posted July 18, 2005 06:00 PM            

San Francisco Chronicle:
Comet chasers reel in dust, chart soft landing on tiny rock

When Deep Impact blasted a crater in a distant comet early this month, the tricky feat of navigation from Earth to a moving target across 83 million miles of space astonished the world -- but a European spacecraft already flying toward another comet has an even more demanding mission.

This robot vehicle, named Rosetta, is on a 10-year voyage looping across a billion miles of space in an attempt to land on its tiny target so softly that the spacecraft can photograph the comet's unknown surface and drill into it to find out what lies underneath.

posted June 16, 2006 03:55 AM            

The spacecraft will remain in Passive Cruise Mode until 26 July 2006. During the entire period, the spacecraft will be monitored on the basis of weekly ground station passes.

Operations for the Mars swing-by (February 2007) will start in August 2006, with another payload passive checkout (PC3), an intense tracking campaign around the Trajectory Correction Manoeuvre (DSM-2) in September, and the first payload Active Checkout (PC4) in November/December.

posted February 25, 2007 09:24 AM               

Rosetta successfully swings-by Mars -- next target: Earth

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.

posted February 25, 2007 09:35 AM               

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

posted November 13, 2007 10:41 AM               

From Technovelgy.com via SPACE.com:
Near-Miss Asteroid Found to be Artificial

The Minor Planet Center, the world clearinghouse for information about newly discovered asteroids, raised the alarm last week. In an email to professional observatories, they announced that a previously unknown asteroid would miss the Earth by just 5,600 kilometers.

The newly discovered space rock was given an official label by the MPC, which is run by the Smithsonian Astrophysical Observatory, Massachusetts, for the International Astronomical Union. Observations for 2007 VN84 were collected from astronomers around the world, to track the threatening celestial body. This would be one of the closest approaches ever by a sizable asteroid -- its distance away being less than half the diameter of the Earth.

Then Denis Denisenko, of Moscow's Space Research Institute (IKI), made an interesting discovery. He noticed that the incoming asteroid's track matched that of the European space probe Rosetta on a scheduled flyby of Earth.

posted November 14, 2007 10:22 AM               

• Images of Earth and Moon captured by Rosetta
  
• Cities at night: Extraordinary Rosetta images

posted September 04, 2008 04:16 PM               

Rosetta Steins fly-by timeline

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 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.

Time	-	Event
1 September
02:20	-	Instruments switched on (except OSIRIS which was already on for the navigation campaign)
4 September
07:20-11:20	-	Slot for possible trajectory correction manoeuvre (36 hours before closest approach)
13:20-18:20	-	Last opportunity to acquire images for optical navigation campaign
5 September
07:20-10:20	-	Slot for possible trajectory correction manoeuvre (12 hours before closest approach)
10:20	-	Navigation cameras switch to tracking mode - initially both used, then use CAM 'A' only (to be decided)
11:00	-	Uplink fly-by commands for asteroid fly-by mode (AFM). Includes an update to the command profile already on board & the final updated AFM commands (only if 1 CAM at least is tracking)
20:18-20:38	-	Spacecraft flip over
20:39	-	Spacecraft switches automatically to asteroid fly-by mode
20:56	-	Sun illuminates Rosetta from the back and the asteroid fully
20:58	-	Closest approach, at a planned distance of 800 km from the asteroid
22:27	-	First post-fly-by acquisition of signal (AOS) - telemetry received via NASA's Goldstone ground station
22:30	-	Start of science data download via Goldstone
6 September
12:00	-	Live streaming of Rosetta Steins fly-by press conference from the European Space Operations Centre begins
13:00	-	Images from fly-by published on ESA web
15:00	-	End of press conference streaming
16:01	-	End of reception of first set of science data

posted September 05, 2008 04:59 PM               

Rosetta Steins fly-by confirmed

The Rosetta control room at ESA's European Space Operations Centre, ESOC, received the first radio signal after closest approach to asteroid (2867) Steins at 22:14 CEST, confirming a smooth fly-by.

Closest approach took place at 20:58 CEST ground time, 20:38 CEST spacecraft time, at a distance of 800 km. Rosetta's relative speed with respect to Steins was 8.6 km/sec, or about 31 000 km/h. The exact time of closest approach will be confirmed over the next few days after a detailed analysis of telemetry data.

To optimise the science return from this historic encounter, a series of critical operations were executed before closest approach, some of which required the spacecraft flip over and change its orientation rapidly, pushing it to its design limits.

After the flip, at 20:39 CEST (ground time), Rosetta switched to the asteroid fly-by mode, during which its orientation was automatically controlled by the on-board navigation cameras. The asteroid was tracked continuously and kept it in the field of view of the imaging instruments.

At 20:48 CEST (ground time), while still in asteroid fly-by mode, Rosetta's high gain antenna was turned away from Earth and the science observations were carried out. Radio contact established again at 22:14 CEST and the first bit of telemetry was received through NASA's Goldstone antenna.

Science data download will start tomorrow morning, 6 September at about 02:00 CEST and continue through the night. Images and the preliminary results from the fly-by will be presented tomorrow at a press conference which be held at ESOC starting at 12:00 CEST. The press conference will be streamed on the web.

posted September 06, 2008 12:28 PM               

Steins: A diamond in the sky

Asteroid Steins seen from a distance of 800 km, taken by the OSIRIS imaging system from two different perspectives. The effective diameter of the asteroid is 5 km, approximately as predicted. At the top of the asteroid (as shown in this image), a large crater, approximately 1.5-km in size, can be seen. Scientists were amazed that the asteroid survived the impact that was responsible for the crater.

The first images from Rosetta's OSIRIS imaging system and VIRTIS infrared spectrometer were derived from raw data this morning and have delivered spectacular results.

"Steins looks like a diamond in the sky," said Uwe Keller, Principal Investigator for the OSIRIS imaging system from the Max Planck Institut Fuer Sonnensystemforschung, Lindau.

Visible in the image are several small craters on the asteroid, and two huge ones, one of which is 2 km in diameter, indicating that the asteroid must be very old.

The images are 50 to 60 pixels in diameter, enough to characterise the shape and other characteristics of the body of the asteroid.

Rita Schulz, Rosetta Project Scientist, said, "In the images is a chain of impact craters, which must have formed from recurring impact as the asteroid rotated. The impact may have been caused by a meteoroid stream, or fragments from a shattered small body."

The chain is composed of about 7 craters. To determine the age of the asteroid, a count of the craters on the asteroid's surface has been started (the more the number of craters, the older the asteroid). So far, 23 craters have been spotted.

From the images, scientists will try and understand why the asteroid is unusually bright, and how fine grains of the surface regolith are. This will tell them more about how the asteroid formed.

Gerhard Schwehm, Mission Manager for Rosetta said, "It looks like a typical asteroid, but it is really fascinating how much we can learn from just the images. This is our first science highlight; we certainly have a lot of promising science ahead of us. I'm already looking forward to encountering our next diamond in the sky, the much bigger Lutetia."

The OSIRIS imaging system's Wide Angle Camera (WAC) worked perfectly through the fly-by.

The OSIRIS team expects that the images that they will retrieve from the Narrow Angle Camera (NAC) will be of comparable resolution. This will add to the detailed colour information and hence to knowledge of the surface composition.

Science team members noted that the Narrow Angle Camera (NAC) appears to have switched to safe mode a few minutes before closest approach, but switched back on after a few hours. The software is programmed to switch to safe mode when certain parameter thresholds are crossed to protect the camera. The team will concentrate investigating the reasons for this anomaly once the science data has been analysed.

After analysis of the Rosetta data, Steins will be one of the best-characterised asteroids so far.

posted November 13, 2009 12:49 AM               

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

First view of Earth as Rosetta approaches home

This spectacular image of our home planet was captured by the OSIRIS instrument on ESA's Rosetta comet chaser on November 12 as the spacecraft approached Earth for the third and final swingby. Closest approach is due at 08:45 CET, 13 November 2009. Follow Rosetta's progress at ESA's dedicated Rosetta site and via the Rosetta Blog.

The image was acquired with the OSIRIS narrow-angle camera from a distance of 633 000 km on 12 November 2009 at 13:28 CET. The resolution is 12 km/pixel.

Three images with an orange, green, and blue filter were combined to create this one. The illuminated crescent is centered roughly around the South Pole (South at the bottom of the image). The outline of Antarctica is visible under the clouds that form the striking south-polar vortex. Pack ice in front of the coastline with its strong spectacular reflection is the cause for the very bright spots on the image.

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) is a wide-angle camera and a narrow-angle camera to obtain high-resolution images of the comet's nucleus and the asteroids that Rosetta passes on its voyage to Comet 67P/Churyumov-Gerasimenko. It will help in identifying the best landing sites.

posted July 09, 2010 06:45 PM               

Rosetta lines up for spectacular asteroid flyby

On 10 July, ESA's Rosetta will fly past 21 Lutetia, the largest asteroid ever visited by a satellite. After weeks of manoeuvres and a challenging optical navigation campaign, Rosetta is perfectly lined up to skim by at 3162 km at 18:10 CEST.

Rosetta is expected to pass Lutetia at a relative speed of 54 000 km/hr, when both are located some 454 million km from Earth. As Lutetia is a major scientific target of Rosetta's mission, most of the orbiter and lander instruments will be on for flyby, studying the asteroid's surface, dust environment, exosphere, magnetic field, mass and density.

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) camera system is expected to obtain visible-spectrum images before and at closest approach. The powerful imaging system is operated by the Max Planck Institute for Solar System Research, Germany. Although most scientific observations will be performed in the few hours around closest approach, several instruments will be on several days before or after.

Challenging optical navigation technique

Since 31 May, the navigation cameras and the OSIRIS scientific imaging system have been used in a challenging optical navigation campaign aimed at visually tracking Lutetia and determining its orbit with more accuracy.

Initially, images were taken twice a week; since late June, images have been taken daily and this will continue until 9 July.

The results of the optical navigation campaign have been used to programme a series of Trajectory Correction Manoeuvres (TCM), or thruster burns, to nudge Rosetta onto the optimum trajectory. After the last TCM on 18 June, analysis of the spacecraft's orbit indicated that remaining manoeuvre slots (one week, three days, 40 hours and 12 hours before flyby) will most likely not be used.

Intense preparations for a deep-space encounter

Preparations for Lutetia flyby have been underway for a number of months by scientists and engineers at ESA, the German Aerospace Center (DLR) and two dozen institutes and universities in Europe and the USA. In the past weeks, activities at the Agency, and especially within the mission's science and operations teams, have intensified.

"There are several special configurations for Rosetta, including a special 'Asteroid Fly-by Mode' in which the spacecraft can operate autonomously and use its cameras to guide its attitude. It's been a challenge, but we are looking forward to an excellent flyby," said Andrea Accomazzo, Rosetta Spacecraft Operations Manager at ESOC, ESA's European Space Operations Centre, Darmstadt, Germany.

Scientists at ESAC, ESA's European Space Astronomy Centre, in Spain, have generated a series of coordinated commands for individual instruments so that observations can be conducted autonomously as Rosetta passes the asteroid. These will be radioed up to Rosetta in advance of the flyby, which will be conducted without ground station contact.

About four hours before closest approach, mission controllers at ESOC will issue commands that will flip Rosetta over and ready the spacecraft to enter Asteroid Fly-by Mode. During this mode, the orientation of the spacecraft is automatically driven by the navigation cameras to continuously keep the asteroid in the field of view of the imaging instruments.

ESA-NASA cooperation for tracking Rosetta

Increased ground tracking support has been scheduled throughout the fly-by period. In addition to ESA's 35m deep-space stations at New Norcia, Australia, and Cebreros, Spain, NASA's 70m Deep Space Network (DSN) stations at Goldstone, California, Canberra, Australia, and Madrid, Spain, will assist in relaying commands and data. The two agencies often work together and regularly share tracking station resources.

Time-line of critical events 10 July

Note: Times shown are ground event times in Central European Summer Time (CEST = UTC/GMT + 2 hours). Spacecraft event time is 25 mins and 21 secs earlier. All times are estimates and may change.

Watch the live fly-by webcast from ESA/ESOC, 10 July 2010, starting 18:00 CEST.

Time	Event
00:00:00	Start of tracking - NASA/DSN Goldstone (GDS)
00:25:05	Start - Rosetta's NAVCAM asteroid tracking
05:30:00	End of tracking - NASA /DSN Goldstone (GDS)
05:33:00	Start of tracking - ESA/ESTRACK New Norcia station (NNO)
08:00:00	Final telecommands for flyby ready from ESA Flight Dynamics team
10:00:00	Uplink of updated final fly-by commands
10:20:00	Start of tracking - NASA/DSN Canberra (CAN)
12:20:00	End of tracking - NASA/DSN Canberra (CAN)
13:05:00	Start of tracking - ESA/ESTRACK Cebreros (CEB) & NASA/DSN Madrid (MAD)
14:30:00	End of tracking - ESA/ESTRACK Cebreros station (CEB)
15:26:00	End of tracking - ESA/ESTRACK New Norcia station (NNO)
13:50:07	Start Rosetta flip manoeuvre
14:30:07	End Rosetta flip manoeuvre
15:10:07	Start asteroid closed-loop tracking - Rosetta on self-navigation
18:00:00	Start media event live from ESA/ESOC
18:05:07	Stop - radio communications via high-gain antenna - Loss of signal (earliest)
18:10:07	Closest approach to Lutetia
18:20:07	End asteroid closed-loop tracking
18:45:07	Resume radio communications via high-gain antenna - Acquisition of signal (latest)
18:47:00	Media event pause
20:05:35	Start science data downlink
23:00:00	Resume media event - Science team presents data
23:45:00	End media event
23:55:00	End of tracking - NASA/DSN Madrid (MAD)

posted July 10, 2010 11:58 AM               

First pre-flyby images now available

Largest view of Lutetia shows asteroid at a distance of 80,000 km.

Credit: ESA

posted July 10, 2010 05:14 PM               

Rosetta triumphs at asteroid Lutetia

Asteroid Lutetia has been revealed as a battered world of many craters. ESA's Rosetta mission has returned the first close-up images of the asteroid showing it is most probably a primitive survivor from the violent birth of the Solar System.

Credit: ESA

Lutetia at Closest approach.

The flyby has been a spectacular success with Rosetta performing faultlessly. Closest approach took place at 18:10 CEST, at a distance of 3162 km.

The images show that Lutetia is heavily cratered, having suffered many impacts during its 4.5 billion years of existence. As Rosetta drew close, a giant bowl-shaped depression stretching across much of the asteroid rotated into view. The images confirm that Lutetia is an elongated body, with its longest side around 130km.

The images come from OSIRIS instrument, which combines a wide angle and a narrow angle camera. At closest approach, details down to a scale of 60 metres can be seen over the entire surface of Lutetia.

Credit: ESA

At a distance of 36000km the OSIRIS Narrow Angle Camera (NAC) took this image catching the planet Saturn in the background.

"I think this is a very old object. Tonight we have seen a remnant of the Solar System's creation," says Holger Sierks, OSIRIS principal investigator, Max Planck Institute for Solar System Research, Lindau.

Rosetta raced past the asteroid at 15 km/s completing the flyby in just a minute. But the cameras and other instruments had been working for hours and in some cases days beforehand, and will continue afterwards. Shortly after closest approach, Rosetta began transmitting data to Earth for processing.

Lutetia has been a mystery for many years. Ground-based telescopes have shown that the asteroid presents confusing characteristics. In some respects it resembles a C-type asteroid, a primitive body left over from the formation of the Solar System. In others, it looks like an M-type asteroid. These have been associated with iron meteorites, are usually reddish in colour and thought to be fragments of the cores of much larger objects.

The new images and the data from Rosetta's other instruments will help to decide but not tonight. Compositional information will be needed for that.

Credit: ESA

Zoom in on a possible landslide and boulders at the highest resolution.

Rosetta operated a full suite of instruments at the encounter, including remote sensing and in-situ measurements. Some of the payload of its Philae lander were also switched on. Together they looked for evidence of a highly tenuous atmosphere, magnetic effects, and studied the surface composition as well as the asteroid's density. They also attempted to catch any dust grains that may have been floating in space near the asteroid for on-board analysis. The results from these instruments will come in time.

The flyby marks the attainment of one of Rosetta's main scientific objectives. The spacecraft will now continue to its primary target, comet Churyumov-Gerasimenko. It will rendezvous with the comet in 2014, mapping it and studying it. It will then accompany the comet for months, from near the orbit of Jupiter down to its closest approach to the Sun. In November 2014, Rosetta will deploy Philae to land on the comet nucleus. "Wunderbar!" says David Southwood, ESA Director of Science and Robotic Exploration, "It has been a great day for exploration, a great day for European science. The clockwork precision is a great tribute to the scientists and engineers in our Member States in our industry and, not least, in ESA itself. Roll on 2014 and our comet rendezvous."

But for now, analysing the Lutetia data will now become the focus for the Rosetta instrument teams. Just twenty-four hours ago, Lutetia was a distant stranger. Now, thanks to Rosetta, it has become a close friend.