August 5, 2016 – NASA’s Solar Dynamics Observatory (SDO), saw a lunar transit – when the moon passes between the spacecraft and the sun – on August 2, 2016, from 5:13 a.m. to 6:08 a.m. MDT. The spacecraft did not go back into science mode at the end of the transit.
In “science mode” the spacecraft uses AIA Guide Telescope signals for fine sun-pointing control. SDO instead went to an inertial mode (an attitude-control mode). SDO scientists and engineers are still receiving data from the spacecraft and assessing the problem.
As of late afternoon on August 4, two of SDO’s three science instruments – the Helioseismic and Magnetic Imager (HMI) and the Extreme Ultraviolet Variability Experiment (EVE) – were back online and sending science data to Earth.
The SDO team is working on getting its third science instrument – the Atmospheric Imaging Assembly (AIA) – back online.
SDO provides ultra high-definition imagery of the Sun in 13 different wavelengths, utilizing AIA and HMI. Each wavelength was chosen to highlight a particular part of the sun’s atmosphere, from the solar surface to the upper reaches of the sun’s corona. EVE uses different wavelengths to measure the amount of extreme ultraviolet (EUV) light coming from the Sun. These measurements will help scientists predict the amount of EUV coming towards Earth at any time based on the activity of the Sun’s magnetic field.
EVE was built at the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics (LASP). CU Professor Tom Woods is EVE’s principal investigator. The Helioseismic and Magnetic Imager (HMI) was built by Stanford University, and the Atmospheric Imaging Assembly (AIA) was built at Lockheed Martin’s Solar & Astrophysics Laboratory.
Goddard built, operates and manages the SDO spacecraft for NASA’s Science Mission Directorate in Washington, D.C. SDO is the first mission of NASA’s Living with a Star Program.