NASA’s Curiosity rover recently took a step closer to its historic first drilling on Mars, as it tested its drilling system. Last Saturday, the nuclear-powered explorer conducted a "drill-on-rock checkout" on a rock designated “John Klein” in Gale Crater. The brief test of the drill’s percussive action in a back and forth motion was part of a series of tests to determine if the rover’s drill is ready for full operation.
The February 2 test was part of a series of trials to make certain that the rover’s drill and robotic arm are receiving orders and operating properly, in advance of the first use of a drill on the Red Planet. On January 27, Curiosity carried out a "pre-load" test where it placed its drill on four locations on a Martian rock and pressed down with the rover's arm, in order to test whether forces on the drill and arm match earthside predictions.
This was followed by an overnight version of the test on Monday. This was necessary because temperatures vary greatly between the Martian day and night ranging from 32ºF (0ºC) in the afternoon to -85ºF (-65ºC) at night. This causes the rover to shrink by about a tenth of an inch (about 2.4 mm). That may not seem like much, but its enough to produce potentially damaging stresses on the robotic arm if it’s placed improperly as part of an overnight maneuver.
Curiosity’s drill bit as seen by the micro-imager of the Chemistry and Camera instrument (Image: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS)
"We don't plan on leaving the drill in a rock overnight once we start drilling, but in case that happens, it is important to know what to expect in terms of stress on the hardware," said The Jet Propulsion Laboratory’s Daniel Limonadi, the lead systems engineer for Curiosity's surface sampling and science system. "This test is done at lower preload values than we plan to use during drilling, to let us learn about the temperature effects without putting the hardware at risk."
In the run-up to the first drilling operation, Curiosity still has a number of hardware checks to carry out as well as evaluation of candidate rocks for drilling. Next on the agenda is a “mini-drill" test, which will produce a small ring of tailings by penetrating less than eight-tenths of an inch (2 cm) by means of rotary and percussive action. This isn’t deep enough to push the powdered rock into the sample-gathering chamber, but it will allow mission control to examine the tailings to make sure the drill is cutting as it should.
The drilling operation is part of Curiosity’s two-year mission to explore Mars, with the goal of finding areas where life might have once or could still exist.