A space probe is an unmanned spacecraft that, unlike earth observation satellites and space telescopes, is sent on a journey to one or more objects to be examined in the solar system . In a clear connection with space research , the term can also be abbreviated to “probe” and thus form compounds with target object names , for example “ moon probe ” or “ Mars probe ”.
The launch of space probes requires a large delta v, especially for flights to destinations beyond Mars and Venus . Course corrections are made after the first measurement of the path and at different distances from the target. The navigation of space probes takes place with the help of the Doppler effect and the signal propagation times to an accuracy of sometimes less than one meter in position and less than one centimeter per hour in speed.
Due to the long signal propagation times for control commands, space probes must have systems that make them independent of ground stations to a certain extent. This applies in particular to position control and the sequence control of path maneuvers and observations.
For space probes to the moon and the inner planets, energy is usually supplied by solar cells , which are buffered by an accumulator . Space probes for the flight to outer planets often use radionuclide batteries for the power supply , since solar cell surfaces become more inefficient the further away from the sun. However, the progress in solar cell technology makes it possible to supply even a space probe near Jupiter with energy from solar cells (see: Juno ).
Depending on the task at hand, space probes are divided into:
- Flyby Probes - Probes that only perform a flyby of a celestial body to make observations along the way and nearby, and then may have another target.
- Orbiter - probes that go into orbit around a celestial body, sometimes also at a Lagrangian point .
- Landers - probes that land on a celestial body.
- Sample recovery ( English sample return ) - probes that samples of a celestial body, attributed collected particles or prepared samples to Earth in space.
Sufficiently gently landed probes or parts of them that remain on a celestial body and are equipped with a passive element retroreflector are used as a survey point and for measurements of dust deposits and the transparency of the atmosphere.
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