This story is part of Welcome to Mars, our series exploring the red planet.
In just a year and a half on Mars, NASA’s Perseverance rover has absolutely rocked its mission. The agency held a briefing Thursday to discuss the highlights of the science mission so far, and it was a celebration of rock samples and the discovery of organic matter.
Organic molecules at Wildcat Ridge
A rock called Wildcat Ridge, located in an ancient river delta region of Jezero Crater, was one of the stars of the show. Percy successfully collected two samples from the muddy rock. Wildcat Ridge is particularly exciting because the organic molecules (called aromatics) found there are considered a potential biosignature, which NASA describes as a substance or structure that could be evidence of past life, but may also have occurred without the presence of life.
The rover team emphasized that finding organic matter does not mean evidence of ancient life has been found. Organic molecules have been detected on Mars before, by the Curiosity rover in Gale Crater and also by Perseverance, which found carbon-containing molecules before the mission.
Perseverance collected two core samples from Wildcat Ridge and also scraped a round patch to inspect the rock with its Sherloc instrument.
NASA, JPL-Caltech, ASU, MSSS
The rover’s Sherlock instrument investigated the rock. (Sherloc stands for Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals.) “In its analysis of Wildcat Ridge, the Sherloc instrument recorded the most abundant organic detections on the mission to date,” NASA said.
Scientists are seeing familiar signs in the Wildcat Ridge analysis. “In the distant past, the sand, mud and salts that now make up the Wildcat Ridge sample were deposited under conditions where life could have thrived,” Perseverance project scientist Ken Farley said in a statement. “The fact that the organic matter was found in sedimentary rock, which is known to preserve fossils of ancient life here on Earth, is important.”
Perseverance is not equipped to find definitive evidence of ancient microbial life on the Red Planet. “The reality is that the burden of proof to establish life on another planet is very, very high,” Farley said during the press conference. For that, we need to examine Martian rocks up close and personal in laboratories on Earth.
sample drop
Percy currently has 12 rock samples on board, including pieces from Wildcat Ridge and samples from another sedimentary delta rock called Skinner Ridge. It also collected samples of igneous rock earlier in the mission that point to the impact of long ago volcanic action in the crater.
NASA is so pleased with the diversity of samples collected that it is looking to drop some of the full tubes to the surface soon in preparation for the future Mars Sample Return (MSR) campaign. MSR is an ambitious plan to send a lander to Mars, collect samples of Percy, launch them off the surface and bring them back to Earth for close study. The mission is in progress. If all goes as planned, these rocks could be here by 2033.
The complexity and importance of MSR means that NASA and its partners are looking for ways to ensure that samples can be collected. It is hoped that Perseverance will still be operating in good condition when the MSR lander arrives, and that I can meet him and personally deliver samples. Leaving some samples on the ground early in the mission at a cache site in the crater will give MSR another chance to bring the precious rocks on board.
Percy has been collecting paired samples. For example, I could keep one Wildcat Ridge tube on board and drop the other on the ground. “That we are weeks away from deploying Perseverance’s fascinating samples and just a few years away from bringing them back to Earth so that scientists can study them in exquisite detail is truly phenomenal,” said Laurie Leshin, director of NASA’s JPL. “We will learn a lot.”
What’s next for Percy
As exciting as the delta has been, the rover team looks forward to future adventures beyond. Perseverance could walk the rim of the crater, with the team looking at several possible paths for ascent. Its companion Ingenuity helicopter is in good health and is expected to fly again.
NASA chose Jezero Crater for exploration because of its fascinating history of water and how the rocks there could preserve evidence of ancient life, if it existed during more habitable times on Mars. Sherlock scientist Sunanda Sharma compared the mission to a treasure hunt for organic life on another planet, saying the aromatic samples are a clue. The Martian mystery is just beginning to unfold.