One of the more ambitious things the Perseverance rover currently exploring the surface of Mars has been doing is gathering samples of Martian rocks and soil, setting them aside for a future mission to Mars to retrieve and return to Earth. NASA has confirmed that testing is underway on what it calls the most sophisticated endeavor ever attempted on Mars as it prepares a mission to retrieve the rock and soil samples Perseverance is collecting.
Designing the mission to collect the Martian samples is part of the multi-mission Mars Sample Return campaign that began last February when Perseverance arrived on Mars. NASA has collected the samples and wants to return them to Earth to allow hands-on testing to determine if life in microbial form may have existed on Mars in the distant past.
Perseverance was equipped with 43 sample tubes for soil and rock, and so far, four have been filled with rock core samples, and one has been filled with a sample of the Martian atmosphere. NASA plans to take a page from the Apollo mission book when it returned lunar samples to Earth. While some of the Martian samples will be studied straight away, others will be set aside for future generations to investigate.
Lunar samples returned from the Apollo missions were used the same way, holding some samples to be tested in the future when testing equipment and processes were more sophisticated. It’s very challenging to retrieve and return samples from the surface of Mars to Earth, and the entire process will take a decade. However, NASA isn’t working alone. It’s also working with European partners, including the ESA, to develop the rover to be used in the mission.
The rover intended to retrieve the samples from the surface of the Red Planet and transfer them to the lander is being developed by the NASA Jet Propulsion Laboratory. The lander will use a robotic arm developed by the ESA to pack the samples retrieved into a small rocket called the Mars Ascent Vehicle. The small rocket is being developed by the Marshall Space Flight Center in Alabama.
Preparing samples to be packed into the rocket on the surface of Mars is a complicated endeavor. Preparation of the samples requires sealing the sample capsule within a clean container to trap any Martian material inside. Next, the seal of the clean container would be sterilized, and then it would be placed into an Earth-entry capsule.
One of the most critical aspects of the mission is the lander’s design. If the lander fails in its job, other portions of the mission will likely fail as well. The lander has to be quite large at 5291 pounds to carry and launch the Mars Ascent Vehicle. That’s almost twice as heavy as the Perseverance rover, which used a rocket-powered jet pack to lower to the surface of Mars via cables.
With the extra weight, the Sample Retrieval Lander, which will be the largest and heaviest spacecraft of the type to ever go to Mars, will need a different type of landing system. JPL is building the lander with legs to absorb the impact of touchdown and retrorockets to slow its descent. Its landing system will be similar to what was used for the Phoenix and InSight lander missions.
To prepare for the difficulties of landing such a large rover, JPL’s Pavlina Karafillis has been drop testing a prototype lander. She and colleagues on the team have dropped the lander using a crane system and recorded it with high-speed cameras. The data gathered by those cameras is used to update computer models to improve the understanding of how energy would be dispersed through the lander when it impacts the surface of Mars.
Currently, the prototype being tested is only one-third the size of the actual spacecraft. JPL says testing a lighter prototype is one way to learn how the rover will behave on Mars since Mars has less gravity. However, JPL does plan to drop test a full-size prototype as well.
Mars Ascent Vehicle
Another critical aspect of the mission is the rocket Mars Ascent Vehicle. The rocket is nine feet long and has two stages that will sit on the lander’s deck. To prevent any issues with slipping or tilting the Lander from the rocket exhaust, engineers developed a system that will throw the rocket in the air at a rate of 16 feet per second just before the engines ignite.
The image below shows the system that will toss the rocket in the air during testing. Engineers use a cradle equipped with a gas-powered piston to fling at 881-pound mock rocket 11 feet in the air. During the test, cables suspended from a tower 44 feet high offloaded more than half the test rockets wait to simulate Martian gravity. The system is called Vertically Ejected Controlled Tip-off Release or VECTOR.
The system is designed to add a slight rotation to the rocket launch to help pitch it up and away from the surface of Mars. That system ensures that the rocket launch will happen even if the lander is oriented the wrong way on a slope. NASA has so far conducted 23 tests on the rocket changing its mass and center of gravity, with more testing to be conducted next year.
Without the Perseverance Rover performing its mission flawlessly so far, the mission NASA is currently working on to retrieve its samples would be useless. Perseverance has been gathering interesting data on the surface of Mars, including using its microphones to capture the sounds of the Red Planet.
Perseverance Rover has also been working together on evidence of liquid water on the surface of Mars and possibly signs of microbial life from Jezero Crater. The crater was a large lake in the distant past, and Perseverance is exploring what was a river delta in the distant past. Perseverance has also been recording flights for the Ingenuity helicopter. Last month it recorded the Mars helicopter’s 13th flight.