Mars 2020 @ Oak Ridge National Laboratory

The Mission

Fueled by technologies developed at Oak Ridge National Laboratory, the Perseverance rover is exploring Mars, assessing the planet’s habitability and looking for signs of microbial life.

Plutonium-238 — encased in iridium-alloy cladding and insulated by carbon-bonded carbon fiber — is at the heart of the general purpose heat source module that fuels Perseverance’s multi-mission radioisotope thermoelectric generator. As the material decays, the heat released is converted to electricity, charging the rover’s batteries and powering the onboard advanced imaging and sensor systems.

NASA’s Mars 2020 mission launched from Cape Canaveral, Florida, on July 30, 2020. After a seven-month journey to the Red Planet, the Perseverance rover landed in Jezero Crater on February 18, 2021.

The mission continues a 50-year legacy of the lab’s contributions to deep-space exploration, including technologies for the Voyager I and II, Cassini, and Mars Curiosity missions. ORNL-produced Pu-238 also will power NASA’s 2027 Dragonfly mission to explore Titan, Saturn’s largest moon.

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Team Effort

Watch now: ORNL’s team discusses the mission during a U.S. Department of Energy STEM Rising event.

"The ability to use plutonium-238 to travel into deep space is what fascinates me. There’s no way to accomplish those missions without this specific radioisotope. It’s so meaningful to be a part of something that’s integral to the Mars mission."

Robert Wham,

Pu-238 Supply Program manager, Isotope and Fuel Cycle Technology Division

"Our part is a grain of sand in this gigantic effort, but it fits perfectly and helps fulfill the great mission of exploring space. And my girls love it – it's been great to bring this experience home to my children and see them excited about it."

Nidia Gallego,

Carbon Materials Technology group leader, Materials Science and Technology Division

"We play a small part, but I have great pride in our work. Some missions take years to reach their destination; with the Mars mission, it’s really rewarding that we’ll get to see it launch and, several months later, see it land and start to see the fruits of our work."

George Ulrich,

Radioisotope Power Systems program manager, Alloy Behavior and Design group leader Materials Science and Technology Division

Clad vent sets

CBCF sleeves and discs

Years of continuous power

Powering the Rover: Pu-238

The decay of Pu-238 provides steady heat that can be converted to electricity used to power instrumentation systems. Its long half-life makes deep-space exploration possible. NASA depends on the capabilities of the Department of Energy to produce the radioactive isotope, using ORNL’s exceptional neutron source and radiochemical processing facilities. Mars 2020 is the first space mission to be powered by new ORNL-produced Pu-238, alongside an existing Pu-238 supply at Los Alamos National Laboratory.

Encasing the Power: Iridium cladding

Within the radioisotope thermoelectric generator, iridium alloy clad vent sets — virtually indestructible metal cups — encapsulate Pu-238. Iridium, among the platinum-group metals on the periodic table, is extremely durable, can withstand high temperatures and has a melting point of more than 4,000 degrees Fahrenheit. Since the 1970s, ORNL scientists have custom designed the alloy cladding for space travel to ensure the fuel within would remain contained even during anomalous events.

Protecting the Power: CBCF

Carbon-bonded carbon fiber insulation provides another layer of protection for the spacecraft’s hot iridium-clad plutonium fuel. The low-density thermal insulator sleeves and discs balance iridium’s properties to help maintain the temperature of the power system but it is light enough that it adds negligible weight. At the on-site DOE user facility for carbon fiber innovation, ORNL continues to refine the mechanical properties of carbon fiber material for a range of applications, focusing on structural properties and processing improvements.