Innovative Space Propulsion Systems (ISPS) has cleared a NASA safety review panel to demonstrate its NOFBX green propulsion system on board the International Space Station (ISS) in mid-2013.

ISPS passed NASA's ISS Payload Safety phase 1 review in April. Funded by an award from NASA's ISS National Laboratory program, the company's NOFBX Green Propellant Demonstration will put a deep-throttling 440 N (100-lbf) engine assembly and associated feed system to the ISS. The system will be carried up to ISS in the unpressurized cargo compartment of SpaceX's (News - Alert) Dragon spacecraft on a CRS delivery mission. Once Dragon is berthed with the space station, a station robotic arm will pull out the NOFBX test package from Dragon and put it on the outside of the European Columbus module. 

NOFBX will remain in orbit for one year and undergo a series of in-space performance tests, including steady-state, pulses, throttling and long-term storage and re-start demonstrations. The NOFBX technology is a made-in-the-USA, nitrous oxide-based monopropellent system with many different applications, including spacecraft, launch vehicles and landers. 

Nitrous oxide -- the gas used for dentistry, whipped cream bottles and boosting race car engines -- is a benign, non toxic gas at room temperature and doesn't have the hazards of and handling expenses of more toxic storable propellants.    Currently used hypergolic propellants require special handling and last minute fueling, adding to the cost of preparing satellites before launch.

Ansari XPRIZE winner, SpaceShipOne used a hybrid engine fueled by nitrous oxide and rubber, combining high performance and safety.   Scaled Composite's suborbital SpaceShipTwo and Sierra Nevada's low earth orbit (LEO) Dream Chaser -- both manned spacecraft -- also use hybrid nitrous oxide rocket motors. SpaceShipTwo, anticipated to start powered flight tests this year, will take six passengers and two crew from a flying "drop start" from a carrier aircraft at 45,000 feet to soar over 100 kilometers into space for a short suborbital hop with about four minutes of microgravity at the top of its flight.

Sierra Nevada Space Systems has built and tested its hybrid rocket motor for Dream Chaser under a variety of conditions, including three successful test fires of a single motor in one day with one firing under vacuum ignition conditions. The motor would be the main propulsion system of Dream Chaser during orbital operations.   Dream Chaser is one of four commercial manned spacecraft concepts currently funded by NASA under its Commercial Crew program.