Flyby (space travel)

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A flyby is a flight of a probe that explores a planet or another celestial body without entering its orbit or significantly changing its trajectory due to the gravitation of the celestial body. The transition to swing-by , where this influence is desired, is fluid, but flyby is also a generic term for both types of maneuver.

A flyby probe is a space probe that flies past one or more celestial bodies and collects data about the object passed. Flyby probes are technically and energetically cheaper than orbiters that enter orbit around a celestial body. The scientific results are less due to the flyby, which only takes a few hours to days, than with an orbiter that observes the celestial body for months or years from an orbit. Another concept of space probes are landers that land on a celestial body in order to carry out research there.

Voyager 2 flyby probe in deep space (artist's impression)


If, with appropriate control of a spacecraft, the gravity field of a celestial body is used to change its course in a targeted manner and to increase or decrease its speed , this is called swing-by.

Fly by the moon

See also: List of all visits to the moon (V = flyby )

In the early years of space travel , flying past the moon or the Earth's neighboring planets was the only way to remotely sense other celestial bodies. The accuracy and reliability of the control of a spacecraft determines the minimum distance that can be achieved. The burnout speed of the early launch vehicles could not yet be maintained as precisely as would have been necessary for close pass-by flights. With the increasing precision of the take-off, the direct approach to the moon for the purpose of a hard landing came into the realm of possibility.

The first successful flybys of the Earth's moon were those of the Soviet lunar probe Lunik 1 on January 2, 1959 at a distance of 6,000 km from the moon and the American Pioneer 4 on March 4, 1959 at a distance of 60,000 km. These missions were preceded by a total of seven false starts between August and December 1958. Both probes carried out radiation and particle measurements between the earth and the moon and became artificial planets of the sun after the passage through the moon. Lunik 1 was able to prove the predicted existence of the solar wind .

The sixth Soviet lunar probe Lunik 2 , on September 12 and 13, 1959, hit the moon for the first time. Lunik 3 , with a flight from October 4 to 10, 1959, was able to transmit the first photos of the back of the moon by radio after the flyby and discovered the only lunar sea in this hemisphere , the Mare Moscoviense .

After four more failures each by the USSR and the United States, there followed the flyby of Ranger 2 in November 1961, the hard landings of Ranger 4 in 1962 and Ranger 6 in 1964, which did not transmit any data, and the flyby of Luna 4 in 1963. were entirely successful only the close-ups of the lunar surface by Ranger 7 in 1964 and Ranger 8 and Ranger 9 in 1965, as well as by Zond 3 in 1965.

The first soft landings came in Luna 9 from the USSR in 1966 and Surveyor 3 from the United States in 1967 .

Fly by planets

Flying past the two neighboring planets of the earth, Venus and Mars , require an accuracy that is one to two powers of ten higher, which can only be achieved by subsequent orbit maneuvers . Therefore, they only come after a few failures and a further two to three years of technical development. The following list is arranged chronologically: first the planets after the first flyby, then again chronologically within the sections:


See also: List of all visits to Venus (V = flyby )

  • Venera 1, after three months of flight, on May 20, 1961 at a distance of 100,000 km, the radio failed just a few days after take-off.
  • Mariner 2, after three and a half months of flight, on December 14, 1962, 34,000 km away. First measurement data from Venus, which invalidated the hypothesis of a warm and humid climate.
  • Venera 2 and Venera 3 also lost radio contact with the earth. Venera 4 in 1967 and from 1969 succeeded in setting down atmospheric or landing probes on Venus. The high gas pressure destroyed them after 50 to 90 minutes.
  • Mariner 10 took off on November 4, 1973. The flyby, during which 4,200 close-ups were taken, occurred on February 5, 1974 at a distance of 5800 km. This controlled so precisely that the planned deflection of the flight path to Mercury was exactly achieved. In order to get to the planet closest to the sun, about 60 percent of the orbital energy had to be removed from the earth's orbit during this swing-by maneuver . This enabled the cheaper Atlas Centaur rocket to be used instead of the Titan IIIC .
  • MESSENGER took off on August 3, 2004 on board a Delta II . On its way to Mercury, the probe passed Venus twice. The first time on October 24, 2006 in 2990 km and the second time on June 5, 2007 in only 337 km from the planet's surface.


See also: List of all Mars visits (V = flyby )

  • After three false starts, the Soviet Mars 1 (1963), although radio contact was lost a few months earlier
  • Mariner 4 (launched November 28, 1964), Mars passage on July 15, 1965 at a distance of 9846 km. For the first time, the probe provided 22 close-up images of the Red Planet, which surprisingly showed numerous Martian craters - and life was practically impossible.
  • Rosetta (probe) (launched March 2, 2004), Mars flyby on February 25, 2007 at a distance of almost 240 km. Her lander Philae (probe) took a photo of Mars during the passage, showing a solar panel and some of the main body of Rosetta.
  • Dawn (space probe) (launched September 27, 2007), Mars flyby on February 17, 2009 at a distance of almost 543 km. During the flyby, the probe photographed one of the larger Martian craters.


See also: List of all visits to Mercury (V = flyby)

  • The first flyby of Mercury (March 19, 1974) took place at a distance of 705 km by Mariner 10 and was used for remote sensing of this hot, crater-covered planet (2500 pictures taken). Mercury then directed the missile into a 176-day solar orbit, which was exactly double its orbit . A second encounter took place on September 21, 1974 (as planned at a distance of 50,000 km and further recordings) and a third on March 16, 1975 at a distance of only 375 km, during which the magnetic field was examined. After that the fuel was exhausted and the probe was switched off.
  • The second flyby of Merkur was made on January 14, 2008 by the MESSENGER probe launched in August 2004. This flew past the planet twice (October 6, 2008 and September 29, 2009) before entering orbit around Mercury on March 18, 2011 .

Jupiter, Saturn, Uranus and Neptune

See also: Lists of all Jupiter , Saturn , Uranus and Neptune visits (V = flyby )

With Voyager 1 and Voyager 2 (1977 to 1979) for the first time get flybys on Jupiter and the moons of Jupiter - and after successful swing-by maneuvers the required acceleration to go to Saturn , Uranus and Neptune to go.

Fly past other celestial bodies

See also: Lists of all asteroid and comet visits (V = flyby)

Halley's Comet

In 1985, the unmanned Giotto spacecraft was sent into space to study Halley's Comet . It was "ESA's first interplanetary probe and the first scientific payload on board an Ariane rocket."

Comet 9P / Temple 1

Deep Impact was a mission to comet 9P / Tempel 1 launched by NASA on January 12, 2005 , during which a projectile with a mass of around 370 kg and a speed of 10.2 m / s was launched on July 4, 2005 by the probe hit the surface of the comet. The effects of the impact were observed by the probe, space telescopes, and telescopes on Earth. Examination of the material thrown up and the impact crater should increase understanding of the structure and formation of comets and the solar system .

Comet 103P / Hartley 2

In the combined, extended mission EPOXI (Extrasolar Planet Observation / eXtended Investigation of comets), the Deep Impact spacecraft explored the core of Comet 103P / Hartley 2 (formerly P / Hartley 2) during a flyby from a distance of 700 on November 4, 2010 km. Then she observed five previously discovered extrasolar planetary systems with one of her two telescopes .


See also: List of all Pluto fly-bys

The New Horizons spacecraft launched on January 19, 2006 for the dwarf planet Pluto . After a swing-by maneuver on Jupiter 2007, it flew past Pluto and its moons on July 14, 2015.

See also


Individual evidence

  1. ^ E. Julius Dasch : fly-by. In: A Dictionary of Space Exploration. Oxford University Press , January 2005, accessed November 28, 2012 (English, ISBN 978-0-19-172801-3 ): “A spacecraft flight that explores a planet or other astral body by passing it without being captured into its orbit and without having its flight path altered by the body's gravitational pull. "
  2. Heinz Habeler , Erich Übelacker : The stars . In: What is what (=  what is what ). tape  6 . Tesloff, Nuremberg 2001, ISBN 978-3-7886-0246-8 , Sternwisch, p. 242 ( online [accessed December 4, 2012]).
  3. Peter Leibundgut: Extraterrestrials and what you should know about them . Science versus speculation. Novum, Neckenmarkt 2011, ISBN 978-3-99003-549-8 , pp. 39 ( Online [accessed on December 4, 2012] Bibliography of the Austrian National Library , issue: 4/2012, p. 4 (PDF; 636 kB)).
  4. ↑ Flyby probe. (No longer available online.) Astronomy Knowledge, archived from the original on January 6, 2016 ; Retrieved December 2, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot /
  5. ^ E. Julius Dasch : swing-by. In: A Dictionary of Space Exploration. Oxford University Press , January 2005, accessed November 28, 2012 (English, ISBN 978-0-19-172801-3 ): "The path of a spacecraft as it flies past another planetary body and its course is changed and speed increased"
  6. ^ Deep Impact. In: knowledgemedia at inmediaONE GmbH, accessed on December 2, 2012 .
  7. ^ 'Hitchhiker' EPOXI: Next Stop, Comet Hartley 2. In: NASA , accessed December 2, 2012 .

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