Magnum 1

 1985-010B

---

The first MAGNUM satellite was launched from Space Shuttle Discovery on mission 51-C in 1985. This was the first highly classified payload aboard a Shuttle, and the mission was conducted with unprecedented secrecy for a piloted flight.

From the UN data it appears that the two-stage IUS-11 placed MAGNUM in a geostationary transfer orbit, leaving its own on-board propulsion to circularize the orbit. This contrasts with the TDRS and DSCS profiles in which the IUS second stage is used as the apogee motor, and suggests that MAGNUM is, as its name suggests, significantly heavier than these payloads. Some other sources indicate that SRM-2 did indeed make it to GEO, but the revelation that RHYOLITE used a liquid apogee motor and that MAGNUM was an enhanced follow-on suggest the possibility that MAGNUM had a similar motor.

Apparently the solid motor SRM-1 performance on IUS-11 was at about 15 m/s lower than planned. IUS first stage RCS thrusters were used to make up the shortfall.

Other sources suggest that the launch was a more conventional one with SRM-1 to GTO and SRM-2 to GEO, with no MAGNUM apogee motor; the data provided by the US to the UN would then be deliberately deceptive.

 

 

USA 8
Date	Time	Event	Orbit
1985 Jan 24	1950:00	Launch from LC39A
	1952:07	SRB sep
	1958:32	MECO
	1958:49	ET sep
	2035?	OMS-2	300 x 300 x 28.5
1985 Jan 25	0645	probable USA-8 deploy
	0656?	OMS-3 sep?	91.64 334 x 375 x 28.5
	0740	IUS burn, eq crossing N
		SRM-1 burn, T0 (deploy+55)
	0742	SRM-1 cutoff T0+2:26
	0743	IUS Stage 1 RCS, T0+3:10
		1826m/s burn to UN orbit 1
		Scenario 1 SRM-1 orbit	284.3 335 x 15553 x 28.4 (UN)
	0745?	Stage 1 sep
	0746?	SRM-2 burn in Scenario 1
	0830?	SRM-2 sep
		SRM-2 orbit	612.3 341 x 34670 x 28.4 (UN)
	1236?	LAE burn
		2410m/s burn to Scenario 2 orbit 1
		Scenario 2 SRM-1 orbit 340 x 35600 x 28.4 (guess)
	1235?	SRM-1 sep
	1240?	SRM-2 burn, T0+5 hr?, 1:43 burn
	1320?	SRM-2 sep
			1428.40 35513? x 35758? x 0?