View source for Astronomy:Project Longshot

{{short description|Design for a 400 tonne nuclear pulse propelled uncrewed spacecraft to reach and orbit Alpha Centauri}}

[[File:Project Longshot configurations.svg|right|thumb|{{ordered list |Initial configuration |Configuration at 33 years |Configuration at 67 years |Configuration at 100 years}}]]
'''Project Longshot''' was a conceptual interstellar spacecraft design. It would have been an [[Engineering:Uncrewed spacecraft|uncrewed]] [[Engineering:Starship|starship]] (about 400 tonnes), intended to fly to and enter orbit around [[Astronomy:Alpha Centauri|Alpha Centauri B]] powered by [[Physics:Nuclear pulse propulsion|nuclear pulse propulsion]].<ref name="long1">{{cite news |author=<!--Staff writer(s); no by-line.--> |title=Project Longshot |url=http://www.realclearscience.com/lists/3_canceled_nasa_projects/ |newspaper=Real Clear Science |location=United States |date =22 April 2014 |access-date=9 June 2016}}</ref>

==History==
Developed by the US Naval Academy and [[Organization:NASA|NASA]], from 1987 to 1988, Longshot was designed to be built at [[Astronomy:Space Station Freedom|Space Station ''Freedom'']], the precursor to the existing [[Astronomy:International Space Station|International Space Station]]. Similar to [[Engineering:Project Daedalus|Project Daedalus]], Longshot was designed with existing technology in mind, although some development would have been required; for example, the Project Longshot concept assumes "a three-order-of-magnitude leap over current propulsion technology".<ref name="long1"/>

==Mission==
Unlike Daedalus, which used an open-cycle [[Physics:Fusion power|fusion engine]], Longshot would use a long-lived [[Physics:Nuclear fission|nuclear fission]] reactor for power. Initially generating 300 kilowatts, the reactor would power a number of [[Physics:Laser|laser]]s in the engine that would be used to ignite [[Physics:Inertial confinement fusion|inertial confinement fusion]] similar to that in Daedalus. The main design difference is that Daedalus also relied on the fusion reaction to power the ship, whereas in the Longshot design the internal reactor would provide this power.<ref name="long1"/>

The reactor would also be used to power a laser for communications back to Earth, with a maximum power of 250&nbsp;kW. For most of the journey, this would be used at a much lower power for sending data about the [[Astronomy:Interstellar medium|interstellar medium]]; but during the flyby, the main engine section would be discarded and the entire power capacity dedicated to communications at about 1 kilobit per second.

Longshot would have a mass of {{convert|396|t|lb}} at the start of the mission including 264 tonnes of [[Physics:Helium-3|helium-3]]/[[Physics:Deuterium|deuterium]] pellet fuel/propellant. The active mission payload, which includes the fission reactor but not the discarded main propulsion section, would have a mass of around 30 tonnes.

A difference in the mission architecture between Longshot and the Daedalus study is that Longshot would go into orbit about the target star, while the higher-speed Daedalus would do a one shot [[Engineering:Planetary flyby|fly-by]] lasting a comparatively short time.

== See also ==
{{div col}}
* [[Astronomy:Alpha Centauri Bb|Alpha Centauri Bb]]
* [[Astronomy:Breakthrough Starshot|Breakthrough Starshot]]
* [[Engineering:Interstellar travel|Interstellar travel]]
* [[Physics:Nuclear pulse propulsion|Nuclear pulse propulsion]]
* [[Engineering:Project Daedalus|Project Daedalus]]
* [[Astronomy:Project Orion (nuclear propulsion)|Project Orion (nuclear propulsion)]]
* [[Engineering:Project Icarus (interstellar)|Project Icarus]]
* [[Astronomy:Spacecraft propulsion|Spacecraft propulsion]]
{{div col end}}

== References ==
{{reflist}}

==Bibliography==
Beals, K. A., M. Beaulieu, F. J. Dembia, J. Kerstiens, D. L. Kramer, J. R. West and J. A. Zito. [http://large.stanford.edu/courses/2012/ph241/klein2/docs/19890007533_1989007533.pdf ''Project Longshot: An Unmanned Probe To Alpha Centauri.''] U S Naval Academy. NASA-CR-184718. 1988.

== External links ==
 (This article refers to an Alpha and Beta Centauri as the orbital target of the mission, but the correct nomenclature for these two components of the Alpha Centauri binary star system is Alpha Centauri A and B. [[Astronomy:Beta Centauri|Beta Centauri]] is an entirely different, unassociated star.)

{{Nuclear propulsion}}

[[Category:Hypothetical spacecraft]]
[[Category:Nuclear spacecraft propulsion|Longshot]]
[[Category:Interstellar travel]]
[[Category:NASA programs]]
[[Category:Alpha Centauri]]

{{Sourceattribution|Project Longshot}}