When the next Mars rover launches into space in July 2020, it will be powered by a piece of Idaho.
The radioisotope power system that powers the rover, a vehicle that can land on and explore the surface of Mars, will be assembled and tested at the Materials and Fuels Complex at Idaho National Laboratory.
The New Horizons probe that launched in 2006 and flew past Pluto in 2015 also was powered by a system designed and tested at INL, as was the last Mars rover, Curiosity, which was launched from Cape Canaveral, Florida, in November 2011 and has been exploring Mars ever since landing there in August 2012. Earlier this year New Horizons flew past Ultima Thule, which is 1 billion miles beyond Pluto.
The next rover, which has yet to be named, is planned for launch in July 2020 and is expected to land on Mars in February 2021. Due to the alignment of Earth, Mars and the sun, a new rover can only be launched in a three-week window every 26 months, which drives NASA’s, and in turn INL’s, timetable.
“Every time there’s a launch window, we want to send something to Mars,” said Steve Johnson, director of Space Nuclear Power and Isotope Technologies at INL.
Johnson has directed the space nuclear power program here since its beginning — he wrote the proposal that led to it being moved from the now-closed Mound Laboratories in Ohio to INL in 2002. The program employs 60 to 65 people, which Johnson said represents a little more than 1 percent of the lab’s employees. The funding it brings to INL, he said, can range from $20 million to $50 million a year.
“We’re what I would call a big small program,” he said.
His crew is going to be busy for the rest of the year. INL is in charge of procurement for the power systems, while a private contractor builds them. The power systems are then assembled at INL using special handling techniques to shield workers from the plutonium fuel. And they are tested in a vacuum chamber that simulates the conditions and the rotation they will face in space.
The rover’s power system is fueled by plutonium-238, which gives off heat as it decays and has an 88-year half-life. The thermocouples, a device consisting of two different conductive materials joined together and kept at different temperatures, convert the heat into electricity.
“No moving parts, and it runs a long time,” Johnson said.
INL also works with Los Alamos National Laboratory in New Mexico and Oak Ridge National Laboratory in Tennessee at various stages of the power system’s development. Johnson said work will start at INL to fuel the power system this summer, and start testing in August or September. He expects to be done with testing by Christmas.
Early next year, the power system will make the four-day trip to John F. Kennedy Space Center in Florida, accompanied by space nuclear power workers with spare parts for everything in case anything happens.
“At that point, it’s a $100 million widget, so we’re all about the risk minimization,” he said.
Finally, there’s the process of attaching the power system to the rover, which Johnson said takes 36 to 48 hours. Johnson said he tries to bring as much of his team to Kennedy as he can, or at least as many as there are jobs for.
One of INL’s tasks is making sure the dispersal of plutonium into the atmosphere is minimized should something happen. Johnson said the power systems are tested extensively to reduce the possibility of anything happening.
“There is very, very minimal risk of any plutonium contamination, extremely minimal,” he said.