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Explorer: SME


The SME (Solar Mesosphere Explorer) mission objective was primarily to investigate the processes that create and destroy ozone in the Earth's mesosphere and upper stratosphere. Some specific goals were to:

  • determine the nature and magnitude of changes in mesospheric ozone densities resulting from changes in the solar ultraviolet flux;
  • determine the interrelationship between solar flux, ozone, and the temperature of the upper stratosphere and mesosphere;
  • determine the interrelationship between ozone and water vapor; and
  • determine the interrelationship between nitrogen dioxide and ozone.

The satellite experiment complement consisted of a solar ultraviolet spectrometer, an ultraviolet ozone spectrometer, an infrared radiometer, a 1.27-micrometer spectrometer, and a nitrogen dioxide spectrometer. In addition, a solar proton alarm detector was carried on-board to measure the integrated solar flux in the range 30-500 MeV.

Spin stabilized at 5 rpm, the satellite moved in a 3 a.m. to 3 p.m. sun-synchronous orbit. The spacecraft body was a cylinder approximately 1.7 m × 1.25 m and consisted of two major modules: the observatory module that housed the scientific instruments, and the spacecraft bus. The spin axis was oriented normal to the orbital plane. The command system was capable of executing commands in real time or from stored program control. Power was supplied by a solar cell array. The telemetry system was used either in a real-time or in a tape-recorder mode.

All instruments on-board the SME were turned off in December 1988 because of energy considerations.

Nation: USA
Type / Application: Research
Operator: NASA
Contractors: Ball Aerospace
Propulsion: ?
Power: Solar cells, batteries
Mass: 145 kg
Orbit: 481 km × 486 km, 97.69
Satellite COSPAR Date LS Launch Vehicle Remarks
SME (Explorer 64) 1981-100A 06.10.1981 Va SLC-2W Delta-2310 with UoSat 1


  • NSSDC Master Catalog: SME
Further Explorer missions: