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Explorer: TERRIERS (STEDI 2)


TERRIERS (Topographic Experiment using Radiative Recombinative Ionospheric EUV and Radio Sources) was a mission to study the ionosphere.

  • Gas Ionization Solar Spectral MOnitor (GISSMO) is an optics-free solar EUV spectrometer. It is designed to monitor solar EUV emissions in the wavelength range from 7 to 40 nm.
  • TESS is a Single element imaging spectrograph (SEIS) designed for both high wavelength and high spatial resolution (in one dimension).
  • Photometers: These instruments measure visible light produced by chemical reactions in the upper atmosphere
  • Radio Beacon: Several different ground based facilities support the TERRIERS mission by providing coordinated observations and by monitoring the TERRIERS satellite beacon during radio tomography experiments

After the first 3 contacts it was clear that the spacecraft's attitude control system was not functioning properly, since the solar array was pointing away from the sun and the system was nutating. Sometime shortly thereafter the spacecraft ran out of battery power. Further attempts to reactivate the spacecraft failed.

TERRIERS is one of three satellite projects selected for the Student Explorer Demonstration Initiative program (STEDI). STEDI is funded by NASA and managed by the Universities Space Research Association (USRA).

Nation: USA
Type / Application: Atmospheric Research
Operator: NASA
Contractors: AeroAstro
Equipment: GISSMO, TESS, Photometers, Radio Beacon
Configuration: HETE-Bus, spin stabilized
Propulsion: None
Power: Fixed solar array, batteries
Lifetime: 1 year (planned)
Mass: 125 kg
Orbit: 540 km × 553 km, 97.7
Satellite COSPAR Date LS Launch Vehicle Remarks
TERRIERS (STEDI 2, Explorer 76) 1999-026A 18.05.1999 Va, L-1011 Pegasus-XL HAPS with MUBLCOM