The lead scientist for NASA’s Perseverance Mars rover is excited about the materials stored in the rover’s sample tubes, both deposited on the surface of Mars and contained within the rover itself as it travels through Jezero Crater .
Examining Mars samples collected by Perseverance, scientists say one tube appears to contain what the rover was looking for: evidence of past microbial life on the Red Planet.
The preliminary results reinforce the need to return these samples from Mars to Earth, so that these valuable collectibles from the Red Planet can be sent to laboratories for more rigorous analysis.
Related: If life exists on Mars, don’t count on sample return missions to find it, scientists say
Lively question
Caltech’s Kenneth Farley, project scientist for NASA’s Perseverance Mars rover program, briefed the Extraterrestrial Materials Analysis Group (ExMAG) at a meeting May 13-15 in Houston, Texas.
Marked “Lefroy Bay,” Farley drew attention to this sample collected by the Perseverance rover, which contained hydrated silica. Here on Earth, this mineral has the greatest potential for preserving signs of ancient life.
A burning, unanswered question then arises: perhaps Lefroy Bay harbors preserved signs of ancient life on Mars?
Paleoenvironmental conditions
“The Lefroy Bay sample and two other samples from the same unit – the ‘Margin Unit’ – are on board Perseverance,” Farley told Space.com. “Samples from the margin unit contain abundant carbonate and silica, clearly indicating the dominant role of liquid water in their formation,” he said.
But it remains unclear whether that water was surface water in a lake or river, or groundwater, Farley added. Either could constitute an ancient (more than 3.4 billion years old) habitable Martian environment, he said.
These samples host phases that, on Earth, are very useful for establishing “paleoenvironmental” conditions, Farley noted, and can also preserve biosignatures. “As such, these samples are particularly important for returning to Earth for further study,” Farley said.
Objective: set in stone
Perseverance is “on the verge of making a really fundamental shift in exploring the environment that we’re working in,” Farley explained in his ExMAG briefing. “One of the challenges we face,” he said, “is not ideal terrain for a rover to drive through.”
So far, the Martian machinery has traveled about 27 kilometers after being lowered into the area by crane on February 18, 2021. The robot’s goal is set in stone: “Search for signs of ancient life and collect samples Rock. and regolith for a possible return to Earth,” explains NASA.
But why was the Jezero crater, 45 kilometers wide, chosen as the rover’s reconnaissance location?
Scientists believe the area was once flooded with water and was home to an ancient river delta. The anticipation is that Jezero Crater is literally “spilling” the bean on the recurring, recurring nature of Mars’ wet past. More than 3.5 billion years ago, river channels overflowed the crater wall and created a lake.
What is possible is that microbial life could have lived in Jezero during one or more of these wet periods. If true, traces of the remains of these small creatures could be discovered in lakebed or shoreline sediments.
Rover Challenges
When it comes to the overall health of the Perseverance rover, Farley highlighted a few issues: first, the loss of the wind sensors that are part of the Mars Environmental Dynamics Analyzer (MEDA), built by an international team led by the Spanish Centro de Astrobiología. “We have largely lost the wind sensors. They hardly work anymore,” he reported.
Additionally, the spectroscopy parts of the Robotic Arm for Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals, SHERLOC for short, are put to the test. This is caused by a lens cover no longer functioning properly. However, some preliminary work suggests that scientists may be able to recover SHERLOC’s spectroscopy capabilities. “We will know more in the coming months,” Farley said.
Trois Fourches Depot
The rover was sent to Mars with 38 tubes that can be used for sampling rocks, regolith and even the atmosphere. “We’re about two-thirds of the way through the sample collection process,” Farley said.
The operating robot sampled igneous rocks, mudstone, sandstone/pebble conglomerates, carbonate-silica-olivine, and sand from upper Mars and captured a whiff of Martian atmosphere.
Earlier in its trek to Mars, Perseverance dropped 10 sealed sample tubes into a repository nicknamed “Three Forks” in Jezero Crater. The intention is that a future Mars Sample Return (MSR) mission will collect sample tubes to propel these pieces of Mars back to Earth.
However, this joint NASA and European Space Agency project is currently under detailed review due to an expected cost of $11 billion and an expected, but unsatisfactory, time frame to complete such a complicated undertaking.
Stay the course
Farley told ExMAG Group that rover operators are working to qualify Perseverance as a 55-mile (90-kilometer) traverse, allowing it to make its way toward a bustling landscape.
“There’s obviously a huge amount of uncertainty about what the MSR will be. We’re waiting to find out how we’re going to play a role in that as part of the Perseverance mission,” Farley said. “But for now, we’re going to stay the course. We’re going to continue to behave essentially as we have so far, with a strong emphasis on sample collection.”
Now the rover’s travel route involves carrying out tasks in an area called Bright Angel, then ascending to the crater rim, where the rover can study fundamentally different geology, Farley added.
By returning to the edge, “we will quickly complete the sampling. The sooner we have done the sampling, the sooner we can all rest easy … that we have done our job,” Farley said.
What happens next for Perseverance is status TBD.
“Maybe we’ll return to the crater floor to encounter MSR, maybe not. It will depend on what actually happens with MSR,” Farley concluded.