Curiosity has been on Mars for more than four years now, much longer than the primary mission of about 23 months.
NASA
builds ’em to last, though. Curiosity has sent back a wealth of data
from Mars, but it can’t last forever. Indeed, it’s wheels are getting
banged up, the ChemCam autofocus has gone wonky, and now Curiosity’s
rock drill stopped working on December 1. Mission scientists have a
better idea what’s going on with the drill, though they haven’t worked
out if it’s fixable.
Curiosity has instruments to study the
composition and structure of Martian geology, but it can only learn so
much from scanning the surface. That’s why the rover was equipped with a
percussion drill at the end of its 7-foot robotic arm. This allows
Curiosity
to extract samples from deeper layers of strata that haven’t been
exposed the radiation on the surface. It’s been used to drill into 15
different targets so far. It’s an important tool for the rover as it
climbs ever higher on Mount Sharp, so losing it would be a real blow to
the mission.
The drill carries two spare drill bits in case
one of them breaks, but the problem doesn’t appear to be the bit.
Mission scientists originally narrowed the problem down to
either the brake or electronic sensors
that monitor the drill’s rotation. More recently, the issue has mostly
been narrowed down to the brake. If they can’t get the brake to
disengage correctly, the drill can’t be spun up.
The team had some success since the issue
first appeared on December 1st. Curiosity was able to get the mechanism
working by moving the drill feed around — I suppose that’s the rover
equivalent of jiggling the handle. However, the problem came back a few
days later. The team is still looking at ways to potentially fix the
drill, but Curiosity is on its own out there. There’s no one around to
walk over and give it a kick.
This isn’t the first time Curiosity has had
issues with the drill. There have been a number of short circuits that
temporarily took the drill offline. When and if the current drill issue
is resolved, the team plans to be gentler with the tool. As a
“percussion” drill, it’s able to both hammer and rotate. They’ll try to
stick to just rotating whenever possible. Testing on Earth suggests that
just rotating should be sufficient to bore into softer rocks.
Even if the drill can’t be completely fixed,
Curiosity can still be of use on Mars. It’s already covered more
distance than all past rovers, and carries plenty of atmospheric sensors
and cameras.
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