Tuesday, September 6, 2016

Philae Lander Found Wedged in ‘Dark Crack’ on Comet 67P

This series of photos shows exactly where Philae lnded on Comet 67P. Photo Credit: ESA

After months of poring over images to search for the precise landing location of the lost Philae lander, European Space Agency (ESA) scientists finally located it with the Rosetta orbiter’s high-resolution camera. The tiny spacecraft was seen to be wedged in a “dark crack” on the smaller lobe of Comet 67P/Churyumov-Gerasimenko.

The high-resolution images were taken Sept. 2 by Rosetta’s OSIRIS narrow-angle camera at a distance of 1.7 miles (2.7 kilometers). They show the main body of Philae as well as two of its three landing legs. The pictures also prove the orientation of the spacecraft and why communications with it were so difficult.

“With only a month left of the Rosetta mission, we are so happy to have finally imaged Philae, and to see it in such amazing detail,” said Cecilia Tubiana of the OSIRIS camera team. She was the first person to see the images when they were downloaded Sept. 4.

Philae was the lander portion of the Rosetta mission to the Comet 67P. It detached from the spacecraft Nov. 12, 2014, and made an hours-long descent toward the surface of an area called Agilkia. The plan was for the spacecraft to deploy harpoon to anchor itself to avoid bouncing away in the extremely low surface gravity.

However, there was a malfunction and the harpoons didn’t fire allowing the spacecraft to bounce not once, but twice before settling to its present location – an area called Abydos.

After sending data for three days, the batteries on board Philae were drained and could not be recharged quickly due to the shadows of the features around it. As such, it automatically went into hibernation. It woke up again to communicate ever-so-briefly in June and July of 2015. As the comet got closer to the Sun, more power was available to charge what little of the spacecrafts solar panels were exposed to light.

It took many months of searching and until the recent images were released, the exact location was not known. Radio signals from Philae centered the location down to an area of around a few tens of meters. A low-resolution image released Nov. 6, 2015, was the best candidate the team had, but were unable to point the high-resolution camera in that location until recently.

“After months of work, with the focus and evidence pointing more and more to this lander candidate, I’m very excited and thrilled that we finally have this all-important picture of Philae sitting in Abydos,” said ESA’s Laurence O’Rourke, who has been coordinating the search efforts over the last number of months.

Scientists were hoping to find out exactly what happened to the lander before the end of the Rosetta mission in order to put Philae’s three days worth of science into context.

“Now that the lander search is finished we feel ready for Rosetta’s landing, and look forward to capturing even closer images of Rosetta’s touchdown site,” said Holger Sierks, the principal investigator of the OSIRIS camera.

The Rosetta orbiter is currently scheduled to descend to the comets surface at the end of September 2016. The spacecraft is not expected to survive the comets journey back to the outer solar system. As the Sun will be much farther away, the decreased solar power will not be enough to power the probes heaters.

As such, the descent will be a one-way mission to study the comet from extremely close up. In particular, the science team wants to to study open pits in the Ma’at region in hopes the observations will reveal information about the comets interior structure.

Rosetta was launched March 2, 2004 atop an Ariane 5 rocket. After spending 10 years catching up to Comet 67P using various gravity-assists of Earth and Mars to sling it toward its destination. Finally, the spacecraft achieved orbit around the 2.7-mile (4.3 kilometer) wide comet on Sept. 10, 2014.

On Sept. 30, 2016, Rossetta will begin its final descent. Communications with the spacecraft will cease once it reaches the surface, officially ending the mission.

Written by: Derek Richardson
Original source: spaceflightinsider.com

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