WASHINGTON — NASA and DARPA have selected Lockheed Martin to develop a spacecraft to demonstrate nuclear propulsion technologies in Earth orbit later this decade.
The two government agencies announced July 26 that they had reached an agreement with Lockheed Martin to develop the spacecraft for the Demonstration Rocket for Agile Cislunar Operations (DRACO) program. NASA and DARPA announced in January that they would collaborate on DRACO to demonstrate nuclear thermal propulsion (NTP) technologies that are of interest to both agencies.
Lockheed is working with BWXT on the program, with BWXT providing the nuclear reactor for DRACO and providing its high-assay low-enriched uranium (HALEU) fuel. That reactor will heat up liquid hydrogen carried on the spacecraft, turning it into high-temperature gas that provides thrust.
The agreement is structured as a milestone-based other transaction authority agreement with a total value of $499 million, said Tabitha Dodson, program manager for DRACO at DARPA, during a call with reporters. The costs are split evenly between NASA, responsible for the nuclear reactor, and DARPA, responsible for the spacecraft and regulatory approvals. The Space Force will provide the launch of the vehicle, planned for no later than 2027.
Both Lockheed and BWXT are contributing their own funds to the program. Kirk Shireman, vice president of lunar exploration campaigns at Lockheed Martin, described his company’s investment into DRACO as “significant” but did not have a specific amount available. Similarly, Joe Miller, president of BWXT Advanced Technologies, said his company had been investing for several years on fuel development for the reactor, but also did not provide a specific amount.
Both NASA and the Defense Department are interested in NTP because of its much higher efficiency: two to three times more than chemical propulsion, noted Anthony Calomino, NASA space nuclear technologies portfolio manager, in the call. For NASA that means potentially faster trips to Mars, while the military is interested in greater maneuverability in cislunar space.
However, DRACO will be a very limited demonstration of NTP. “It’s a flying test stand, essentially,” said Dodson. After launched into an operational orbit, likely between 700 and 2,000 kilometers high, the spacecraft will not make any major maneuvers. Instead, the focus will be on the vehicle’s reactor and its use of HALEU fuel, which has not been used in nuclear reactors in space before. “This will be the primary focus of the DRACO demo, and the act of collecting data on the HALEU reactor will define mission success.”
Officials did not disclose the thrust the DRACO engine will produce, although Calomino said it will have a specific impulse, a measure of efficiency, of about 700 seconds. That is significantly higher than even the best chemical engines although the design goal for NTP systems is 850 to 900 seconds. “For the DRACO mission, we’re right at the level where we can get that engineering relevance that we need for a better understanding for higher-thrust engines.”
Those tests are easier to do in space than on Earth, which was done with earlier NTP programs like NASA’s NERVA a half-century ago. Calomino said NASA studied the feasibility of a ground test, which requires special infrastructure to prevent the engine’s exhaust from venting into the atmosphere, “and the costs of that are actually higher than what we’re estimating is going to be to conduct this test in space.”
Dodson described the DRACO spacecraft as similar in size to a typical launch vehicle upper stage. It will be able to fit within standard launch vehicle payload fairings, with the Space Force using its National Security Space Launch contract to secure a launch of the vehicle on either a Falcon 9 or Vulcan Centaur from Cape Canaveral, Florida.
Once in orbit, the DRACO mission will last only a couple months, limited by the supply of liquid hydrogen on board. “Keeping the hydrogen around is a big challenge, so we will want to expedite the checkout of the spacecraft and of the nuclear reactor,” Shireman said.
However, both he and government officials left open the possibility of refueling DRACO to allow for continued tests. Dodson said DARPA has had discussions with the Space Force, which is interested in in-space refueling, to see if the spacecraft can be designed with a port to enable transfer of liquid hydrogen into it.
Shireman noted that in-space liquid cryogenic propellant transfer has not been demonstrated yet, although that technology will be a key part of the design for Blue Origin’s Blue Moon lunar lander, for which Lockheed Martin is developing a “cislunar transporter” vehicle to refuel it.
“In the end, I still think you still meet the propulsion demonstration even if can’t refuel it,” he said, “but I’d love to refuel it and keep it around and use it for years to come.”