Pioneer Venus probes

Pioneer Venus involved two launches: an orbiter and a 'multiprobe bus' spacecraft to carry four entry probes, for release into the Venusian atmosphere prior to the destructive entry of the bus itself. To meet the objectives of both detailed measurements in the atmosphere and multiple measurements at different locations, one large probe and three smaller ones were flown, the Large Probe having seven times the payload capacity of each of the Small Probes (Day, North and Night). The bus also carried a small payload, returning mass spectrometer measurements down to 110 km altitude.

Target Venus

Objectives In situ measurements of the atmosphere and surface of Venus

Prime contractor NPO Lavochkin (formerly OKB-301)

Launch site, vehicle Baikonour, Molniya 8K78M

Venera 4

Cosmos 167

Venera 5

Venera 6

Venera 7

Cosmos 359

Venera 8

Cosmos 482

Launch date

12/06/1967

17/06/1967

05/01/1969

10/01/1969

17/08/1970

22/08/1970

27/03/1972

31/03/1972

Arrival date

18/10/1967

-

16/05/1969

17/05/1969

15/12/1970

-

22/07/1972

-

Landing site

Entry at 19° N,

Entry at 3° S,

Entry at 5° S,

10.70° S,

co-ordinates

38° E

-

18° E

23° E

5° S, 351° E

-

335.25° E

-

Mission durations

94 min TX,

53 min TX,

51 min TX,

35 min descent

55 min descent

- (still in

ended at

ended at

ended

+23 min on

+50 min on

Earth

25 km altitude

18 km

at 18 km

surface

surface

orbit!)

-

altitude

altitude

-

Entry mass (kg)

383

383

405

405

500

500

495

495

Payload experiments Venera 4: 1 m diam

• MDDA T, P, density sensors (Avduevskii, Marov, Rozdestvensky, Mikhnevich)

(TPV beta-ray densitometer & Pt resistance thermometers integrated in Mikhnevich's IS-164D unit)

• G-8 & G-10 chemical gas analysers (Florenskii (Surkov??))

• Doppler expt (Kerzhanovich)

• Radio altimeter using FMCW technique (? @ NU-17) The Project Scientist was Mikhail Ya. Marov

Venera 5, 6: Im diam

• MDDA & IS-164D T, P & VIP tuning-fork densitometer sensors (Avduevskiii, Marov, Rozdestvensky)

• Improved G-8 & G-10 chemical gas analysers (Florenskii (Surkov??))

• Doppler expt (Kerzhanovich)

• FO-69 Airglow photometer (Moroz)

• Radio altimeter using FMCW technique (? @ NU-17) The Project Scientist was Mikhail Ya. Marov

Venera 7: Im diam (egg-shaped)

• ITD T, P sensors (Avduevskii, Marov, Rozdestvensky)

• Doppler expt (Kerzhanovich)

• Possibly also beta particle densitometer (Mikhnevich), DOU-1M accelerometer (Avduevskii) and GS-4 gamma ray spectrometer (Vinogradov?, Surkov)

The Project Scientist was Mikhail Ya. Marov

Venera 8:1m diam (egg-shaped).

• DOU-1M Accelerometer (Avduevskii)

• IOV-72 photometers (Selivanov, Avduevsky?, Ekonomov?)

• Doppler expt (Kerzhanovich)

• Radar altimeter (Natalovich, Tseitlin @ RNII KP)

• IAV-72 Ammonia analyser (Surkov)

• GS-4 Gamma-ray spectrometer (Vinogradov?, Snrkov) The Project Scientist was Mikhail Ya. Marov

Delivery architecture Thermal aspects

Power aspects Communications architecture EDL architecture

Landing speed(s) Active operations

(deployments, etc.) Key references

Separation from flyby s/c 20 OOO^K) 000 km from Venus

Pre-cooling to —10 °C before probe separation; pressurized main compartment;

internal fan; lithium nitrate trihydrate (V-72 only) 28Ah Primary battery

One-way DTE at 920 MHz, data rate -1 bit s 1 using FSK

Entry angles 43-65° at ~ 11.2 km s 1. Spherical or egg-shaped aeroshell; pilot and main parachutes. Peak entry loads 400-500 g 16.5 m s-1 (Venera 7)

Deployment of radar altimeter antennas, communications antenna and surface communications antenna (Venera 8 only) Jastrow and Rasool, 1969; Hunten et al., 1983; Marov and Grinspoon, 1998

Figure 16.3

Figure 16.3

Figure 16.4 Venera 7.
Figure 16.5 Venera 8.

The Small Probes carried no parachutes and retained their entry heat shields down to the surface, and the parachute of the Large Probe was jettisoned at 45 km altitude. This was to ensure rapid descent of the probes in the most hostile, lower part of the atmosphere. A particular challenge for the probes was the design of the (gas-filled) pressure vessels and the necessary hull penetrations that could withstand differential thermal expansion of the components. Optical windows of diamond and sapphire were used. All four probes were successful in their operation, two of the Small Probes even surviving for a time on the surface (Figures 16.6 and 16.7).

Pioneer Venus Large Probe

Target Objectives

Prime contractor Launch site, vehicle Launch date Arrival date

Landing site co-ordinates End(s) of mission(s) Entry mass (kg) Payload experiments

Delivery architecture

Thermal aspects

Power aspects Communications architecture EDL architecture

Venus

Atmospheric structure, dynamics, cloud structure and optical properties Hughes

ETR 36A Atlas-Centaur (on probe bus)

08/08/1978

09/12/1978

At impact

316.5

• LAS (atmospheric structure) (Seiff)

• LCPS (cloud particle-size spectrometer) (Knollenberg)

• LNMS (neutral particle-mass spectrometer) (Hoffman)

• LSFR (solar-flux radiometer) (Tomasko)

• DLBI (differential long baseline interferometer) (Counselman)

• MPRO (atmospheric propagation) (Croft)

• MTUR (atmospheric turbulence) (Woo?) Totals: 35 kg, 106W.

The Project Scientist was Lawrence Colin.

Release on approach by 15 rpm spin-stabilised probe bus carrying large probe and small probes. Release by spring, 23 days from encounter 0.78 m diameter 3-piece Ti pressure vessel with internal MLI and Be shelves. Pressurization with N2 AgZn secondary battery 22 V, 40 A-hr One-way DTE: 40W, 2.3 GHz, 256 bit s-1 (128 bit s-1

during entry blackout). Receiver for two-way Doppler only Entry at -11.7km s-1, flight path angle -34°. 1.42m diameter, 45° blunt half-cone, carbon-phenolic

Ablative aeroshell released after deployment of pilot chute, back cover and main parachute (conical ribbon); main parachute then released at 45 km. Peak entry load 280 g. Landing speed(s) 9 m

Active operations EDL aspects only

(deployments, etc.)

Key references Brodsky, 1979; Pioneer Venus, 1980; Fimmel et al.,

1983, 1995; Hunten et al., 1983; Bienstock, 2004

Pioneer Venus Small Probes

Target Objectives Prime contractor Launch site, vehicle Launch date Arrival date

Landing site co-ordinates End(s) of mission(s) Entry mass (kg) Payload experiments

Venus

Atmospheric structure, dynamics, cloud structure and optical properties Hughes

ETR 36A, Atlas-Centaur (on probe bus)

08/08/1978

09/12/1978

Day Probe North Probe Night Probe

31.3° S, 317° E 59.3° N, 4.8° E 28.7° S, 56.7° E

67 min after impact at impact 2 s after impact

• SAS (atmospheric structure) (Seiff)

• DLBI (differential long base-line interferometer) (Counselman)

• MPRO (atmospheric propagation) (Croft)

• MTUR (atmospheric turbulence) (Woo) Totals: 5 kg, 10W.

The Project Scientist was Lawrence Colin

Delivery architecture Release and dispersion on approach by 48 rpm spin-stabilized probe bus carrying large probe and small probes, 19 days from encounter. Despin to 17 rpm by yo-yo mechanism 0.46 m diameter 2-piece Ti pressure vessel with internal MLI and Be shelves. Pressurization with Xe AgZn secondary battery 22 V, 11 A-hr One-way DTE: 10 W, 2.3 GHz, 64 bit s-1 during entry blackout and at high altitude; 16 bit s-1 below 30 km Entry at ~11.7km s-1, flight path angles from -23° to -71°. 0.76m diameter, 45° blunt half-cone, carbon-phenolic ablative aeroshell

Thermal aspects

Power aspects Communications architecture EDL architecture

Landing speed(s) Active operations

(deployments, etc.) Key references remained attached through out descent. Peak load 223-458 g 10m s 1

Yo-yo despin mass release; door mechanisms for instrument deployment

Brodsky, 1979; Pioneer Venus, 1980; Fimmel et al., 1983, 1995; Hunten et al, 1983; Bienstock, 2004

Pioneer Venus
Figure 16.6 Pioneer Venus Large Probe.
Figure 16.7 Pioneer Venus Small Probes.

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