Last sacrifice for science as Rosetta signs off
Long mission ends with close-up photographs before craft deliberately crash-lands on comet
THIS time, it was the crash landing everyone wanted. At Rosetta mission control, a pensive silence gave way to emotional applause as the spiky green waves on a large screen turned flat.
That was the moment contact with the craft was lost and the 12-year spaceflight to intercept and investigate Comet 67P/C-G finally came to an end.
Less than two years ago, the same team of scientists was standing in the same room as the most precarious phase of their mission, another “controlled descent”, that time of the detachable probe Philae, looked perilously close to disaster. The harpoon “feet” on the lander failed to deploy, causing it to bounce several times before coming to rest in a sun-starved niche where it was barely able to operate. Miraculously, the tiny craft found enough power to send back an unprecedented trove of chemical data from the comet, rich with clues about the beginnings of the universe and origins of life on Earth.
Yesterday, Rosetta followed its dependent craft on to the comet, touching down just 130ft away from its original target in the pockmarked Ma’at region at around 11.20 am BST.
By now more than 700 million miles from Earth, Rosetta would soon have been so far from the Sun that it could not have recharged its solar cells. Project scientist Matt Taylor said the team had decided to squeeze the last drops of power out the probe for a final series of close-up observations, rather than leaving it to orbit the comet.
“I’ve seen certain rock bands with certain singers that can’t sing any more,” he said. “They should have been stopped when they were fully functioning – and that’s what we are doing here with Rosetta. This plunge is the only way to get this science.”
If anything captures the sheer audacity of the mission, which was first conceived in the mid-Eighties, it was the decision not to fire Rosetta’s arrester rockets during the 19km descent.
Doing so would have bought an extra 45 minutes’ worth of photography, but risked contaminating the atmosphere around the craft and, therefore, the science. Instead, the team decided to go for pictures of crystal-clear quality, but left themselves less time to downlink the data back to Earth before touchdown. However, tension turned to relief at the ESA mission headquarters at Darmstadt, Germany yesterday as dazzling pictures streamed in from Rosetta. These including some of the most coveted images, taken from just 50ft above the surface, only seconds before final impact.
Dr Taylor summed up the significance of the mission on human understanding of the universe.
“Rosetta’s blown it all open. It’s made us have to change our ideas of what comets are, where they come from, and the implications of how the solar system formed and how we got to where we are today,” he said. “We have only just scratched the surface. We have decades of work to do on this data.”