Geologist among team of scientists exploring how to work with robots on lunar expeditions
May 3, 2010
Mark Helper looked out the windshield of his pressurized lunar rover at a gray otherworldly landscape that stretched in every direction as far as he could see. With time running short, he and his teammate drove on across the rubble-strewn floor of a vast impact crater. They stopped and Helper used the vehicle's robotic arm to pick up a rock and hold it in front of the windshield to examine with a flashlight. He quickly decided it wasn't what he wanted and moved on. Occasionally, when he found something especially interesting, he would don a pressurized spacesuit and step out onto the surface for a closer examination.
Along with his numerous field geology skills, Helper had to use a dash of imagination. The crater was not actually on the moon, but instead an island in the Canadian High Arctic. The lunar rover was actually a Humvee and the spacesuit a non-pressurized mockup. The robotic arm was a guy following along who bent down, picked up a rock and held it in front of the windshield.
It was, as Helper described, a "low fidelity" simulation of a real moon mission. Yet experiments like this are invaluable as scientists try to understand what preparation will be required for astronauts to live and work on the moon and eventually on Mars. Sure, he could have just opened the door of the Humvee and leaned out to pick up a rock, but he wouldn't have learned half as much.
"I had much more of a sense of what those guys on the moon faced during Apollo and what these astronauts are going to face compared to what I was used to as a field geologist," said Helper.
Robots Are Your Friends
Haughton Crater, a 20-kilometer-wide depression on Devon Island, was created by a meteorite impact about 39 million years ago. Because it's cold, dry, dusty and lacks any significant vegetation, scientists consider it a good analog for Mars and the moon.
In 1997, planetary scientist Pascal Lee started the Haughton-Mars Project (HMP), an international field research project focused on Earth processes, impact cratering and life in extreme environments, as well as evaluating technologies and strategies for future missions to the moon and Mars. Each summer, scientists from around the world participate in studies at the HMP Research Station.
Helper, a field geologist in the Jackson School of Geosciences, was invited by NASA to fly to the HMP research station last July to simulate geological traverses on the moon. He had never visited the site or read the scientific literature. He went in with blinders on. The goal was to imagine himself as an astronaut visiting a site on the moon for the first time and try to conduct a realistic geological survey with only some basic remote sensing data, such as might be available for the moon from orbiting spacecraft. As on the moon, there would be constraints on how long he could spend driving around on the surface, how far he could drive, how long he could spend out of the vehicle in a spacesuit and a whole list of other restrictions.
In addition to having a pressurized rover, one big difference between the Apollo missions and a future lunar mission is that astronauts will be able to deploy robotic rovers with a suite of geophysical and geological instruments to help with the work. The three-year research project Helper is part of is largely aimed at figuring out how best to use robots to follow up on human exploration in a way that boosts the efficiency of scientific research.
"Along the way, I tried to think about the kinds of things you could set aside for a robotic rover if you didn't have time to do them," he said. "And then next year, we'll go back with a rover and try to check things off the list."
On the moon, humans might do the initial scouting, looking for interesting clues about the geology, and then based on that, give a robot instructions to go out and do the slower, more tedious "clean-up" work. Much of that could be done after the humans have headed back to Earth.
NASA's Constellation program is designed to create a new spacecraft system for low Earth orbit, return humans to the moon, and eventually make that first historic footfall on the red planet. A panel convened this year by President Barack Obama found that without increases in funding or new partnerships with other countries or private companies, the agency would be forced to delay a return to the moon. Still, scientists continue to prepare for what they feel is an inevitable return.
Stuck Behind the Wheel
Helper said as with any field work there were setbacks. The team got the vehicle stuck up to its axles in a part of the permafrost that had melted and softened up. They were forced to "break the sim" for a few hours as they struggled to release it from the muck. Helper's experience with numerous stuck vehicles on field trips eventually paid off. In addition to his own field research, he's led dozens of student field trips, including more than 20 years of the annual multi-week undergraduate tour of the western U.S. known as GEO 660.
The next day, rain forced cancelation of a full day's work out of safety concerns. Video crews from media outlets also proved distracting at times. But through it all, he managed to learn some valuable lessons.
Following protocols already developed for Constellation, Helper could spend no more than three and a half hours out of an eight-hour field day in the spacesuit. On top of that, he had to allot 20 minutes to don the suit and another 20 minutes to doff it.
"There's a lot of overhead to put the suit on," he said. "So the question becomes well, how much do I really need to get out and do this stuff and how much can I do from within the vehicle and preserve that 40 minutes of observation time?"
As it turns out, the geology of Haughton Crater, like much of the lunar surface, lent itself to less direct observations.
"That's largely because most rocks aren't in place," Helper said.
Impact craters leave only a partial record of the impact process. Much rock is destroyed or ejected great distances. In addition, Haughton Crater was later glaciated, and modern periglacial processes such as annual freezing and thawing have weathered the rocks even further.
"Most of the interior of the crater is rubble-covered and can only be sampled by scooping rocks up from the ground," Helper added. "Outside the crater, there's not much utility in banging a rock out of an outcrop when you can pick one up from the ground that has already fallen off."
For Helper, it meant doing geology in an entirely different way.
"I thought, I'm a field geologist, I've got to get out and touch the rocks, I've got to be out there thinking about where I'm going to go next," he said. "But in fact, I was pretty amazed at what I could do from inside. I had never tried to do field geology sitting in a vehicle. After having done a detailed plan knowing I was going to be sitting in a vehicle, I was actually quite surprised at what I could accomplish."
He said that bodes well for a mission that integrates humans and robotic rovers.
"That was the big revelation for me, just how much you can do without ever putting a suit on," he said.
There is Orange Soil!
The only geologist to walk on the moon was Harrison "Jack" Schmitt on Apollo 17 in December 1972. He knows firsthand what it's like to explore a new world on a tight schedule. He and commander Gene Cernan had just begun exploring an impact crater when Schmitt looked at the dust his feet had stirred up.
"Oh, hey," he said excitedly. "There is orange soil!"
Cernan quickly confirmed that his eyes weren't playing tricks on him. It was a strange sight in the midst of a world painted in dusty shades of gray and white. Unfortunately, everything was tightly scripted. Planners back in Houston had only allotted the astronauts 34 minutes before they had to begin their return of more than 4 kilometers to the lunar module.
Schmitt quickly dug a trench revealing additional soil layers of red and black. The two scrambled to take samples and photographs for future study. Then they were off to the next stop, never to return.
"He's often said if he just had a little more time, we'd know much more about the site," said Helper. "The idea of robotic follow up was born from that experience."
Based on the samples they did collect, scientists determined that the colored soils were made of tiny beads of volcanic glass spewed out by an ancient fire fountain. Different colors indicated different rates of cooling. They turned out not to be a sign of water as Schmitt had first supposed, but they did hint at a fascinating history.
Scientists thinking about how to make the next generation of lunar exploration more productive believe robotic rovers following up on promising leads is one part of the solution. Another idea is to give the astronauts more autonomy in the first place.
"Geologists don't just go out and methodically pick up rocks, they try to make sense of what they see around them," said Helper. "To do that, you have to have some latitude about where you're going to go next, integrating new discoveries into your thinking and decision making. Even though he was a Ph.D. geologist from Harvard, Jack had very little latitude. If the moon is to be a training ground for Mars, then there has to be a greater degree of freedom for those doing science on the surface. Pressurized rovers and robotic follow up are two ways to provide it."
For more information, contact: By Marc Airhart
College of Natural Sciences