Topic: Spaceflight

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πŸ”— Alcubierre drive

πŸ”— Spaceflight πŸ”— Physics πŸ”— Alternative Views πŸ”— Physics/relativity

The Alcubierre drive, Alcubierre warp drive, or Alcubierre metric (referring to metric tensor) is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by Mexican theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created.

Rather than exceeding the speed of light within a local reference frame, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel. Objects cannot accelerate to the speed of light within normal spacetime; instead, the Alcubierre drive shifts space around an object so that the object would arrive at its destination faster than light would in normal space without breaking any physical laws.

Although the metric proposed by Alcubierre is consistent with the Einstein field equations, construction of such a drive is not necessarily possible. The proposed mechanism of the Alcubierre drive implies a negative energy density and therefore requires exotic matter. So if exotic matter with the correct properties cannot exist, then the drive could not be constructed. At the close of his original article, however, Alcubierre argued (following an argument developed by physicists analyzing traversable wormholes) that the Casimir vacuum between parallel plates could fulfill the negative-energy requirement for the Alcubierre drive.

Another possible issue is that, although the Alcubierre metric is consistent with Einstein's equations, general relativity does not incorporate quantum mechanics. Some physicists have presented arguments to suggest that a theory of quantum gravity (which would incorporate both theories) would eliminate those solutions in general relativity that allow for backwards time travel (see the chronology protection conjecture) and thus make the Alcubierre drive invalid.

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πŸ”— Konstantin Tsiolkovsky

πŸ”— Biography πŸ”— Soviet Union πŸ”— Russia πŸ”— Russia/technology and engineering in Russia πŸ”— Spaceflight πŸ”— Biography/science and academia πŸ”— Transhumanism πŸ”— Russia/science and education in Russia πŸ”— Biography/arts and entertainment πŸ”— Rocketry

Konstantin Eduardovich Tsiolkovsky (Russian: ΠšΠΎΠ½ΡΡ‚Π°Π½Ρ‚ΠΈΜΠ½ Эдуа́рдович Циолко́вский; 17 SeptemberΒ [O.S. 5 September]Β 1857 – 19 September 1935) was a Russian and Soviet rocket scientist who pioneered astronautics. Along with the Frenchman Robert Esnault-Pelterie, the Germans Hermann Oberth and Fritz von Opel, and the American Robert H. Goddard, he is one of the founding fathers of modern rocketry and astronautics. His works later inspired leading Soviet rocket-engineers Sergei Korolev and Valentin Glushko, who contributed to the success of the Soviet space program.

Tsiolkovsky spent most of his life in a log house on the outskirts of Kaluga, about 200Β km (120Β mi) southwest of Moscow. A recluse by nature, his unusual habits made him seem bizarre to his fellow townsfolk.

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πŸ”— Satellite killed by trajectory patent

πŸ”— Spaceflight

AMC-14 is a communications satellite. Initially owned by SES Americom, AMC-14 was designed to be placed in geostationary orbit, following launch on a Proton rocket. Built by Lockheed Martin and based on the A2100 satellite bus, AMC-14 was to have been located at 61.5Β° west longitude for DISH Network service.

It was launched atop a Proton-M/Briz-M rocket at 23:18:55 GMT on 14 March 2008, from LC-200/39 at the Baikonur Cosmodrome in Kazakhstan. The satellite was placed in an unusable orbit, following a malfunction of the Briz-M upper stage. Over a six-month period, it was maneuvered into a geosynchronous orbit, and is now near 35Β° East and in an inclined orbit.

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πŸ”— Kessler Syndrome

πŸ”— Spaceflight πŸ”— Environment πŸ”— Disaster management

The Kessler syndrome (also called the Kessler effect, collisional cascading, or ablation cascade), proposed by NASA scientist Donald J. Kessler in 1978, is a theoretical scenario in which the density of objects in low Earth orbit (LEO) due to space pollution is high enough that collisions between objects could cause a cascade in which each collision generates space debris that increases the likelihood of further collisions. One implication is that the distribution of debris in orbit could render space activities and the use of satellites in specific orbital ranges difficult for many generations.

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πŸ”— Project Orion (nuclear propulsion)

πŸ”— Spaceflight

Project Orion was a study of a spacecraft intended to be directly propelled by a series of explosions of atomic bombs behind the craft (nuclear pulse propulsion). Early versions of this vehicle were proposed to take off from the ground (with significant associated nuclear fallout); later versions were presented for use only in space. Six non-nuclear tests were conducted using models. The project was eventually abandoned for multiple reasons such as the Partial Test Ban Treaty which banned nuclear explosions in space as well as concerns over nuclear fallout.

The idea of rocket propulsion by combustion of explosive substance was first proposed by Russian explosives expert Nikolai Kibalchich in 1881, and in 1891 similar ideas were developed independently by German engineer Hermann Ganswindt. Robert A. Heinlein mentions powering spaceships with nuclear bombs in his 1940 short story "Blowups Happen." Real life proposals of nuclear propulsion were first made by Stanislaw Ulam in 1946, and preliminary calculations were made by F. Reines and Ulam in a Los Alamos memorandum dated 1947. The actual project, initiated in 1958, was led by Ted Taylor at General Atomics and physicist Freeman Dyson, who at Taylor's request took a year away from the Institute for Advanced Study in Princeton to work on the project.

The Orion concept offered high thrust and high specific impulse, or propellant efficiency, at the same time. The unprecedented extreme power requirements for doing so would be met by nuclear explosions, of such power relative to the vehicle's mass as to be survived only by using external detonations without attempting to contain them in internal structures. As a qualitative comparison, traditional chemical rocketsβ€”such as the Saturn V that took the Apollo program to the Moonβ€”produce high thrust with low specific impulse, whereas electric ion engines produce a small amount of thrust very efficiently. Orion would have offered performance greater than the most advanced conventional or nuclear rocket engines then under consideration. Supporters of Project Orion felt that it had potential for cheap interplanetary travel, but it lost political approval over concerns with fallout from its propulsion.

The Partial Test Ban Treaty of 1963 is generally acknowledged to have ended the project. However, from Project Longshot to Project Daedalus, Mini-Mag Orion, and other proposals which reach engineering analysis at the level of considering thermal power dissipation, the principle of external nuclear pulse propulsion to maximize survivable power has remained common among serious concepts for interstellar flight without external power beaming and for very high-performance interplanetary flight. Such later proposals have tended to modify the basic principle by envisioning equipment driving detonation of much smaller fission or fusion pellets, in contrast to Project Orion's larger nuclear pulse units (full nuclear bombs) based on less speculative technology.

To Mars by A-Bomb: The Secret History of Project Orion was a 2003 BBC documentary film about the project.

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πŸ”— Project A119

πŸ”— Spaceflight πŸ”— Military history πŸ”— Military history/North American military history πŸ”— Military history/United States military history πŸ”— Military history/Military science, technology, and theory πŸ”— Moon πŸ”— Military history/Cold War πŸ”— Cold War πŸ”— Solar System πŸ”— Solar System/Moon

Project A119, also known as A Study of Lunar Research Flights, was a top-secret plan developed in 1958 by the United States Air Force. The aim of the project was to detonate a nuclear bomb on the Moon, which would help in answering some of the mysteries in planetary astronomy and astrogeology. If the explosive device detonated on the surface, not in a lunar crater, the flash of explosive light would have been faintly visible to people on Earth with their naked eye, a show of force resulting in a possible boosting of domestic morale in the capabilities of the United States, a boost that was needed after the Soviet Union took an early lead in the Space Race and was also working on a similar project.

The project was never carried out, being cancelled primarily out of a fear of a negative public reaction, with the potential militarization of space that it would also have signified, and because a Moon landing would undoubtedly be a more popular achievement in the eyes of the American and international public alike. A similar project by the Soviet Union also never came to fruition.

The existence of the US project was revealed in 2000 by a former executive at the National Aeronautics and Space Administration (NASA), Leonard Reiffel, who led the project in 1958. A young Carl Sagan was part of the team responsible for predicting the effects of a nuclear explosion in vacuum and low gravity and in evaluating the scientific value of the project. The project documents remained secret for nearly 45 years, and despite Reiffel's revelations, the United States government has never officially recognized its involvement in the study.

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πŸ”— Launch loop

πŸ”— Spaceflight πŸ”— Engineering

A launch loop or Lofstrom loop is a proposed system for launching objects into orbit using a moving cable-like system situated inside a sheath attached to the Earth at two ends and suspended above the atmosphere in the middle. The design concept was published by Keith Lofstrom and describes an active structure maglev cable transport system that would be around 2,000Β km (1,240Β mi) long and maintained at an altitude of up to 80Β km (50Β mi). A launch loop would be held up at this altitude by the momentum of a belt that circulates around the structure. This circulation, in effect, transfers the weight of the structure onto a pair of magnetic bearings, one at each end, which support it.

Launch loops are intended to achieve non-rocket spacelaunch of vehicles weighing 5 metric tons by electromagnetically accelerating them so that they are projected into Earth orbit or even beyond. This would be achieved by the flat part of the cable which forms an acceleration track above the atmosphere.

The system is designed to be suitable for launching humans for space tourism, space exploration and space colonization, and provides a relatively low 3g acceleration.

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πŸ”— Project West Ford

πŸ”— United States/U.S. Government πŸ”— United States πŸ”— Spaceflight πŸ”— Military history πŸ”— Military history/North American military history πŸ”— Military history/United States military history πŸ”— United States/Military history - U.S. military history πŸ”— Cold War

Project West Ford (also known as Westford Needles and Project Needles) was a test carried out by Massachusetts Institute of Technology's Lincoln Laboratory on behalf of the United States Military in 1961 and 1963 to create an artificial ionosphere above the Earth. This was done to solve a major weakness that had been identified in US military communications.

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πŸ”— Starlight (Interstellar Probe)

πŸ”— Spaceflight

Project Starlight is a research project of the University of California, Santa Barbara to develop a fleet of laser beam-propelled interstellar probes and sending them to a star neighboring the Solar System, potentially Alpha Centauri. The project aims to send organisms on board the probe.

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πŸ”— J002E3

πŸ”— Spaceflight πŸ”— Astronomy

J002E3 is the designation given to an object in space discovered on September 3, 2002, by amateur astronomer Bill Yeung. Initially thought to be an asteroid, it has since been tentatively identified as the S-IVB third stage of the Apollo 12 Saturn V rocket (designated S-IVB-507), based on spectrographic evidence consistent with the titanium dioxide in the paint used on the rockets. The stage was intended to be injected into a permanent heliocentric orbit in November 1969, but is now believed instead to have gone into an unstable high Earth orbit which left Earth's proximity in 1971 and again in June 2003, with an approximately 40-year cycle between heliocentric and geocentric orbit.

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