Vega 1

 1984-125A

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The final probes in the 4MV series were the Venera-Galley (VeGa) probes, 5VK No. 901 and No. 902. Vega 1 (spacecraft 901) was launched on 1984 Dec 15 from Baikonur by Proton-K with an 11S824M fourth stage.

Vega-1
Date	Time	Event	Orbit
1984 Dec 15	0916:24	Launch by Proton	KB
	0925	Stage 3 MECO
	0929?	11S824M burn 1
	0931?	11S824M MECO1	181 x 217 x 51.6
	1030?	11S824M burn 2
	1034	Asc node
	1038?	11S824M MECO2	Solar orbit
	1038?	11S824M sep
	1950?	Pass EL1:4
1984 Dec 18		TCM-1
1984 Dec 20	1730?	Leave Earth sphere
1985 Jun?	TCM-2
1985 Jun 7	1900?	Enter Venus sphere
1985 Jun 11	0330?	Venus encounter, 39000 km
1985 Jun 14	0930?	Leave Venus sphere
1985?		TCM
1986 Mar 6	0720:06	Halley encounter, 8912 km at 0.7923AU from Sun
1987		Decommissioned

Payload:

• Vidicon camera

• Plasma wave analyser

• Dust counter

• Neutral mass spectrometer

• Plasmag ion/solar wind analyser

• Opt-UV spectrometer

• IKS IR spectrometer 2.5-12mu,7-14 mu

• Magnetometer

1984-125E

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The Vega-1 Spuskaemiy Apparat separated from Vega-1 on 1985 Jun 9 and entered on a -430 km periapsis trajectory. It landed on Venus on Jun 10, at +07 11 latitude, 177 48 longitude and 1.5 km below mean 6050 km radius. It transmitted for 21 minutes and surface conditions were 95 atm, 738 K. During descent, it deployed a balloon, the Aerostatniy Zond.

Vega-1 SA
Date	Time	Event	Orbit
1985 Jun 9		Sep from Vega-1
1985 Jun 11	0159:49	Entry, 10.75 km/s 18.23 deg 125 km
		93 km begin science data
	0200:27	Drogue para deploy 65 km 280 m/s
		Begin 64 min descent
	0200:38	E+1 min Heat shield upper half sep, 64 km 160 m/s
	0200:38	Balloon sep and parachute, (from upper half) 57 km 30m/s
	0200:38	Deploy main chute 64.5 km
	0200:42	Lower half shell sep 63 km, 100 m/s
	0209:37	Main chute release 47 km 20 m/s
	0232	18 km, valve failed, XRFS deploy
	0302:54	Landed on Venus
	0324	End of transmission, 21 min
1985 Jun 13	0100?	AZ failed

Payload:

• Aerostatniy Zond (deployed)

• Temp, pressure

• ISAV UV spectrometer

• VM-4 hygrometer, H20 concentration

• IPF aerosol analyser

• ISAV-A particle size spectrometer/nephelometer

• Sigma-3 gas phase chromatograph

• BDRP-AM25 XR spectrometer

• Malachit GCMS mass spectrometer

• Orage: electrical storms analyser 

• GS-15-SCV gamma ray spectrometer (surface)

• Sample scoop (surface)

• X-ray flourescence spectrometer (surface)

1984-125F

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The 3-m balloon was ejected from the Vega-1 Spusakaemiy Apparat during its descent at an altitude of 55 km. It operated in the Venusian atmosphere for 47 hours.

The AZ (Cruising Balloon) consists of the nacelle and a 3.4m diameter, 12 kg balloon made of Ftorlon fabric covered with varnish and inflated with helium, attached to the nacelle with a 12 m cable. The nacelle is 1.0m long, 0.13m dia and 7 kg mass, and the total AZ mass is 21 kg.

There is a toroidal container on the upper surface of the lander's upper aerodynamic stabilizer which contains the balloon wrapped around the central science cylinder. The toroid cover and balloon are ejected with the upper half reentry shell.

After travelling 9000 km, the balloon entered the Venus dayside, and solar heating caused the envelope to expand and burst.

Vega 1 AZ
Date	Time	Event	Orbit
1985 Jun 10		Sep from Vega-1 SA, alt 55 km
1985 Jun 12	0200:38	E+1 min Heat shield upper half sep, 64 km 160 m/s
	0201:00	Balloon sep 62 km
	0201:08	Balloon drogue parachute, 57 km 30m/s
	0203:38	Balloon main para
	0206:10	"Input" at 176.9 8.1N
	0206:38	Toroidal lower half sep
	0206:58	Fill balloon envelope 55 km 8m/s
	0210:48	Parachute and filling system sep 53 km, 5m/s
	0211?	Ballast release H=50 km
	0215?	Begin drift after 15 min, 54 km
1985 Jun 13	1220	Terminator passage 97.5E 8.1Nm after 8500 km range
1985 Jun 14	0038	End of transmissions at 68.8E 8.1N after 11600 km range

Payload:

• Temperature and pressure sensors

• Wind velocity sensor