Curiosity’s study of Martian sands halted due to anomaly
As NASA’s Curiosity rover studies an active sand dune, it is adding some sample-handling procedures not previously used on Mars. Sand from the second and third scoops that the rover is digging from “Namib Dune” will be sorted by grain size using two sieves. Curiosity is employing its coarser sieve for the first time, and using it also changes the way the treated sample is dropped into an inlet port for scientific analysis inside the rover.
Positioning the rover so that it could scoop samples out of the dune also proved to be difficult. Curiosity reached its sampling site, known as “Gobabeb”, on January 12.
“It was pretty challenging to drive into the sloping sand and then turn on the sand into the position that was the best to study the dunes,” said Michael McHenry of NASA’s Jet Propulsion Laboratory, Pasadena, California. McHenry serves as the Curiosity mission’s campaign rover planner for collecting these samples.
This in only the second location where Curiosity has scooped up sample material. The first was at a site called “Rocknest”, where the rover sampled dust and sand from a windblown drift in October and November of 2012. Since then, Curiosity has gathered samples for analysis by drilling into rock rather than scooping.
Namib and other nearby mounds of sand are part of the “Bagnold Dune Field”, which lies on the northwestern flanks of Mount Sharp, the layered mountain where Curiosity is studying rock records of ancient environment conditions on Mars. The rover’s work at Bagnold Dunes is the first close-up examination of active sand dunes on a planet other than Earth. By investigating the dunes, scientists will learn more about how wind moves and sorts sand grains in conditions with less atmosphere and lower gravity than on Earth.
Curiosity scooped its first sample on January 14, after first scuffing the dune with a wheel to probe its depth.
“The scuff helped give us confidence we have enough sand where we’re scooping that the path of the scoop won’t hit the ground under the sand,” McHenry said.
The first scoop was processed in the same manner as the samples from Rocknest. A series of complex moves of a multi-chambered device on the rover’s arm passed material through a sieve that screened out material larger than 150 microns (0.006 in). Some of the material that passed the sieve was dropped into laboratory inlets. Material that was too big to pass through the sieve was dropped on the ground.
On January 19, Curiosity collected its second scoop from Gobabeb. This time, the rover used its coarser sieve which allows particles up to 1 millimeter (1,000 microns, or 0.04 in) to pass through.
Sand from the second scoop was first fed to the 150-micron sieve. Sand that didn’t pass through that sieve was then fed to the 1-milimeter sieve. The portion routed for laboratory analysis was grains that didn’t pass through the finer sieve, but did pass through the coarser one.
“What you have left is predominantly grains that are smaller than 1 millimeter and larger than 150 microns,” said JPL’s John Michael Morookian, rover planning team lead for Curiosity.
Then, on Monday, January 25, the Curiosity team reported in a mission update that the rover’s CHIMRA (Collection and Handling for In-Situ Martian Rock Analysis) device had experienced an anomaly. The CHIMRA behaved in an unexpected way during processing of the third scoop. Further operations of the arm will be halted until the problem can be diagnosed and recovery plan developed.
Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.