Tricky terrain: Helping to assure a safe rover landing

Tricky Terrain: Helping to Assure a Safe Rover Landing
Mars 2020’s Perseverance rover is provided with a lander imaginative and prescient system based mostly on terrain-relative navigation, a sophisticated methodology of autonomously evaluating real-time photographs to preloaded maps that decide the rover’s place relative to hazards within the touchdown space. Divert steerage algorithms and software program can then direct the rover round these obstacles if wanted. Credit score: NASA/JPL-Caltech

After a virtually seven-month journey to Mars, NASA’s Perseverance rover is slated to land on the Pink Planet’s Jezero Crater Feb. 18, 2021, a rugged expanse chosen for its scientific analysis and pattern assortment prospects.


However the very options that make the positioning fascinating to scientists additionally make it a comparatively harmful place to land—a problem that has motivated rigorous testing right here on Earth for the lander imaginative and prescient system (LVS) that the will depend on to securely contact down.

“Jezero is 28 miles broad, however inside that expanse there are numerous potential hazards the rover might encounter: hills, rock fields, dunes, the partitions of the crater itself, to call only a few,” mentioned Andrew Johnson, principal robotics methods engineer at NASA’s Jet Propulsion Laboratory in Southern California. “So, in the event you land on a kind of hazards, it may very well be catastrophic to the entire mission.”

Enter Terrain-Relative Navigation (TRN), the mission-critical know-how on the coronary heart of the LVS that captures photographs of the Mars terrain in actual time and compares them with onboard maps of the touchdown space, autonomously directing the rover to divert round recognized hazards and obstacles as wanted.

“For Mars 2020, LVS will use the place data to determine the place the rover is relative to secure spots between these hazards. And in a kind of secure spots is the place the rover will contact down,” defined Johnson.

If Johnson sounds assured that LVS will work to land Perseverance safely, that is as a result of it permits the rover to find out its place relative to the bottom with an accuracy of about 200 ft or much less. That low margin of error and excessive diploma of assurance are by design, and the results of in depth testing each within the lab and within the area.

Tricky Terrain: Helping to Assure a Safe Rover Landing
Masten’s Xombie VTVL system sits on a launchpad in Mojave, California in December 2014, ready for a flight take a look at that may assist show lander imaginative and prescient system capabilities for the Mars 2020 Perseverance rover mission. Credit score: Masten Area Programs

“Now we have what we name the trifecta of testing,” defined JPL’s Swati Mohan, steerage, navigation, and management operations lead for Mars 2020.

Mohan mentioned that the primary two testing areas—{hardware} and simulation—have been carried out in a lab.

“That is the place we take a look at each situation and variable we are able to. Vacuum, vibration, temperature, electrical compatibility—we put the {hardware} by means of its paces,” mentioned Mohan. “Then with simulation, we mannequin varied eventualities that the software program algorithms could encounter on Mars—a too-sunny day, very darkish day, windy day—and we make certain the system behaves as anticipated no matter these situations.”

However the third piece of the trifecta—the sphere checks—require precise flights to place the lab outcomes by means of additional rigor and supply a excessive stage of technical readiness for NASA missions. For LVS’s early flight checks, Johnson and workforce mounted the LVS to a helicopter and used it to estimate the automobile’s place robotically because it was flying.

“That bought us to a sure stage of technical readiness as a result of the system might monitor a variety of terrain, but it surely did not have the identical sort of descent that Perseverance may have,” mentioned Johnson. “There was additionally a have to exhibit LVS on a rocket.”

That want was met by NASA’s Flight Alternatives program, which facilitated two 2014 flights within the Mojave Desert on Masten Area Programs’ Xombie—a vertical takeoff and vertical touchdown (VTVL) system that features equally to a lander. The flight checks demonstrated LVS’s potential to direct Xombie to autonomously change course and keep away from hazards on descent by adopting a newly calculated path to a secure touchdown website. Earlier flights on Masten’s VTVL system additionally helped validate algorithms and software program used to calculate fuel-optimal trajectories for planetary landings.

2014 flight checks on Masten’s Xombie VTVL system demonstrated the lander imaginative and prescient system’s terrain-relative navigation and fuel-optimal massive divert steerage (G-FOLD) capabilities. The flights proved the system’s potential to autonomously change course to keep away from hazards on descent and undertake a newly calculated path to a secure touchdown website. The profitable area checks enabled the know-how to be greenlighted for inclusion on NASA’s Mars 2020 mission. Credit score: NASA/JPL-Caltech

“Testing on the rocket laid just about all remaining doubts to relaxation and answered a crucial query for the LVS operation affirmatively,” mentioned JPL’s Nikolas Trawny, a payload and pointing management methods engineer who labored carefully with Masten on the 2014 area checks. “It was then that we knew LVS would work in the course of the high-speed vertical descent typical of Mars landings.”

Johnson added that the suborbital testing in truth elevated the know-how readiness stage to get the ultimate inexperienced gentle of acceptance into the Mars 2020 mission.

“The testing that Flight Alternatives is about as much as present was actually unprecedented inside NASA on the time,” mentioned Johnson. “But it surely’s confirmed so worthwhile that it is now turning into anticipated to do these kinds of flight checks. For LVS, these rocket flights have been the capstone of our know-how growth effort.”

With the know-how accepted for Mars 2020, the mission workforce started to construct the ultimate model of LVS that may fly on Perseverance. In 2019, a duplicate of that system flew on yet one more helicopter demonstration in Loss of life Valley, California, facilitated by NASA’s Expertise Demonstration Missions program. The helicopter flight offered a remaining verify on over six-years of a number of area checks.

However Mohan identified that even with these profitable demonstrations, there will probably be extra work to do to make sure a secure touchdown. She’ll be at Mission Management for the touchdown, monitoring the well being of the system each step of the best way.

“Actual life can at all times throw you curve balls. So, we’ll be monitoring all the things in the course of the cruise part, checking energy to the digital camera, ensuring the info is flowing as anticipated,” Mohan mentioned. “And as soon as we get that sign from the rover that claims, ‘I’ve landed and I am on steady floor,’ then we are able to rejoice.”


NASA flight program tests Mars lander vision system


Quotation:
Difficult terrain: Serving to to guarantee a secure rover touchdown (2021, February 8)
retrieved 14 February 2021
from https://phys.org/information/2021-02-tricky-terrain-safe-rover.html

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