The years-long delay of the NASA-ESA Mars Sample Return (MSR) mission leaves astrobiologists —- indeed most of humanity —- longing for some sort of next level closure on whether Mars ever had microbial life.
Luckily, the European Space Agency (ESA) will likely launch its long-awaited ExoMars Rosalind Franklin rover to the red planet in 2028.
The ESA rover will be capable of doing in-situ sample analysis in an area that some 3.5 billion years ago was likely a vast northern ocean. The ESA rover with NASA cooperation is the next best shortcut to answering the question of whether enigmatic Mars ever had a microbial Past.
We know there was water there in Mars’ Oxia Planum area because the clays that dominate the mineralogy there need water to form, Jorge Vago, project scientist for ESA’s Rosalind Franklin ExoMars rover, recently told me at the European Astrobiology Network Association (EANA) 2024 conference in Graz, Austria.
The beauty of the Rosalind Franklin rover is that it’s not a sample return mission. But it is still capable of detecting subsurface microfossils, if they are there.
While we wait for the first Mars samples to be brought to Earth, Rosalind Franklin —with its drill and novel instruments— will investigate whether the subsurface holds molecular traces of early life, says Vago.
Eventually, NASA will provide the MSR lander. And ESA will provide both a robotic arm on NASA’s lander to retrieve the samples that Perseverance has collected. ESA will also furnish the mission with an Earth Return Orbiter (ERO) that will bring back the Perseverance samples that NASA’s lander will launch into Mars orbit. However, both NASA’s lander and ESA’s orbiter are due for separate launches, perhaps years apart.
All of this waiting has been more than a little frustrating, particularly since the recent tantalizing news of Perseverance’s so-called “leopard spot” sample which offers a clear indication of possible past microbial activity.
Yet the ESA Rosalind Franklin rover can hopefully offer an astrobiology shortcut in finding signs of past Mars life.
Collecting samples from the Martian subsurface at a depth of some six feet is very important for the preservation of organic matter, says Vago. Since Rosalind Franklin is looking for biosignatures, or possible traces of life, it is very interesting to the scientific community to analyze these subsurface samples, he says. That’s because subsurface samples will be protected from ionizing radiation and from the environment on the surface of the planet, which is very hostile, says Vago.
The ESA rover will use solar panels supplemented by small radio isotope pellets to generate enough heat so that it doesn’t need the panels to supply so much electrical energy during the Martian night.
The nominal mission for the rover, again, is about seven months, but we hope we will have an extended mission, says Vago.
As for the joint NASA-ESA Mars Sample Return Mission (MSR)?
MSR is a bit in flux, so its architecture has not been concluded, but our working assumption now is that the NASA MSR lander with an embedded ESA-built sample transfer arm will be launching in 2031, Pantelis Poulakis, ESA’s Sample Transfer Arm Project Manager, told me via phone.
The MSR team is waiting for NASA to conclude a series of new architectural studies as well as to secure final funding before setting exact launch dates. But the current plan calls for NASA’s Perseverance rover to move to the lander to offload its samples collected from inside Mars’ Jezero Crater.
After a testing and commissioning period for the lander and the sample transfer arm, the arm will begin transferring the samples from Perseverance to the NASA lander’s sample canister which will be launched in orbit. The current plan is for the 2.5-meter transfer arm to autonomously use its embedded computer guidance system to transfer one to two samples per day.
The hope is the sample transfers will all be done within thirty days of starting the process.
NASA’s Mars lander will then use a rocket to launch the samples into a Mars orbit where it will deliver the basketball-sized sample container to the earth return orbiter.
Rendezvous In Mars Orbit
ERO will track both (the rocket is larger and easier to spot) but only capture the container, Tiago Loureiro, ESA’s Earth Return Orbiter Project Manager, told me via email. Once we know where the container is, we will command ERO to gently approach its position, he says. When we get close enough, we will authorize ERO to execute the final stages of rendezvous and then capture the sample canister autonomously, says Loureiro.
A Complicated Maneuver
Now targeted to launch in 2030, ERO will use its electric propulsion system to spiral up from a low Mars orbit into an escape orbit and then to perform an interplanetary transfer from Mars to earth.
The hope is to have Perseverance’s samples back to earth by 2035.
The orbiter will not land on earth after the delivery of the samples, says Loureiro. Instead, it will be sent onto a stable heliocentric orbit that is compliant with the planetary protection requirements, he says.
But ERO will ferry the canister loaded with Perseverance’s samples back to earth orbit and then be released onto a landing trajectory to the Utah Test and Training Range.
Final Architecture Undecided
Even so, the final architecture of the MSR mission has yet to be decided. China, meanwhile, has announced that it hopes to launch a Mars Sample Return mission in 2028, potentially beating both NASA and ESA back to earth with samples of its own.
If NASA and/or ESA allow any more delays to interfere with the timely retrieval of Perseverance’s carefully curated samples, humanity will miss a once in a generation opportunity to characterize potential evidence of past life in our solar system.
