Chuck Bednar for redOrbit.com – Your Universe Online
The search for the Philae lander on Comet 67P/Churyumov-Gerasimenko (67P/C-G) has been unsuccessful, and ESA officials will now wait to hear from the probe to confirm its location.
Philae, which landed on the comet last November, is believed to have come to rest on a 350m by 30m “landing strip” on the smaller lobe of 67P/C-G, the ESA said on Friday. A dedicated search using the OSIRIS near-infrared integral field spectrograph has not found its exact location.
Upon first contact with the comet, Philae bounced twice and crossed a large depression known as “Hatmeht” before settling down in a site that has been dubbed “Abydos.” That area is believed to be located just off the top of the duck-shaped comet’s “head,” according to BBC News.
The general location was imaged by the Rosetta orbiter on December 12, 13 and 14, and each picture was then scanned by eye for telltale signs of Philae – “a set of three spots that correspond to the lander,” according to OSIRIS principal investigator Holger Sierks from the Max Planck Institute for Solar System Research in Germany.
So far, the search has been unsuccessful, Sierks exlplained: “The problem is that sets of three spots are very common all over the comet nucleus. Hatmehit and the area around its rim where we’re looking is full of boulders and we have identified several sets of three spots.”
While Rosetta will be flying to within six kilometers of the comet’s surface on February 14, its current trajectory will bring to closer to the lower part of the larger comet lobe than the Philae’s potential landing site. The ESA has said that it does not plan to conduct any additional, dedicated searches for the lander, according to the BBC, and will simply wait for it to wake up.
“Rosetta’s busy science schedule is planned several months in advance, so a dedicated Philae search campaign was not built into the plan for the close flyby,” said Rosetta project scientist Matt Taylor. “We’ll be focusing on ‘co-riding’ observations from now on, that is, we won’t be changing the trajectory of Rosetta to specifically fly over the predicted landing zone in a dedicated search, but we can modify the spacecraft pointing and/or command images to be taken of the region if we’re flying close to the region and the science operations timeline allows.”
“After the flyby we’ll be much further away from the comet again, so are unlikely to have the opportunity for another dedicated lander search until later in the mission, maybe even next year,” added ESA’s Rosetta mission manager Fred Jansen. “But the location of Philae is not required to be able to operate it, and neither does it need to be awake for us to find it.”
Philae is expected to reactivate shortly after the comet’s southern hemisphere becomes in the next few weeks, and once it boots up, it should be able to communicate with Rosetta. The orbiter will call out to the probe and wait for a reply, and while the energy required for this process will make Philae immediately fall back to sleep, it will continue to gather light using its solar panels.
Eventually, it will recharge enough to maintain a stable telecommunications link and begin recharging the battery as well, according to the BBC. It could begin communications as soon as May or June, and resume its science operations sometime around August, when 67P/C-G will be closest to the Sun (perihelion) and in its most active phase.
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