A chunk of rock that was once part of Mars, but landed on Earth as a meteorite, will return to the Red Planet aboard a NASA rover set to launch in 2020.
The meteorite, known as Sayh al Uhaymir 008 (SaU008) was found in Oman in 1999, but geologists determined that it likely originated on Mars, according to a statement from NASA's Jet Propulsion Laboratory. Scientists think collisions between Mars and other large bodies in the solar system's early days sent chunks of the Red Planet into space, where they might wander for eons before falling onto Earth's surface.
Now, NASA scientists are using the meteorite to calibrate an instrument that will fly on the Mars 2020 rover, which is scheduled to drop down on the Red Planet's surface and collect rock samples that could one day be returned to Earth. One of the rover's main goals is to evaluate the potential habitability of ancient and present-day Mars. [How NASA's Mars 2020 Rover Will Work (Infographic)]
The meteorite is being used to calibrate an instrument called the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals), which will use techniques often used in forensic science to identify chemicals in the Martian rock samples, in features as thin as a human hair.
The researchers will study the meteorite on Earth, where they are able to make sure their instruments are producing a correct analysis of the rock, and understand what features of the rock are perceptible to their instruments. When the rover settles onto Mars, researchers can once again use the rock to make sure their instruments are working as they should be, before pointing them at features of the Martian surface.
"We're studying things on such a fine scale that slight misalignments, caused by changes in temperature or even the rover settling into sand, can require us to correct our aim," said Luther Beegle, principal investigator for SHERLOC, in the statement. "By studying how the instrument sees a fixed target, we can understand how it will see a piece of the Martian surface."
There are only about 200 confirmed Martian meteorites that have been found on Earth, according to the statement. The SaU008 meteorite comes from London's Natural History Museum, which lends out hundreds of meteorites (most of them not from Mars) every year for scientific studies. The SHERLOC team needed a Martian meteorite that was robust enough to endure the journey to Mars without flaking or crumbling. (Launch from Earth and entry into the Martian atmosphere are both very strenuous events for everything on board.) The rock also "needed to possess certain chemical features to test SHERLOC's sensitivity. These had to be reasonably easy to detect repeatedly for the calibration target to be useful," according to the statement.
Usually, instruments like SHERLOC are calibrated with a variety of materials including rock, metal and glass. And Mars meteorites have been used for instrument calibration in the past. In fact, another instrument aboard the Mars 2020 rover, called SuperCam, will be adding a Mars meteorite to NASA's calibration target, according to the statement. And while this would be the first Mars meteorite to return to the surface of the Red Planet, NASA's Mars Global Surveyor, which orbits the Red Planet, carries a chunk of a Martian meteorite.
SHERLOC will carry other materials from Earth in addition to Su008, including materials that could be used to make a spacesuit for use on Mars. Observations of how the material withstands the radiation, atmosphere and temperature variations on Mars will provide valuable information for possible crewed trips to the Red Planet.
"The SHERLOC instrument is a valuable opportunity to prepare for human spaceflight as well as to perform fundamental scientific investigations of the Martian surface," Marc Fries, a SHERLOC co-investigator and curator of extraterrestrial materials at Johnson Space Center, said in the statement. "It gives us a convenient way to test material that will keep future astronauts safe when they get to Mars."