Micrometeoroid collected from the antarctic snow

A Micrometeoroid (also micrometeorite, micrometeor) is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram. For other uses of the words gram or gramme see Gram (disambiguation.

Scientific interest

See also: Cosmic dust

Micrometeoroids are very small, typically metallic, pieces of rock broken off from larger chunks of rock and debris, often dating back to the formation of the solar system. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. Micrometeoroids are extremely common in space, particularly near the Earth. These tiny particles are a major contributor to space weathering processes. Space weathering is a blanket term used for a number of processes that act on any body exposed to the harsh space environment When they impact the surface of the Moon, or any airless body (Mercury, the asteroids, etc), the resulting melting and vaporization causes darkening and other optical changes in the regolith. Regolith ( Greek: "blanket rock" is a layer of loose Heterogeneous material covering solid rock. In order to understand the micrometeoroid population better, a number of spacecraft (including Lunar Orbiter 1, Luna 3, Mars 1 and Pioneer 5) have carried micrometeoroid detectors. The Lunar Orbiter 1 Robotic (unmanned Spacecraft, part of the Lunar Orbiter Program, was designed primarily to photograph smooth areas of the The Soviet spaceprobe Luna 3 (E-3 series was the third spacecraft sent successfully to the Moon and was an early triumph in the human exploration of outer space Mars 1 (1962 Beta Nu 1 was an automatic interplanetary station launched in the direction of Mars on November 1, 1962, the first of the Soviet Pioneer 5 (also known as 1960 Alpha 1, Pioneer V, Pioneer P-2, and Thor Able 4) was a spin-stabilized space probe in the NASA

While meteoroids tend to remain in stable orbits, micrometeoroids are more likely to fall to Earth, and can provide information on millimeter scale heating events in the solar nebula. Micrometeorites (as they are known upon arrival at the Earth's surface) can only be collected in areas where there is no terrestrial sedimentation, typically polar regions. A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface Ice is collected and then melted and filtered so the micrometeorites can be extracted under a microscope.

Sufficiently small micrometeoroids avoid significant heating on entry into the earth's atmosphere. Collection of such particles by high flying aircraft began in the 1970's, since which time these samples of interplanetary dust have become an important component of the extraterrestrial materials available for study in laboratories on earth. The interplanetary dust cloud is Cosmic dust (small particles floating in space which pervade the space between Planets in the Solar System and in Most atoms on earth came from the interstellar dust and gas from which the sun and solar system formed

Effect on spacecraft operations

See also: Space debris

Micrometeoroids pose a significant threat to space exploration. Space debris or orbital debris, also called space junk and space waste are the objects in Orbit around Earth created by humans that no Their velocities relative to a spacecraft in orbit can be on the order of kilometers per second, and resistance to micrometeoroid impact is a significant design challenge for spacecraft and space suit designers (See Thermal Micrometeoroid Garment). A spacecraft is a Vehicle or machine designed for Spaceflight. A space suit is a complex system of Garments equipment and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space An ( Integrated) Thermal Micrometeoroid Garment ( TMG or ITMG) is the outer layer of a Space suit. While the tiny sizes of most micrometeoroids limits the damage incurred, the high velocity impacts will constantly degrade the outer casing of spacecraft in a manner analogous to sandblasting. Sandblasting or Bead blasting is a generic term for the process of smoothing shaping and cleaning a hard surface by forcing solid particles across that surface at high speeds Long term exposure can threaten the functionality of spacecraft systems.

Impacts by small objects with extremely high velocity are a current area of research in terminal ballistics. Terminal ballistics, a sub-field of Ballistics, is the study of the behavior of a Projectile when it hits its target Accelerating objects up to such velocities is difficult; current techniques include linear motors and shaped charges. A linear motor or linear induction motor is essentially a multi-phase Alternating current (AC Electric motor that has had its Stator "unrolled" A shaped charge is an Explosive charge shaped to focus the effect of the explosive's energy The risk is especially high for objects in space for long periods of time, such as satellites. This article is about artificial satellites For natural satellites also known as moons see Natural satellite. They also pose major engineering challenges in theoretical low-cost lift systems such as rotovators, space elevators, and orbital airships. A space elevator is a proposed structure designed to transport Material from a celestial body 's Surface into space. The orbital airship, also called the space blimp, is a proposed space transportation system that carries payloads to and from Low Earth orbit.

See Also

• Interplanetary dust cloud
• Extraterrestrial materials