Kosmos 1900

 1987-101A

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Kosmos-1900 was the only US-A satellite to use a 95-rev (6 day) repeating orbit instead of the standard 111-rev (7 day) orbit. It was the first of a new series designed by KB Arsenal.

Kosmos-1900 lost stabilization in Apr 1988 and began a slow reentry, watched by the world and with extensive exchanges of assurances between the USSR and the UN. Just as it felt the outer fringes of the atmosphere on Sep 30, the new automatic backup system kicked in and fired the reactor to a higher orbit. The orbit achieved, however, was significantly lower than the standard reactor disposal orbit of the US-A series. The DU and radar decayed the next day.

Kosmos-1900
Date	Time	Event	Orbit
1987 Dec 12	0540:00	Launch by Tsiklon-2	KB
	0542	Stage 1 sep
	0544?	Stage 2 sep	-800? x 265 x 65
	0554?	DU burn
	0604?	Stage 2 reentry
1987 Dec 12			263x287x65.0
1988 Jan 30			89.78 257x270x65.0
1988 Feb 14			89.78 258x270x65.0
1988 Apr 12			89.77 257x270x65.0
1988 Apr 12-14?		end of stabilization
1988 Apr 20			89.74 255x268x65.0
1988 May 11			89.62 249x263x65.0
1988 Jun 14			89.45 239x256x65.0
1988 Sep 30.9			87.76 154x174x64.94
1988 Sep 30			87.76 154 x 174 x 64.9
1988 Sep 30	2048?	Reactor separated automatically	160? x 735?
	2133?	Burn 2
1988 Sep 30		Reactor	99.37 695 x 763 x 66.1
1988 Oct 1			87.71 153x170x64.95
1988 Oct 1	2129	DU orbit	86.78 108 x 120 x64.9 (TLE)