When it comes to Martian rocks, details matter. NASA intends to bring tiny rock samples collected by the Perseverance rover back to Earth for study. This means keeping track not only of where the samples came from in Jezero Crater, but also of their original orientation in the host rock. To do this, the rover engages in a small physical graffiti on the red planet.
In June, Perseverance used a laser part of the SuperCam instrument mounted on its mast to etch three L-shaped dots into a rock. But this is not free graffiti. There is a compelling scientific reason.
SuperCam principal investigator Roger Wiens described the L as “the first letter to be laser-engraved on Mars” in a mission update on Thursday, which explains in detail why this was necessary.
In search of ancient traces of life
The rover is studying an ancient river delta that may be the best chance of finding evidence of past microbial life on Mars. This means that the rock samples collected there are particularly important.
Beyond the search for life, the rocks brought back could also help researchers piece together the history of Mars’ magnetic field and its impact on the planet’s atmosphere. Scientists studying this question want to know the orientation of rock pieces “to understand the original directions of the magnetic domains in the samples. This is where the laser marking technique comes into play.
As Wiens points out, it is easy to determine the orientation of rock samples that exhibit easily recognizable features. “However, if the surface is fine-grained, there may be nothing to distinguish its original orientation. In this case, we have to make artificial marks on the surface,” he wrote. The fine-grained rocks of the river delta region were the perfect place to test this method.
The team chose a capital L as an easy and effective way to make a directional mark. “The test having been conclusive, we are ready to use this procedure to mark future samples,” writes Wiens.
The rover could use its writing skills to carve all sorts of messages into Martian rocks (like “Percy’s been here”), but NASA wants to use the rolling lab’s energy more for science, not nonsense. Perseverance may not venture any further in the alphabet than L, but this small letter could be very important for the sequel.
CNET.com article adapted by CNETFrance