We’ve learned a lot about Mars in recent years. Multiple orbiters and hugely-successful rover missions have delivered a cascade of discoveries about our neighbouring planet. But to take the next step in unlocking Mars’ secrets, we need to get Martian samples back to Earth.
Both the ESA and NASA plan to get samples from Mars back to laboratories here on Earth, where they can be subjected to the type of detailed analysis that’s simply not possible with rovers on the surface of Mars. That effort is called the Mars Sample Return Campaign. Perhaps surprisingly, the hardest part might not be getting the samples back to Earth, but deciding on the order of scientific investigations into those samples.
The samples will be highly-coveted by scientists around the world. They have the potential to unlock secrets and answer pivotal questions in our quest to understand Mars.
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“Mars Sample Return would be a huge advancement for Mars science and the exploration of the Solar System”, concludes Sanjay Vijendran, ESA’s Mars Sample Return Campaign Coordinator. “The samples will fundamentally advance our understanding of Mars, the history of our Solar System, and will help us plan for future exploration missions.”
For these samples to live up to their potential, they need to be handled carefully. But it all starts with getting the samples back to Earth.
The ESA and NASA are working together to get these samples to Earth. NASA’s 2020 Mars rover will prepare samples and leave them in vessels on the surface. Then the Sample Return Lander will land a platform near the Mars 2020 Rover landing site. An ESA rover, called the Sample Fetch Rover (SFR), will depart from that platform and gather the samples.
The SFR will deliver them to the platform where they’ll be placed in a canister on the Mars Ascent Vehicle (MAV). The MAV will be the first vehicle to lift off from the Martian surface and will deliver the samples into Mars orbit.
Next is the ESA’s Earth Return Orbiter (ERT), where the samples will be put into a sealed bio-containment system, then delivered to Earth orbit. From there, the samples will be sent to the surface, with the aid of parachutes, to be retrieved. Then the analysis begins.
NASA and ESA are both thinking ahead to how to handle these samples, including rocks, gas, and dust, for maximum science benefit.
The first consideration is controlling contamination. Any exposure to Earth’s atmosphere will change the samples. Just like samples from the Moon, the Martian samples will go into quarantine for protection.
There are guidelines in place to not only protect samples from Earth’s environment, but also to protect Earth from the samples, just in case. In 1959, at the dawn of the space age, the international community created COSPAR, the Committee on Space Research. COSPAR developed many of the guidelines that sought to protect other worlds from Earthly contamination, and vice versa.
Right now, COSPAR is updating its guidelines to prepare for the Mars samples.
It all starts with a Sample Receiving Facility (SRF) where the samples will be quarantined. Even before the sample containers are opened, scientific investigation can begin. These Martian samples will be extremely valuable, so even any Martian dust that has settled on the surface of the sample containers will be studied, before the containers are even opened. The samples can also be studied with non-invasive x-rays before being opened.
Before any samples are opened, the order of investigation and study will be predetermined.
“The sample tubes will contain martian rocks, dust and atmosphere,” says Elliot Sefton-Nash, the MSR Study Scientist from ESA’s Science Support Office, “Even though the plan is to open the tubes in a contained and inert environment, for a few measurements the clock will be ticking: for example, trapped gases in the sample material might start to mix with their surroundings, which could modify the martian chemical signatures that we want to measure.”
There are a multitude of measurements that scientists want to take. The trick is to find the best way to proceed, since some of those measurements are time-sensitive, and others will alter the samples. Also, the samples, according to planetary protection protocols, will eventually have to be sterilized, in case any Martian hitchhikers rode them to Earth.
But the sterilization of the samples is problematic. They have to be sterilized using radiation, chemical processes, or heat, and all those methods can alter the samples. So any scientific investigations that are sensitive to those methods have to be prioritized.
The body that decides how the samples should be handled is called the Mars Sample Return Science Planning Group. The good news is that that group says that roughly 3/4 of the scientific investigations can be done after sterilization.
But there’s still a lot of decisions to puzzle through.
The order in which investigations are done after sterilization is still important, because some measurements will influence the results of others. For example, some measurements will destroy samples in order to get results, and not all measurements can be done on all samples. According to the ESA, the nature of the laboratory doing the work can be a decisive factor.
Precision measurements of carbon in the samples dictates strict control of carbon in the laboratory. It may be that an all-metal laboratory is needed to guarantee valid results. But an all-metal laboratory could contaminate samples for other measurements. Finding the right balance is a big puzzle.
Once the ESA’s Space19+ Council meets and finalizes their involvement with the Mars Sample Return Mission, planning for handling the samples can begin in earnest. It’ll be up to the ESA, NASA, and the scientific community to come up with a plan that delivers the most science from the samples.