The Mars Science Laboratory is a long-term robotic exploration to assess if Mars is, or ever has been, an environment that can support life. It will be the biggest, most capable robot to ever land on another planet. e2v imaging sensors equip both the rover’s Chemistry and Mineralogy instrument (CheMin) which was developed by NASA’s Jet Propulsion Laboratory (JPL) and the Chemistry & Camera instrument (ChemCam) which was developed by the Los Alamos National Lab under an agreement with NASA’s JPL. CheMin will identify and measure the minerals on the planet using sophisticated x-ray detection techniques. The ChemCam instrument consists of a laser, which will be used to vaporise rock samples, and a camera which will then use Laser Induced Breakdown (LIB) spectroscopy to analyse the material produced.
CheMin uses the e2v CCD224, a specialised imaging sensor array optimised for the detection of x-rays in a space environment. This high performance imaging sensor is based upon technology originally implemented in the European Space Agency’s XMM-Newton X-Ray observatory, where it has been operating successfully in the EPIC Instrument for the last 10 years. CheMin will expand the use of e2v’s x-ray imaging sensor technology to the Martian surface.
ChemCam uses the e2v CCD42-10 which is part of a standard range of imaging sensors used for various commercial and high performance applications including ground and space borne astronomy, and spectroscopy. The variant used in ChemCam was back-thinned to maximise sensitivity and coated with a custom graded anti-reflection coating to match the spectroscopic requirements of the mission.
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| Mars Science Laboratory using laser instrument, artist's concept - courtesy of NASA/JPL-Caltech |
Does anyone know if CMOS image sensors are making any in-roads in these space applications? It seems like using a CCD sensor technology that was space-proved a decade ago is a really conservative approach considering the last decade of development of other image sensor technologies. Are there technical advantages for CCD over CMOS in the extreme environment of space (or for CMOS over CCD) or is the main issue that the sensor cost is such a small fraction of the overall mission cost that cutting-edge performance and/or custom pricing don't matter as long as the imager doesn't fail on launch, transit, or during operation?
ReplyDeleteMaybe my comment needs a headline:
ReplyDelete"CMOS Sensors Power CDM Curiosity"
Well, the problem is you can't fix it if it breakes somewhere in space or on Mars. And I think it would be very very hard to find a CMOS sensor that can work as a replacement for such high end / specialized CCDs - that still are unbeaten in scientific cameras.
ReplyDeleteWhen making every photon count, CCD still has the advantage over traditional CMOS. CMOS has advantages in integration and system cost, but they are much less unimportant for a one-off specialty camera.
ReplyDeleteFor an X-ray sensor one needs thick, fully depleted device - something that at the moment cannot be done with CMOS. CMOS imagers are being used as star trackers, so they do make inroads in some applications.
ReplyDeleteAs usual there has to be a compelling reason to use CMOS. For space, the compelling reason has to overcome the risk of inserting "new" technology. So far it is hard to justify the risk, even though we all believe the risk is quite low.
ReplyDeleteI was at JPL (home of the Mars Rover Curiousity) just a couple of weeks ago and observed that the US has been slower than Europe to adopt CMOS technology for space. Part of this had to do with just one person at JPL who regularly advised science instrument PIs not to take any risk with the new image sensor technology. Since he left JPL (and this world, RIP) there has been a slow but steady increase in new image sensor technology insertion for US-based science missions. Of course what Gregory said above is also quite true for his particular application.
For people who´s interested in CMOS application space, you should check up the recent CNES CMOS workshop. You will be amazed to see how many CMOS sensors are currently flying in space besides star trackers.
ReplyDeletee2v imaging also does CMOS chips for space applications see:
ReplyDeletehttp://www.electronicsweekly.com/Articles/09/12/2011/52495/e2v-secures-major-satellite-deal-for-cmos-imagers.htm
Thanks for the feedback. It looks like I have some reading to do over the next few weeks.
ReplyDelete