The Mars Sample Return (MSR) campaign is an ambitious multi-year collaborative effort between NASA and the European Space Agency (ESA) to return scientifically selected rock and soil samples from Mars to Earth. Bringing samples back from Mars has been a priority goal of the planetary science community for decades as samples would provide a wealth of scientific information that cannot be obtained by current robotic surface missions or remote sensing from orbit. Analyzing the samples in advanced laboratories here on Earth has the potential to revolutionize our understanding of Mars and help answer key questions about the potential for life beyond Earth.
Perseverance’s role in the MSR campaign is to collect scientifically worthy rock and soil samples from Jezero Crater using its drill and sample caching system. Jezero Crater is a 28-mile wide basin located on the western edge of Isidis Planitia, just north of the Martian equator. Billions of years ago, Jezero was the site of an ancient lake filled by a river delta. Scientists believe this location preserves a rich geological record that could provide vital clues about the early climate and potential for life on Mars.
Perseverance carries 43 sample tubes that can each store one core sample about the size of a piece of chalk. Using its 7-foot long robotic arm, drill, and other instruments like cameras and spectrometers, Perseverance will identify and study geologically interesting rock formations and sedimentary layers that could contain traces of ancient microbial life or preserve a record of past environments like a lake. Under careful sterile conditions, Perseverance’s drill will then take core samples from selected rocks and the rover will transfer them to sealed tubes.
The carefully cached samples will then remain on the surface of Mars until a future MSR mission can retrieve them for return to Earth, hopefully within the next 10 years. Leaving the samples on the surface minimizes the risk of contaminating Earth with any Martian material and allows the scientific study of samples to happen under optimal laboratory conditions here with sophisticated equipment far beyond the capabilities of any Mars surface mission.
Perseverance began caching samples in its first session at “Rochette” in October 2021 and as of March 2022 had already cached 9 samples. It plans to continue collecting samples at Jezero Crater through at least 2033 to ensure the most scientifically compelling samples are returned to Earth for detailed analysis. The tubes will be deposited in carefully documented “cache” locations along the rover’s route so future missions know where to retrieve them. In total, Perseverance has the capability to cache up to 38 samples by the end of its prime mission.
The ambitious MSR architectural plan currently envisions three complex separate missions to retrieve and return the cached Perseverance samples. The first mission, currently targeted for launch in 2028, is the Mars Ascent Vehicle/Orbiting Sample (MAV/OS). This rocket and spacecraft combo would land near Perseverance’s cached samples, lift off from the Martian surface, and deploy the Sample Retrieval Lander containing the Mars Orbiting Sample canister.
The Sample Retrieval Lander would then touch down, deploy a small rover to retrieve the cache tubes left by Perseverance at the designated cache location(s), and transfer the samples to the Sample Orbiting Sample canister. The MAV would then lift back into Martian orbit where it would rendezvous with the orbiter and transfer the Sample Orbiting canister into the secure containment orbiting Mars.
The next critical MSR mission is the Earth Return Orbiter (ERO) launch, targeted for 2030. The ERO spacecraft would travel to Mars and capture the orbiting sample container left by the MAV/OS mission. The ERO would then depart Mars and begin the seven-month 230-million-mile trip back to Earth carrying the priceless samples. To prevent terrestrial contamination, the samples would remain sealed in the containment orbiter for re-entry.
The third mission planned is the Earth Entry Vehicle (EEV) targeted to launch in 2031. This mission would capture the returning ERO spacecraft and utilizing a capsule, heat shield, and parachutes, would safely land the sample containers in Utah’s west desert where scientists can extract the Mars samples under strict planetary protection protocols in new laboratories built specifically for this purpose.
The unprecedented MSR campaign has the potential to revolutionize our understanding of Mars and address questions that have intrigued scientists for generations like whether Mars ever supported microbial life. Careful caching by Perseverance and meticulous retrieval and return by the future MSR elements provides the best opportunity for scientific discovery while ensuring planetary protections. Perseverance’s diligent efforts at Jezero Crater to select and cache compelling rock core samples in its ambitious multi-year exploration leaves promising potential for future scientists to examine Martian treasures from the safety of Earth.