First Spacecraft Successfully Lands On The Surface Of A Comet
CBS News – For the first time ever, a space probe has landed on the surface of a comet. Cheering and hugs erupted at the European Space Agency Wednesday as mission controllers received a signal from the Philae landing craft confirming a successful touchdown. The agency announced the landing on Twitter:
“Everyone’s been on the edge of their seat waiting to see if this mission’s going to be a success or failure,” said CBS News space consultant Bill Harwood, who’s been tracking the mission throughout its 10-year journey.
The Philae lander was released from the Rosetta space probe on schedule at 3:35 a.m. EST (GMT-5). At a distance of 317 million miles from Earth, it took 28 minutes for radio signals confirming separation to reach anxious flight controllers at the European Space Operations Center in Darmstadt, Germany.
The lander was expected to move at a normal walking pace on the final leg of its journey, a 7-hour descent to the surface of Comet 67P/Churyumov-Gerasimenko. The target was a 1,600-foot-wide landing zone.
Shortly after it separated from Rosetta, the Philae lander sent back its first photo — a “selfie” confirming its deployment.
Because the comet has a gravity field 100,000 times weaker than Earth’s, the ice screws on the lander’s three legs would be required to dig into the comet’s surface to help prevent the spacecraft from bouncing back into space.
Two downward firing harpoons were designed to provide a firmer grip using cold gas thruster to offset the impulse of their release, but flight controllers were unable to get confirmation overnight that the thruster system was working, making it even more challenging to stick the landing.
Mark McCaughrean, senior advisor with ESA’s Directorate of Science and Robotic Exploration, said the landing was a risky operation even if all the technology worked perfectly.
“You won’t gain anything without taking risk. exploration is all about going to the limits, exploring the envelope,” he told reporters Tuesday. “We’ve been past comets before, but nobody’s ever actually dared to stop next to one, orbit around it, and of course naturally, you’re going to want to land on it. But we know how difficult that is.”
With the landing accomplished, he said the mission will be “in shape to do brilliant science next year as the comet lights up as it gets closer to the sun.”
“We know the risk is worth taking, the rewards are enormous,” McCaughrean said.
The Philae lander, tipping the scales at just 220 pounds, is equipped with 10 sophisticated instruments and cameras designed to document the spacecraft’s approach and collect data about the immediate environment.
It should be able to send back 360-degree 3D panoramic imagery, giving scientists a detailed look at the landing site, along with microscope views of the soil directly beneath the lander. A drill will penetrate a foot below the surface to collect pristine material for chemical analysis.
Its target, the comet 67P/Churyumov-Gerasimenko, was discovered in 1969 and circles the sun in an elliptical orbit extending nearly 500 million miles from the sun at its farthest point — beyond the orbit of Jupiter. The comet measures 2.5 miles across and rotates every 12.4 hours.
Like all comets, 67P/Churyumov-Gerasimenko is a frozen remnant of the primordial material used to form the sun and planets 4.6 billion years ago.
“When the solar system was forming out of gas and dust, it formed the planets, the one we live on today, it formed asteroids and it formed the comets,” said McCaughrean. “And the comets are a remnant, therefore, something we can investigate about the very earliest phases of the evolution and the birth of our own solar system.”
The European Space Agency has said that even if Philae’s landing didn’t succeed, the 1.3 billion-euro ($1.6 billion) mission would not be a failure because Rosetta could still perform about 80 percent of the scientific mission on its own.