NASA’s Self-Driving Perseverance Mars Rover ‘Takes the Wheel’

The agency’s newest rover is trekking across the Martian landscape using a newly enhanced auto-navigation system.

Perseverance relies on left and right navigation cameras. The view seen here combines the perspective of two cameras rover during the rover’s first drive using AutoNav, it’s auto-navigation function.
Credits: NASA/JPL-Caltech

NASA’s newest six-wheeled robot on Mars, the Perseverance rover, is beginning an epic journey across a crater floor seeking signs of ancient life. That means the rover team is deeply engaged with planning navigation routes, drafting instructions to be beamed up, even donning special 3D glasses to help map their course.

But increasingly, the rover will take charge of the drive-by itself, using a powerful auto-navigation system. Called AutoNav, this enhanced system makes 3D maps of the terrain ahead, identifies hazards, and plans a route around any obstacles without additional direction from controllers back on Earth.

This computer simulation shows NASA’s Perseverance Mars rover as it carried out its first drive using its auto-navigation feature, which allows it to avoid rocks and other hazards without input from engineers back on Earth.
Credits: NASA/JPL-Caltec

“We have a capability called ‘thinking while driving,’” said Vandi Verma, a senior engineer, rover planner, and driver at NASA’s Jet Propulsion Laboratory in Southern California. “The rover is thinking about the autonomous drive while its wheels are turning.”

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Vandi Verma, an engineer who now works with NASA’s Perseverance Mars rover, is seen here working as a driver for the Curiosity rover. The special 3D glasses she’s wearing are still used by rover drivers to easily detect changes in terrain that the rover may need to avoid. Credits: NASA/JPL-Caltech

That capability, combined with other improvements, might enable Perseverance to hit a top speed of 393 feet (120 meters) per hour; its predecessor, Curiosity, equipped with an earlier version of AutoNav, covers about 66 feet (20 meters) per hour as it climbs Mount Sharp to the southeast.

“We sped up AutoNav by four or five times,” said Michael McHenry, the mobility domain lead and part of JPL’s team of rover planners. “We’re driving a lot farther in a lot less time than Curiosity demonstrated.”

As Perseverance begins its first science campaign on the floor of Jezero Crater, AutoNav will be a key feature in helping get the job done.

This crater once was a lake, when, billions of years ago, Mars was wetter than today, and Perseverance’s destination is a dried-out river delta at the crater’s edge. If life ever took hold on early Mars, signs of it might be found there. The rover will gather samples over some 9 miles (15 kilometers), then prep the samples for collection by a future mission that would take them back to Earth for analysis.

“We’re going to be able to get to places the scientists want to go much more quickly,” said Jennifer Trosper, who has worked on every one of NASA’s Martian rovers and is the Mars 2020 Perseverance rover project manager. “Now we are able to drive through these more complex terrains instead of going around them: It’s not something we’ve been able to do before.”

The Human Element

Of course, Perseverance can’t get by on AutoNav alone. The involvement of the rover team remains critical in planning and driving Perseverance’s route. An entire team of specialists develops a navigation route along with planning the rover’s activity, whether it’s examining a geologically interesting feature on the way to its destination or, soon, taking samples.

Because of the radio signal delay between Earth and Mars, they can’t simply move the rover forward with a joystick. Instead, they scrutinize satellite images, sometimes donning those 3D glasses to view the Martian surface in the rover’s vicinity. Once the team signs off, they beam the instructions to Mars, and the rover executes those instructions the following day.

Perseverance’s wheels were modified as well to help with just how swiftly those plans are executed: Along with being slightly greater in diameter and narrower than Curiosity’s wheels, they each feature 48 treads that look slightly wavy lines, as opposed to Curiosity’s 24 chevron-pattern treads. The goals were to help with traction as well as durability.

“Curiosity couldn’t AutoNav because of the wheel-wear issue,” Trosper said. “Early in the mission, we experienced small, sharp, pointy rocks starting to put holes in the wheels, and our AutoNav didn’t avoid those.”

Higher clearance for Perseverance’s belly also enables the rover to roll safely over rougher ground – including good-size rocks. And Perseverance’s beefed-up auto-navigation capabilities include ENav, or enhanced navigation, an algorithm-and-software combination that allows more precise hazard detection.

Unlike its predecessors, Perseverance can employ one of its computers just for navigation on the surface; its main computer can devote itself to the many other tasks that keep the rover healthy and active.

This Vision Compute Element, or VCE, guided Perseverance to the Martian surface during its entry, descent, and landing in February. Now it’s being used full-time to map out the rover’s journey while helping it avoid trouble along the way.

The rover also keeps track of how far it’s moved from one spot to another using a system called “visual odometry.” Perseverance periodically captures images as it moves, comparing one position to the next to see if it moved the expected distance.

Team members say they look forward to letting AutoNav “take the wheel.” But they’ll also be ready to intervene when needed.

And just what is it like to drive on Mars? The planners and drivers say it never gets old.

“Jezero is incredible,” Verma said. “It’s a rover driver’s paradise. When you put on the 3D glasses, you see so much more undulation in the terrain. Some days I just stare at the images.”

Where is Perseverance Right NOW?

Scroll and pan around this map to see the latest location and traverse path for the Mars Perseverance rover at Jezero Crater. The goal of the mission is to seek signs of ancient life and collect samples of rock and regolith (broken rock and dust) for a possible return to Earth.

This map is composed of two layers: a grayscale Jezero Crater map, and a true-color base map. The greyscale base map was created with images from the HiRISE camera on NASA’s Mars Reconnaissance Orbiter, while the color base map is from the European Space Agency Mars Express High-Resolution Stereo camera.

Some color processing has been applied to highlight surface features. The original image can be found here. A high-resolution Digital Elevation Model was created from the images to provide critical information for rover drivers, who need to know how steep the hills areas they plan a path forward through this rocky terrain.

Engineers created this experience with software used by the mission team who decide where Perseverance will explore, and how to get there. Each dot represents the endpoint of a drive and is labeled with the day, or sol, on Mars, that the rover stopped.

The Extraordinary Sample-Gathering System of NASA’s Perseverance Mars Rover

Two astronauts collected Moon rocks on Apollo 11. It will take three robotic systems working together to gather up the first Mars rock samples for return to Earth.

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The samples Apollo 11 brought back to Earth from the Moon were humanity’s first from another celestial body. NASA’s upcoming Mars 2020 Perseverance rover mission will collect the first samples from another planet (the red one) for return to Earth by subsequent missions.

In place of astronauts, the Perseverance rover will rely on the most complex, capable, and cleanest mechanism ever to be sent into space, the Sample Caching System.

The final 39 of the 43 sample tubes at the heart of the sample system were loaded, along with the storage assembly that will hold them, aboard NASA’s Perseverance rover on May 20 at Kennedy Space Center in Florida.

(The other four tubes had already been loaded into different locations in the Sample Caching System.) The integration of the final tubes marks another key step in preparation for the opening of the rover’s launch period on July 17.

“While you cannot help but marvel at what was achieved back in the days of Apollo, they did have one thing going for them we don’t: boots on the ground,” said Adam Steltzner, chief engineer for the Mars 2020 Perseverance rover mission at NASA’s Jet Propulsion Laboratory in Southern California.

“For us to collect the first samples of Mars for return to Earth, in place of two astronauts we have three robots that have to work with the precision of a Swiss watch.

Mars 2020 Perseverance Rover Sample Cache System: Engineers test the Sample Caching System on the Perseverance Mars rover. Described as one of the most complex robotic systems ever built, the Sample and Caching System will collect core samples from the rocky surface of Mars, seal them in tubes and leave them for a future mission to retrieve and bring back to Earth. Credits: NASA/JPL-Caltech.

While many people think of the Perseverance rover as one robot, it’s actually akin to a collection of robots working together. Located on the front of the Perseverance rover, the Sample Caching System itself is composed of three robots, the most visible being the rover’s 7-foot-long (2-meter-long) robotic arm.

Bolted to the front of the rover’s chassis, the five-jointed arm carries a large turret that includes a rotary percussive drill to collect core samples of Mars rock and regolith (broken rock and dust).

The second robot looks like a small flying saucer built into the front of the rover. Called the bit carousel, this appliance is the ultimate middleman for all Mars sample transactions: It will provide drill bits and empty sample tubes to the drill and will later move the sample-filled tubes into the rover chassis for assessment and processing.

The third robot in the Sample Caching System is the 1.6-foot-long (0.5 meter-long) sample handling arm (known by the team as the “T. rex arm”). Located in the belly of the rover, it picks up where the bit carousel leaves off, moving sample tubes between storage and documentation stations as well as the bit carousel.

Clocklike Precision

All of these robots need to run with clocklike precision. But where the typical Swiss chronometer has fewer than 400 parts, the Sample Caching System has more than 3,000.

“It sounds like a lot, but you begin to realize the need for complexity when you consider the Sample Caching System is tasked with autonomously drilling into Mars rock, pulling out intact core samples and then sealing them hermetically in hyper-sterile vessels that are essentially free of any Earth-originating organic material that could get in the way of future analysis,” said Steltzner.

“In terms of technology, it is the most complicated, most sophisticated mechanism that we have ever built, tested and readied for spaceflight.”

The mission’s goal is to collect a dozen or more samples. So how does this three-robot, steamer-trunk-sized labyrinthine collection of motors, planetary gearboxes, encoders and other devices all meticulously work together to take them?

“Essentially, after our rotary percussive drill takes a core sample, it will turn around and dock with one of the four docking cones of the bit carousel,” said Steltzner.

“Then the bit carousel rotates that Mars-filled drill bit and a sample tube down inside the rover to a location where our sample handling arm can grab it. That arm pulls the filled sample tube out of the drill bit and takes it to be imaged by a camera inside the Sample Caching System.”

After the sample tube is imaged, the small robotic arm moves it to the volume assessment station, where a ramrod pushes down into the sample to gauge its size. “Then we go back and take another image,” said Steltzner. “After that, we pick up a seal — a little plug — for the top of the sample tube and go back to take yet another image.”

Next, the Sample Caching System places the tube in the sealing station, where a mechanism hermetically seals the tube with the cap. “Then we take the tube out,” added Steltzner, “and we return it to storage from where it first began.”

Getting the system designed and manufactured, then integrated into Perseverance has been a seven-year endeavor. And the work isn’t done. As with everything else on the rover, there are two versions of the Sample Caching System: an engineering test model that will stay here on Earth and the flight model that will travel to Mars.

“The engineering model is identical in every way possible to the flight model, and it’s our job to try to break it,” said Kelly Palm, the Sample Caching System integration engineer and Mars 2020 test lead at JPL.

“We do that because we would rather see things wear out or break on Earth than on Mars. So we put the engineering test model through its paces to inform our use of its flight twin on Mars.”

To that end, the team uses different rocks to simulate types of terrain. They drill them from various angles to anticipate any imaginable situation the rover could be in where the science team might want to gather a sample.

“Every once in a while, I have to take a minute and contemplate what we are doing,” said Palm. “Just a few years ago I was in college. Now I am working on the system that will be responsible for collecting the first samples from another planet for return to Earth. That is pretty awesome.”

About the Mars 2020 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 17-Aug. 11 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.