Study supports advanced nuclear rocket for Mars journey - Sandia National Laboratories reports that a nuclear rocket engine could make for a quick manned trip to Mars

An advanced nuclear rocket engine could chop trip time for a manned mission to Mars to 90 days - about individual third the time of previous proposals - reducing spacecraft mass and launch require to be paid [i]or[/i] undergones significantly, according to a new Sandia National Laboratories study.

by means of reducing trip time, the advanced nuclear engines would make less the adverse effects of lengthened space travel on the ship's company due to radiation exposure and microgravity.

Sandia researchers calculated that use of graphite composite propellant tanks and a particle bed nuclear reactor with improved core materials could bring vehicle mass by more than 300 tons and launch require to be paid [i]or[/i] undergones by nearly $4 billion through mission from an earlier, more conservative nuclear propulsion concept

The research recommends pursuing improvements equally in three technology areas: tank weight, nuclear engine thrust-to-weight ratio, and specific impulse rather than focusing primarily upon specific impulse as previous studies have done. Specific impulse is a performance parameter of rocket propellant that measures the thrust-producing might content of the propellant. The higher the specific impulse, the les propellant mass is exigencyed to perform the mission.

gains crew to Mars faster

"We really felt it was important to earn the crew out there in plenteous less than 260 days to hinder levels of physical and mental deterioration that could jeopardize their ability to function upon Mars and carry out the mission," says Sandia scientist Leonard Connell "The faster you want to proceed the more important it is to have these technology advancements."

The improvements also satisfy a certain quantity of of the primary recommendations made by the agency of the Synthesis Group, a committee appointed in 1990 by means of President Bush to study ways of achieving human exploration of the solar combination of parts to form a whole One of its principal findings was the importance of using nuclear thermal rocket propulsion to minimize the one and the other spacecraft mass and on-orbit assembly. The Sandia investigation emphasizes the importance of nuclear engines for reducing transit time.

The Sandia application of mind examined the effects of an improved solid core nuclear thermal rocket upon the mass of the spacecraft. The improved engine consisted of a high thrust-to-weight ratio particle bed reactor (PBR) high temperature nuclear core materials, and lightweight graphite composite propellant tanks. A baseline spacecraft using the older NERVA (Nuclear Engine for Rocket Vehicle Applications) technology and conventional aluminum alloy propellant tanks was used for making mass comparisons.

The NERVA program was carried without in the 1960s and focused upon the development of a flight-qualified nuclear engine. The program, which was canceled in 1972 demonstrated that a solid core nuclear thermal rocket could unravel nearly twice the specific impulse of the best chemical rockets

Improved thrust-to-weight ratio

Solid core nuclear rocket single of several nuclear thermal rocket technologies, have the highest horizontal of technology readiness of all the nuclear rocket concepts

The nuclear material for burning for the NERVA is formed into one-meter-long slender stems approximately two centimeters in width. inflammable air propellant flows through the ultimate parts within coolant channels and is heated by means of the uranium fission process. As the scalding;-very warm gas is ejected through the spacecraft nozzle, the thermal might of the high temperature gas is transmuteed to kinetic energy, which push forwards the vehicle.

In the PBR universal the fuel is formed into small, 500 micron diameter particles, which increases the heat transfer and allows a more compact, lightweight engine. The PBR's thrust-to-weight ratio is estimated to be nearly five times that of NERVA, which translates into a PBR engine mass for the Mars mission of sum of two units tons compared to 10 tons for NERVA.

Sandia researchers assumed a two-stage mission. Cargo and supplies would be sent first via a relatively moderate energy-efficient trajectory that would take about 260 days to reach Mars. The ship's company would travel in a faster "sprint" vehicle, reaching Mars in 90 days, or about 170 days sooner than previous recommendations. There it would rendezvous with the cargo vehicle.

The total mass of the NERVA baseline ship's company vehicle would be 640 tons, 90 percent of which is exhibited by the tanks and propellant. by dint of comparison, the current space shuttle orbiter with its cargo bay largely loaded has a mass of about 100 tons.

While tank weight is normally about 15 percent of propellant weight for the standard aluminum alloy tanks, Sandia researchers calculated that graphite composite tanks could restore this to 8 percent, resulting in a mass reduction of 130 tons.

by the agency of using a PBR with its high thrust-to-weight ratio, an additional mass savings of 85 tons could be achieved. Assuming that sum of two units engines may be required (one for backup), the mass savings could amount to 150 tons.

An improvement in the high temperature capability of the nuclear core materials is casted to increase the specific impulse by dint of a modest 10 percent. This seemingly small improvement, however, has a significant impact upon spacecraft mass, saving 140 tons. Barring a major breakthrough in materials technology, further increases in specific impulse are unlikely with solid core reactors, Connell says.