ESSA-1

ESSA-1

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

ESSA-1 (or OT-3) was a spin-stabilized operational meteorological satellite.

Launch

ESSA-1 was launched on 3 February 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 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 6 October 1966, when the camera system failed. The spacecraft was fully deactivated on 8 May 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 on 2009-03-05).