Space environment

Space environmentis a branch ofastronautics,aerospace engineeringandspace physicsthat seeks to understand and address conditions existing in space that affect the design and operation of spacecraft. A related subject,space weather,deals with dynamic processes in the solar-terrestrial system that can give rise to effects on spacecraft, but that can also affect the atmosphere,ionosphereandgeomagnetic field,giving rise to several other kinds of effects on human technologies.

Effects on spacecraft can arise fromradiation,space debrisandmeteoroidimpact, upperatmospheric dragandspacecraft electrostatic charging.Various mitigation strategies have been adopted.

Radiation

Radiation in space usually comes from three main sources:

1. TheVan Allen radiation belts
2. Solar proton eventsandsolar energetic particles;and
3. Galacticcosmic rays.

For long-duration missions, the high doses of radiation can damage electronic components and solar cells. A major concern is also radiation-induced "single-event effects" such assingle event upset.Crewed missions usually avoid the radiation belts and theInternational Space Stationis at an altitude well below the most severe regions of the radiation belts. During solar energetic events (solar flaresandcoronal mass ejections) particles can be accelerated to very high energies and can reach the Earth in times as short as 30 minutes (but usually take some hours). These particles are mainly protons and heavier ions that can cause radiation damage, disruption to logic circuits, and even hazards to astronauts. Crewed missions to return to the Moon or to travel to Mars will have to deal with the major problems presented by solar particle events to radiation safety, in addition to the important contribution to doses from the low-level backgroundcosmic rays.In near-Earth orbits, the Earth'sgeomagnetic fieldscreens spacecraft from a large part of these hazards - a process calledgeomagnetic shielding.

Debris

Space debris and meteoroids can impact spacecraft at high speeds, causing mechanical or electrical damage. The average speed of space debris is 10 km/s (22,000 mph; 36,000 km/h)while the average speed of meteoroids is much greater. For example, the meteoroids associated with thePerseid meteor showertravel at an average speed of 58 km/s (130,000 mph; 210,000 km/h).Mechanical damage from debris impacts have been studied through space missions includingLDEF,which had over 20,000 documented impacts through its 5.7-year mission.Electrical anomalies associated with impact events includeESA's Olympus spacecraft, which lost attitude control during the 1993 Perseid meteor shower.A similar event occurred with theLandsat 5spacecraftduring the 2009 Perseid meteor shower.

Electrostatic charging

Spacecraft electrostatic charging is caused by the hotplasmaenvironment around the Earth. The plasma encountered in the region of thegeostationaryorbit becomes heated during geomagneticsubstormscaused by disturbances in the solar wind. "Hot" electrons (with energies in the kilo-electron voltrange) collect on surfaces of spacecraft and can establish electrostatic potentials of the order of kilovolts. As a result, discharges can occur and are known to be the source of many spacecraft anomalies.

Mitigation strategies

Solutions devised by scientists and engineers include, but are not limited to, spacecraft shielding, special "hardening"of electronic systems, various collision detection systems. Evaluation of effects during spacecraft design includes application of various models of the environment, including radiation belt models, spacecraft-plasma interaction models and atmospheric models to predict drag effects encountered in lower orbits and during reentry.

The field often overlaps with the disciplines ofastrophysics,atmospheric science,space physics,andgeophysics,albeit usually with an emphasis on application.

The United States government maintains aSpace Weather Prediction CenteratBoulder, Colorado.The Space Weather Prediction Center (SWPC) is part of theNational Oceanic and Atmospheric Administration(NOAA). SWPC is one of theNational Weather Service's (NWS)National Centers for Environmental Prediction(NCEP).

Space environmentalism

See also:Space sustainability,Space debris,Planetary protection,andMoon § Pollution and contamination

Space environmentalism is an advocacy that sees space as not devoid of needing regulation and protection, and has gained attention by an increasing number of academics,such asMoriba Jah.

See also

• ECSSstandard E-ST-10-04C onSpace environment
• Graveyard orbit
• Karman line
• Outer space
• Outline of space science
• Space climate
• Spacecraft cemetery
• Space Environment Data System (SEDAT)
• Space Environment Information System(SPENVIS)
• Space weathering

External links

• Space Environment Technologies (SET)
• Space Weather Center (SWC)
• ESA Space Environment and Effects Analysis Section
• International Space Environment Service (ISES)