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ESSA-1 (or OT-3) was a spin-stabilized operational meteorological satellite. Its name was derived from that of its oversight agency, the Environmental Science Services Administration (ESSA).

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ESSA-1

ESSA 1
Mission type	Weather satellite
Operator	ESSA/NASA
COSPAR ID	1966-008A
SATCAT no.	1982
Spacecraft properties
Manufacturer	RCA Astro
Launch mass	304 kilograms (670 lb)[1]
Start of mission
Launch date	February 3, 1966, 07:41:23 (1966-02-03UTC07:41:23Z) UTC[2]
Rocket	Delta C
Launch site	Cape Canaveral LC-17A
End of mission
Disposal	Decommissioned
Deactivated	June 12, 1968 (1968-06-13)[3]
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Semi-major axis	7,115.60 kilometers (4,421.43 mi)
Eccentricity	0.0083082
Perigee altitude	685 kilometers (426 mi)
Apogee altitude	803 kilometers (499 mi)
Inclination	97.94 degrees
Period	99.56 minutes
Epoch	December 7, 2013, 20:11:52 UTC[4]
TOS ← TIROS-10 TIROS program ESSA-2 →

Launch

ESSA-1 was launched on February 3, 1966, at 07:41 UTC. It was launched atop a Delta rocket from Cape Canaveral, Florida. The spacecraft had a mass of 304 kilograms (670 lb) at the time of launch. ESSA-1 had an inclination of 97.91°, and an orbited the earth once every 100 minutes. Its perigee was 702 kilometers (379 nmi) and its apogee was 845 kilometers (456 nmi).

ESSA-1 had a similar design to that of the TIROS satellite series. It was an 18-sided right prism, measuring 107 centimeters (42 in) across opposite corners and 56 centimeters (22 in). It had a reinforced baseplate, which carried most of the subsystems and a cover assembly (hat). ESSA-1 had approximately 10,000 1-cm by 2-cm solar cells, which charged 21 nickel–cadmium batteries. ESSA-1 was designed to take pictures of daytime cloud cover, record them, and transmit them when it was in range of a ground acquisition station.

The satellite spin rate and attitude were determined primarily by a magnetic attitude spin coil (MASC). The MASC was a current-carrying coil mounted in the cover assembly. The magnetic field induced by the coil interacted with that of the Earth's magnetic field, and provided the necessary torque to maintain a desired spin rate of 9.225 revolutions per minute (rpm). Five small solid-fuel thrusters mounted on the baseplate provided a secondary means of controlling the spin rate.

ESSA-1 operated normally until October 6, 1966, when the camera system failed. The spacecraft was fully deactivated on May 8, 1967, after being left on for an additional period of time for engineering purposes.

References

 This article incorporates public domain material from the National Aeronautics and Space Administration document: "ESSA 1". Retrieved March 5, 2009.

External links

• "NASA - NSSDC - Spacecraft - Details - ESSA 1". NSSDC. May 14, 2012. Retrieved January 1, 2013.
• "Tiros OT-3 spacecraft handling plan" (PDF). NASA. October 1, 1965. Retrieved January 1, 2013.
• "Operational procedures for telemetry data processing for the TIROS 9 and OT-3 meteorological satellite system" (PDF). NASA. December 17, 1965. Retrieved January 1, 2013.
• "Instruction and operating handbook Tiros 9 and OT-3 meteorological satellite system" (PDF). NASA. December 27, 1965. Retrieved January 1, 2013.
• "Early orbit and attitude determination plan and prelaunch analysis for the satellite TIROS OT-3" (PDF). NASA. January 1, 1966. Retrieved January 1, 2013.
• "Tiros OT-3 spacecraft handling plan" (PDF). NASA. January 7, 1966. Retrieved January 1, 2013.
• "Alignment and calibration data for the TIROS OT-3 meteorological satellite" (PDF). NASA. January 17, 1966. Retrieved January 1, 2013.
• "ESSA 1 (TIROS OT-3) Meteorological Satallite System, Vol. I" (PDF). NASA. April 20, 1966. Retrieved January 1, 2013.
• L. J. Allison (May 1, 1972). "The development of hurricane Inez, 1966, as shown by satellite nighttime radiometric and daytime television coverage" (PDF). NASA. Retrieved January 1, 2013.

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