European spacecraft snaps selfie with comet in background



CS Monitor

Spacecraft “selfies” are always a treat and this one is doubly awesome: taken by the Philae lander piggybacked onto ESA’s Rosetta, it shows one of the spacecraft’s 14-meter-long (46-foot) solar arrays glinting with reflected sunlight while off in the distance is the double-lobed nucleus of Comet 67P/Churyumov-Gerasimenko!

Rosetta has been circling the comet for over a month now and returning some truly amazing images, but leave it to little Philae to put it all into perspective. Such a show-stealer! (Not that we mind, of course.)

The image above was acquired with Philae’s CIVA (Comet nucleus Infrared and Visible Analyzer) instrument on Sept. 7, 2014, from a distance of 50 km (31 miles) from Comet 67P/C-G. It’s actually a composite of two separate images made with different exposures adjusted for the lighting disparities between the spacecraft and comet.

The Philae (say “FEE-lay”) lander itself weighs 100 kg (220 lbs) and is about a meter wide and 80 cm high (3.2 x 2.6 feet). The CIVA instrument, one of ten installed on the lander, is composed of seven miniature cameras that will take panoramic pictures of 67P’s surface and reconstruct its structure in 3D, as well as a microscope and a near-infrared imager to study its composition, texture, and reflectivity. (Source)

This is the second image from Philae this year to feature part of the Rosetta spacecraft (but the first to show the comet); the previous one was taken in April 2014.

Back in 2007 Philae took a shot that showed Rosetta’s solar panel and Mars; check that one out here.

Currently Rosetta is being transitioned to its Global Mapping Phase (GMP). This is an incredibly intensive process that will determine how close the spacecraft will be able to get to the surface of the comet as engineers search for the best landing area to which to deploy Philae in November.


No easy parking spot for first-ever comet landing

New Scientist

Eenie, meenie, miney, mo… (Image: ESA/Rosetta/MPS for OSIRIS Team)

Landing on a comet will be even harder than we thought. The strange shape of comet 67P/Churyumov-Gerasimenko does not present as many safe landing sites for the European Space Agency’s Rosetta spacecraft as mission planners had hoped.

“Its shape is exciting scientifically but it [creates] a lot of challenges,” says project scientist Matt Taylor at the European Space Research and Technology Centre in Noordwijk, the Netherlands. He calls the comet “the duck” because from some angles it resembles a rubber one.

The probe arrived at 67P on 6 August after a 10-year journeyMovie Camera. The plan is to release a probe called Philae to land on the comet’s surface on 11 November. ESA announced five candidate touchdown sites on 25 August, but on 8 September at the European Planetary Sciences Congress in Cascais, Portugal, the team admitted that none of the sites looked very safe.

“All landing sites are worse than expected because of the shape of the body,” said the lander’s lead scientist, Hermann Böhnhardt of the Max Planck Institute for Solar System Research in Göttingen, Germany.

Worse means smaller. Philae is designed to land within an ellipse 1 kilometre in length. Of the five shortlisted sites, only site B (pictured below), at the “head” of the duck, meets that requirement. There are some larger, smoother sites on the base of the duck’s “body” but they are too poorly lit to let the lander recharge its batteries during its four-month mission.

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