THE SECOND VENUS SPACECRAFT: 1964

Campaign objectives:

By the end of 1962, the Soviets had made five attempts at Venus. Only one mission. Venera 1, survived its launch vehicle and succeeded in reaching interplanetary space but the spacecraft failed early in transit. All six spacecraft in the second-generation 2MV Mars/Venus series, including the three Venus missions, fell victim to launch failures. Adding to the frustrations, the Americans had a successful flyby of Venus in 1962 with their Mariner 2. Undaunted, the Soviets improved the 2M V as the 3M V for the 1964 opportunities to Venus and Mars.

The initial flight tests of the new spacecraft were lost to launch vehicle failures, the first in November 1963 on a test to Mars distance and the second in February 1964 on a test to Venus distance. Despite of these losses, the Soviets proceeded with their 1964 program for Venus and Mars.

Spacecraft launched
First spacecraft:	3MV-1A No.4A
Mission Type:	Venus Spacecraft Test
Country; Builder:	USSR OKB-1
fjnmch Vehicle:	Molniya-M
Launch Date ‘: I ime:	February 19, 1964 at 05:47:40 UT (Baikonur)
Outcome:	Launch failure, third stage exploded.
Second spacecraft:	3MV-1 No.5 (Cosmos 27)
Mission Type:	Venus Atmosphere .’Surface Probe
Countryi Builder:	USSR OKB-1
Launch Vehicle:	Molniya-M
Launch Date! Time:	March 27, 1964 at 03:24:42 UT (Baikonur)
Outcome:	Failed to leave Harth orbit, fourth stage failure.
Third spacecraft:	Zond 1 (3MV-1 No.4)
Mission Type:	Venus Atmosphere; Surface Probe
Country і Builder:	USSR OKB-1
launch Vehicle:	Molniya-M
Launch Date: Time:	April 2, 1964 at 02:42:40 UT (Baikonur)
Mission End:	May 25, 1964
Encounter Date/Time:	July 19, 1964
Outcome:	Failed in transit, pressurization lost.

Launches to Venus were attempted on March 27 and April 2, straddling the ideal date. The first spacecraft was stranded in parking orbit but the second was deployed on a trajectory for Venus. Just as the launch vehicle was plagued by a troublesome fourth stage, the spacecraft had troublesome avionics systems. Immediately named Zond 1 when it became evident 3MV-1 No.4 would not be able to fulfill its mission at Venus, the spacecraft fell silent after less than 2 months in flight. Even if it had succeeded in deploying its entry probe, the decent capsule would not have survived to the surface, it was designed to survive only to 1TC and withstand pressures up to 5 bar. At the time there were two opposing theories for conditions on the surface of Venus. The high brightness temperatures measured by terrestrial radio telescopes, and confirmed by Mariner 2 during its flyby in 1962, could be interpreted either as a surface as hot as 400°C or as a hot ionosphere and cool surface. The easier design path was for the popular vision of a planet like Earth with a cool surface and maybe even an ocean. When the 1964 Venus launch window opened and Zond 1 set off, the controversy was not yet settled, although the weight of evidence was leaning to a hot surface. Radio observations of the planet from Earth later in 1964 would discredit the cool surface theory, but by then it was too late to redesign the Venus probes for the 1965 launches. The hot surface theory was firmly established after the flight of Venera 4 in 1967, which coincided with the highly successful Manner 5 llyby.

Spacecraft:

Currier spacecraft:

The 3MV Venus spacecraft were almost identical to their 3MV Mars counterparts, although the solar panels were less densely populated with solar cells. On the probe versions of the 2MV and 3MV, the entry vehicle was to be deployed just prior to the spacecraft entering the atmosphere and burning up. Instruments for interplanetary science and measurements in the near vicinity of the planet prior to destruction were carried on the main spacecraft. Communications from the probe would be direct to the Earth.

Figure 9,8 The 3MV-1 Venus probe spacecraft (courtesy Energiya Corp).

Launch mass: 800 kg (3MV-1A No.4A)

Launch mass: 948 kg (Cosmos 27 and Zond 1)

Entry system mass: 290 kg

Entry vehicle:

The 3MV entry probes were intended to obtain data during the descent through the atmosphere, survive impact, and return data from the surface. In the case of Venus the dense atmosphere that meant the probes would impact slowly enough to have a fair chance of surviving and operating for a short period of time on the surface. The 3MV probes were similar to the 2MV ones, being 90 cm in diameter and containing parachutes, batteries, sequencers, and two redundant 32 cm transmit­ters each with an antenna for direct communications to Earth, in addition to science instruments.

Figure 9.9 Zond 1.

Payload:

The payload for the test flight to Venus distance was probably similar to that of the lost test flight to Mars distance. The payloads for the missions to Venus launched on March 27 and April 2. 1964. were identical.

Zond l carrier spacecraft:

1. Radiation detector

2. Charged particle detector

3. Gas discharge and scintillation cosmic ray and gamma-ray detectors

4. Ion traps

5. Magnetometer

6. Micrometeoroid detector

7. Lyman-alpha atomic hydrogen detector

Zond 1 descent I landing capsule:

1. Temperature, pressure and density sensors

2. Atmospheric composition, acidity and electrical conductivity experiments

3. Gamma-ray surface composition detector and cosmic ray detector

4. Visible air glow photometer

5. Mercury level experiment

The atmospheric structure experiment consisted of two platinum wire resistance thermometers with ranges of -60 C to 460 C and 0 to 330 C, an aneroid barometer with a range of 0.13 to 6.9 bar. and a beta ray ionization chamber densitometer that was integrated with the thermometers and had a range of 0.0005 to 0.015 g/cc with a 5% error. The atmospheric composition, acidity and electrical experiments consisted of a set of gas analyzer cartridges wnth chemical and electrical tests for various gases including carbon dioxide, nitrogen, oxygen, and water vapor. The photometer was to search for airglow during the night landing. It was sensitive over the range 0.001 to 10,000 lux, and included the mercury level experiment to measure wave motion in a putative ocean. The anti-coincidence gas discharge and scintillation counter cosmic ray and gamma-ray detector was primarily to measure the surface composition of radioactive elements potassium, thorium and uranium from gamma-ray emissions on the surface, but it was also to be used during the interplanetary cruise to measure primary cosmic rays.

A micro-organism detector w as planned for the 3MV Venus and Mars landing capsules, but was never included in the payloads.

Mission description:

The first lest launch of this series failed when the third stage exploded. LOX leaking through a valve froze a fuel line which later broke. The loss of 3MV-1A No.4A so close to the imminent Venus launch window must have been disheartening, but the Soviets continued with preparations to launch the other two spacecraft.

The first attempt to launch the 3MV-1 No.5 spacecraft on March 1 was postponed owing to problems with the launcher during pre-launch tests. The second attempt on March 27 using the same vehicle failed when an electrical fault caused the fourth stage to lose attitude control and the engine did not restart for the escape burn. It was designated Cosmos 27 by the Soviets. This loss did have a very valuable result. For the first time a flight recorder had been added to the fourth stage telemetry system, and on its second pass the downlinked telemetry indicated a failure that was able to be traced to a generic problem in the I-100 control system circuitry. It required only 20 minutes of re-soldering to fix this for subsequent flights.

The third Venus spacecraft was dispatched successfully on April 2, 1964, but its initial trajectory was inaccurate and a midcourse maneuver was made the next day at a range of 564,000 km from Earth. It was the first midcourse maneuver carried out by a Soviet planetary spacecraft. Venera 1 and Mars 1 had both had this capability, but neither had been able to exercise it. However, Zond 1 w as in serious trouble. Л leak in the pressurized avionics section was detected right after launch due to a erack in the weld seam of the quartz dome for the Sun and star navigational sensors. The location of the leak w as determined from analysis of how’ the escaping gas perturbed the spacecraft. After a week, the transmitters and other electronics failed when they were switched on as the pressure fell to about 5 millibars, which permitted coronal discharges to short out power lines. The ion engines also failed their test, operating erratically. Owing to sensible backup design, communications w^ere able to continue using the entry system, and a second midcourse maneuver w7as made on May 14 at a distance of more than 13 million km from Earth. This resulted in a trajectory that would fly by the target at 100,000 km. In fact, the initial trajectory w’as probably so wide of the mark that even if the spacecraft had been fully functional, it would not have been able to adopt a collision course. Due to the pressure leak the Soviets did not reveal Venus as the target, merely announcing that the mission w7as a deep space engineering test, and named it Zond 1 rather than Venera 2. The leak was fatal, and on May 25 thermal control w? as lost and communications failed. The inert spacecraft passed Venus on July 19.

Results:

Zond 1 did return data on interplanetary plasma, including cosmic ray and Lyman – alpha measurements from the avionics module and proton measurements from the cosmic ray instrument in the lander capsule, but much of the data returned appears to have been lost.