On Friday (30 September 2016) the European Space Agency’s Rosetta mission ended by crashing the space probe into comet 67P. This was done deliberately. With the comet moving further and further from the Sun, Rosetta’s solar panels were getting to the point where they could not supply enough power to the spacecraft to operate its instruments. Mission scientists had to choose between putting Rosetta into hibernation, with the risk that the probe would not wake up properly when it next came near enough to the Sun, or to deliberately crash the probe into the comet and gain some extra science. They chose to do the latter.
As Rosetta gently approached the surface of comet 67P (remember, the gravity of the comet is so weak that the fastest that it “fell” was only about 1 metre per second) it took pictures in ever increasing detail. The last image it took is shown above, when the probe was only some 20 metres from the surface.
Rosetta has been a hugely successful mission, and it will take scientists many years to analyse all the data which it and Philae have returned to us. I have blogged about Rosetta before, here, here, here and here.
Some of the most important findings so far are
- that comet 67P is spongy, with about 70% of its volume being empty space
- complex organic molecules have been found on the comet’s surface, supporting the theory that the building blocks of life on Earth may have been brought by comets
- the composition of the water jets emanating from comet 67P was found to be different to water on Earth. This seems to contradict the idea that water on Earth was brought here by comets
There are thousands of images and spectra taken by Rosetta, so there is far more science to come in the future. But, perhaps Rosetta’s greatest success was the way in which the mission captured the public imagination. Surely Rosetta will be just the first mission that we send to orbit and land on a comet.