Pioneer Venus 2

 1978-078A

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The second Pioneer Venus probe, the Pioneer Venus Multiprobe or Pioneer Venus 2 was launched at 0733 on 1978 Aug 8 by Atlas Centaur from Cape Canaveral. The Centaur placed the PVM on a Type 1 trajectory to Venus. The initial trajectory would have led to a 14000 km altitude Venus flyby. Trajectory correction maneuvers were carried out on Aug 15, Oct 19, and Nov 9.

The large Sounder Probe was released at 0237:13 on Nov 16. At 1306:29 on Nov 20 the three small probes were separated. The Multiprobe Bus made a trim maneuver at 1137:12 on Dec 9, and at 2021:52 on Dec 9 began its entry at a -9.4 deg angle over -38.6 deg latitude, 291.8 deg longitude. At 2022:55 it burnt up at 110 km altitude, at -41.2 deg latitude, 284.1 deg longitude.

PVM
Date	Time	Event	Orbit
1978 Aug 8	0733	Launch by Atlas Centaur AC-51	CC LC36
		T+2:19 BECO
		T+2:22 Booster sep
		T+3:04 Insulation panels
		T+4:11 Atlas SECO
		T+4:13 Atlas sep
	0737	T+4:23 Centaur MES-1
	0742	T+9:42 Centaur MECO-1	165 x 170 x 28?
		18 min coast
	0800	T+27:30 Centaur MES-2 165 km Vrel 7.406 km/s
	0802	T+29:38 Centaur MECO-2 186 km Vrel 10.157 km/s
	0804	T+31:53 Centaur sep 361 km Vrel 10.851 km/s
	0805	T+32:02 Spinup to 15 rpm
		Control to PMOC
	1722	Pass EL1:4
1978 Aug 13	1650?	Leave Earth sphere (L1)
1978 Aug 15	1750	TCM-1 axial 2.2m/s
	1919	TCM-1 radial 1.3m/s
1978 Oct 19		TCM-2
1978 Nov 9	2215	TCM-3 radial
1978 Nov 10	0305 TCM-3 axial
1978 Nov 16	0237:13	SP sep
	1821	Axial delta-V, targeting
1978 Nov 20	1000	Axal trim delta-V
	1050	Radial trim delta-V
	1306:29	Small probes sep
1978 Nov 22	0319	Bus targeting delta-V axial
	0516	Turn to entry attitude
1978 Dec 7	1700?	LP Enter Venus sphere
	1700?	DP in sphere
	1710?	NoP in sphere
	1710?	NiP in sphere
1978 Dec 7	1825?	Bus Enter Venus sphere
1978 Dec 8?		BNMS cap ejected 0.31kg
1978 Dec 9	1137:12	Trim burn, axial dV
	1349	Attitude trim
1978 Dec 9	2021:52	Entry at -9.4 deg
	2022:55	Burn up at 110 km

Payload:

• BNMS Neutral mass spectrometer (Bonn/von Zahn)

• BIMS Ion mass spectrometer (GSFC/Taylor)

1978-078D

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The large Sounder Probe separated from the Multiprobe Bus at 0237:13 on 1978 Nov 16. Range to Venus was 11 Mkm. The coast timer timed out at 1824:26 on Dec 9, and telemetry switched on at 1829:27. Atmospheric entry at an angle of -32.4 (-31.1 older value) deg and an altitude of 200 km at 11.537 km/s began over 5.7 deg latitude, 306.0 deg longitude at 1845:32. Blackout was from 1845:53 to 1846:55. At 1846 the drogue chute pulled off the probe aft cover. The parachute was deployed at 1846:21 and jettisoned at 1903:28. At around 1847 the Deceleration Module (heatshield) was jettisoned and the Descent Module was on its own. After a 54 min 21s descent, the probe impacted and fell silent at 1939:53 on 1978 Dec 9. The impact site was 4.0 deg latitude, 304.0 deg longitude.

Sounder
Date	Time	Event	Orbit
1978 Nov 16	0237:13	Sep from PV2
		Coast timer
1978 Dec 9
	1829:27	Activated
	1845:32	Entry 200 km
		Mortar fire
		Pilot deploy
	1846:21?	Aft cover+pilot sep, para deploy at 67 km
	1847	Main deploy, aeroshell sep
	1847	LNMS breakoff cap sep 66 km
	1903:28	Para sep, 46 km, begin free fall
	1939:53	Impact

Payload:

• LNMS Neutral mass spectrometer (UTD/Hoffman)

• LGC Gas chromatograph (ARC/Oyama)

• LAS Comparative Atmospheric structure instrument (ARC/Seiff) Temperature, pressure, accelerometers

• LSFR Solar flux radiometer (Arizona/Tomasko)

• LIR IR radiometer (ARC/Boese)

• LCPS Cloud particle size spectrometer (PMSI/Knollenberg)

• LN Nephelometer (ARC/Paris/Ragent,Blamont)

1978-078E

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The North Probe (Small Probe 1) separated from the Multiprobe Bus at 1306:29 on 1978 Nov 20.

Landing was on Dec 9. The coast timer timed out at 1827:57 and telemetry began at 1832:55. Entry was at 1849:40 at 200 km altitude, 59.7 deg lat, 5.0 deg longitude. The entry angle was -68.7 (-69.5 according to older sources) deg at 11.537 km/s. Blackout was from 1849:58 to 1850:55. The North Probe impacted on the surface of Venus at 60.1 deg latitude, 4.4 deg longitude and signals ceased immediately afterwards.

NoP
Date	Time	Event	Orbit
1978 Nov 20	1306:29	Sep from Bus
1978 Dec 9	1832:55	Telemetry on
	1845:55	Despin weights release?
	1849:40	Entry at 200 km
	1849:58	LOS
	1850:55	AOS
	1942:40	Impact

1978-078F

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The Day probe (Small Probe 2) separated from the Multiprobe Bus at 1306:29 on 1978 Nov 20. The coast timer timed out at 1830 on Dec 9, and telemetry was switched on at 1835:27. The probe entered the Venusian atmosphere at an altitude of 200 km at 1852:18. The location of the entry was 320.8 deg longitude, -30.6 deg latitude and the entry angle was -25.3 deg at 11.537km/s. Blackout lasted for 66 s from 1852:40 to 1853:46. Descent time was 55:41 with imact at 1947:59 at location 318.4 longitude, -32.4 latitude. The probe survived impact and transmitted until 2055:34.

DP
Date	Time	Event	Orbit
1978 Nov 20	1306:29	Sep from Bus
1978 Dec 9	1835:27	Telemetry on
	1847:18	Despin weights release?
	1852:18	Entry at 200 km
	1852:40	LOS
	1853:46	AOS
	1947:59	Impact
	2055:34	End of data

1978-078G

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The Night Probe (Small Probe 3) separated from the Multiprobe Bus at 1306:29 on Nov 20. Range to Venus was 9.3 million km. Telemetry switched on at 1834:08 on 1978 Dec 9, and the 200 km altitude entry interface point was crossed at 1856:13, at -26.1 lat, 56.0 long. The entry angle was -41.5 deg at 11.537 km/s at 200 km. Blackout lasted from 1856:27 to 1857:48. and descent for 55m 52s. Entry orbit was -2220 x -32100 km x 68 deg. The Night Probe impacted on the surface of Venus at -27.4 lat, 56.7 long at 1952:05 on 1978 Dec 9. It stopped transmitting at most 2 seconds later, at 1952:07, but a later review suggested data ended at impact.

NP
Date	Time	Event	Orbit
1978 Nov 20	1306:29	Sep from Bus
1978 Dec 9	1834:08	Telemetry on
	1851:13	Despin weights release (48 rpm to 15 rpm)
	1856:13	Entry at 200 km
	1856:27	LOS
	1857:48	AOS
		Nephelometer window open
		ASI and NFR housing doors open
	1952:05	Impact