NIST assists in solar stake-out to improve space weather forecastsJuly 11, 2008The sun is about to undergo unremitting scrutiny. About six times each minute of every hour for at least five years, a soon-to-be launched NASA satellite will measure the sun's quirky-and sometimes stormy-output of extreme ultraviolet (EUV) light. To ensure that this solar stake-out yields data useful for understanding the weather in space and its earthly consequences, researchers at the National Institute of Standards and Technology (NIST) are helping a NASA team prepare for annual rocket-borne check-ups of key instruments aboard the Solar Dynamics Observatory (SDO). From one multi-year solar cycle to the next, the amount of ultraviolet radiation generated by the sun can change as much as tenfold. On shorter time scales-during, for example, a violent solar flare-ultraviolet output can jump by a factor of 1,000 in a matter of minutes. EUV light is highly energetic. It is absorbed by the Earth's upper atmosphere, ionizing gases and creating electric currents that form the inner edge of the Earth's magnetosphere. Changes in the sun's magnetic field driven by the solar wind in turn affect the Earth's atmospheric electric currents and magnetic fields, and can cause such disruptive effects as wreaking havoc with the Nation's electric power grid. In addition, the ionization of atmosphere gases by EUV and X-ray irradiation disrupts the high-frequency radio communication and decreases the accuracy of GPS systems. Related phenomena can change the density of the upper atmosphere, increase the drag on satellites in low-Earth orbit, and knock them out of orbit. To better understand the origins and impacts of EUV phenomena, the SDO's three onboard experiments will make nearly continuous observations of changes in the sun's magnetic field, solar-flare and other activity on the surface and in the interior, and energy outputs. According to NASA, the experiment will produce enough data on solar EUV output to fill one compact disc every 36 seconds. Key to the success of the experiments is ensuring that the instruments stay calibrated and record accurate data. "Good calibrations are necessary for quality data and for ensuring consistency of data across space missions," explains NIST physicist Robert Vest. In October, a few months before the SDO's tentatively scheduled launch, the NASA team will perform a dry run of the rocket-science equivalent of telemedicine. A rocket will carry duplicates of instruments built for SDO's EUV Variability Experiment, or EVE. If only for a minute or two, the duplicate devices will take measure of the Sun's EUV emissions. Data gathered during the brief outing will enable NIST to complete its characterization of the EUV spectrophotometer, which detects EUV emissions at several specific wavelengths, including those associated with solar flares. Once a year, measurements made by rocket-borne spectrophotometers will be used to recheck accuracy of the counterpart instruments on the SDO as it orbits 22,000 miles (about 35,400 kilometers) above the Earth. From the comparison, the NASA team can determine whether values in the data beamed to scientists on Earth should be adjusted. Once recalibrated, the onboard instruments also will be used to check the measurement performance of two other spectrographs desigend to measure the brightness of radiation in portions of the EUV spectrum. The Space Weather Prediction Center will be a major user of SDO solar surveillance data. Jointly operated by the National Oceanic and Atmospheric Administration and the U.S. Air Force, the Boulder, Colo., center is the national and world warning center for disturbances that can affect people and equipment working in the space environment. EVE is led by principal investigator Tom Woods of the University of Colorado Laboratory for Atmospheric and Space Physics. The EUV spectrophotometers were designed and built at the Space Science Center at the University of Southern California. Calibrations of the spectrophotometers as well as other devices in the EVE instrument package were performed on high-accuracy beamlines at the NIST SURF III Synchrotron Ultraviolet Radiation Facility, which are partially supported by NASA. For more information on SDO and its three experiments, go to: http://sdo.gsfc.nasa.gov/. National Institute of Standards and Technology (NIST) |
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| Related Space Weather Current Events and Space Weather News Articles UI astronomers capture first-of-kind image at distant star Two University of Iowa researchers have made the first direct radio image of a stellar coronal loop at a star, other than the sun, thereby providing scientists with information that may lead to a better understanding of how such phenomena as space weather affect the Earth. Eclipses yield first images of elusive iron line in the solar corona Solar physicists attempting to unlock the mysteries of the solar corona have found another piece of the puzzle by observing the sun's outer atmosphere during eclipses. NRL sensor observes first light The Special Sensor Ultraviolet Limb Imager (SSULI) developed by NRL's Spacecraft Engineering Department and Space Science Division, launched October 18, 2009 on the U.S. Air Force Defense Meteorological Satellite Program (DMSP) F18 (flight 18) satellite, observed first light on December 1, 2009. A Lightning Strike in Africa Helps Take the Pulse of the Sun Sunspots, which rotate around the sun's surface, tell us a great deal about our own planet. Scientists rely on them, for instance, to measure the sun's rotation or to prepare long-range forecasts of the Earth's health. NRL sensor provides critical space weather observations Launched from Vandenberg Air Force Base, Calif., aboard an United Launch Alliance Atlas V launch vehicle, Oct. 18, 2009, the Special Sensor Ultraviolet Limb Imager (SSULI) developed by NRL's Space Science Division and Spacecraft Engineering Department offers a first of its kind technique for remote sensing of the ionosphere and thermosphere from space. A special issue on the International Workshop of the 2008 Solar Total Eclipse On August 1, 2008 a total solar eclipse was visible within a narrow corridor that traversed from North America to China. Final look at ESA's SMOS and Proba-2 satellites As preparations for the launch of SMOS and Proba-2 continue on schedule, the engineers and technicians at the Russian launch site say goodbye as both satellites are encapsulated within the half-shells of the Rockot fairing. Scientists make first discovery using revolutionary long wavelength demonstrator array Scientists from NRL's Space Science and Remote Sensing Divisions, in collaboration with researchers from the University of New Mexico (UNM) and the National Radio Astronomy Observatory (NRAO) located in Socorro, N.M., have generated the first scientific results from the Long Wavelength Demonstrator Array (LWDA). NRL's ANDE-2 Launches Aboard STS-127 The Naval Research Laboratory's satellite suite, the Atmospheric Neutral Density Experiment 2 (ANDE-2), launched aboard NASA's Space Shuttle Endeavour on July 15, 2009. Scientists create first comprehensive computer model of sunspots In a breakthrough that will help scientists unlock mysteries of the sun and its impacts on Earth, scientists have created the first-ever comprehensive computer model of sunspots. More Space Weather Current Events and Space Weather News Articles |
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