Emily LakdawallaApr 22, 2014

Rosetta update: Instrument commissioning going well; Philae cameras activated

Rosetta and Philae have very nearly completed a six-week phase of spacecraft and instrument checkouts to prepare the mission to do science. Recently, the lander used its cameras for the first time since hibernation, producing some new photos of Rosetta in space. This one, taken by the Rosetta Lander Imaging System (ROLIS) camera, is staring at the Rosetta spacecraft's thermal blanketing. ROLIS is a downward-looking camera -- it will eventually be used to take images of the landing site before and after landing, like the Mars Descent Imager (MARDI) on Curiosity.

Portrait of Rosetta from Philae ROLIS, April 2014
Portrait of Rosetta from Philae ROLIS, April 2014 During the post-hibernation instrument commissioning phase, Philae's instruments were put through their paces. This photo, from Philae's ROLIS camera, shows thermal blanketing material covering the Rosetta spacecraft. ROLIS is a downward-looking color camera that will map the landing site on the comet both before and after landing; after landing it will be about 31 centimeters above the comet surface.Image: ESA Rosetta / Philae / Rolis / via CNES

And these two photos, taken by CIVA, show the spacecraft's solar panels. Unfortunately, the version of the image shared with the public was badly chewed up by JPEG compression artifacts; I've adjusted the contrast in the image to suppress those and give a cleaner view of the barely-lit edges of solar cells and panels that make up the two huge Rosetta solar arrays. (A version shared by CNES is marginally less JPEGgy than the one shared by ESA.) If you're having trouble seeing the geometry of the solar panels, compare the view to this colorized one taken by CIVA during the Mars flyby, which sees the panels against Mars. Here, the panels are imaged against black space, and the sun glints off the hardware are much brighter than any background stars would be, so you don't see stars. (I'm not even sure CIVA is sensitive enough to pick up light from background stars even if the glints weren't there. I have not checked.)

Philae CIVA portrait of Rosetta's solar panels, April 14, 2014
Philae CIVA portrait of Rosetta's solar panels, April 14, 2014 During Rosetta's post-hibernation instrument commissioning phase, the CIVA cameras on the Philae lander were powered on and commanded to take photos. From their position on the lander, they saw sunlight glinting off of edges in Rosetta's two solar panels.Image: ESA Rosetta / Philae / CIVA / via CNES / processed by Emily Lakdawalla

What else has been accomplished in recent weeks? Here are some highlights, distilled from the CNES Rosetta website, the ESA Rosetta blog, and the MPS Philae blog. (Here is a handy list of the Rosetta instruments, and a handy list of the Philae instruments.)

  • Since taking its first post-hibernation image of the comet on March 20, OSIRIS has been busy taking more photos for navigation purposes, as well as light-curve measurements that will allow scientists to determine the comet's rotation period.
  • As part of their commissioning, most of the instruments on both orbiter and lander have had software upgrades in the past few weeks.
  • I've only seen one glitch reported, by Philae lead scientist Hermann Böhnhardt in a Philae blog entry dated April 13: "all went very well with the lander units and instruments commissioning during part I except until the very end. One of the last items to be tested was the radio frequency link between orbiter and lander and one of the tested configurations caused troubles such that the final preparation settings for the lander switch-off could not be transferred to Philae properly before it was switched off. This came as a complete surprise of an otherwise satisfying lander commissioning week and will require extra work to solve it or at least to get a work-around in place. For the moment the second part of the lander post-hibernation commissioning is meant to start on 14 April 2014."

As I mentioned in a previous blog entry, following the completion of instrument commissioning this month, the next step is for the spacecraft to match velocity with comet Churyumov-Gerasimenko. Four maneuvers are scheduled to happen every other Wednesday beginning May 7.

Stay tuned for more Rosetta and Philae news!

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