A space probe (also space probe ) is an unmanned missile, which is sent to exploration purposes into space. In contrast to a (ground ) it leaves the satellite orbit ( orbit ) of the earth. Most fly as planetary probes a distant target in space at around this investigate (eg, Mars, asteroids, comets, moons of Jupiter ), few explore interplanetary space, which makes fewer demands on the path calculation.
Because of the many years of duration of spacecraft missions are placed on the technical equipment of spacecraft highest requirements. The components of spacecraft are assembled in a clean room and tested elaborately. A big problem with space probes against orbiting satellites is the great Erdabstand, the long durations of the light emitted by the ground station control commands causes. For this reason, space probes shall have systems that make them independent to some extent of ground stations.
For spacecraft missions of the bullet angle must be determined with an accuracy of less than one second of arc. The navigation of space probes must be carried out with maximum accuracy. This is achieved with the help of the Doppler effect and the signal propagation times. In this way, their position with an accuracy of less than one meter - regardless of their distance from the Earth - determined.
Power is supplied at space probes to the moon and the inner planets Mercury to Mars mostly with solar cells that are buffered by a battery. For spacecraft with a short life cycle or operating time and batteries. Spacecraft for the flight to outer planets used for the power supply often isotopic batteries because more and more ineffective with increasing distance from the sun solar panels. The progress in solar cell technology since 2010 allows, however, a spacecraft by Jupiter to be supplied with energy from solar cells when the spacecraft is not immersed in Jupiter's intense radiation belts, which would destroy the solar cells.
Depending on the task, one divides space probes in:
- Flyby probes - probes that perform only a flyby of a celestial body.
- Orbiter - probes that follow an orbit around a celestial body.
- Lander - probes that land on a celestial body. Here, a further subdivision is useful: Hydrobot - a probe that can explore the depths of unknown waters independently.
- Cryobot - a probe that melts through ice through which to explore this and underlying media.
- Penetrator - a space probe that pierces at a braked landing up to a few meters in the heavenly bodies to be examined.
- Rover - a mobile lander, can be explored with the larger regions.
For a complete list of all space probes with mission descriptions is available under List of unmanned space missions.