Rosetta Comet Landing: Success!

Chuck Bednar for – Your Universe Online
UPDATE: Wednesday, November 12, 2014 (12:15 p.m. CST)
John Grunsfeld, astronaut and associate administrator for NASA’s Science Mission Directorate in Washington, issued this statement about the successful comet landing by the European Space Agency’s Rosetta spacecraft:

“We congratulate ESA on their successful landing on a comet today. This achievement represents a breakthrough moment in the exploration of our solar system and a milestone for international cooperation. We are proud to be a part of this historic day and look forward to receiving valuable data from the three NASA instruments on board Rosetta that will map the comet’s nucleus and examine it for signs of water.

“The data collected by Rosetta will provide the scientific community, and the world, with a treasure-trove of data. Small bodies in our solar system like comets and asteroids help us understand how the solar system formed and provide opportunities to advance exploration. We look forward to building on Rosetta’s success exploring our solar system through our studies of near earth asteroids and NASA’s upcoming asteroid sample return mission OSIRIS-REx. It’s a great day for space exploration.”
UPDATE: Wednesday, November 12, 2014 (10:15 a.m. CST)
Today’s historic comet-landing mission has come to a successful conclusion, as the ESA confirmed at 11:03am EST via its Twitter account that it had received a signal from Philae on the surface of comet 67P/Churyumov-Gerasimenko (67P/C-G).
Furthermore, Sarah Knapton of The Telegraph noted that the probe has successfully secured itself to the surface of the comet. Philae’s flywheel has been switched off, and in the next few moments, it will begin using its CIVA-P panoramic imaging to begin capturing the first images ever obtained from the surface of a comet.
UPDATE: Wednesday, November 12, 2014 (9:00 a.m. CST)
Earlier this morning, shortly after separating from Rosetta, the Philae lander captured the following picture of its mothership. According to the ESA, the image was taken using the probe’s CIVA-P imaging system and depicts one of the orbiter’s 14 meter-long solar arrays.

Image Above Credit ESA/Rosetta/Philae/CIVA
The image was stored onboard the lander until the radio link was established with Rosetta, which occurred approximately two hours after separation, and then relayed to Earth. As for the probe itself, Philae is said to be proceeding as planned. Its landing legs have been deployed and it should reach the comet’s surface in about an hour.
UPDATE: Wednesday, November 12, 2014 (5:30 a.m. CST)
ESA mission control personnel have confirmed that they were able to successfully re-establish contact with Philae and Rosetta at 12:07 CET (6:07 am EST). The lander is continuing its descent onto the surface of comet 67P/C-G (a process which is expected to take a total of seven hours) and should be providing the first images from the separation process shortly.
ORIGINAL: Wednesday, November 12, 2014 (4:58 a.m. CST)
In just a few short hours, the ESA Rosetta Mission’s Philae probe is scheduled to touchdown on comet 67P/Churyumov-Gerasimenko, capping off a decade-long mission and making history as the first spacecraft ever to successfully complete such a landing.
ESA officials confirmed shortly after 4 am EST that Philae had successfully separated from Rosetta and was en route to 67P/C-G. The probe should establish a communications link with Rosetta and send its first signal approximately two hours after separation. Once the connection is established, Philae will relay a status report and the first batch of science data.
Prior to separation, the lander underwent a series of crucial go/no-go checks overnight to ensure the mission was on track and that the probe was operating normally. During the fourth and final series of checks, an issue was discovered with Philae’s active descent system, which provides a thrust to avoid rebound at the moment of touchdown.

The ESA explained that the active descent system will not be able to be activated, and that Philae’s landing gear will have to absorb the force of the impact while the ice screws in each of its feet and a harpoon system work to secure the probe to the surface. At the same time, the thruster on top of the lander is expected to push it downward, effectively servicing as a counterbalance to the impulse of the harpoon imparted in the other direction.
Philae is expected to arrive sometime around 10:35am EST, and officials with the agency should receive confirmation of the landing approximately 30-40 minutes later. During its journey, the lander is scheduled to take measurements of the environment surrounding the comet, as well as capture images of the final moments of descent, the ESA said.
As BBC News science correspondent Jonathan Amos pointed out on Tuesday, the mission’s success is far from guaranteed. The rubber duck-shaped comet is “a strange landscape containing deep pits and tall ice spires,” and the landing site itself is “far from flat,” he explained. “Philae could bash into cliffs, topple down a steep slope, or even disappear into a fissure.”
Despite the risks, ESA Rosetta mission manager Fred Jansen told Amos and other members of the media that he was very hopeful that the mission’s outcome would be a positive one. Speaking from ESA mission control in Darmstadt, Germany, he said, “We’ve analyzed the comet, we’ve analyzed the terrain, and we’re confident that the risks we have are still in the area of the 75 percent success ratio that we always felt.”
Assuming it can successfully land on 67P/C-G, Philae will then attempt to capture the first-ever images from the surface of a comet, NASA said in a statement earlier this month. Afterwards, the probe will begin drilling into the comet’s surface in order to study its composition, and to get an up-close look at any changes that occur as its exposure to the sun varies.
Philae will be able to remain active on the comet’s surface for roughly 2 1/2 days. Rosetta, on the other hand, will maintain orbit around 67P/C-G through the end of next year. The spacecraft will use a suite of 16 instruments to perform ongoing analysis of the comet as it approaches the sun, and then moves further out into deep space.
Rosetta originally launched in March 2004, spending a total of 957 days in a hibernation-like state as it traveled through space, officials at the US space agency added. It was reactivated in January in order to prepare for an August arrival in orbit around 67P/C-G, and upon its arrival it began capturing images of various features on visible areas of the comet.
The location of the landing attempt, originally known as Site J, was officially renamed Agilkia on November 4. The new moniker – which was selected as part of a contest sponsored by the ESA and the German, French and Italian space agencies – is in honor of Agilkia Island, an island located on the Nile River in southern Egypt, the agency noted.

Image Above: What does Philae do during descent? Credit: ESA/ATG medialab
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