DARPA has awarded a US$14-million contract to the Gryphon Technologies engineering firm to support the development and demonstration of a nuclear rocket engine for the agency's Demonstration Rocket for Agile Cislunar Operations (DRACO) program. The High-Assay Low Enriched Uranium (HALEU) Nuclear Thermal Propulsion (NTP) system will allow the US military to carry out missions in cislunar space.
The single greatest limitation in space travel is the propulsion system. On Earth, it's possible to create motors that have a very high payload ratio, so one can, in the words of an early aviator, make a tea tray fly by putting enough power behind it. However, getting into space requires such high velocities and such high energies that engineers are forced to use very large engines and huge amounts of fuel to put very small payloads into orbit.
Once in space, there are essentially two options. One is to use chemical rockets, but these have largely reached their theoretical limits when it comes to thrust, or eclectic propulsion systems that produce very small thrust for very long periods of time.
As far back as 1945, it was recognized that there was a third option, which is to harness the power of the atom to produce a rocket that is more powerful than its chemical counterparts. The problem has been to create a practical design that produces enough thrust to warrant the investment.
For the DRACO program, DARPA is looking at Nuclear Thermal Propulsion (NTP) to power spacecraft beyond the Earth's atmosphere out to just beyond the orbit of the Moon. The idea is that a nuclear reactor would heat a propellant, such as hydrogen, to extreme temperatures, resulting in thrust that would be 10,000 times that of an electric engine and up to five times the efficiency of a chemical rocket.
According to DARPA, DRACO is being moved forward on two tracks. Track A is to develop the reactor design and track B is to produce an operational system. For the present contract, Gryphon will look at developing a HALEU propulsion system that uses nuclear fuel made from recycled civilian reactor fuel that has been reprocessed and enriched to between five and 20 percent – greater than that of civilian reactors and less than that of naval reactors.
The result will be a reactor core that will be small, produces less waste, have a longer core life and greater efficiency, making it more suitable for use in space than previous designs.
"A successfully demonstrated NTP system will provide a leap-ahead in space propulsion capability, allowing agile and rapid transit over vast distances as compared to present propulsion approaches," says Dr. Tabitha Dodson, Gryphon’s Chief Engineer on the support team and a national expert in NTP systems.
Source: Gryphon Technologies
