The successful landing of the Perseverance rover on Mars on February 18 was not just the start of its surface mission but also the start of a multinational, decade-long effort to obtain pristine samples of Mars and return them to Earth for intensive study.
The Mars Sample Return project is the most complex robotic planetary mission ever created, involving four spacecraft in three missions that span the 11 years from 2020 through 2031 – when the ESA Earth Return Orbiter ejects the sample container for a parachute landing on Earth.
The Mars Sample Return effort has been planned, designed, and developed for many decades. As early as the 1970s, space agencies were looking to a robotic sample return mission as a vital precursor to a human landing on Mars and as an important mission in its own right. In the 1990s, a sample return mission was endorsed by NASA’s Mars Exploration Program, and in 2001, the Jet Propulsion Laboratory requested proposals for a Mars sample return mission.
The effort to bring back samples of Mars was dealt a setback when NASA pulled out of a joint ExoMars project with the ESA, and the MAX-C rover (which would have cached samples and conducted astrobiology studies) was canceled.
However, a Mars sample return was designated as the highest priority flagship mission by the National Research Council’s Planetary Science Decadal Survey in early 2011, and after Curiosity’s successful landing in 2012, the Mars 2020 rover was approved as the first step in this effort.
The Mars 2020 rover, named Perseverance before its launch last year, is the first mission in the Mars Sample Return series. Perseverance contains the Sample Caching System, which consists of three robotic devices.
The first device is the rover’s large robotic arm which drills into the surface and collects the core sample. The sample is moved to a bit carousel inside the rover’s Sample Caching System. The bit carousel moves the sample to a small, sample handling arm which images the core sample and measures its volume before sealing it and moving the core sample into storage.
Presently, the doors on the top and bottom of the rover where new samples will be stored have been opened, in addition to separating the “belly pan” which protects the sampling system.
A quick-look mosaic my team pulled together of the belly pan, now on the surface of Mars. Up next is to check my sampling system now that its cover panel is off.
— NASA's Perseverance Mars Rover (@NASAPersevere) March 13, 2021
Perseverance is currently tasked to collect up to 43 samples and deposit them onto the surface of Jezero Crater for collection. The time frame for starting sample collection is expected to be sometime in summer 2021, and the science team will obtain samples from different geologic units in Jezero Crater, which is an ancient river delta that scientists believe may preserve evidence of ancient life.
After Perseverance collects its samples and deposits the sample tubes on the surface at known locations, called “depots”, the next step will be the arrival of the NASA Sample Retrieval Lander.
This return vehicle will include an ESA-built fetch rover and a Mars Ascent Vehicle with a Northrop Grumman-built solid-fuel rocket known as MAPS – short for Mars Ascent Propulsion System – that will land in Jezero Crater in 2028 after launch in 2026.
The lander will use a similar Terrain Relative Navigation system that performed so well for Perseverance, and the fetch rover, about the size of the MER-A (Spirit) and MER-B (Opportunity) rovers, will collect up to 36 of the 43 samples left behind by Perseverance and transport them to the Mars Ascent Vehicle.
The ESA Sample Fetch Rover is currently being designed by Airbus in Stevenage, England, under a study contract known as Advanced B2. In December 2020, NASA approved the Mars Sample Return project to proceed to Phase A, meaning critical design decisions will be made and critical technologies will be matured.
Already, algorithms for spotting the sample tubes left by Perseverance have been developed and design work for the robotic arm that will collect the samples is underway.
The fetch rover will have four wheels instead of six for a better ability to cope with the Jezero Crater landing site terrain and for better speed to get the samples to the lander in a timely manner.
When the rover returns to the Mars Ascent Vehicle, the samples will be moved to a basketball-sized container aboard the MAV that will keep the samples at less than 30°C (86°F) to preserve them in their most natural state.
The MAV, developed by the Marshall Space Flight Center and using the Northrop Grumman solid rocket booster which will be built in Elkton, Maryland, will wait for the ESA Earth Return Orbiter (ERO) to launch aboard an Ariane 64 rocket from Kourou, French Guiana in 2026.
The ERO, featuring the largest solar arrays ever built, will make a year-long cruise to Mars using a solar-electric propulsion package, and after arrival will act as a communications relay for the surface sample return missions.
The MAV will launch from the surface of Mars after the ERO arrives in Martian orbit. The basketball-sized sample container, known as the Orbiting Sample, will be placed in low Mars orbit, and the ERO will use automated rendezvous technology using Automated Transfer Vehicle (ATV) heritage to maneuver to the Orbiting Sample, which will be captured for the return journey to Earth.
The ERO will use a NASA-developed Capture, Containment, and Return system to transfer the sample to a NASA developed Earth Entry Vehicle for a sample return landing in the Utah desert near Dugway in 2031.
The ERO, like the Sample Fetch Rover, will be developed by Airbus. The Airbus facility in Toulouse, France, will develop and build the ERO, while mission analysis will be performed at the facility in Stevenage, England.
Design work for other elements is also underway at various facilities around the world, but many details of the Mars Sample Return missions are still being worked out, including the launch of the NASA Sample Retrieval Lander with the Sample Fetch Rover and the Mars Ascent Vehicle.
The Mars Sample Return mission will take over a decade to complete, but Earth-based laboratories that will study the samples are now being chosen and prepared.
These laboratories, located in both the United States and Europe, will use similar bio-safety protocols to Biosafety Level 4 laboratories that handle dangerous pathogens. This is done to prevent cross contamination from the Martian samples, which could tell us much about the history, habitability, and possibility of ancient life on Mars.
(Lead image via NASA)