Radioisotope rocket

Radioisotope rocket

The radioisotope rocket is a type of rocket engine that uses the heat generated by the decay of radioactive elements to heat a working fluid, which is then exhausted through a rocket nozzle to produce thrust. They are similar in nature to the nuclear thermal rockets such as NERVA, but are considerably simpler and often have no moving parts.

The basic idea is a development of existing radioisotope thermoelectric generator, or RTG, systems, in which the heat generated by decaying nuclear fuel is used to generate power. In the rocket application the generator is removed, and the working fluid is instead used to produce thrust directly. Temperatures of about 1500 to 2000°C are possible in this system, allowing for specific impulses of about 700 to 800 seconds (7 to 8 kN·s/kg), about double that of the best chemical engines such as the LH2-LOX SSME.

However the amount of power generated by such systems is typically fairly low. Whereas the full "active" reactor system in a nuclear thermal rocket can be expected to generate over a gigawatt, a radioisotope generator might get 5 kW. This means that the design, while highly efficient, can produce thrust levels of perhaps 1.3 to 1.5 N, making them useful only for thrusters. In order to increase the power for medium-duration missions, engines would typically use fuels with a short half-life such as Po 210, as opposed to the typical RTG which would use a long half-life fuel such as plutonium in order to produce more constant power over longer periods of time.

TRW maintained a fairly active development program known as Poodle from 1961 to 1965, and today the systems are still often known as Poodle thrusters. The name was a play on the larger systems being developed under Project Rover, which led to NERVA. In April 1965 they ran their testbed engine for 65 hours at about 1500°C, producing a specific impulse of 650 to 700 seconds (6.5 to 7 kN·s/kg).

The inadvertent construction of a radioisotope rocket is one of the suggested solutions to the Pioneer anomaly. The Pioneer space probes are powered by radioisotope thermal generators located on the end of a long arm to keep their radiation away from the spacecraft electronics. In this position the back of the main radio dish is preferentially exposed, meaning that radiation (primarily infra-red) scattered by the dish would tend to be scattered to the rear of the spacecraft. This could lead to a "tiny" amount of net thrust being generated, although all calculations to date suggest it is not enough to explain the effect.


*United States Patent 3315471; Direct cycle radioisotope rocket engine; 1967; Lee, Dailey Charles, Verdes, Estates Palos
*United States Patent 3306045; Radioisotope rocket; 1967; Buford Jr., William H. Thomas Jr., Arthur N.


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Rocket engine — RS 68 being tested at NASA s Stennis Space Center. The nearly transparent exhaust is due to this engine s exhaust being mostly superheated steam (water vapor from its propellants, hydrogen and oxygen) …   Wikipedia

  • Nuclear photonic rocket — In a nuclear photonic rocket, a nuclear reactor would generate such high temperatures that the blackbody radiation from the reactor would provide significant thrust. The disadvantage is that it takes a lot of power to generate a small amount of… …   Wikipedia

  • Nuclear electric rocket — In a nuclear electric rocket, nuclear thermal energy is changed into electrical energy that is used to power one of the electrical propulsion technologies. Technically the powerplant is nuclear, not the propulsion system, but the terminology is… …   Wikipedia

  • Nuclear thermal rocket — Sketch of nuclear thermal rocket …   Wikipedia

  • Gas core reactor rocket — Gas core reactor rockets are a conceptual type of rocket that is propelled by the exhausted coolant of a gaseous fission reactor. The nuclear fission reactor core may be either a gas or plasma. They may be capable of creating specific impulses of …   Wikipedia

  • Nuclear salt-water rocket — A nuclear salt water rocket (or NSWR) is a proposed type of nuclear thermal rocket designed by Robert Zubrin that would be fueled by water bearing dissolved salts of Plutonium or U235. These would be stored in tanks that would prevent a critical… …   Wikipedia

  • Fusion rocket — A fusion rocket is a theoretical design for a rocket driven by fusion power which could provide efficient and long term acceleration in space without the need to carry a large fuel supply. The design relies on the development of fusion power… …   Wikipedia

  • Variable Specific Impulse Magnetoplasma Rocket — Artist s impression of several VASIMR engines propelling a craft through space The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is an electro magnetic thruster for spacecraft propulsion. It uses radio waves to ionize and heat a… …   Wikipedia

  • Cryogenic rocket engine — Vulcain engine of Ariane 5 rocket …   Wikipedia

  • Monopropellant rocket — A monopropellant rocket (or monoprop rocket ) is a rocket that uses a single chemical as its propellant. Contents 1 Chemical reaction monopropellant rockets 2 Solar thermal monopropellant thrusters 3 See also …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.