Plans are firming up to bring a sample of Mars back to Earth in 2031.
A joint webinar last month by NASA and Lockheed Martin, which has participated in NASA sample return missions before, l went over the Mars sample return mission and how NASA's Perseverance rover will support that effort. The hope is that, by bringing some of the Red Planet back to Earth, we can gain more insight into Mars' potential for life by using high-resolution lab instruments to examine Martian rocks.
The discussion took place just days after the Biden administration announced its intention to allocate discretionary funds to the sample mission, which would involve a series of U.S. and European spacecraft carefully ferrying pieces of Mars back to Earth.
The first small step of that effort will happen relatively soon on Mars. Perseverance will dump its first cache of materials at the end of its primary mission in 2023, webinar participants said, and mission planners have already mapped out a potential route that will make the most of the watery environment that filled Jezero Crater with potentially life-friendly materials billions of years ago.
"Lakes and rivers and deltas on Earth are great places to preserve ancient life, and so we think this is a great place – if ancient life ever existed on Mars – to be able to find it," Jennifer Trosper, Mars 2020 deputy project manager at NASA's Jet Propulsion Laboratory in California, said of Perseverance's location.
Trosper showed a map filled with colorful lines, plotting potential "traverse routes" for the rover as it moves from its landing area, dodging some sand dunes en route before arriving at a suspected delta. At the delta, it will take samples of the lake bed and then move on to a nearby crater wall, Trosper said.
Then, it will be time for Perseverance to deposit its cache of samples somewhere. "We have 43 sample tubes onboard the rover, and we plan to do an initial cache at the end of our prime mission … of hopefully 15 or 20 samples," she said. "It'll probably be near the crater rim or even on the delta, and then we'll continue on."
In 2026, if all goes according to plan, a sample retrieval lander will alight near the cache, using terrain-relative navigation. A fetch rover will pick up the samples and put them inside an orbiting sample container, which will then be placed aboard a Mars ascent vehicle to bring the precious package up to Martian orbit, Trosper noted.
The relay race will continue with the Mars ascent vehicle handing off the samples to an Earth-return orbiter, which will then make the several-month trip back to our planet for arrival in 2031. After entering Earth's atmosphere, the samples — carefully quarantined to avoid any contamination of our planet or the package — will eventually make their way to NASA's Johnson Space Center in Texas, Trosper said. (Johnson Space Center already contains numerous Apollo moon samples and is well equipped for protecting space stuff.)
While the Mars sample return mission is the first effort to retrieve a sample from a potentially life-friendly area, other missions have returned samples from other bodies in the solar system. Humans and robots picked up rocks from the moon in the 1960s and 1970s and sent those back to Earth, allowing scientists to hypothesize that the moon was formed from a collision between Earth and a Mars-like object billions of years ago. More recent studies of Apollo samples in the 2010s, using more advanced equipment, revealed traces of water inside samples that were previously thought to be dry.
Spacecraft have also sampled numerous comets and asteroids, and two sample-return missions are happening right now. Scientists are examining samples from Japan's Hayabusa2 mission, which landed at asteroid Ryugu in December. They're also eagerly awaiting the return of NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) capsule that will bear bits of asteroid Bennu in 2023.
But the Mars sample return will be even more ambitious, said David Mitchell, director of the Engineering and Technology Directorate at NASA's Goddard Space Flight Center in Maryland. "The significance in this program versus past sample-return missions is it requires several different missions to occur over various points in time," he said.
Past missions such as Stardust, which returned a sample from a comet in 2006, show the potential for Mars samples to be examined in high definition, said University of Washington astronomer Don Brownlee, principal investigator of the comet sample return mission. As with the Apollo samples before it, scientists keep revisiting the results of the Stardust mission as equipment improves, he said. One later find in 2014, for example, revealed interstellar particles in the sample.
Brownlee said Stardust "revolutionized" scientists' understanding of comets because the mission showed a strange combination of "ice and fire" forming these icy bodies. The rocky materials in the sample were made in the inner solar system at temperatures of perhaps 1,000 to 2,000 degrees Fahrenheit (540 to 1,100 degrees Celsius). Yet the icy materials were made in temperatures as low as "10s of degrees" above absolute zero, the coldest temperature that can exist, he said.
"We believe that most of the rocky materials in comets formed close to the sun," Brownlee said, noting that over time, the materials were ejected to the Kuiper Belt, the region just outside the orbit of Neptune and including Pluto's orbit where most solar system comets come from. Even more notable, most of the rocky material includes biosignatures or biological processes that are indicative of life, he said.
These findings wouldn't have been possible in space because of the power and mass requirements of the instruments, Brownlee said. "I mean, the biggest instruments used to analyze the return samples were synchrotrons, which can be as big as a shopping center," he said.
While Mars sample return is high on NASA's wish list, the agency does plan to send astronauts to the moon to collect samples. again This time, it will be as part of the Artemis program, which may set humans on the moon as soon as 2024, depending on whether the Biden administration carries through the deadline set by the previous administration.
When Artemis goes forward, a "close second" to Mars on NASA Chief Scientist Jim Green's wish list would be to see humans or helpful robots picking up a core sample from permanently shadowed craters on the moon, where volatiles such as water ice collected over 4.5 billion years from the start of the solar system.
"This will be an incredibly exciting set of material that will, I think, tell us a lot about the origin and evolution of the Earth-moon system," Green said during the webinar.
Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.