On July 8, 2011, the space shuttle Atlantis blasted off from the Kennedy Space Center into a cloudy sky in the last launch of the three-decade-old program.
In the 10 years since that day, NASA engineers have been developing the Space Launch System (SLS), a powerful rocket that could be the backbone for deep-space missions beyond Earth’s orbit. It’s an effort that involves people, industry and researchers in every state in the nation. And with work that has applications right here on terra firma, our own engineering faculty, staff and students are working to tackle the challenges of this next generation of travel to the moon and beyond.
When humans return to the moon or make it to Mars for the first time, they’ll likely need vehicles to traverse extraterrestrial surfaces. That’s where Dan Negrut, the Mead Witter Foundation Professor of Mechanical Engineering, comes in. Negrut is an expert in using simulations to predict how complex mechanical systems change in time—for example, a vehicle operating on soft terrain or a vessel plowing through ice north of the Arctic Circle.
He and his students are working on a NASA project to simulate how the VIPER rover—which is scheduled for launch in 2023—will traverse the lunar surface as it searches for frozen water. They are leveraging Project Chrono, an open-source physics simulation engine developed at UW-Madison in collaboration with scientists from Italy, where European Space Agency researchers use it to simulate how a rover might travel across the surface of Phobos, one of the Mars moons.
“The gravitational pull on Phobos is 1,700 times weaker than on Earth,” Negrut says. “The question is, can rovers move in gravity that low, or are they just going to bounce? They have some interesting wheel designs that aren’t like a typical cylinder. The shape of the wheel has grooves that are almost like hands or scoops that can grab granular material, which behaves differently in low gravity.”
Negrut says he sees rover simulations as vital to preparing manned or autonomous vehicles to traverse the surfaces of the moon and Mars. As those simulations improve, he can more accurately predict how such vehicles might behave with human drivers.
A manned mission in space for any length of time also will require some sort of power source, and Paul Wilson, the Grainger Professor of Nuclear Engineering and an expert in modeling complex nuclear energy systems, says portable nuclear reactors could help.
It’s an idea that’s more plausible than you might think: In July 2020, NASA and the U.S. Department of Energy announced a call for proposals from industry partners to build a nuclear power plant for use on the moon and, eventually, Mars. In 2018, the National Nuclear Security Administration and NASA revealed KRUSTY—a kilowatt reactor that could serve as the foundation for the type of reactors used to power outposts on distant planets. “You’d need enough fissile material to keep a reaction going,” Wilson says. “But once you have that, you can usually operate it at different power levels. So if you can carry and deploy that power source once you get there, it could provide you with a steady source of electricity.”
As we look toward traveling deeper into space, solar sails that gather energy emitted from the sun could help propel those journeys, says Ramathasan Thevamaran, an assistant professor of engineering physics. Solar sails aren’t a new concept; some small satellites, such as the Planetary Society’s Lightsail 2, use them to orbit Earth. “The idea is that you create these large mirrors made up of thin, very lightweight materials,” says Thevamaran, who develops revolutionary materials for a variety of engineering applications. “If you make a mirror on one side, the sun’s radiation will exert pressure on that. The amount of thrust you get is very small, but it’s constant.”
Such solar sails could play a role in scheduled transits; for example, says Thevamaran, they could ferry regular supply payloads to a hypothetical Mars outpost if the trips are correctly planned.
In the future, faculty, staff and students in the College of Engineering likely will focus their attention even more directly on these and other questions related to air and space: The Department of Engineering Physics has added an aerospace engineering option to its engineering mechanics major. Wilson, who is the department’s chair, says this new option meets growing student demand and builds upon the department’s historical astronautics option, which focuses on space. “We have an opportunity to educate students in all the skills it’s going to take to do this kind of work,” he says. “It allows us to look at the combination of technologies across the spectrum of things that fly. There’s never been, in Wisconsin, an aerospace degree program, so we’re filling an important gap to give students exposure to aerospace topics within our engineering physics program.”
Author: Alex Holloway