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STS 99



STS 99 is an American shuttle spacecraft that was launched from Cape Canaveral at 17:43 UT. The main mission was to obtain a 3-D map of about 70% global terrain. It is a joint mapping mission by NASA and the National Imagery and Mapping Agency (NIMA), utilizing the Shuttle Radar Topography Mission (SRTM) radars. The 13,600 kg SRTM instrument consisted of a pair of transmit/receive antennas below the cargo bay, and a pair of receiving antennas at the end of a 60 m "rigid" tower. The operation was in interferometric synthetic aperture radar (IF-SAR) modes with steerable C-band (5.6 cm) and a non-steerable X-band (3.0 cm) transmissions of pulse widths 100 milliseconds, and power levels 10 kW. The accuracy of the mapping was modest: in any "terrain" segment, the relative height accuracy was 10 m and the relative horizontal accuracy was 20 m; on forests, the surface of reflection at both frequencies were the canopy tops, not the terrain. The tower was an assembly of stacked cubical frames made of steel, titanium and plastic, initially contained in a three meter can, pushed out by a motor and held in rigid shape by a thruster at the high end. It was erected at an angle of 450 from the vertical. The cargo bay antennas and the transmitters were the same that were used in the SIR-C/X-SAR radars that were flown on two shuttle missions in 1994. SRTM just had additional receiving antennas at the end of the mast to do interferometry.

It landed back in Cape Canaveral on 22 February at 23:22 UT after mapping 112 million square-kilometers of the Earth's land mass onto 300 digital tapes. Data reduction at analysis centers will take two or three years to complete. More information on SRTM is available at and the data will be distributed by the EROS Data Center,

Alternate Names

  • 26088
  • STS99

Facts in Brief

Launch Date: 2000-02-11
Launch Vehicle: Shuttle
Launch Site: Cape Canaveral, United States
Mass: 13600 kg

Funding Agency

  • Unknown (United States)


  • Earth Science

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

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