Project Longshot was a conceptual interstellar spacecraft design. It would have been an uncrewed

starship A starship, starcraft, or interstellar spacecraft is a theoretical spacecraft designed for interstellar travel, traveling between planetary systems. The term is mostly found in science fiction. Reference to a "star-ship" appears as early as 1 ...

(about 400 tonnes), intended to fly to and enter orbit around

Alpha Centauri B Alpha Centauri (, α Cen, or Alpha Cen) is a star system in the southern constellation of Centaurus. It consists of three stars: Rigil Kentaurus (), Toliman (), and Proxima Centauri (). Proxima Centauri is the closest star to th ...

nuclear pulse propulsion Nuclear pulse propulsion or external pulsed plasma propulsion is a hypothetical method of spacecraft propulsion that uses nuclear explosions for thrust. It originated as Project ''Orion'' with support from DARPA, after a suggestion by Stanislaw ...

History

Developed by the

US Naval Academy The United States Naval Academy (USNA, Navy, or Annapolis) is a federal service academy in Annapolis, Maryland. It was established on 10 October 1845 during the tenure of George Bancroft as Secretary of the Navy. The Naval Academy is the sec ...

and

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

, from 1987 to 1988, Longshot was designed to be built at Space Station ''Freedom'', the precursor to the existing

International Space Station The International Space Station (ISS) is a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...

. Similar to

Project Daedalus Project Daedalus (named after Daedalus, the Greek mythological designer who crafted wings for human flight) was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible uncrewed interstellar probe.Pr ...

, 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".

Mission

Unlike Daedalus, which used an open-cycle fusion engine, Longshot would use a long-lived

nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...

reactor for power. Initially generating 300 kilowatts, the reactor would power a number of

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

s in the engine that would be used to ignite

inertial confinement fusion Inertial confinement fusion (ICF) is a fusion energy process that initiates nuclear fusion reactions by compressing and heating targets filled with fuel. The targets are small pellets, typically containing deuterium (2H) and tritium (3H). Typical ...

similar to that in Daedalus. The main design difference is that Daedalus also relied on the

fusion reaction Nuclear fusion is a reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutron by-products. The difference in mass between the reactants and products is manifested as either the release or absorption of energy ...

to power the ship, whereas in the Longshot design the internal reactor would provide this power. The reactor would also be used to power a laser for communications back to Earth, with a maximum power of 250 kW. For most of the journey, this would be used at a much lower power for sending data about the

interstellar medium The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...

; 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 at the start of the mission including 264 tonnes of

helium-3 Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and hydrogen-1 are the only stable nuclides with ...

deuterium Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more c ...

pellet fuel/propellant. The active mission payload, which includes the

fission reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. They are used for commercial electricity, marine propulsion, weapons production and research. Fissile nuclei (primarily uranium-235 or plutonium-23 ...

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 fly-by lasting a comparatively short time. A travel to Alpha Centauri with a Longshot spacecraft would take about one century.

References

Bibliography

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.

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.

Beta Centauri Beta Centauri is a triple star system in the southern constellation of Centaurus. It is officially called Hadar (). The Bayer designation of Beta Centauri is Latinised from β Centauri, and abbreviated Beta Cen or β Cen. The syst ...

is an entirely different, unassociated star.) {{Nuclear propulsion Hypothetical spacecraft Longshot Interstellar travel NASA programs United States Naval Academy Alpha Centauri 1987 in science 1988 in science

History

Mission

See also

References

Bibliography

External links