charging is caused by the hot plasma environment around the Earth. The plasma encountered in the region of the geostationary orbit becomes heated during geomagnetic substorms caused by disturbances in the solar wind. "Hot" electrons (with energies in the kilo-electron volt range) 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. 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 of astrophysics, atmospheric science, space physics, and geophysics, albeit usually with an emphasis on application. The United States government maintains a Space Weather Prediction Center at Boulder, Colorado. The Space Weather Prediction Center (SWPC) is part of the National Oceanic and Atmospheric Administration (NOAA). SWPC is one of the National Weather Service's (NWS) National Centers for Environmental Prediction (NCEP). Space weather effects on Earth can include ionospheric storms, temporary decreases in ozone densities, disruption to radio communication, to GPS signals and submarine positioning. Some scientists also theorize links between sunspot activity and ice ages. Space environmentalism 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 as Moriba Jah. See also Astronautics ECSS standard E-ST-10-04C on Space environment Karman line Outer space Space Environment Data System (SEDAT) Space Environment Information System (SPENVIS) Space climate Space science Space weather Space weathering Space Weather Prediction Center (SWPC) References External links Space Environment Technologies (SET) Space Weather Center (SWC) ESA Space Environment and Effects Analysis Section International Space Environment Service (ISES) Astronautics Aerospace engineering Space physics