CMU’S FIELD ROBOTICS PREPARES STUDENTS FOR CRITICAL ROLES IN NASA MISSIONS
MARK ROTH
As the Mars Perseverance rover made its descent to the red planet on Feb. 18, 2021, Andrew Johnson (CS 1997) sat nervously in the control room, waiting to see if the Lander Visual System (LVS) he helped design would work properly. Adding to the tension was the fact that every signal he received was old news — messages from the past — because it took just seven minutes for the craft to descend to Mars, but 11 minutes for its signals to reach Earth.
Watching his instruments intently, Johnson received notification and shouted “LVS System valid” — a huge relief, since in the flight’s final moments he was convinced “that our system had not turned on.” A few seconds later, Perseverance touched down safely on Mars and the Jet Propulsion Laboratory (JPL) Control Room staff at the California Institute of Technology erupted in cheers.
Beginning at a remarkable 2.6 miles above Mars, the LVS took photos of the surface during descent, comparing them to images previously captured by the Mars Reconnaissance Orbiter circling high above, and automatically rotated each image to match those taken by the orbiter. “The challenge is to get it to work perfectly the first time you ever use it,” said Johnson. “And if it doesn’t work perfectly, you’ve cost the taxpayers a lot and wasted years of work. So yes, it’s stressful all along, and it certainly builds to a peak during the actual landing moments.”
Andrew Johnson (CS 1997) with the Lander Visual System for the Perseverance Mars rover
William “Red” Whittaker, Founders University Research Professor in The Robotics Institute
Robotics students testing the Iris rover
Johnson stands alongside several notable CMU graduates working on Mars and Moon missions at JPL, and he is part of the long list of space exploration experts who received their basic training at CMU's Robotics Institute and School of Computer Science.
Widely considered the world’s premier training and testing site for advanced field robots, CMU assumed a natural leadership position in supplying scientists for America’s space missions. Over the past 40 years, its robots have probed damaged nuclear reactors, trekked across Antarctica and are now about to head to the Moon.
From the beginning, the Robotics Institute, under the leadership of William “Red” Whittaker, Founders University Research Professor, operated on the principle that the best way to advance the science of robots is to put them to work in real world situations.
“The notion of field robotics was really created at the Robotics Institute,” said David Wettergreen, Research Professor at the institute and a longtime colleague of Whittaker. “Applying these systems in the world is an important part of their technological development, and provides insight into what’s necessary to be successful. From the early days of The Robotics Institute, in putting robots in the real world — nuclear reactors, mines, farms or just Schenley Park — we learned there is important scientific knowledge in integration and testing outside the laboratory.”
The next big test of the field robotics approach will be rovers that have undergone tests in a variety of situations on Earth in preparation to land on the Moon.df
TO EXPLORE IS HUMAN
Edgar Mitchell
Not only does Edgar D. Mitchell (E 1952) hold the distinction of being one of only 12 humans to set foot on the Moon, but he also entered in one of the greatest computer hacks in space exploration history.
DRIVING ROBOTS ON MARS
“I’ve been driving almost 13 years now, and you bring the experience from one rover to the next. You get very familiar with only seeing what the rovers’ sensors can see.”
— VANDI VERMA (CS 2005)
Vandi Verma (CS 2005), chief engineer for robotic operations for the Mars Perseverance rover, plays a key role in the exploration of the red planet. Working with JPL, Verma’s Robotics Operation mission encompasses how Perseverance moves, collects samples for later analysis and interacts with the first mini-helicopter on Mars.
One of the innovations that Verma worked on for the Perseverance rover is its robotic arm, used to collect samples from the planet. In the past, scientists on Earth have resorted to using a terrain model to guide robotic arms. But Perseverance has software that allows it to autonomously build a terrain model in order to detect the movement of its arm and to prevent it from hitting the rover’s body or hazards on the ground. “This is my fourth Mars rover,” Verma said. “I’ve been driving almost 13 years now, and you bring the experience from one rover to the next. You get very familiar with only seeing what the rovers’ sensors can see.”
And while she loves the overall engineering challenge of planning the rovers, Verma still gets a thrill out of remotely driving them around Mars.
Because the planetary explorers’ computers have to be hardened against radiation damage, they are not very powerful. This means it remains more effective for people on Earth to plan routes for the rovers and steer them to sites of interest, deciding when it is safe to allow the rovers to engage in autonomous driving — all using algorithms first developed at CMU.
While at CMU, Verma worked with robots in Chile’s Atacama Desert, which the university uses as a stand-in for Mars because of its austere, bone-dry landscape.
Looking back on her experience at Carnegie Mellon, Verma said she “learned as much from my classmates and peers as from the faculty because we were all doing cutting-edge research in the field. You’re out there in the student lounge while you’re playing foosball and discussing your algorithms with each other.”
The no-second-chances nature of her current work excites Verma. “There’s a difference when you’re designing a robot that is doing something humans can’t,” she said. “You want to push the envelope, but there is no replacing a part.”
SCS GOES TO THE MOON
If everything goes according to plan, the shoebox sized rover Iris will arrive on the surface of the Moon next year, courtesy of a lander developed by Astrobotic Technology, a spinoff company from CMU located on Pittsburgh’s North Side. The Astrobotic Peregrine lander will deliver several payloads to the surface of the Moon at Lacus Mortis, touching down in a pit roughly the size of Heinz Field. On board the lander will be the compact Iris rover, developed by a team of students at CMU under the mentorship of Whittaker. Also on board will be MoonArk, a highly collaborative digital art project developed by hundreds of people and spearheaded by Carnegie Mellon's School of Design.
Iris, weighing in at just 4.4 pounds, contains a camera and has the ability to move to locations at the direction of controllers on Earth. It operates on a battery with a limited life, intended as “a technical demonstration of what’s possible with a very limited mass,” Wettergreen said. “It’s meant to show you don’t have to send a rover that’s the size of a small car” to get useful data back to Earth.
Following Iris, a larger rover developed by Astrobotic and CMU known as MoonRanger will launch aboard a commercial lander to explore the south polar region of the Moon, with a particular focus on identifying areas with an abundance of water. This rover will be able to range up to a quarter mile away from its lander, using cameras and lasers to build a model of the surrounding terrain and chart a path toward likely locations for ice. On board MoonRanger, a Neutron Spectrometer System developed by NASA will find water by detecting how neutrons emitted by the Sun are modulated by hydrogen bound up in ice in the soil.
David Wettergreen, Research Professor at the Robotics Institute
Astrobotic Peregrine Lander
The purpose of searching for water on the Moon is not to find ancient signs of life. Rather, any ice found on the Moon could be invaluable for future space missions. Moon ice could not only provide water for astronauts to drink, but they could also split the water into hydrogen and oxygen to provide breathable air and rocket fuel for missions to such places as Mars, Pluto or the moons of Jupiter.
“One of the challenges to space exploration,” Wettergreen said, “is getting enough fuel off the surface of the Earth to get to Mars or Europa or Pluto. If water on the Moon can be extracted, it’s actually more efficient to get fuel from the Moon than to launch it into orbit from the Earth.”
Finally, Astrobotic and NASA plan to launch a much larger lander known as Griffin in 2023. This lander, weighing more than 1,000 pounds, will have seven rocket engines, as well as dedicated power and communication capabilities. NASA expects the mission to carry the VIPER — Volatiles Investigating Polar Exploration Rover — that will include instruments and a drill designed to extract water on the Moon.
THE KEY PROTOTYPES
Over the past four decades, Carnegie Mellon developed a long line of robots that roll, walk, slither and hop, all with a variety of purposes and each an important step in its own right. But in the ramp up to robots exploring space, two stand above the rest: Dante and Zoë. Dante, a walking robot developed in the 1990s by Whittaker and Wettergreen, rappelled down the sides of active volcanoes. The prototype, tested at Mt. Erebus in Antarctica in 1992, held hope of sampling magma inside the volcano crater. However, technical problems, including a severed fiber optic cable, ended the field test early.
A second Dante robot fared better, exploring the Mt. Spurr volcano in Alaska for more than five days in 1994, sometimes operating autonomously and at other times under direction of human controllers stationed miles away.
The Dante robots demonstrated that a field robot could operate at least partly on its own in environments that were too harsh or dangerous for humans — a simulacrum for what many space missions require.
Today, CMU roboticists continue development on a robot named Zoë, an autonomous scientific exploration device deployed primarily in the harsh Atacama Desert. Verma worked on earlier iterations of Zoë, which has been operational for the past decade.
Reaching for the Stars
Entering CMU with a perfect SAT score of 1600, Judith Resnik (E 1970) let her adventurous and brilliant mind shine early in life.
Wettergreen is careful to note Zoë’s shortcomings as well as its strengths. On the plus side, “it doesn’t get tired. It’s precise and repeatable, and it knows exactly where it is,” he said. On the minus side, it knows what to do and how to do it, but not why. People have the advantage of a larger perspective and intuition, and can draw on their experience,” said Wettergreen. “Robots haven’t yet come up with a hypothesis that they can test as they explore.”
The ability of robots to act on their own will be increasingly vital the further away space missions get from Earth, Wettergreen noted.
While radio communication with Mars takes nine to 20 minutes, radio communication with Europa, a watery moon of Jupiter, would take 10 1/2 hours. One goal of a Europa mission might be to tunnel through the moon’s icy oceans and explore the liquid water beneath.
“The communication back to Earth will take days,” said Wettergreen. “You’re not going to hear from that robot until it gets back to the surface. We’ve told it to look for life, but what does life look like? It’s hard to imagine doing that by remote control. It’s got to be able to make those decisions, interpret the data, explore on its own and then come back and communicate results.”
From Dante testing volcanic gases in the 90s to Zoë seeking out microorganisms in the deserts of Chile today, Carnegie Mellon experts have continually added power, flexibility and autonomy to their field robots, in the hopes that one day, a truly independent robot may become our first pioneer in the vast reaches of space.
THE NEXT BIG STEP
Simple as it is, CMU’s Iris rover will be the first unmanned American rover to land on the Moon. Scheduled to leave Earth as part of the Peregrine payload sometime in 2022, Iris represents the work of nearly 70 CMU students over many years.
“The vision, design and implementation for this robot are driven by amazing student power — unprecedented for a space venture of this ambition and technical challenge,” said Whittaker. “It requires the highest standards of commitment, collaboration and cross-disciplinary skill, as well as incredible resourcefulness.”
Once there, Iris will not be the swiftest or most technologically advanced rover ever put on a space mission. But it marks an early entry of what will be known as CubeRovers — lightweight planetary travelers that can be used by all sorts of companies and organizations that want to engage in space exploration but don’t have enormous resources. And it’s yet another example of the reality-based training that CMU robotics students get week in and week out, making them prized job candidates around the world.
“Our graduates are all over the place,” said Wettergreen, “and in many cases are involved in the cutting-edge research that is creating new technologies or moving things from the lab into the real world.” ■
Just some of the many students on the teams that put CMU robots like Zoë into space
TO EXPLORE IS HUMAN
Edgar Mitchell
Not only does Edgar D. Mitchell (E 1952) hold the distinction of being one of only 12 humans to set foot on the Moon, but he also entered in one of the greatest computer hacks in space exploration history. Just over 50 years ago, on Feb. 5, 1971, Edgar Mitchell and Alan Shepard orbited the Moon inside their lunar excursion module Antares. While preparing to land on the moon’s surface, the two men ran through the checklist and discovered an abort signal lighting up incorrectly. A soldering short was later found to be the cause, but they found that tapping the abort signal panel made the signal go away, though it intermittently returned. Four times. If the signal triggered on during Antares’ descent, even erroneously, it would activate the abort sequence, cancel the landing and automatically return Antares to a safe orbit.
NASA was coming off the tragic Apollo 13 mission and desperately needed a landing to show the American public that they were back on track in lunar exploration.
The challenge became how to reprogram the Apollo guidance computer so the erroneous abort code would not fire. However, the hardwired system had read-only memory. There would be no software solution.
Here’s the hack they came up with: Computer programmer Don Eyles figured out that the abort signal could be overridden if the guidance system already thought an abort was in progress. So, he wrote a few lines of code and instructed Mitchell to key them into the system: You can listen to the audio of Mitchell keying in the hack here: https://www.youtube.com/watch?v=oZZe-xXx9_o&t=192s
While they still had to make a few adjustments with the thrusters for landing, the hack saved the Apollo 14 mission and allowed Edgar Mitchell to be the sixth person to set foot on the Moon. Mitchell, who was also the backup lunar module pilot for the Apollo 10 and Apollo 16 missions, died on Feb. 4, 2016, at his home in West Palm Beach, Florida.
REACHING FOR THE STARS
Judith Resnik Astronaut and Engineer
Entering CMU with a perfect SAT score of 1600, Judith Resnik (E 1970) let her adventurous and brilliant mind shine early in life. After earning her bachelor's degree in electrical engineering, Resnik went on to get her Ph.D. from the University of Maryland.
When the NASA Astronaut Corps opened its applicant pool to women, Resnik was one of six chosen from more than 8,000 applicants. Resnik wanted to be the first American woman in space, but was the second. She was the first Jewish American in space.
Resnik put her engineering talents to work as a mission specialist aboard the space shuttle Discovery on its initial mission in 1984. She helped create the shuttle’s robotic arm and was in charge of its operation while onboard.
Judith Resnik died aboard the space shuttle Challenger, when it exploded over the Atlantic Ocean, 73 seconds into its flight on Jan. 28, 1986. Much of the country watched the explosion live or on replay, as all seven crew members onboard perished. It was a moment that all Americans alive at the time remember where they were when they heard the news.
Resnik received many honors during her life and in the years following. Many schools have been named after her and, of course, CMU dedicated the Resnik House dormitory on campus. The Resnik Challenger Medal is awarded each year by the Society of Women Engineers to the woman who contributes innovative technology to the exploration of space.
Members of Tau Beta Pi, the National Engineering Honor Society, help maintain a memorial to Resnik, located at the base of at the base of Hammerschlag Hall.