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 space travel time thanks to nuclear propulsion.
One of the biggest challenges in making a martian missionmartian mission is the travel time. With current liquid-fuel propulsion technologies, it is possible to achieve this in at least six months. For a manned mission, this remains an essential problem for the physiquephysique and the minds of astronautsastronauts (particularly exposure to radiation), and this immediately closes the porteporte to a more distant inhabited exploration in the Solar systemSolar system.
Given that we will not have in the near future theUSS Enterprise or Millennium Falconwe must nevertheless find a way to drastically reduce the travel time of astronauts to the Red Planet, without weighing down the ship by loading tens of tons ofergolergol liquids. Nuclear propulsion is a very advantageous solution.
The revival of the race for the nuclear engine
A first race for this technology took place during the Cold War, then the programs were stopped. However, in recent years, Russia, China and the United States have again become involved in these projects. NASA has relaunched a bimodal nuclear propulsion program, binderbinder both 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 program program Niac — Nasa Innovative Advanced Concepts – is in its first phase, namely collecting concepts and supporting their maturation, before moving on to more concrete stages.
Rally nuclear thermal and nuclear electric
These are the two nuclear propulsion concepts that have been studied so far. The NTP is based on a thrusterthruster classic with as propellantHydrogenHydrogen liquid (LH2), 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 pressionpression which is channeled with a nozzlenozzle. The thrust generated is very effective. The concept has been studied by NASA and the US AirAir Force from the 1950s, and by the USSR between 1965 and 1980.
NEP propulsion is based on a nuclear reactor supplying electricity to a ion engineion engine (thruster at effet Halleffet Hall). This generates a electromagnetic fieldelectromagnetic field which accelerates gas particles to create thrust. The gas generally used is XenonXenon.
Did you know ?
Nuclear power has already been used in space for decades! Atomic batteries power several probes like 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 rovers Curiosity and Perseverance, which operate without a solar panel!
Combining these two propulsions for a single mission makes it possible to be more flexible in the thrust required. Indeed, an interplanetary journey requires both large thrusts (departure and arrival for braking) but also for small trajectory corrections. Moreover, for the comfort of the astronauts, the thrust must not be too powerful. On the other hand, it must be able to last longer. For example, a CIP concept can maintain thrust 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 Topping Cycle proposed by Professor Ryan Goose, head of the Hypersonics program at the University of Florida, suggests the addition of a pressure wave compressor. Associated with the NTP engine, the compressor uses the pressure generated by the heating of the LH2 to compress it even more, and thus further increase the thrust. With a CIP engine, the thrust is also improved. According to Goose, adding this compressor to a bimodal system combining NTP and CIP can reduce travel time to Mars to 45 days.
