Robot explorers are helping pave the way for human exploration of the Red Planet. NASA’s newest Mars rover, Perseverance, is equipped with technology to teach us more about the environment and demonstrate what’s needed to support future crewed missions.
“Perseverance paves the way for new science and technological discoveries,” said Jim Reuter, the associate administrator for NASA’s Space Technology Mission Directorate (STMD). “The knowledge and capabilities we gain from this mission will help prepare us for human missions on Mars as early as the 2030s. Technology will drive that exploration.”
Capabilities needed by future pioneers will get their first test on the Red Planet in 2021. Hardware to ensure a precise landing, a mobile weather station, and a brand-new method of producing oxygen from carbon dioxide are packed with all of the science gear.
The aeroshell designed to protect Perseverance during entry into the Martian atmosphere includes a heat shield and a cone-shaped back shell. The former must withstand temperatures of more than 2,700 degrees Fahrenheit (about 1,480 degrees Celsius).
The Mars Science Laboratory Entry, Descent, and Landing Instrumentation (MEDLI) on the aeroshell around the Curiosity rover that landed on Mars in 2012 confirmed its heat shield worked effectively. It also revealed that the actual entry environments and the computer model predictions differed slightly. Engineers developed a second version of the technology, called the Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2) to observe a broader range of entry environment conditions, such as changes in temperature, the wind’s impact on the vehicle trajectory, and heating on the backshell.
The technology’s 28 sensors are positioned across the heat shield and backshell of the Mars 2020 entry vehicle. During the seven minutes of atmospheric entry – when the spacecraft slows from 12,500 miles per hour to just under 2 (from about 20,100 kilometers per hour to 3.2) – the sensors will continuously record heat and pressure across the entry vehicle. These will be NASA’s first-ever measurements of the heat experienced by the backshell of an entry vehicle.
“We are interested in how well the entire vehicle actually operates as it’s going through that crucial phase of incredibly high heating and high-pressure loads,” said Todd White, principal investigator for MEDLI2 based at NASA’s Ames Research Center in California’s Silicon Valley. “We tend to think our predictive models for supersonic flight are pretty good at Mars, but we don’t necessarily have the proof for that.
Getting the spacecraft into the best position for a controlled descent will make it easier for terrain relative navigation, or TRN, to identify the safest landing spot.
“TRN is a new subsystem that allows the lander to figure out its position and where it’s going to land by taking images while it’s on the parachute,” said Andrew Johnson, manager for the guidance, navigation, and control subsystem at NASA’s Jet Propulsion Laboratory in Southern California. “Past missions haven’t had this capability.”
This autopilot technology uses a map of the designated landing ellipse created from pictures taken by the Mars Reconnaissance Orbiter. Landmarks and hazards are identified, and the annotated maps are loaded on the TRN computer.
TRN uses a camera designed to take a picture in one-tenth of a second, resulting in clear pictures even during rapid descent. To enable fast image processing, the system includes a high-performance computer that uses algorithms to compare the descent pictures with data previously loaded via the onboard map.
Johnson likened the process to the way people use landmarks to navigate. “For instance, turn left at the market and turn right before the bridge,” he said.
TRN evaluates the landing area only seconds before touchdown. If the area is considered safe, TRN’s job is done. But if the rover is headed towards a dangerous area, TRN will select a nearby spot free of hazards, send that information to the spacecraft’s landing computer, a trajectory is created, and the spacecraft targets that spot.
While an orbiter can’t see small rocks, there’s enough known about the surface of Mars to identify multiple landing options. Alternatives are identified throughout the landing ellipse in case something unexpected happens, such as wind pushing the parachute off course.
Wind on Mars can be unpredictable, and the dust storms it creates can make entry, descent, and landing dangerous by interfering with navigation. This makes it imperative to learn more about atmospheric conditions before humans explore the planet.
The Mars Environmental Dynamics Analyzer, or MEDA, will fill gaps in atmospheric data that pose risks for human exploration. Manuel de la Torre Juárez, deputy principal investigator for MEDA at JPL, explained that international collaboration is behind the suite of instruments. The U.S. contribution is a camera dedicated to one of the most significant factors in Martian weather: dust.
“Those measurements are going to inform us about the aerosols,” he said, adding that both dust and ice have previously been observed in the Martian atmosphere. “What is the particle size of these aerosols? How do they change within the same day? This is something that we could not measure regularly on the other missions,” said de la Torre Juárez.
The Martian dust contains perchlorates, which are toxic to humans, and thus introduce another challenge for human explorers. MEDA measurements could help inform technologies to keep this pesky dust from contaminating habitats, space suits, and surface systems.
Learning when and how various atmospheric conditions occur and interact with the dust cycle will influence the design of infrastructure such as power systems, so they perform consistently in all conditions.
One method for identifying the type and physical properties of particles in the air is to examine how sunlight is transformed by the atmosphere. The intensity of solar radiation, how it changes depending on its angle, and the color distribution that reaches the surface all yield information.
These measurements will also provide important details about the ultraviolet (UV) light filtered out by dust and ozone in the Martian atmosphere. This is important for future astronauts. UV radiation can cause skin cancer in humans, but it also might kill any bacterial contamination people bring. This information can help fine-tune the protective habitat, clothing, and other resources astronauts bring to Mars.
De la Torre Juárez believes the effort to get people to Mars will do more than create technological marvels. “Exploring other planets increases both our understanding and our appreciation of our own planet,” he said.
Atmospheric data will also help NASA engineers test life-sustaining technology being built for future explorers.
When astronauts set foot on the Red Planet for the first time, they’ll rely on technologies tried and tested by their robotic predecessors. The Mars Oxygen In-Situ Resource Utilization Experiment, or MOXIE, is one of the instruments arriving with Perseverance that will demonstrate a new, critical capability: making oxygen directly from the Martian atmosphere. This means access to air for breathing, but more importantly, vast quantities of it that could be used to burn the fuel of a return rocket.
MOXIE is the first demonstration of its kind – the first test of an in-situ resource utilization technology to generate mission products with local resources – on another world.
The instrument is like a miniature electronic tree on the rover, producing oxygen from the carbon dioxide in the Martian atmosphere. MOXIE will produce oxygen by transforming carbon dioxide into carbon monoxide and oxygen molecules
MOXIE works in a three-step process. The instrument collects carbon dioxide from the atmosphere using a compressor, or pump. Next, it separates the molecule into carbon monoxide and oxygen via a catalytic reaction. Then, electrical current applied to a hot, permeable membrane – in this case, a type of ceramic – selectively pulls the negative oxygen ions from one side to the other, leaving behind the carbon monoxide. The pure oxygen is then collected, analyzed, and released back into the Martian atmosphere, while the carbon monoxide is sent to an exhaust along with any unused carbon dioxide.
“It’s like a fuel cell operated in reverse,” said Jeff Mellstrom, instrument manager at JPL. “A fuel cell will use fuel and an oxidizer to generate electricity and exhaust gas. We take in what would normally be considered an exhaust gas, the carbon dioxide, applying electricity to generate fuel and oxidizer, carbon monoxide, and oxygen, respectively.”
Testing MOXIE on Mars will validate how the technology functions outside of a lab, after the stressors of launch and traveling through space, and how it adapts to the harsh environment on the Martian surface. Scientists and engineers built the instrument to be robust enough to work through these conditions.
The primary goal for this technology is to prove that it could be feasible to make liquid oxygen propellant in situ, on Mars. Before astronauts even land on Mars, a larger system could begin producing metric tons of rocket fuel.
This car battery-sized model on Perseverance is the first step for developing a full-sized version to support future exploration. A mega-MOXIE won’t be 200 times more massive, but it would produce oxygen 200 times faster. That’s because, with enough of a power supply, it could run continuously. The full-sized instrument would be about the size of a washing machine.
“The ability to use resources on Mars, instead of bringing everything with us from Earth, can eliminate the need to bring tons of propellant on a human mission to Mars,” said Reuter.
The two instruments (MEDA and MOXIE) and two entry, descent, and landing technologies (MEDLI2 and TRN) were developed with funding from STMD. There are a total of seven instruments, including MEDA and MOXIE, onboard Perseverance.
About the Mission
Perseverance is a robotic scientist weighing about 2,260 pounds (1,025 kilograms). The rover’s astrobiology mission will search for signs of past microbial life. It will characterize the planet’s climate and geology, collect samples for future return to Earth, and pave the way for human exploration of the Red Planet. No matter what day Perseverance lifts off during its July 30-Aug. 15 launch period, it will land at Mars’ Jezero Crater on Feb. 18, 2021.
The two subsequent (follow-on) missions required to return the mission’s collected samples to Earth are currently being planned by NASA and the European Space Agency.
The Mars 2020 Perseverance rover mission is part of a larger program that includes missions to the Moon as a way to prepare for human exploration of the Red Planet. Charged with returning astronauts to the Moon by 2024, NASA will establish a sustained human presence on and around the Moon by 2028 through the agency’s Artemis lunar exploration plans.
For more about Perseverance, visit:
NASA’s Space Technology Mission Directorate