Landing on a Comet Millions of Miles Away

by Joe McGonegal on February 20, 2014 · 0 comments

in Science, Space

Update 11/12/14: After the Philae Lander touched down on November 12, Kletzkine emailed along this dispatch from Paris: “I was at the large science museum today for the landing event…to our own amazement, the media in Europe went wild with coverage. As you may have gathered from the media, analysis of the various data received indicates that Philae is likely to have rebounded twice and settled down quite far from the original touch-down but still in good health and attitude. Instruments work. The drawback is that Philae has now settled in a much less sunny area of 67P, so it will take a long time to recharge the secondary battery when the primary (not rechargeable but much higher electrical capacity per unit mass) is empty. This will be worked around by rearranging the long-term sequence of science observations. For now, the short-term sequence has also been rearranged to take into account that Philae is likely not anchored: we do not want to upset it or send it back into space by trying to drill the surface too soon.”

A month ago today, the European Space Agency’s Rosetta spacecraft awoke from a 31-month-long nap and transmitted a simple message back to Earth, 420 million miles away: “Hello, world.”

Artist impression of the lander approaching the comet. (Courtesy ESA)

Artist impression of the lander approaching the comet. (Courtesy ESA)

Philippe Kletzkine SM ’83 smiled when he heard the news. The last time Kletzkine saw Rosetta was at its launch, on March 2, 2004. As ESA’s manager for the Rosetta Philae Lander, he had great hopes but he knew he would need great patience, too.

And the Rosetta team’s patience has been tried, especially for the past three years. Since Rosetta was so far away from the sun, gathering momentum for its trip to a comet, it was programmed to power down for 31 months to conserve energy. Whether it awoke from that nap in January was quite literally a long shot.

The orbiter did wake, but now Kletzkine hopes his comet landing probe, still in hibernation on the orbiter, will awaken too. In November, it has a date to become the first such probe to land on a comet.

“The next big milestone will be the awakening of the Lander, in a few weeks, so its own housekeeping telemetry can be analyzed on ground for a thorough health check,” says Kletzkine. “And then, on to the comet phase. If all goes well, it will land in late 2014, and with a bit of luck more science [will come] from the surface of the comet thereafter. Lots to look forward to, even for those, like me, who are no longer in the driver’s seat.”

Like many who joined the Rosetta project before its launch, Kletzkine has moved on. He is currently project manager for the ESA’s Solar Orbiter, an even more ambitious effort aimed at traveling closer to the sun than ever before (though still 27 million miles from it). Scheduled for a 2017 launch, the orbiter aims to photograph the sun’s two poles for the first time.

When he joined the Rosetta team in 2000, Kletzkine was uncertain that Rosetta would even make it to liftoff. Landing a satellite on a comet millions of miles away from one’s lab can be daunting.

“The greatest difficulty was to design to an unknown environment,” Kletzine says. “How do you specify the elements of a landing gear when you don’t know whether you will land on compact hard rock, porous terrain, or fluffy regolith? Is the danger to rebound, or maybe to sink into the surface? If you try to cover all worst cases, you create a versatile but enormously bulky and costly monster. If you cover too few possibilities, your chances of mission success dwindle. Remember, too, that all this was done with 1990s technology and a limited budget.”

Why land on a comet? From flybys of other comets, satellite photographs have revealed that comets have a great deal of ice. That’s prompted the question of whether water on earth is a result of a comet collision. Ultimately, comets may also hold secrets to where water—and possibly life—exist elsewhere in the universe.

Kletzkine is not the only alum working at ESA. Anne Pacros SM ’02, a payload systems engineer, works alongside Kletzkine on the Solar Orbiter project.

Pacros still remembers vividly the day ESA launched Rosetta.

“I was thrilled to hear about Rosetta’s successful ‘wake-up,’” she says, “but also thought, wow—already 10 years have passed.”

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