Mariner 4

Space probes are significant tools in space exploration. These robotic spacecrafts are sent to the moon, to other planets, comets, asteroids, or other objects in the solar system to study their weather conditions and topographical features.

Space probes also take pictures and sometimes, even bring back soil and rock samples to Earth. They provide many important data about various celestial bodies which enable scientists to have a deeper understanding of our neighbors in space.

There are five basic types of space probes, depending on their function: flybys, orbiters, atmospheric probes, landers, and rovers.

• A flyby makes its observations as it passes by a celestial body from a distance. Flyby missions enable a probe to visit more than one celestial object. Examples of this type of probe are the Mariner 2 which made a flyby on Venus on December 14, 1962 and the Mariner 4 which took the first close-up images of Mars on July 14 and 15, 1965.

• An orbiter is designed to “park” itself in a stable orbit around a celestial object for an extended period of time. An orbiter that is closely circling a body with a substantial atmosphere will be gradually slowed down by atmospheric friction. This will cause it to lose altitude and eventually crash. An example of an orbiter is Venera 9 (launched on June 8, 1975) which conducted atmospheric and magnetic studies on Venus.

• An atmospheric probe is a package of instruments that descends into the atmosphere of a celestial object, taking readings as it makes its way down. This probe continues to transmit data until it reaches the surface of the object or is destroyed by heat or atmospheric pressure. Examples of atmospheric probes are Venera 4 and 5 which were sent to Venus on June 12, 1967 and January 5, 1969, respectively.

• A lander is designed to safely land on a celestial body and analyze soil samples and surface conditions. An example is Venera 7 which made the first successful landing on another planet, Venus, on December 15, 1970.

• A rover is a robot vehicle with wheels or treads that allow it to roam across a surface. It is carried to the surface of a celestial body by a lander. A rover has the advantage of not being confined to one spot. Popular examples are the Mars rovers, Spirit and Opportunity, which have been exploring the Martian landscape since 2003.