On Comet, Philae Lander Still Silent as Europe Keeps Listening

Comet 67P/Churyumov–Gerasimenko on March 18, 2015
This image, taken by Europe's Rosetta spacecraft, shows Comet 67P/Churyumov–Gerasimenko. The Philae lander (located somewhere on the surface of the comet) has been silent since its landing in November 2014. (Image credit: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0)

The first spacecraft to make a soft-landing on a comet is still quiet on the dusty cosmic body, despite being hailed by another probe orbiting the lander.

The European Space Agency's Philae spacecraft hasn't responded to pings from the Rosetta orbiter since officials began trying to revive the spacecraft parked in a shady spot on Comet 67P/Churyumov–Gerasimenko this month.

Philae made a bumpy landed on the comet in November 2014, but its batteries ran down when it didn't have enough sunlight to recharge. The lander has been quiet ever since. However, the comet is much closer to the sun now than it was six months ago. Mission managers started trying to contact the lander mid-month in the hopes that it had enough energy to respond. But so far, no luck.

"It was a very early attempt; we will repeat this process until we receive a response from Philae," Stephan Ulamec , German Space Agency (DLR) project manager, said in a statement. "We have to be patient."

The next favorable opportunity for listening in will likely take place in the first half of April, but the timing hasn't yet been finalized, DLR added. Periodic listening attempts are expected to take place at least through the summer.

There's still a chance that Philae could respond next time, DLR added. Previously, the space agency sent commands to the hibernating spacecraft to help it conserve power.

The spacecraft is designed to wake up when its solar panels can generate 5.5 watts of power and its internal temperature is higher than minus 49 degrees Fahrenheit (minus 45 degrees Celsius) The lander, however, needs to generate about three times as much power (19 watts) before its transmitter can respond to Rosetta.

If the spacecraft does awaken, the first priority for controllers will be seeing how healthy it is after half a year hibernating. If the spacecraft can, it will do more observations of the surface to see how Comet 67P/C-G changes while approaching the sun.

The Rosetta mission has made numerous discoveries since arriving at the comet in August. Among them: organic molecules on the surface, the first detection of molecular nitrogen in comet gases, and water that is likely of a different isotope composition than what arrived at the early Earth.

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for Space.com for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: https://qoto.org/@howellspace