SDO's Extreme Ultraviolet Variability Experiment, or EVE, uses sounding rockets for calibration. During roughly 15-minute flights, these suborbital rockets carry a duplicate of the EVE instrument about 180 miles above Earth, where it records measurements to keep its twin instrument aboard SDO in tune. Tom Woods, a solar physicist at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, is the principal investigator of the EVE instrument.
The 30-minute launch window for the next EVE calibration flight opens at 11:25 a.m. MT on Sept. 9, 2021, at the White Sands Missile Range in New Mexico.
EVE is a space instrument that measures the sun's extreme ultraviolet light and the namesake for the EVE sounding rocket mission. The sun's activity causes huge variations in outputs of this powerful radiation, which is invisible to our eyes and is absorbed by Earth's atmosphere before it reaches the ground.
Solar flares, for example, unleash massive amounts of extreme ultraviolet light. EVE makes it possible for researchers to keep tabs on the sun in almost real-time. It takes less than a second for SDO data to reach Earth and another 15 minutes for the data to be processed into a usable form.
The EVE payload is loaded onto a cart for transport at the White Sands Missile Range. Credit: NASA
The images show the sun as seen by another SDO instrument, AIA, in 304 Angstrom light in 2021 before degradation correction (left) and with corrections from a sounding rocket calibration (right). Credit: NASA/SDO