Saturday, January 28, 2012
Among many other relevant technologies, JP Aerospace is investigating the use of low thrust, high ISP ion thrusters to accelerate their spacecraft from near space to orbit. These are not traditional rockets made out of metal, but rather lighter-than-air spacecraft which float to high altitude (over 100,000 feet) and then slowly accelerate and climb to orbit using propellers and later plasma rockets. This kind of flight is slow, but also gentle and quite inexpensive once the system gets working. A minimal amount of fuel is required because much of the lift and propulsion is done using lift gas and solar power. When fuel is consumed, perhaps xenon for the plasma engines, it is burnt at a very high isp, so that only a few kg are required to orbit payloads. In addition to orbital craft, there are plans for massive high-altitude stations where astronauts can live for extended periods. Payloads can be held here for staging to orbital craft as well. Once in orbit, the craft can drop payload, and slowly return to the Earth. Because reentry is gradual, there may be ways to prevent the high-energy reentry with the requisite heat and deceleration. If this can be done, the spacecraft can reenter deep space, rendezvous with the large floating station, and pick up a new payload. Refueling can be accomplished by transferring minimal amounts, dozens of kg perhaps, of propellant.
See more about this specific project here.