![Artist concept of Demonstration for Rocket to Agile Cislunar Operations (DRACO) spacecraft, which will demonstrate a nuclear thermal rocket engine.](https://cdn.arstechnica.net/wp-content/uploads/2023/07/draco-4-darpa-nasa-ussf-caption-800x448.jpg)
DARPA
4 years from now, if all goes well, a nuclear-powered rocket engine will launch into space for the primary time. The rocket itself can be conventional, however the payload boosted into orbit can be a unique matter.
NASA announced Wednesday that it’s partnering with the US Department of Defense to launch a nuclear-powered rocket engine into space as early as 2027. The US space agency will invest about $300 million within the project to develop a next-generation propulsion system for in-space transportation.
“NASA is trying to go to Mars with this method,” said Anthony Calomino, an engineer at NASA who’s leading the agency’s space nuclear propulsion technology program. “And on this test is absolutely going to offer us that foundation.”
Back to the longer term
Traditional chemical propulsion is great for blasting rockets off the surface of the Earth, but such machines are terribly inefficient for moving across the Solar System. They do not sip fuel, they guzzle it. To go so far as Mars would require an enormous amount of propellant and liquid oxidizer and take at the very least six months. For humans to actually turn out to be a spacefaring species, there must be a greater way.
Wernher von Braun, the German engineer who defected to america after World War II, recognized the potential of nuclear thermal propulsion even before his Saturn V rocket landed humans on the Moon with chemical propulsion. Eventually, this led to a project called NERVA (Nuclear Engine for Rocket Vehicle Application). It was eventually canceled to assist pay for the Space Shuttle.
The essential idea is easy: A nuclear reactor rapidly heats up a propellant, probably liquid hydrogen, after which this gas expands and is passed out a nozzle, creating thrust. But engineering all of this for in-space propulsion is difficult, after which there’s the regulatory difficulty of constructing a nuclear reactor and safely launching it into space.
And so nuclear thermal propulsion technology sat on the shelf for an extended, very long time. Finally, in 2020, the curious folks on the US Defense Advanced Research Projects Agency said they desired to test a flyable nuclear thermal propulsion system. This planted the seed for a program called the Demonstration Rocket for Agile Cislunar Operations (DRACO). The military was serious about efficiently moving payloads around Earth and the Moon—hence the inclusion of cislunar.
NASA later joined in, with the goal of developing similar technology for a Mars mission. The explanation is apparent: A variety of scientists and engineers imagine that the one sustainable strategy to develop and Mars exploration program is thru the usage of nuclear propulsion.
The plan forward
On Wednesday, NASA and DARPA announced they’d chosen Lockheed Martin to function the first contractor to assemble the experimental nuclear thermal reactor vehicle (X-NTRV) and its engine. BWX Technologies can be one among Lockheed Martin’s partners, and it can develop the nuclear reactor and fabricate the high-assay low-enriched uranium fuel to power the reactor.
The worth of the award is $499 million, said Tabitha Dodson, program manager for the trouble at DARPA, in a teleconference with reporters.
NASA will take the lead on developing the nuclear engine, and DARPA will oversee a number of other issues, from the nuclear regulatory requirements to the mission’s operations and all analyses of the vehicle’s safety. The nuclear reactor will launch in “cold” mode for safety reasons and is not going to be turned on until it reaches a sufficiently high orbit.
This final orbit has yet to be determined, but it surely is prone to be 700 to 2,000 km above the surface of the Earth, such that the vehicle’s reentry into the planet’s atmosphere will happen tons of of years after any nuclear reactions occur.
The nuclear-powered vehicle will launch throughout the payload fairing of Falcon 9 or Vulcan rocket, Dodson said, and look much the identical because the upper stage of a standard rocket. It can consist of a big hydrogen fuel tank, a nuclear reactor, a supporting spacecraft structure, and a nozzle. Once it reaches a protected orbit, the reactor can be turned on. The liquid hydrogen will then be heated from 20 Kelvin—just 20° Celsius above absolute zero—to 2,700 Kelvin in lower than a second.
After which? Well, we’ll see. There are some unknowns in regards to the performance of a reactor and its uranium fuel in zero gravity
“It is vital to take into account that that is an indication engine,” Dodson said. “And just like every other test of a rocket engine, NASA may have to do a series of follow-on engine development work in an effort to catch up with to their perfect operational engine.”
Remember in regards to the hydrogen
This experiment is exciting beyond just the testing of the nuclear engine. While plenty of latest technology will go into developing a nuclear reactor that may operate in microgravity, numerous effort will even go into managing the vehicle’s liquid hydrogen propellant.
Until now, liquid hydrogen has only been successfully stored in space for days because it boils above the extremely cold temperature of 20 Kelvin. Dodson said this mission would try and store liquid hydrogen in its ultra-cold state for a few months, allowing enough time for multiple tests of the nuclear thermal engine.
After the propellant runs out, the engine will now not have the ability to operate, although mission controllers on the bottom will still retain communication with the spacecraft. The mission could possibly be prolonged if it could possibly be robotically refueled, and Dodson said the spacecraft designers are trying to permit for this possibility.
Perhaps NASA and DARPA may have learned enough by then, nonetheless, to maneuver into the event of an operational engine that may fly somewhere.