Curiosity landed on Mars sporting a radioisotope thermoelectric generator (RTG) in 2012, and a second NASA rover, Perseverance, landed in 2021. Both are still rolling across the red planet in the name of science. Another exploratory craft with a similar plutonium-238–fueled RTG but a very different mission—to fly between multiple test sites on Titan, Saturn’s largest moon—recently got one step closer to deployment.

On April 25, NASA and the Johns Hopkins University Applied Physics Laboratory (APL) announced that the Dragonfly mission to Saturn’s icy moon passed its critical design review. “Passing this mission milestone means that Dragonfly’s mission design, fabrication, integration, and test plans are all approved, and the mission can now turn its attention to the construction of the spacecraft itself,” according to NASA.

Europe’s first Mars rover—named Rosalind Franklin—was months away from a planned September launch when the European Space Agency (ESA) convened a meeting a few weeks after Russia’s February 2022 invasion of Ukraine. The ESA Council unanimously agreed on “the present impossibility” of working with Roscosmos as its launch partner and later decided to reboot its ExoMars mission with a new lander, new partners, and a new launch date.

Zeno Power announced on January 26 that it will get the strontium-90 that it needs to fuel full-scale radioisotope power systems (RPSs) for national security and space exploration missions from the Department of Energy’s Oak Ridge Office of Environmental Management (OREM). Under a public-private partnership, a large legacy RPS known as the BUP-500 that had languished, unused, in storage at Oak Ridge National Laboratory has been transported to an unnamed commercial radiological facility in Pennsylvania—Zeno Power’s subcontractor—where the Sr-90 it contains will be repurposed as heat sources for Zeno Power devices.

NASA’s Mars 2020 Perseverance rover took its first drive on the surface of Mars on March 4, traversing 21.3 feet and executing a 150-degree turn in about 33 minutes. The drive was one part of an ongoing check and calibration of every system, subsystem, and instrument on Perseverance, which landed on Mars on February 18.

The NASA team has also verified the functionality of Perseverance’s instruments, deployed two wind sensors, and unstowed the rover’s 7-foot-long robotic arm for the first time, flexing each of its five joints over the course of two hours.

With relatively little fanfare, the functionality of Perseverance’s radioisotope thermoelectric generator (RTG)—assembled at Idaho National Laboratory and fueled by the decay of plutonium-238—is also being proved. It is reliably providing the power that Perseverance’s mechanical and communication systems require.

This high-resolution still image is from a video taken by several cameras as NASA’s Perseverance rover touched down on Mars on February 18. Credits: NASA/JPL-Caltech

NASA’s Perseverance rover, which successfully landed on Mars on February 18, is powered in part by the first plutonium produced at Department of Energy laboratories in more than 30 years. The radioactive decay of Pu-238 provides heat to radioisotope thermoelectric generators (RTGs) like the one onboard Perseverance and would also be used by the Dynamic Radioisotope Power System, currently under development, which is expected to provide three times the power of RTGs.

Idaho National Laboratory is scaling up the production of Pu-238 to help meet NASA’s production goal of 1.5 kg per year by 2026, the DOE announced on February 17.

Members of the Perseverance rover team in Mission Control at NASA’s Jet Propulsion Laboratory react after receiving confirmation of a successful landing. Photo: NASA/Bill Ingalls

NASA mission control and space science fans around the world celebrated the safe landing of the Mars 2020 Perseverance rover on February 18 after a journey of 203 days and 293 million miles. Landing on Mars is difficult—only about 50 percent of all previous Mars landing attempts have succeeded—and a successful landing for Perseverance, the fifth rover that NASA has sent to Mars, was not assured. Confirmation of the successful touchdown was announced at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., at 3:55 p.m. EST.

“This landing is one of those pivotal moments for NASA, the United States, and space exploration globally—when we know we are on the cusp of discovery and sharpening our pencils, so to speak, to rewrite the textbooks,” said acting NASA administrator Steve Jurczyk. “The Mars 2020 Perseverance mission embodies our nation’s spirit of persevering even in the most challenging of situations, inspiring, and advancing science and exploration. The mission itself personifies the human ideal of persevering toward the future and will help us prepare for human exploration of the Red Planet.”

Only radioisotope thermoelectric generators (RTG) can provide the long-lasting, compact power source that Perseverance needs to carry out its long-term exploratory mission. Perseverance carries an RTG powered by the radioactive decay of plutonium-238 that was supplied by the Department of Energy. ANS president Mary Lou Dunzik-Gougar and CEO and executive director Craig Piercy congratulated NASA after the successful landing, acknowledging the critical contributions of the DOE’s Idaho National Laboratory, Oak Ridge National Laboratory, and Los Alamos National Laboratory.