Philae sniffs out organic molecules from the surface of 'tough nut' Comet 67P
Tuesday, November 18, 2014, 12:07 PM - The Rosetta mission's Philae lander may have only gathered data from the surface of Comet 67P for a few days before going to sleep, but scientists here on Earth are already buzzing about what the plucky robot has found there.
When Philae finally came to rest, after over two hours of bouncing around on the surface of Comet 67P/Churyumov–Gerasimenko, the European Space Agency team back here on Earth was very concerned about how long the lander would last, given the 'shady spot' it ended up in. However, unconcerned about this, the lander itself immediately got down to work, deploying as many science instruments as it could to test the environment around it.
Although it's going to take awhile to fully explore most of what Philae transmitted back to Earth, the science team at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, or DLR) is talking about some of the results so far.
A whiff of organic molecules
Upon landing, Philae was programmed to drill into the surface of the comet, collect a 'soil' sample, and return that sample to two instruments inside it for examination. There's still some questions about how much of that sequence was completed, but one of the instruments - COSAC (Cometary Sampling and Composition experiment) - sampled the thin atmosphere that was around the lander and detected organic molecules.
This isn't exactly a new discovery for comets. Back in August, a team of scientists reported that their study of Comet ISON and Comet Lemmon found hydrogen cyanide (HCN), hydrogen isocyanide (HNC) and formaldehyde (H2CO) - all organic moledules - in the atmospheres of both. Just last month, the ESA released findings from the Rosetta spacecraft that showed Comet 67P was putting off a 'stink' of chemicals that included methanol(CH3OH), carbon disulphide (CS2) and formaldehyde (H2CO).
However, the science team is still going over the data, and they may find other organic molecules in the mix.
'Tough nut' Comet 67P
Original estimates of what the surface of Comet 67P would be like included the potential for it to be quite 'soft' and 'fluffy', which is why Philae came equipped with thrusters and harpoons and such to ensure that it was able to remain attached to the comet. However, the 1-kilometre bounce that Philae performed upon its first touchdown came as a bit of a surprise, and tests following the landing procedure showed why.
According to the report from DLR, attempts to hammer a probe into the comet's surface, using the MUPUS (Multi-Purpose Sensors for Surface and Sub-Surface Science) instrument found Comet 67P to be a "tough nut to crack."
"Although the power of the hammer was gradually increased, we were not able to go deep into the surface," Tilman Spohn from the DLR Institute of Planetary Research said in a statement.
Another instrument package, SESAME (Surface Electrical, Seismic and Acoustic Monitoring Experiment) also took readings of the icy surface, projecting sound waves into it, reading electrical properties and examining dust falling back to the surface after it was disturbed by Philae's landing.
"The strength of the ice found under a layer of dust on the first landing site is surprisingly high," Klaus Seidensticker, the lead scientist for SESAME's CASSE instrument, said in the DLR press release.
Under Philae's feet
In addition to the strength of the ice that Philae encountered on its bouncing and final landing, SESAME apparently found that much it is frozen water (as opposed to frozen CO2 or other gases).
Any information about the deeper structure of the comet is going to have to wait for at least a short time, unfortunately. Both Rosetta and Philae did start up their CONSERT instruments after the landing, which beam radio waves between the two, allowing them to scan through the interior of the comet and produce a 3-dimensional map of it. However, it would seem that this experiment was the one that finally used up the last of the juice in Philae's battery on Friday, forcing it to go into hibernation, and we'll have to wait a bit longer to see if there's any results from their scans.
"We have collected a great deal of valuable data, which could only have been acquired through direct contact with the comet," Ekkehard Kührt, the Scientific Director for the Philae Lander at the DLR, said in a statement. "Together with the measurements performed by the Rosetta orbiter, we are well on our way to achieving a greater understanding of comets. Their surface properties appear to be quite different than was previously thought."