SCATHA

 1979-007A

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The Spacecraft Charging At High Altitudes (SCATHA) project, satellite P78-2, was launched into an elliptical synchronous orbit in Jan 1979. The spacecraft was built by Martin Marietta and operated by USAF Sunnyvale AFSCF.

SCATHA was spin-stabilized at 1 rpm. Initially SCATHA had its spin axis in the orbit plane, requiring frequent attitude maneuvers to keep the solar panels pointing at the Sun. When fuel ran low the spin axis was reoriented to ecliptic normal. This caused nutation of the satellite. AOCS propulsion was a hydrazine system with a 22N thruster and three 1N thrusters. The satellite had 10 kg of hydrazine at beginning of life; 5 kg was used in the nominal mission, 0.1 kg in th ecliptic-normal phase, and 1.5 kg in the termination phase.

Mission control was by TSC-1 (Test Support Complex 1) under Vehicles Operations-F at the CSTC (Consolidated Space Test Center) in Sunnyvale.

SCATHA
Date	Time	Event	Orbit
1979 Jan 30	2142	Launch by Delta 2914	Canaveral LC17
		T+3:48 MECO
		T+3:56 St 1 sep
		T+4:01 SES-1 4:54
		Fairing
	2150	T+8:55 SECO-1	189 x 869 x 28.6
	2204	T+22:35? St 2 sep
	2205	T+23:20? TES 43s
	2206	T+24:03? TECO	185 x 43903 x 27.4
	2206	Star 37 sep from P78-2
1979 Jan 31	0500?	Apo 1
	1800?	Apo 2
1979 Feb 1	0700?	Apo 3
1979 Feb 1	0853		781.23 180 x 43260 x 27.3
	2000?	Apo 4
1979 Feb 2	0900?	Apo 5
	2200?	Apo 6
1979 Feb 2	2144	AIM burn at 6th apo, 32s burn	1416.2 27543 x 43251 x 7.8
1979 Feb 2		AIM ejected
1979 Feb 5		final orbital burns
1979 Mar 1			1416.21 27580 x 43212 x 7.9
1979 Mar 9		E field antennae out
1982 Sep 22		Arcing events
1984 Aug 1			1417.10 27737 x 43090 x 4.3
1987 Jan 15		Reorienting to ecliptic normal
1987 Feb 4		end of reorientation burns
1987 May?		Transmitter 2 power decrease
1988 May 21			1415.65 28399 x 42371 x 5.8
1990 May 20		Transmitter 1 failed
1991 Jan 1		Orbit raise
1991 May 24		Final attitude maneuver
1991 May 28		end of ops
1991 Aug 6			1418.32 28327 x 42548 x 8.2
1993 Mar 24			1418.32 28114 x 42761 x 9.6