John Bridges: Mars Science Laboratory Blog
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Today marks the closest approach of Comet Siding Spring to Mars. Curiosity will be pointing MastCam and ChemCam towards it, and have been practising targeting at stars like Spica. Its a tough targetting job but ChemCam might be able to get molecular information about the composition of gases in the comet's coma from passive spectra. One of the challenges of the targetting is that we dont really know for sure how large the comet is.
To date the most detailed information we have got about the composition of comets has been from the Stardust mission. That brought back to Earth micron-size solid grains from the Jupiter Family Comet Wild2. However, Siding Spring is from much further out in the farthest parts of the Solar System - the Oort Cloud, 1000's AU away from Mars, so this is a particularly special (and very close) encounter.
Meanwhile on Mars , Curiosity is finishing analysing drill dump piles and rock and vein targets at the Confidence_Hills drillsite in Pahrump Hills.
This is a night time MAHLI image of the Pahrump drillhole , illuminated by the LEDs. It is a 'MAHLI merge' which means that multiple images within individual focus were taken in order to get a deeper depth of field in the combined image. You can see an array - a '10 by 1' set of ChemCam laser shots which has hit the side of the drillhole.
We have spent the last 2 weeks analysing the area around the drillhole, more driving next week.
This Left MastCam ('M34' because of the focal length) view shows the Pahrump drilled grains just before they are about to be sieved by closing up the scoop and sieve, then turning the whole robotic arm turret. As this is going on, and before we dump the drilled material, there are engineering restrictions on how we can move the robotic arm. We are getting APXS for the major element chemistry and ChemCam to show us spot analyses, in addition to the X-ray diffraction for mineral abundances.
Pahrump Hills Drillhole
We have completed the mini and main drill holes, at the Confidence Hills locality in Pahrump Hills. Over the weekend the drill powder is being sieved and transferred to CheMin. The lighter colour compared to the Kimberley drillhole suggests there is less Fe oxide at this locality. One of the other features of this drill site is the presence of concretions along the fractures, we will be analysing these with ChemCam and APXS over the next week to try and determine the nature of the fluids. One idea is to do a depth profile of 150 shots with the ChemCam laser to get below the uppermost, exposed surface. I will be Science Theme Lead for a couple of days during the week and we will be aiming to get as much information as possible from the drill site and its surrounding area.