On September 29th, 2016 we learned about

Rosetta spacecraft signs off shortly before colliding with Comet 67P

Humanity’s first attempt to land a robot on a comet didn’t go exactly as planned, but that was no reason not to try again. After years of chasing the comet 67P/Churyumov–Gerasimenko, the Rosetta spacecraft is finally catching up, or rather, colliding with it in order to get a last batch of data only obtainable from a close distance. Crashing a delicate instrument into an ancient, icy rock doesn’t sound like many people’s definition of success, but the comet’s orbit was taking Rosetta further and further from the sun, making it increasingly difficult to build enough of a solar charge for normal operations. Rather than go back into sleep mode and risk losing the satellite, mission commanders opted to tie things off while gaining insights about the comet that would have otherwise been inaccessible.

Mission(s) accomplished

Over the last two years, Rosetta has already sent home mountains of data about 67P, much of which has implications for the origins of our solar system. Through various forms of measurement and documentation, the comet appears to have been created from some of the original debris from when our solar system was first formed. Samples of icy plumes spurting off the comet when it was closer to the sun found various organic molecules necessary for building amino acids. Combined with evidence for the the amino acid glycine sitting on the comet’s surface, this data elevates the hypothesis that Earth may have been “seeded” with key organic compounds by comets long ago, facilitating life as we know it.

Famously, this mission also included the misadventures of the lander Philae, which did not go very smoothly. The lander deployed, but couldn’t stick its landing, leaving it in the shadow of a boulder where it couldn’t get enough sunlight to recharge its batteries. Tidying up loose ends, Rosetta actually photographed the lander just weeks ago, allowing for the data the lander did gather to be substantiated by the reference point of it’s final location. Now Rosetta’s final measurements will provide some further closure, with some last-second samples of the comet’s “atmosphere” as well as photos of the comet that Philae couldn’t have ever offered.

Colliding with care

The final collision site was selected near a few interesting pits in the comet a couple of hundred feet across. Unlike craters from a foreign body with would mash the surface materials, they may be points where some of the icy plumes burst forth earlier in the summer. As Rosetta zooms in, it will take photos of the layers of material in the wall of the pits which will hopefully help explain more about how the comet was formed long ago. After that, the spacecraft is expected to be destroyed when contacts the comet, as it was never designed to survive an impact like this. Despite the guaranteed damage, Rosetta’s last job will be to deactivate itself as a precaution against errant transmissions causing unintended electromagnetic noise across space. In the end, the spacecraft will be able to go out with a bit of a bang, but also a quiet farewell.

…and piles of new data, of course.

Source: ESA Euronews: Rosetta heads for glorious crash-landing by European Space Agency, Rosetta Blog

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