Project Longshot is a design for an interstellar spaceship, an unmanned probe intended to fly to Alpha Centauri powered by nuclear pulse propulsion. Developed by the US Navy's Naval Academy and NASA, Longshot was designed to be built at the Space Station Alpha, the much larger precursor to the existing International Space Station. Unlike the somewhat similar Project Daedalus, Longshot was designed solely using existing technology, although some development was required. Ariane 5 lifts off with the Rosetta probe on 2nd of March, 2004. ... Alpha Centauri (α Cen / α Centauri) is the brightest star system (a triple star system) in the southern constellation of Centaurus, and contains the fourth brightest star in the night sky, with an apparent visual magnitude of −0. ... An artists conception of a spacecraft powered by nuclear pulse propulsion Nuclear pulse propulsion (or External Pulsed Plasma Propulsion, as it is termed in one recent NASA document) is a proposed method of spacecraft propulsion that uses nuclear explosions for thrust. ... The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ... NASA logo Listen to this article · (info) This audio file was created from an article revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... Space Station Alpha was a design for an American space station that preceded the International Space Station. ... ISS Statistics Crew: 2 As of August 21, 2005 Perigee: 352. ... An artists conception of the British Interplanetary Society design for Project Daedalus Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible interstellar unmanned spacecraft. ...

Unlike Daedalus' closed-cycle fusion engine, Longshot used a long-lived nuclear fission reactor for power. Initially generating 300 kilowatts, the reactor powered a number of lasers in the engine that were used to ignite inertial confinement fusion similar to that in Daedalus. The main design difference was that Daedalus relied on the fusion reaction being able to power the ship as well, whereas in Longshot the external reactor provided this power. Fusion typically refers to the merging of two or more entities into a single one: In physics and technology nuclear fusion is the combination of two atomic nuclei into a single nucleus. ... An induced nuclear fission event. ... The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ... Inertial confinement fusion using lasers rapidly progressed in the late 1970s and early 1980s from being able to deliver only a few joules of laser energy to a fusion target to being able to deliver tens of kilojoules to a target. ...

The reactor was also used to power a laser for communications back to Earth, with a maximum power of 250 kilowatts. For most of the journey this would be used at a much lower power for sending data about the interstellar medium, but during the flyby the engines would be turned off and the entire power dedicated to communications at about 1 kilobit per second.

The baseline Longshot massed 6.4 metric tonnes, which includes a 3.4 tonne allocation for a large flywheel energy storage system. The rest of its mass was fuel.

Reference

Beals, K. A., M. Beaulieu, F. J. Dembia, J. Kerstiens, D. L. Kramer, J. R. West and J. A. Zito. Project Longshot: An Unmanned Probe To Alpha Centauri. U S Naval Academy. NASA-CR-184718. 1988.