Phobos 1

 1988-058A

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The Fobos missions were the first of the fourth generation planetary probes, using a bus derived from both the 4V planetary probe and the E-8 lunar probe. Work began on the project in 1976. The first Fobos spacecraft, 1F No. 101, was launched on 1988 Jul 7 aboard a Proton-K. The three-stage Proton placed Fobos and the specially modified 11S824F (Blok-D-1) fourth stage on a suborbital trajectory. The Blok-D-1 ignited to enter parking orbit, and then coasted until a second burn. The second burn left Fobos-1 in a highly eccentric orbit, and solar orbit insertion was completed using the Fobos spacecraft's own ADU propulsion unit.

On 28 Aug 1988 an error was made in a command to switch on the gamma ray spectrometer; the command actually sent instructed Fobos 1 to turn off its orientation and stabilization system. With the solar panels away from the Sun, the batteries ran down. On the next comms pass on Sep 2, nothing was heard from the probe, although loss of contact was not officially admitted until 1988 Nov 3.

Fobos-1
Date	Time	Event	Orbit
1988 Jul 7	1738:04	Launch by Proton-K	KB
	1747	Stage 3 MECO
	1747	Stage 3 sep
1988 Jul 7	1753:50	Blok-D-2 burn (T+15:46) 95s
	1755:25	Blok-D-2 cutoff (T+17:21)	88.13 169 x 197 x 51.5
	1810	Equator crossing southbound
	1841	Perigee of post-sep D-2 orbit
	1847?	SOZ units sep
	1847?	Blok-D-2 burn 530s?
	1854	SOZ eq crossing north
	1856?	MECO-2
	1900?	Blok-D-2 sep
		Blok D-2 venting	2628 x 130504 x 50.8
	1905?	ADU burn, solar orbit insertion
		Control to OKIK-16/Yevpatoria
1988 Jul 16		TCM-1 8.9m/s
1988 Aug 18		Control to TsNIIMash/Kaliningrad
1988 Aug 28		Command error
1988 Sep 1		failed to respond to commands
1989 Jan 23		Mars flyby

Payload:

• Terek Solar X-ray spectrometer

• SUFR Solar UV

• IPNM Neutron radiation study

• GRUNT Penetrating radar

• ADU Propulsion unit

• DPS Lander