Rapid changes in the ultraviolet radiation of the Sun can cause outages in radio
communications and affect satellites orbiting the Earth. Increases in solar
ultraviolet radiation from flares heat Earth's upper atmosphere, causing it to
expand. The expansion makes the air more dense at low-Earth-orbit altitudes, where many satellites fly. The dense air increases the drag on these satellites, slowing them down and causing them to prematurely burn up in the lower atmosphere if there is no more fuel onboard to give them a boost.
EVE will take measurements of the Sun's ultraviolet brightness as often as every 10 seconds, providing space weather forecasters with warnings of communications and navigation outages.
The Sun's extreme ultraviolet output constantly changes. The small solar flares that happen almost every day can double the output, while the large flares that happen about once a month can increase ultraviolet radiation many times in minutes. This harmful ultraviolet radiation is completely absorbed in the atmosphere, which means we can only observe it from satellites.
"The Laboratory for Atmospheric and Space Physics (LASP) is very excited about delivering the state-of-the-art EVE instrument to measure the solar extreme ultraviolet irradiance with best ever spectral resolution and time cadence," said
Tom Woods, SDO EVE Principal Investigator. "These future SDO EVE measurements are important for many different space weather applications such as how solar storms can degrade or even disrupt our navigation and communications."
After launch, SDO will study how solar activity is created and how space weather comes from that activity. SDO is designed to help us understand the Sun's influence on Earth and near-Earth space by studying the solar atmosphere on small scales of space and time and in many wavelengths simultaneously. SDO's other instruments include the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA). These instruments are expected to arrive at Goddard by the end
"These three instruments together will enable scientists to better understand
the causes of violent solar activity, and whether it's possible to make accurate
and reliable forecasts of space weather," said Liz Citrin, SDO Project
Manager at Goddard. "SDO will provide a full disk picture of the Sun in super
SDO is the first mission of NASA's "Living With a Star" program, which
seeks to understand the causes of solar variability and its impacts on Earth.
SDO is being designed, managed, and assembled at Goddard. HMI is being
built by Stanford University, Stanford, Calif. AIA is being built by the Lockheed
Martin Solar Astrophysics Laboratory (LMSAL), Palo Alto, Calif. EVE is
being built by the University of Colorado.
SDO is expected to launch no earlier than August 2008.
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