- Space travel beyond our moon will require a huge shift in space propulsion.
- That’s partly because quicker flights mean crews are exposed to less radiation during the journey.
- A couple of ideas are in the works to achieve that: nuclear thermal propulsion and ion propulsion.
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The future of human space exploration, such as visiting our moon or even Mars, could be essential for upcoming generations. But despite that and the recent renewed interest in space travel thanks to companies like SpaceX, humans traveling beyond our moon will require a paradigm shift in space propulsion.
According to NASA, a round-trip Mars mission involving humans would take an estimated three years. That includes a six-month journey to the Martian planet, 18 months on the surface awaiting Earth to line up correctly for the shortest trip possible, and another 6-month journey back home. During that time, NASA research shows that, on average, a human would be exposed to approximately 1,200 millisievert of radiation. That’s equivalent to thousands of chest x-rays and around 60 percent of NASA’s career exposure limit for a 35-year old astronaut.
Quicker flights through the vacuum of space equal less radiation to the crews making the journey, and a couple of ideas are in the works to make that possible: nuclear thermal propulsion and ion propulsion, both meant to speed up flight times and lower radiation exposure.
Nuclear thermal propulsion: a way to get to Mars more quickly and safely
One such technology comes from a company called Ultra Safe Nuclear Technologies, which recently created a design concept for a new type of rocket engine that utilizes nuclear thermal propulsion, a method that creates thrust by heating a liquid propellant using nuclear fission. One of these systems would produce twice the thrust per unit of propellant that current conventional chemical systems could, meaning it would be twice as efficient while also producing more power.. Using a system such as this could reduce travel time to Mars by up to 25 percent.
A nuclear thermal propulsion system works by sending a liquid propellant, likely hydrogen, through a reactor core. Uranium atoms would then split inside the reactor core, releasing large amounts of heat via fission that excites the propellant, expanding it into a gas. That gas is then forced through a narrow nozzle to produce thrust.
While this type of propulsion system may sound good on paper, it does come with a couple of issues — both of which Ultra Safe Nuclear Technologies is working to find solutions to so its propulsion system can become mainstream for long-distance space flights. There’s the concern of finding a uranium fuel capable of withstanding the scorching temperatures inside the engine, as well as around the amount of radiation emitted from the nuclear reactor itself and its effects on the crew.
Ultra Safe Nuclear Technologies claims it’s developed a special fuel that is still effective even when exposed to temperatures upward of 4,400 degrees Fahrenheit, and that the distance between the crew and the reactor would provide extra protection from any radiation that may somehow escape.
The idea of using nuclear thermal propulsion for space exploration has been around for quite some time, but advancements made in the 21st century in materials and testing capabilities have finally made it an attractive option for human space exploration missions. Combined with Ultra Safe Nuclear Technologies submitting a design concept for a nuclear thermal rocket engine to NASA late last year, these advancements may mean that the technology could be utilized on a mission in the not-so-distant future.
Ion propulsion: NASA’s work to speed up flights and reduce radiation
NASA itself is also developing a technology that it believes could be essential to future space missions called ion propulsion. And while the idea of creating an ion thruster may not necessarily be new, only in the last few years has it truly begun to appear as a viable technology for space travel.
Ion thrusters work by using electricity to expel a cloud of plasma out of a narrow nozzle, generating thrust. It’s called an ion thruster because the thruster ionizes a neutral gas by extracting electrons from atoms, thus creating a positive ion cloud. The electricity for the ionization process will likely be gathered from solar panels built into the spacecraft using the advanced propulsion system.
Like nuclear thermal propulsion, ion thrusters operate much more efficiently than traditional chemical rockets while delivering significantly faster speeds. NASA predicted that an ion thruster of the future could propel spacecraft up to 200,000 mph; for comparison, that’s 182,000 mph faster than the Space Shuttles were capable of traveling. Using this type of propulsion system would allow a much quicker trip to Mars and beyond.
While these futuristic propulsion systems may seem far from being strapped onto a rocket with humans onboard, in reality, that may not be very far off. Plenty of research into the two propulsion systems has been conducted over the years and continues to this day, even by NASA. And with renewed interest in sending humans out further into the dark abyss of space, the research and advancements will only increase at a quicker rate.
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