The Space Environmental Monitor (SEM-2) provides information on solar activity and space weather which may affect the satellites and instruments.

SEM image

It is important to have information on solar terrestrial phenomena and solar wind occurrences which may impair long-range communication; high-altitude operations; cause damage to satellite circuits and solar panels, or cause changes in drag and magnetic torque on satellites.

What is SEM-2?

The SEM-2 instrument is one of the non-meteorological instruments on Metop. It has been added to the set of American instruments in order to guarantee NASA/NOAA a continuity in the determination of auroral activity — intensities of charged particle radiation within the Earth's atmosphere that can degrade radio communications (occasionally making short wave radio communication impossible in the polar regions); occasionally disrupt the proper operation of satellite systems; increase the radiation dose to astronauts in space (when intensities are high).

The Space Environment Center (SEC) processes the particle counts received from Metop and monitors solar activity and the state of the Earth's near space environment. Warnings are issued to advisories and forecasts of conditions are relayed to customers whose systems are affected.

SEM Summary Budget

  • Mass — TED: 4.7kg, MEPED: 8.7kg, DPU: 4.6kg
  • Dimensions — TED: 184mm x 314mm x 193mm, MEPED: 282mm x 252mm x 138mm, DPU: 287mm x 267mm x 79mm
  • Data rate — 160 bps

EM-2 is provided by NOAA and developed by Assurance Technology Corporation (ATC) under contract to NASA.

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