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The ITOS (Improved TIROS Operational Satellite) series (TIROS-M was the prototype spacecraft) were the second generation of operational sun-synchronous meteorological spacecraft. Operational satellites were renamed NOAA.

The primary objective of ITOS was to provide improved operational infrared and visual observations of earth cloud cover for use in weather analysis and forecasting. Secondary objectives included providing both solar proton and global heat balance data on a regular daily basis. To accomplish these tasks, the spacecraft carried:

  • two television cameras for Automatic Picture Transmission (APT) and
  • two Advanced Vidicon Camera System (AVCS) cameras. It also carried
  • a low-resolution Flat Plate Radiometer (FPR),
  • a Solar Proton Monitor (SPM), and
  • two scanning radiometers that not only measured emitted infrared radiation, but also served as a backup system for the APT and AVCS cameras.

The nearly cubical spacecraft measured 1 by 1 by 1.2 m. The TV cameras and infrared sensors were mounted on the satellite baseplate with their optical axes directed verticially earthward. The satellite was equipped with three curved solar panels that were folded during launch and deployed after orbit was achieved. Each panel measured over 4.2 m in length when unfolded and was covered with 3420 solar cells, each measuring 2 by 2 cm. The ITOS dynamics and attitude control system maintained desired spacecraft orientation through gyroscopic principles incorporated into the satellite design. Earth orientation of the satellite body was maintained by taking advantage of the precession induced from a momentum flywheel so that the satellite body precession rate of one revolution per orbit provided the desired 'earth looking' attitude. Minor adjustments in attitude and orientation were made by means of magnetic coils and by varying the speed of the momentum flywheel.

Nation: USA
Type / Application: Meteorology
Operator: NOAA
Contractors: RCA Astro
Equipment: 2 APT, 2 AVCS, FPR, SPM, 2 Scanning Radiometer
Configuration: TIROS-M Bus
Propulsion: ?
Power: 3 deployable fixed solar arrays, batteries
Mass: 309 kg (#M); 309 kg (#A); 309 kg (#B)
Orbit: 1433 km 1482 km, 102.01 (#M); 1425 km 1474 km, 101.95 (#A)
Satellite COSPAR Date LS Launch Vehicle Remarks
TIROS M (ITOS 1) 1970-008A 23.01.1970 Va SLC-2W Delta-N6 with Australis
NOAA 1 (ITOS A) 1970-106A 11.12.1970 Va SLC-2W Delta-N6 with CEP 1
ITOS B 1971-091# 21.10.1971 Va SLC-2E P Delta-N6 Only fragments reached orbit
ITOS C - not launched Va ITOS E2

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