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| Artist's concept of DRACO | DARPA |
NASA and DARPA have agreed to develop and test a nuclear rocket engine in
space as soon as 2027. Using a nuclear reactor as its power source, it would
outperform chemical rockets and greatly reduce the time for the first crewed
Mars mission.
Humanity has made great strides in the exploration and exploitation of space
over the past 60 years but as far as propulsion is concerned, the rockets of
today are essentially the same as those of the German V-2 ballistic missiles
of the Second World War. There have been innovations like solar sails and
ion thrusters, but for manned missions or ones that must move very heavy
payloads very quickly, the space agencies are still dependent on
chemical-fueled rockets.
There are a number of problems with this, but the biggest one is that
chemical rockets are operating at their theoretical limits. In fact, they
had already come close to those limits by 1942. This means that crewed
missions to the Moon can only be, at best, limited, expensive, and few,
while a crewed Mars mission is at the very limit of the technology and could
never be much more than a stunt.
To overcome this barrier, engineers are looking at more efficient and
energy-dense propulsion based on nuclear reactor technology. NASA last made
a serious attempt to develop a nuclear rocket in the 1960s with its Nuclear
Engine for Rocket Vehicle Application (NERVA) and Rover projects, but these
were abandoned as the Apollo Moon-landing project began to wind down after
1964.
The latest endeavor is the Demonstration Rocket for Agile Cislunar
Operations (DRACO) program, which is tasked with developing a nuclear
propulsion system that is capable of sending a mission to Mars and also to
provide the US Space Force with a means of getting to the Moon and moving
about cislunar space with large payloads at very short notice.
By using a nuclear thermal engine to heat a propellant to extremely high
temperatures to generate thrust, a rocket could have over three times the
efficiency of a conventional chemical-fueled one, which would reduce transit
times and increase payload potential. For a crewed Mars mission, this would
mean less radiation exposure, fewer detrimental effects from weightlessness,
and less of a need for supplies or overly robust flight systems.
In the new NASA/DARPA partnership, NASA's Space Technology Mission
Directorate (STMD) will lead development of the nuclear engine, which will
be integrated into the DARPA spacecraft in the form of an upper stage that
will only operate in space. Meanwhile, DARPA will continue as the
contracting authority for the development of the entire stage, reactor, and
the engine in anticipation of a first flight test in 2027 at the earliest –
hopefully at a discreet distance from Earth.
"With this collaboration, we will leverage our expertise gained from many
previous space nuclear power and propulsion projects," said Jim Reuter,
associate administrator for STMD. "Recent aerospace materials and
engineering advancements are enabling a new era for space nuclear
technology, and this flight demonstration will be a major achievement toward
establishing a space transportation capability for an Earth-Moon economy."