Curiosity rover tests new drilling technique
NASA’s Curiosity rover conducted its first drilling in over a year on Feb. 26, 2018, to test a new technique developed by mission team members on Earth after the motor powering the drill’s feed mechanism malfunctioned in December 2016.
Since landing on Mars in 2012, the rover successfully obtained samples using its drill 15 times before the motor problem occurred.
Curiosity‘s drill was designed to be held in place by two stabilizers on either side that held the drill in place against the rocky surface while the feed mechanism moved the drill bit into the rock. When the motor stopped working, the feed mechanism lost the capability of extending and retracting, making further drilling impossible.
Mission engineers at NASA’s Jet Propulsion Laboratory (JPL), who designed and built the rover, experimented with a twin of Curiosity back on Earth in an effort to work around the problem and find a way to drill into the Martian surface without the use of the stabilizers.
The work was time-consuming, often taking up holidays and weekends and forcing engineers to frequently work double shifts.
To make the twin rover identical to its counterpart on Mars, JPL engineers had to replace a faulty force sensor, which had not previously been needed. Mission scientists and engineers also had to come up with a new method of collecting Martian rock samples without using the feed mechanism.
The new drilling method they devised, known as feed extended drilling, involved placing the bit in a forward position without use of the stabilizers. In place of the feed mechanism, this new method uses Curiosity‘s robotic arm, along with a force sensor inside it, to place the drill on the rock and extended it downward. The force sensor functions as the rover’s sense of touch, keeping the bit from moving sideways.
With the ability to adjust movement of the robotic arm, Curiosity can prevent the drill getting stuck.
Although the first resumption of drilling using the new method produced a half-inch- (one-centimeter-) deep hole in an area called Lake Orcadie, it was not enough to obtain a scientific sample of surface material.
Now that the new method has been shown to work, more tests will be conducted to determine its sample-collecting capability.
“We’re now drilling on Mars more like the way you do at home,”said mission deputy project manager Steven Lee of JPL in a news release. “Humans are pretty good at re-centering the drill, almost without thinking about it. Programming Curiosity to do this by itself was challenging—especially when it wasn’t designed to do that.”
Curiosity’s original design had the drill crush rock samples into powder, then place the powder in two science instruments, the Sample Analysis at Mars (SAM) and the Chemistry and Mineralogy (CheMin) using an instrument known as the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA).
Already tested on Curiosity‘s Earth twin, the new sample collection method will require the drill bit to shake out the grains of powdered rock, much like a salt shaker taps out salt, without CHIMRA‘s help.
Because the atmosphere and gravity on Mars are very different than they are on Earth, it remains unclear whether this method will succeed in correctly portioning the samples to SAM and CheMin. Mission engineers plan to test the method as soon as they drill deeply enough to obtain the needed samples.
Curiosity scientists are eager to obtain samples from Vera Rubin Ridge, the rover’s current location, as it contains red rocks composed of the iron oxide mineral hematite, which forms when water is present.
“This is a really good sign for the new drilling method,” said Curiosity sampling engineer Doug Klein, also of JPL. “Next, we have to drill a full-depth hole and demonstrate our new techniques for delivering the sample to Curiosity’s two onboard labs.”
Video courtesy of JPL
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.