Starting 11 days before closest approach, as the distance with Steins decreases, the two Rosetta navigation cameras will finally be able to see and track the asteroid, too," he added.

For the first three weeks of the campaign, Rosetta will image Steins twice a week and then, starting on 25 August, it will take images daily until 4 September.

The Steins orbital information gathered during the tracking campaign will be used to adjust Rosetta's trajectory for the 5 September fly-by. "We will already be able to use the first data set for the trajectory correction manoeuvre planned for mid-August," said Sylvain Lodiot, from the Rosetta Flight Control Team at ESOC.


"As Rosetta's distance from Steins decreases, the precision of the measurements for Steins' orbit will increase even further, allowing us the best possible trajectory corrections later on before closest approach, especially in early September."

OSIRIS to obtain Steins' 'light curves'

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

Rita Schulz, Rosetta Project Scientist based at ESA's European Space Research and Technology Centre (ESTEC), Noordwijk, the Netherlands, explained that this is the first time in the Rosetta mission that the OSIRIS scientific instrument is being used for tracking purposes.

"But OSIRIS will also take this opportunity to obtain 'light curves' of Steins. Light curves tell us how the asteroid brightness varies with time, providing us with additional preparatory information about the asteroid, such as better knowledge of its shape and rotation characteristics," she said.


The optical navigation campaign follows a series of active check-outs of Rosetta's scientific instrumentation, which lasted from 5 July to 3 August this year. A mission milestone for Rosetta, these activities also verified the instruments' readiness for the fly-by observations, and allowed on-board software modifications to be implemented for several of them.


More information

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

Rita Schulz, ESA Rosetta Project Scientist
Email: Rita.Schulz @ esa.int

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

Source: ESA - Rosetta

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Perfect sight: Rosetta cameras track asteroid target

18 August 2008

Asteroid Steins imaged by Rosetta's OSIRIS camera on 7 & 11 August 2008. On these dates, Rosetta was approximately 21 million and 19 million kms, respectively, from asteroid Steins.

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

On 14 August, Rosetta conducted a successful trajectory correction manoeuvre using data obtained from the Agency's first-ever optical tracking of an asteroid target, (2867) Steins. Images from the spacecraft's cameras were used to calculate the asteroid's location and optimise its trajectory for fly-by next month.

Rosetta's first major correction manoeuvre in the approach phase took place while the spacecraft was just less than 17 million km from Steins. The spacecraft’s thrusters burned continuously for approximately 2 minutes, starting at 13:42 CEST (Central European Summer Time). This achieved a change in Rosetta’s speed with respect to Steins of 12.8 cm/sec.

This tiny change in speed, though, will be enough to correct the spacecraft's 5 September Steins fly-by distance by 250 km. Prior to this manoeuvre, the spacecraft’s trajectory would have led it too close to the asteroid at the time of closest approach; to be compatible with spacecraft performance, Rosetta must be no closer than 800 km from Steins.

Daily imaging

On its way to comet 67/P Churyumov-Gerasimenko, Rosetta is targeting two asteroids for study: (2867) Steins, on 5 September 2008, and (21) Lutetia on 10 June 2010.

Credits: ESA/AOES Medialab

Rosetta's OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) scientific camera and the on-board star-tracker navigational cameras began twice-weekly imaging periods on 4 August, recording 52 images of Steins. Flight dynamics specialists at ESA's European Space Operations Centre (ESOC) used these to calculate the 14 August thruster burn. Optical tracking of Steins will continue twice per week until 22 August, and will intensify with imaging slots daily between 25 August and 4 September - when the asteroid will be much closer.


"The closer we get to Steins, the more accurate our knowledge of the asteroid's position relative to Rosetta will be," said Trevor Morley, leading the Rosetta Flight Dynamics Orbit team at ESOC, Darmstadt, Germany. "Thanks to Rosetta's cameras, we will obtain increasingly precise measurements that will allow us to adjust again, if necessary, Rosetta's orbit for an optimal asteroid encounter."


Slots for possible future trajectory manoeuvres prior to the rendezvous with Steins are set for 28 August and 2, 4 and 5 September.

Exceptional results

According to Andrea Accomazzo, Rosetta Spacecraft Operations Manager at ESOC, the optical navigation campaign is providing exceptional results, far exceeding expectations.

Asteroid Steins is the tiny white dot in the centre of the two concentric circles, as seen by Rosetta's Navigation Camera "A" in the morning of 4 August, when the spacecraft was approximately 24 mn kms from Steins; this was only the first in a series of steadily better images as Rosetta closed the range.

On this day, the asteroid was still fainter than the nominal detection limit of the camera. The larger surrounding white spots are stars; almost all other small white spots are artefacts from the camera's CCD sensor (known as 'pixel dark current'), which considerably degrades the quality of the image. The asteroid was found within 3 arcseconds of its predicted position.

Credits: ESA

"Both of Rosetta's navigation cameras could already see the asteroid from the very beginning of the tracking campaign - despite the long distance from Steins, and contrary to what we expected," Accomazzo said.

"The exceptional quality of the OSIRIS scientific camera – namely its angular resolution – provided data as accurate as expected, and made our current trajectory calculations very precise."


Rosetta's optical tracking campaign marks history for ESA's spacecraft operations. "It is the first time ever that we have used optical instrumentation on board a scientific spacecraft for navigation, as opposed to the usual techniques based on analysing radio signals," said Morley. "The exceptional results are really encouraging and we look forward to using this technique again in the future, if and when it is possible."

The Steins optical tracking campaign will continue right up to Rosetta's closest approach, now expected at 20:58 CEST, 5 September 2008.


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

Rita Schulz, ESA Rosetta Project Scientist
email: Rita.Schulz [@] esa.int

Source: ESA - Rosetta

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Rosetta Steins fly-by timeline

2 September 2008

This diagram shows the approach of Rosetta’s spacecraft to asteroid (2867) Steins on 5 September 2008. Steins is located in the main asteroid belt between the orbits of Mars and Jupiter. The encounter took place during Rosetta’s first incursion into the main asteroid belt while on its way to Comet 67P/Churyumov-Gerasimenko.

Credits: ESA, image by C.Carreau

The Rosetta spacecraft control room is buzzing with anticipation as Rosetta closes in on asteroid 2867 Steins. The fly-by timeline includes a series of critical events, culminating with closest approach - expected at 20:58 CEST, 5 September 2008.

At the time of closest approach, Rosetta is planned to be 800 km from the asteroid, passing by at a speed of 8.6 km/s relative to Steins. Both Rosetta and Steins will be illuminated by the Sun, providing an excellent opportunity for science observations.

Between 40 and 20 minutes before closest approach, Rosetta will be flipped and the spacecraft will switch to a specially designed asteroid fly-by mode, an optimal configuration that supports the intensive observation and tracking activity of the on-board instruments.


Although most scientific observations will take place in the few hours around closest approach, several instruments will be switched on for a longer time around the event.

ESA’s Rosetta spacecraft flew by asteroid (2867) Steins on 5 September 2008 at 20:58 CEST, ground received time (= spacecraft time CEST + 20 minutes), with a closest approach distance of 800 km.

Steins is Rosetta’s first nominal scientific target. The spacecraft encountered the asteroid in the course of its first incursion into the main asteroid belt located between the orbits of Mars and Jupiter, while on its way to Comet 67P/Churyumov-Gerasimenko.

The study of asteroids is extremely important because they represent a sample of Solar System material at different stages of evolution – key to understanding the origin of our own planet and of our planetary neighbourhood.

Credits: ESA, image by C.Carreau

ESA's Cebreros deep space antenna (DSA 2) in Cebreros, Spain, will be used for communications with Rosetta in the two days preceding closest approach. When the spacecraft is not visible from Cebreros or New Norcia, NASA's DSN (Deep Space Network) ground stations at Goldstone, Canberra and Madrid will provide support for tracking and for science operations.


Around closest approach, Rosetta will be 2.41 Astronomical Units, or about 360 million km, from Earth. Radio signals sent to and from the spacecraft will have a 20 minute one-way travel time.


Timeline of nominal fly-by events

Note: All event times are stated in ground time, CEST.

Editor's note

An expanded version of the timeline appears in the Rosetta blog.

Source: ESA - Rosetta

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(2867) Steins getting closer

5 September 2008

Steins approaching

This animation is composed of images used for the optical navigation campaign as Rosetta followed (2867) Steins, refining its trajectory to close in on the asteroid. They were taken daily by Navigation Camera A between 25 August and 3 September.

The images have been adjusted so that the stars are of roughly the same brightness from day to day, although the exposure times decrease and Steins becomes brighter as Rosetta appoaches.

Source: ESA - Rosetta