Orbital maneuver

As orbital maneuvers, a process is known in space and celestial mechanics by which a man-made satellite or interplanetary missile is brought by time- limiting ignition of a recoil engine targeted at a different path.

Subject of railway maneuvers, always a dose change of velocity (acceleration, braking) or its direction. For larger changes, a turn-off rocket motor is required ( with liquid fuel or possibly with ion propulsion ), for minor amendments have nozzles for compressed gas.

Because in addition to the dose of recoil ( backward or forward ) and its exact direction is crucial, the missile in space must be stabilized ( gravitational, magnetic or gyro-stabilization ). These may be supplemented or verified by star sensors.

The purpose of a web maneuver can be:

  • In earth satellites or in artificial satellites around the moon or other planets: the magnification of the path axis ( altitude ) or round trip time ( by acceleration)
  • Reducing the path axis, altitude or orbital period ( by braking )
  • Achieving a particular web form (eg circular path, rendezvous, sun- synchronous path )
  • The change in the orbital plane ( through lateral acceleration)
  • A small course correction (usually by gas nozzles);
  • The enlargement or reduction of the path axis (see above)
  • Driving a transfer orbit to another celestial body
  • The pivoting into orbit around it (see also lunar satellite )
  • The initiation of a landing maneuver
  • Driving a swing-by on a celestial body ( gravitational maneuver to increase or decrease the orbital energy )
  • Course corrections to fine tune the trajectory or its timing.

In the early years of space travel technology of rail maneuvers had not yet developed, so that the paths achieved only it depended on how precisely the rocket launch could be controlled. The deviations of the burning time and the end of firing rate from the nominal value were typically a few thousand, the direction error a few tenths of a degree. In the first lunar probes caused this error, for example, that of a planned " hard landing " on the Earth's natural satellite a flyby at a distance of tens of thousands kilometers was.

Later they went on to insert a so-called parking orbit around the Earth before the transition to the Moon or Mars / Venus. After precise orbit determination then the required acceleration could be dosed much more accurate than directly with a longer focal length of the upper rocket stage.

The flight of today's space probes can be a hundred to a thousand times more accurate than time controlled, but requires a complex sequence of multiple orbital maneuvers. The first time was applied such a series of maneuvers during the flight of the Mercury Mariner 10 between November 1972 and March 1975:

  • Precise orbit determination of the parking orbit
  • Injection into a transfer orbit to the planet Venus
  • Orbital maneuvers for an accurate swing-by of Venus, which the orbital energy decreased by 60 % ( required to achieve close to the Sun planet )
  • Fine modification of the path axis ( distance from the sun )
  • Last course corrections in Mercury close for the first flyby
  • Timing of the sun circulation to after two Merkurumläufen (2x 88 days ) again to get into the vicinity
  • Path corrections for a third approach in lower altitude.

Even more complicated were the flights of the Voyager spacecraft to Jupiter and the outer gas planets, with some special approximations to some moons of Jupiter were carried out.

Even the newer comet probes and the Pluto New Horizons spacecraft were controlled so that gravity assist maneuvers and flybys of other celestial bodies have been possible.

  • Space Physics
  • Celestial mechanics
Ion thruster Orbital plane (astronomy) Brennschluss Gas giant
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