The Extreme Ultraviolet and X-ray Irradiance Sensors detect solar soft X-ray irradiance and solar extreme ultraviolet spectral irradiance in the 5-127 nm range. The X-Ray Sensor (XRS) monitors solar flares that can disrupt communications and degrade navigational accuracy, affecting satellites, astronauts, high latitude airline passengers, and power grid performance. The Extreme Ultraviolet Sensor monitors solar variations that directly affect satellite drag/tracking and ionospheric changes, which impact communications and navigation operations. This information is critical to understanding the outer layers of the Earth’s atmosphere.
EXIS will reside on the Sun Pointing Platform mounted in the yoke of the solar array.
EXIS Subsystems include:
• Extreme Ultraviolet Sensor (EUVS)
• X-Ray Sensor (XRS)
• EUVS/XRS Electrical Box (EXEB)
• Sun Positioning Sensor (SPS)
X-Band Data Rate
L-Band Data Rate
76 x 30 x 37 cm
Active Control, 2 Zones
NOAA requires the realtime monitoring of the solar irradiance variability that controls the variability of the terrestrial upper atmosphere (ionosphere and thermosphere). This requirement supports NOAA’s space weather operations and is implemented with two instruments:
XRS monitors solar flares (and helps predict proton events) that can disrupt communications and degrade navigational accuracy.
• Measures the solar soft x-ray irradiance in two bandpasses at 0.05-0.4 nm and 0.1-0.8 nm
• Pre-GOES-R XRS: Ionization chamber instruments with limited dynamic range (solar min unresolved in noise and bright flares clipped)
• XRS for GOES-R: Solid state detectors that capture full dynamic range of solar variability
EUVS monitors solar variations that directly affect satellite drag/tracking and ionospheric changes, which impact communication and navigation operations.
• Through a combination of measurements and modeling, EUVS determines the solar EUV spectral irradiance in the 5 -127 nm range
• Pre-GOES-R EUVS: Transmission grating spectrographs covering five broad bandpasses
• EUVS for GOES-R: Three reflection grating spectrographs measuring specific solar emission lines from which fullspectrum is reconstructed with a model