A new era of space exploration is dawning. With the resumption of NASA’s Artemis lunar program, our eyes are also on Mars, with a manned mission in the near future, on the horizon of the 2030s. If SpaceX offers its Starship, NASA is studying a way to reduce the time of space travel thanks to nuclear propulsion.
One of the biggest challenges in designing a martian missionmartian mission is travel time. With current liquid-fuel propulsion technologies, this can be achieved in at least six months. For a manned mission, this remains an essential problem for the physicistphysicist and the minds of astronautsastronauts (particularly radiation exposure), and this immediately closes the doordoor to a more distant inhabited holding in the Solar systemSolar system.
Given that we will not have in the near future theUSS Enterprise or millennium falconwe must, however, find a way to drastically reduce the astronauts’ travel time to the Red Planet, without overloading the spacecraft with the cargo of tens of tons ofthrustersthrusters liquids. Nuclear propulsion is a very advantageous solution.
The rebirth of the race for the nuclear engine
A first rush to this technology took place during the Cold War, after which programs were discontinued. However, in recent years, Russia, China and the United States have again become involved in these projects. NASA relaunched a bimodal nuclear propulsion program, BookbinderBookbinder a nuclear thermal propulsion system (NTP) and a nuclear electric propulsion system (NEP).
The goal is to reach Mars in 100 days instead of 180 today. The Niac program — NASA’s Innovative Advanced Concepts – is in its first phase, namely collecting concepts and monitoring their maturation, before moving on to more concrete phases.
Nuclear thermal and nuclear electric rally
These are the two nuclear propulsion concepts that have been studied so far. NTP is based on a propellantpropellant classic with as propellanthydrogenhydrogen liquid (LHtwo), which would be heated by an onboard nuclear reactor. This powerful heating causes the hydrogen to pass into a gaseous state, which drastically increases the pressurepressure which is channeled with a nozzlenozzle. The boost generated is very effective. The concept has been studied by NASA and the US AirAir Strength since the 1950s, and by the USSR between 1965 and 1980.
NEP propulsion is based on a nuclear reactor that supplies electricity to a ion engineion engine (propellant in hall effecthall effect). This generates a electromagnetic fieldelectromagnetic field which accelerates gas particles to create momentum. The gas generally used is xenonxenon.
Did you know ?
Nuclear power has been used in space for decades! Atomic batteries power several probes such as Voyager 1 or Cassini because their distance from the Sun did not allow them to have enough solar energy. This is also the case for the Mars Curiosity and Perseverance rovers, which operate without a solar panel!
The combination of these two propulsions for a single mission allows greater flexibility in the required thrust. In fact, an interplanetary trip requires big impulses (start and arrival to brake), but also small trajectory corrections. Also, for the comfort of the astronauts, the thrust should not be too strong. On the other hand, it must be able to last longer. For example, a CIP concept can maintain momentum for nearly three hours.
The innovation that reduces travel time to 45 days
Selected in Phase I of NASA’s Niac program, the concept ” Bimodal NTP/NEP with a wave rotor top cycle proposed by Professor Ryan Goose, head of the Hypersonics program at the University of Florida, suggests adding a pressure wave compressor. Associated with the NTP engine, the compressor uses the pressure generated by heating the LH2 to further compress it, thus increasing thrust even further. With a CIP engine, thrust is also improved. According to Goose, adding this compressor to a bimodal system that combines NTP and CIP could cut the travel time to Mars to 45 days.