The Department of Defense wants to deploy spacecraft in cislunar space—the area between Earth and the moon’s orbit—with thrust and agility that only nuclear thermal propulsion (NTP) can provide. The Defense Advanced Research Projects Agency (DARPA), through its Demonstration Rocket for Agile Cislunar Operations (DRACO) program, is looking to private industry for the design, development, fabrication, assembly, and testing of a nuclear thermal rocket engine fueled with high-assay low-enriched uranium fuel to heat a liquid hydrogen propellant.

With three commercial teams under contract to produce reactor designs for nuclear thermal propulsion rockets that would use solid high-assay low-enriched uranium fuel to heat hydrogen propellant, NASA’s investment in nuclear thermal propulsion (NTP) has increased in recent years. But just as there is more than one way to fuel a terrestrial reactor, other fuels are under consideration for future NTP rocket engines.

NASA and Idaho National Laboratory have just opened a competitive solicitation for U.S. nuclear and space industry leaders to develop innovative technologies for a fission surface power system that could be deployed on the surface of the moon by the end of the decade. Battelle Energy Alliance, the managing and operating contractor for INL, issued a request for proposals and announced the news on November 19. Proposals are due February 17.

In July 1969, the public’s attention was fixated on NASA’s Apollo 11 mission—a “giant leap for mankind” that was memorably marked by Neil Armstrong as he stepped onto the surface of the moon. This July, the possibilities of spaceflight are once again capturing the public’s imagination and news headlines. While NASA invests in nuclear propulsion research and development to stretch the limits of U.S. space missions, private companies Virgin Galactic and Blue Origin are stretching the definition of “astronaut” and proving they can offer a high-altitude thrill to paying customers.

The U.S. Department of Defense is aiming to demonstrate a novel nuclear thermal propulsion (NTP) system above low Earth orbit by 2025. The Defense Advanced Research Projects Agency (DARPA) announced on April 12 that following a competitive solicitation process, it has awarded a contract to General Atomics Electromagnetic Systems (GA-EMS) for the design of the nuclear reactor that will power the Demonstration Rocket for Agile Cislunar Operations (DRACO). Blue Origin and Lockheed Martin will work on a parallel track to design a spacecraft tailor-made to demonstrate the NTP system.

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.

The RTG used to power the Mars Perseverance rover is shown here being placed in a thermal vacuum chamber for testing in a simulated near-space environment. Source: INL

The Department of Energy’s Idaho National Laboratory is celebrating the scheduled landing of the Perseverance rover on the surface of Mars in just two days’ time with a live Q&A today, February 16, from 3 p.m. to 4:30 p.m. EST).

INL and Battelle Energy Alliance, its management and operating contractor, are already looking ahead to the next generation of plutonium-powered spacecraft: the Dynamic Radioisotope Power System (Dynamic RPS). INL announced on February 15 that it is partnering with NASA and the DOE to seek industry engagement to further the design of this new power system.

Illustration of a Mars transit habitat and nuclear electric propulsion system. Image: NASA

NASA aims to develop nuclear technologies for two space applications: propulsion and surface power. Both can make planned NASA missions to the moon more agile and more ambitious, and both are being developed with future crewed missions to Mars in mind. Like advanced reactors here on Earth, space nuclear technologies have an accelerated timeline for deployment in this decade.

Space nuclear propulsion and extraterrestrial surface power are getting funding and attention. New industry solicitations are expected this month, and a range of proposed reactor technologies could meet NASA’s specifications for nuclear thermal propulsion (NTP). Nuclear electric propulsion could increase the feasibility of crewed missions to Mars with a shorter transit time, a broader launch window and more flexibility to abort missions, reduced astronaut exposure to space radiation and other hazards, expanded payload mass capabilities, and reduced cost.

A “visionary view” of a nuclear thermal propulsion–enabled spacecraft mission. Image: NASA

Secretary of Energy Dan Brouillette and NASA Administrator Jim Bridenstine on October 20 signed a memorandum of understanding to continue decades of partnership between the Department of Energy and NASA and to support the goals of NASA’s Artemis program. These include landing the first woman and the next man on the moon by 2024 and establishing sustainable lunar exploration—using nuclear propulsion systems—by the end of the decade to prepare for the first human mission to Mars.

An Atlas V rocket with NASA’s Mars 2020 Perseverance rover on board launches on July 30. Photo: NASA/Joel Kowsky

The launch of the Mars 2020 Perseverance rover went ahead as scheduled on July 30, lifting off from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida at 7:50 a.m. (EDT) . The rover was onboard a United Launch Alliance Atlas V 541 rocket.

Minutes later, NASA reported that all flight milestones were being met as planned. There are several more milestones to reach before Perseverance—the fifth rover that NASA has sent to Mars—lands on the Red Planet in seven months.