Nuke-thermal rockets like DRACO can’t do much without lots of propellant and large-scale, long-term liquid hydrogen storage and handling capabilities have not been demonstrated in space (and DRACO won’t prove them either). Although it may have national security applications, DRACO also lacks the size and efficiency necessary for human space flight applications. Even after a successful DRACO demo, more billions would need to be spent to develop a nuke thermal humans-to-Mars propulsion capability, for example.
DRACO is an attempt at a quick and cheap demonstration of nuke-thermal in space. If DARPA sees DRACO through, it may break the logjam that has existed on nuke-thermal since NERVA. But I suspect DRACO will be like X-37 — a different capability for moving national security payloads around in Earth orbit but the main obstacles to wider use of will remain.
Knowing DARPA, I’d bet DRACO never flies and is cancelled when it has some hiccups. DARPA does not have the budget to sustain these kinds of expensive space development projects when they hit obstacles. See ALASA, XS-1, etc.
