DARPA’s website says it has always held to a singular mission of making investments in breakthrough technologies for national security. What does a nuclear-powered spaceship have to do with national security? The military’s perspective was hinted at by General James Dickinson, a US Space Command officer, in his testimony before Congress in April 2021.
He said that “Beijing is seeking space superiority through space attack systems” and mentioned intelligence gathered on the Shijian-17, a Chinese satellite fitted with a robotic arm that could be used for “grappling other satellites.” That may sound like a ridiculous stretch, but it was enough get a go-ahead for a nuclear spaceship.
The appeal of nuclear-powered rockets is efficiency. They are twice as efficient as traditional chemical rockets because they only need to carry hydrogen for fuel and don’t need an oxidizer to create ignition in the vacuum of space. That efficiency can be used to reach extremely high speeds. DRACO is intended to be a test bed for rapid-response rockets between Earth and the Moon, a military deterrent in space.