Rosetta mission: the end of the beginning

There have been a lot of amazing space missions that rank among the greatest engineering achievements of all time. The Rosetta mission has to be one of the most impressive ever. Rosetta traveled 10 years and more than four billion miles to rendezvous with comet 67P/Churyumov-Gerasimenko, a rubber-ducky-shaped pile of rocks 2.5 miles across that is zipping through space at about 84,000 miles an hour. It went into orbit around the comet and then it dropped a lander, Philae, that touched down on the surface of the comet back in November. Never mind that Philae didn’t stick the landing; that’s an quite an accomplishment.

Paul Weissman of JPL spoke about the Rosetta
mission Monday at the 225th meeting of the
American Astronomical Association.

Thus it was most enjoyable to hear from one of the Rosetta mission scientists, Paul Weissman of the NASA Jet Propulsion Laboratory, on Monday afternoon at the 225th meeting of the American Astronomical Society. Weissman gave a talk titled “Back to the Beginning: The Rosetta Mission to Comet Churyumov-Gerasimenko.”

“Doing space missions is a work of delayed gratification,” Weissman quipped, noting that they actually started work on Rosetta in 1996, and adding that there had been plans for such a mission for about a decade before that. They finally launched in 2004 and arrived at the comet, often shortened to C-G for obvious reasons, back in August.

“We had been ten years in space,” Weissman said. “It was really exciting to finally arrive at the comet.”

Rosetta carries 11 scientific instruments on board, and the Philae has ten. Even though Philae didn’t operate for long, between them the two craft have sent back a wealth of data.

“We’ve just been flooded with phenomenal results,” Weissman said.

Rosetta’s lander Philae on the surface of Comet 67P/Churyumov-
Gerasimenko. One of the lander’s three feet can be seen in the
foreground. The image is a two-image mosaic.
Credit: ESA/Rosetta/Philae/CIVA

He shared a great many photographs from the mission and explained what all of the instruments have been observing. Among the interesting discoveries are that C-G is spinning faster than it did on its previous trip around the Sun, the result of the forces of outgassing of the comet’s material. There are pits on the nucleus that may be sink holes or outbursts; they’re not quite sure yet. They’ve detected water within the comet, and learned it is colder in its interior than on the surface. And the comet has about 74 percent porosity.

Some of the most fantastic returns are images taken by Philae from the surface of C-G that show exquisite detail.

“We’re looking at millimeter resolution of the surface of the comet,” Weissman noted, “something that’s just astounding in terms of what we’ve been able to do previously.”

Weissman holds out hope that they’ll get more from Philae, even though its batteries are dead because it landed in the shade.

“It may be possible to re-awaken the lander in May of this year,” he noted. “The solar panels that are exposed will gather enough energy to charge up the batteries, and we might have another shot of making measurements with the lander.”

Whether that works or not, there already is a great deal of data that mission scientists simply have not yet had time to analyze, and there’s more to come.

“This is the end of the beginning,” Weissman said, “because we have another whole year that we’re going to be in orbit, studying the nucleus and watching it get active. It reaches perihelion in August, so we’ll also watch it get inactive. And there’s talk of an extended mission into 2016.”

“This is just a remarkable mission.”