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Philae finds life's building blocks on comet's surface

Elizabeth Howell, News Writer
Nov 19, 2014, 5:22 UTC

Sen—In an exciting find for the story of the origin of the Solar System, the Philae lander discovered organic molecules on the surface of its target comet, scientists said. Organics are considered the building blocks of life and a key target for Mars and other Solar System locations.

While a comet is not a friendly spot for life, one theory for how life arose on Earth comes from comets and other small bodies seeding our surface with organic molecules over millions of years. And there is more about the Solar System's history embedded in 67P/Churyumov–Gerasimenko, according to early science results.

The Philae lander touched down on Comet 67P on Wednesday (12 November), hopping twice in two hours before settling in a spot east of its prime landing location. With the lander stuck on its side and receiving only 1.5 hours of sunlight a day, scientists worked frantically to get work done in the approximately 60 hours available in the lander's batteries. More data collection could come later if the solar panels recharge the spacecraft.

Underneath a layer of dust is a surface so icy and hard that Philae's drill only penetrated a few millimetres. These results came from the MUPUS (Multi-Purpose Sensors for Surface and Sub-Surface Science) instrument.

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The primary landing site for Philae in context with the rest of Comet 67P/Churyumov-Gerasimenko. Credit:ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

"Although the power of the hammer was gradually increased, we were not able to go deep into the surface," stated MUPUS research team leader Tilman Spohn from the DLR Institute of Planetary Research. The scientists acknowledged that Philae's awkward position may have contributed to the penetration problem, with Spohn adding the comet was a "tough nut to crack".

That said, other instruments did confirm a rather firm interior to the comet. First results from SESAME (Surface Electrical, Seismic and Acoustic Monitoring Experiment) detected an unexpectedly rigid inside to 67P. Additionally, the CASSE sensors in the feet of the lander had no trouble detecting the comet's first touchdown. More data from these and other experiments are expected to reveal additional properties about the interior, such as early SESAME results suggesting there is water ice.

In Philae's brief time working on the surface, it sent back several pictures to Earth that could be used later to track down the lander's location. The Rosetta Lander Imaging System (ROLIS), picked up images from its location at Philae's underside as the spacecraft made its first descent to the surface. Once the spacecraft settled in one spot, controllers turned on ROLIS again, which sent back pictures of the comet from close-up along with CIVA (Comet Infrared and Visible Analyser).

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The first, unprocessed, panoramic image from the surface of a comet taken by Rosetta’s lander Philae. A sketch shows the lander’s position. Image credit: ESA/Rosetta/Philae/CIVA

Another instrument called CONSERT (COmet Nucleus Sounding Experiment by Radio wave Transmission) worked with the orbiting Rosetta spacecraft to send radio signals through the heart of the comet. This experiment aimed to create a three-dimensional core picture, but it could be used to help triangulate Philae's position on the surface.

While the lander is sleeping right now, scientists believe it is possible it will wake up in spring or summer 2015 as more sunlight reaches the comet's surface. One advantage of Philae sitting in such a shady area is the lander is better protected from heat when 67P makes it closest approach to the Sun next year.

Meanwhile, the Rosetta spacecraft continues working in orbit above 67P and will follow the comet's changes in the next few months.