Opportunity has been driving along an outcrop at the edge of Endeavour Crater known as “Cape York”, investigating rocks that look like they formed during the impact and then were later altered by fluids flowing through them (precipitating the gypsum veins discovered last year).
Opportunity has moved to a site called “Big Nickel”. The plan is to examine this rock in preparation for solar conjunction using both the microscopic imager (MI) instrument and the alpha-particle x-ray spectrometer (APXS), which has been running for so long that it takes a long time to get a good measurement. If the rover has to sit around for a couple days…hey, great time to integrate data!
Perhaps more interesting is what Oppy just finished. The rover has been examining the rock called “Kirkwood”; the rock containing the so-called “newberries” (pictured). These things are some sort of spherical structure found in the rock, and we’re still awaiting a good answer for what they are.
Opportunity threw all of its remaining equipment at this outcrop, including the MI and the APXS, as well as a new one. The rover was sent to Mars with a “Rock Abrasion Tool” (RAT), a device to grind slightly into the rock. The RAT was meant to only be used on a few rocks, and so it’s been out of commission for years. But, on Kirkwood, the engineers figured out something new.
Geologists commonly use a technique called a streak test, in which a small amount of powdered rock is created by grinding a rock up against an abrasive plate. They haven’t explained how they did it, but somehow, the opportunity team managed to use one of the worn parts of the RAT to pull off a streak test; grinding a portion of the Newberry-rich rock along an edge to create a small streak that could be imaged.
The results of the Newberries haven’t yet been published, but hopefully the fact that the rover is rolling away means that a good answer for what they are will be coming shortly.
Image source and Planetary Society piece on the “Newberries: