Rosetta: Space probe drops robotic lander on comet 67P

SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem.

On November 12th, after a 10-year journey, the European Space Agency's space probe, Rosetta, dropped the robotic lander Philae onto the surface of comet 67P. This is the first-ever landing on a comet. In a recent episode, we discussed Rosetta and its mission. Hear it again here. This week, we invited back Jonathan Ward, author of an upcoming book about launching the Apollo missions, and NASA-sanctioned JPL Solar System Ambassador, to discuss what we know so far from the lander. The European Space Agency has placed a six-month embargo on information, but our guest has pieced together what is available.

There was an upward-facing thruster that was supposed to push Philae onto the surface so that the ice screws on the feed could drill into the comet surface. They knew before they released the lander that the thruster wasn't working, but there was no way to fix it. There was also a set of harpoons that were supposed to anchor the lander to the comet. Those did not fire. They think that the propellant in there was not stable over the course of the 10 years. Philae's feet went through a couple of inches of soft dust and then they hit a hard surface. It looks like one of the legs may have hit a rock which caused it to tip slightly and the lander came to rest at an angle against what appears to be a cliff or a crater wall.

Among the unexpected challenges, Philae's landing site is problematic. The solar powered lander is hidden in shadow, and its exact location is unknown.

When the European Space Agency scientists realized that it wasn't getting a lot of sunlight they decided just to go ahead and run as many of the experiments as they could. They had ten instruments on the lander and they used all ten of them, and then tried to get as much of that data back as they could before the batteries finally died.

From what we know so far, results are mixed.

There's an instrument called MUPUS which is a hammer and a probe that are intended to penetrate into the comet surface and get a temperature of the comet. Unfortunately, part of that instrument was in the harpoons, and since those didn't fire, that part didn't get into the surface. The hammer had three increasing strength settings, but none of those was strong enough to be able to get through the surface of the comet. In fact there was a secret setting of 4, and even that wasn't strong enough to break through. What it did show was that, instead of being crumbly, as was initially expected, the comet surface was as hard as ice. They had a drill on board that was supposed to try to drill into the surface and bring back some material that would be dumped into a chemical analyzer oven, but apparently there was nothing but trace amounts of gas when they ran the analyzer. An instrument that was intended to measure the chemical composition of the surface of the comet also didn't work. It appears that the cover of the instrument didn't come off.

While each failure still may tell us something about the comet, Philae's successes give a tantalizing look at what we may know after the European Space Agency's embargo.

Another instrument was able to determine that there are organic molecules on the comet, and that was a very important finding. Organic molecules contain carbon and they are the building blocks of life. So the analyzer was designed to tell if these molecules are left handed or right handed.

Amino acids, in theory, can form as left or right handed, one being a mirror image of the other. Life should be compatible with either, but all life on earth is based on left handed molecules. We don't know why. Determining the handedness of the comet's organic material could give insight to the part comets may have played in seeding Earth with the building blocks of life. So what's in the future for Rosetta and Philae?

Just before the lander went silent, they commanded it lift itself up off the surface and and rotate so that once the comet gets closer to the sun it will start getting more light and maybe they'll be able to re-awaken the lander. Rosetta is going to stay in orbit around the comet as it approaches the sun over the coming year, and they're going to watch the comet begin to develop as it gets closer, gets warmer, and the ice begins to form kind of a gas cloud around the comet. At a recent on-line question-and-answer event, someone asked one of the scientists to summarize what he'd learned so far about the comet, and he said that “the main thing that I take away from this is that the comet is much more complex than I ever thought it would be.” He said, “I saw scientists who've done only comets for all of their careers staring in unbelief at the images they've been seeing from this. It makes it a really cool place where everybody has to take a step back and learn new things.

This Time Round, the theme music for SciWorks Radio, appears as a generous contribution by the band Storyman and courtesy of UFOmusic.com.