NOAA Instruments

The Total Energy Detector (TED)
The Total Energy Detector (TED) monitors the energy fluxes carried into the atmosphere by electrons and positive ions over the energy range between 50 and 20,000 eV. Particles of these energies are stopped by the atmosphere of the Earth at altitudes above 100 km, producing aurora. The instrument design utilizes cylindrical, curved-plate electrostatic analyzers to select (by impressing a variable voltage between the analyzer plates) the species and energy of those particles that are permitted to reach the detector.

The Medium Energy Proton and Electron Detector (MEPED)
In addition to the Total Energy Detector (TED) that provides the data used to determine auroral activity, the Medium Energy Proton and Electron Detector (MEPED) monitors the intensities of charged particle radiation at higher energies extending up to cosmic rays.

The Electron Telescope
The electron telescope is a 25 mm2 silicon solid state detector positioned behind a series of metal apertures that define a 15° (half-angle) cone where charged particles from space may reach the detector. Two identical electron telescopes are included. One, termed the 0° electron detector, is mounted on the 3-axis stabilized NOAA spacecraft to view outward along the Earth-center-to-satellite vector. The second electron telescope, called the 90° detector, is mounted to view in a direction approximately perpendicular to the 0° detector. The pair of electron telescopes provide 3 integral channels of energetic electron data: >30 keV
>100 keV
>300 keV

The Proton Telescope
The proton telescope design is identical to the electron telescope, with two exceptions. The first is that a strong magnetic field is imposed across the aperture structure to prevent electrons from reaching the silicon solid-state detector. The second is that there is no nickel foil covering the detector, so very low energy protons are allowed to enter the detector. Electronic analysis of the pulses produced by the energy lost by protons in the solid state detector identify protons within six energy ranges:
30 - 80 keV
80 - 250 keV
250 - 800 keV
800 - 2500 keV
2500 - 6900 keV
>6900 keV.


The Omnidirectional Proton Detectors.
In order to monitor the intensities of still higher energy protons that arrive at the Earth because of solar energetic particle events, four additional silicon solid state detectors are included. Each of these four detectors contains a 50 mm2 area by 3 mm thick solid state detector mounted beneath a near-hemispherical (120° full angle) shell- shaped metal absorber. The material and thickness of the absorber determines the minimum energy that a proton needs to reach the detector and be counted. On the NOAA satellites earlier than NOAA15 these detectors can also be used to detect relativistic electrons above 1.5 MeV.