The reactor elements will need special cladding, since when carbon dioxide is heated to high temperatures inside the reactor it will oxidize the heck out of everything it touches. There is a second radiation shield right under the crew, to protect them from backscattered radiation reflected off the ground during landing. A secondary toroidal propellant tank surrounds the reactor to protect crew walking on the surface when the reactor is idling. The nuclear engine has a shadow shield on top composed of steel, boron, and lithium hydride to protect the crew from radiation when the reactor is operating.
It has a penalty mass of 4 metric tons, about half of the solar cell array. It can produce about 30 kWe.Īdvantage: practically no radiation.
It also takes three crew members about 2 days to set up and break down, making the total delay about 44 days between flights. The array is about 3,500 m 2 and has a penalty mass of 8.8 metric tons. It can produce about 25 kWe (averaged around the clock to take account of nighttime)ĭisadvantage: The report does not mention how long it will take to fill the tank but presumably 1.2 as much time as the RTG: 60 days (my slide rule says it will take 40 days at 25 kWe for 24,160 kWH. Power can come from a solar cell array.This makes it difficult for the crew to do things like disembark, embark, and linger near the ship. It would also require zero mass for the power supply, since the rocket engine has already been accounted for.ĭisadvantage: is that operating the reactor while the ship is landed with spray deadly radiation all over the landing site. It would produce about 100 kilowatts of electricity (kWe).Īdvantage: The report says this will fill the tank in 12 days (my slide rule says it will take 10 days at 100 kWe for 24,160 kWH). Power can come from the nuclear reactor in the rocket engine, if you make it bi-modal.How long it takes to fill the tank depends upon how many kilowatts the power source can feed the pump. It also has enough Isp to hop the vehicle from point A to any other point on Mars.Īs I mentioned each metric ton of propellant sucked out of the atmosphere takes 80 kilowatt-hours, and the propellant tank holds about 302 metric tons total. Carbon dioxide has enough specific impulse to boost the NIMF from the surface of Mars into low Mars orbit, so the designers figured it was good enough. Other propellants have superior performance but are much harder to manufacture. The Martian atmosphere is about 95% CO 2 so it is not like there is any shortage of the stuff. It can be produced from the Martian atmosphere using just high pressure (690 kPa) with no cryogenic cooling needed (a 30 horsepower pump will do, requiring 25 kW, or 80 kilowatt hours per metric ton). The easiest propellant to manufacture is liquid carbon dioxide. Ideal Specific Impulses of Martian Propellants Temp They all featured a single solid core nuclear thermal rocket engine fed by a single propellant tank.
There were several vehicles designed: including a supersonic winged craft and a ballistic "hopper". So instead of lugging miserly limited amounts of high-performance propellant all the way from Terra, the rocket would make do with unlimited amounts of low-performance propellants available locally on Mars. The basic idea was to attempt to avoid the tyranny of Every Gram Counts by using in-situ resource utilization for the propellant. Nuclear rocket using Indigenous Martian Fuel (NIMF) is from a 1980's Martin Marietta study by Robert Zubrin.
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