THE FIRST VENUS SPACECRAFT: 1961

Campaign objectives:

і’he first ever Venus campaign consisted of two spacecraft, each almost identical to the two lost in the failed Mars launches four months earlier. As had been the case for the Mars spacecraft, the Venus spacecraft w;ere also built in a great hurry. Although there was additional time, the schedule did not provide the iterative design process and extensive ground testing employed by later flight programs. Korolev’s engineers had to spend considerable time and effort debugging the systems. There were many disassemble, reassemble and test cycles to fix failed items, and after one fix another failure would occur. Once again the communications system was a major problem. Design issues emerged and workarounds had to be devised.

The IV Venus spacecraft had originally been intended to be a lander w ith camera, but by the time the Mars spacecraft were launched in October 1960 it had become clear that the lander w ould not be ready for the Venus launch window^ that opened in January, and the payload mass had to be significantly reduced to accommodate the instrumentation for the new launcher. The lander was abandoned and the mission

1VA No. l [Sputnik 7]

Venus Impaclor USSR /ОКВ-1 Molniya

February 4, 1961 at 01:18:04 UT (Baikonur) Failed to depart Earth orbit, fourth stage failure.

Venera 1 (1VA Ко.2)

Venus Impaclor USSR OKB-1 Molniya

February 12, 1961 at 00:34:37 UT (Baikonur) February 17, 1961 May 20, 1961

Failed in transit, communicalions lost.

descoped to a simple impactor. The goal was changed to undertaking science during the interplanetary cruise and in the environment of Venus prior to impact. Л small passive entry capsule was carried containing medallions. The 1VA redesign used as much of the 1M spacecraft as possible. Launched in February 1961, these were the second set of spacecraft to be launched to a planet, and the first to Venus, preceding the first US attempt at Venus by 18 months.

Only one 1VA spacecraft, Venera 1, was successfully launched on a trajectory to Venus. It was the first spacecraft ever successfully sent on a trajectory to another planet. Unfortunately it suffered from severe attitude control and thermal problems, and was lost after less than a week’s flight time.

The truncated flight of Venera 1 was offset by the triumph of the orbital flight by Yuri Gagarin on April 12, 1961. These achievements, together with the capability to launch heavy satellites and three successful Luna missions in 1959, established the USSR as pre-eminent in space flight in mid-1961. All that America could claim was eight lunar mission launch failures and one launch which, due to insufficient boost, resulted in a distant lunar flyby, all involving tiny spacecraft that had been created more as an afterthought to rocket development than as deliberate designs for space exploration.

Spacecraft:

The spacecraft were 2.035 meter long canisters. 1.05 meters in diameter, that were pressurized to 1.2 bar. They had 1 square meter solar arrays, medium-gain antennas on each panel, a boom omnidirectional antenna, and a dome-shaped propulsion unit on top. The sequencer, communications, attitude control, navigation, and propulsion systems w ere the same as the 1M spacecraft. The attitude control system had three modes of operations: a З-axis cruise mode for continuous solar pointing, a

Figure 7.4 Venera 1 spacecraft, front and back.

back-up system for spinning about the solar axis in the event of some failure in the primary system, and a З-axis Earth pointing system for communication using the 2.33 meter high-gain parabolic mesh antenna. Thermal control was by passive louvers activated by internal temperature. A key difference with the Mars spacecraft was the addition of an Earth sensor, instead of a radio beacon, for more precise orientation during a high gain telemetry session.

The spherical entry device was mounted inside the pressurized canister, and not separable. Having been encased with thermal shielding, it was expected to survive as the rest of the spacecraft burned up on atmospheric entry. It was to free-fall through the atmosphere and impact the surface. Although it was not designed to survive an impact with a solid surface, it was expected to be able to float if it happened to come down on an ocean.

At that time the Venus ephemeris was more poorly known than Mars, the errors being about 15 times its radius, so achieving an impact was not an easy task. Radar ranging of Venus wus obtained for the first time in early April, while the planet was at inferior conjunction, enabling the ephemeris error to be reduced to 500 km. It is possible that if Venera 1 was still functioning, the Soviets would have used this new data to program a trajectory correction maneuver a few weeks prior to its arrival at the planet in May.

Launch mass: 643.5 kg

Payload:

Main spacecraft:

1. Boom-mounted triaxial fluxgate magnetometer to search for a Venus magnetic field

2. Ton trap charged particle detectors to investigate the interplanetary medium

3. Micro meteoroid detector to investigate interplanetary spacecraft hazards

4. Cosmic ray detectors to measure radiation hazards in space

5. Infrared radiometer for Venus temperature

These instruments were identical to those on the 1M Mars spacecraft. It is also reported to have had a pair of parallel magnetometers to measure the interplanetary magnetic field.

Figure 7.5 1VA Venera 1 diagram (from Space Travel Encyclopedia): 1. Propulsion module; 2. Solar panels; 3. Magnetometer; 4. Thermal control shutters; 5. Thermal sensors; 6. High gain antenna; 7. Dipole emitters; 8. Medium gain antenna; 9. Ion trap; 10. Earth sensor; Ц, Sun and star sensor; 12. Boom omni antenna.

Figure 7.6 Medallions contained in the Venera 1 entry probe.

Entry probe:

1. Commemorative globe and medallion

The entry probe contained a 70 mm diameter metal globe with a commemorative medallion inside. The terrestrial oceans on the globe were blue-tinted and continents gold-tinted. It was designed to float. The medallion disk was inside the globe, which in turn was contained in a shell composed of pentagonal stainless steel elements on each of which was inscribed (in Russian) ‘Earth-Venus 196Г.

Mission description:

On February 4,1961, the new Molniya planetary rocket managed for the first time to deliver its fourth stage with attached spacecraft into a low ‘parking’ orbit. After 60 minutes of unpowered coast, the engine failed to rcignite, stranding the 1VA No. l spacecraft. The failure was caused by a power supply that used a transformer which not been designed to work in vacuum! The large orbital mass, 6,483 kg including the propulsive stage, prompted speculation in the West that it was a failed manned craft. The Soviets later said that they had been testing an orbiting platform from which an interplanetary probe could be launched. In fact, the ‘platform’ was no more than the new fourth stage of the launcher with the spacecraft attached. The Soviet description was doubtless highlighting the introduction of the parking orbit technique for deep space missions. It was designated Sputnik 7 in the US. On February 26 it re-entered the atmosphere over Siberia. Interestingly, the wreckage was discovered by a young boy and the heat-damaged pennant handed over to the KGB. The recovered articles were returned to the Academy of Sciences, which later sold them at auction in New York in 1996 to raise money for Russia’s impoverished science programs.

The powder supply problem in the first launch was traced to improperly mounting a transformer outside where it would be exposed to vacuum. A quick fix was rigged in time for the second launch by scaling the apparatus inside a vacuum-tight battery box.

On February 12. 1961. an Automatic Interplanetary Station’ that was later named Venera 1 was successfully boosted out of parking orbit. Communications sessions 2 hours and 9 hours after launch confirmed that the spacecraft was on a 96- day type I trajectory that would take it to the vieinity of Venus. Subsequent traeking indicated that a large midcourse correction would be required, but the target was in the cross-hairs! Analysis of the telemetry showed that operation in the Sun-pointing mode was unstable. The spaeeeraft automatically switched to the backup spin – stabilized mode in which most electrical systems except the sequencer and thermal control were shut down. This was a serious design error, since the command receiver was also turned off and denied the ground control of the spacecraft. In this safe mode, the spacecraft would re-activate the communication system every 5 days for a session with Earth. The high gain antenna could not be used because the spaeeeraft could not point at Earth. After an agonizing 5 days, the spacecraft contacted Earth on February 17 at a distance of 1.9 million km. The session was used to check the primary Sun-pointing operation, which failed again. On February 22 the spacecraft failed to respond, and no signal was received. The Soviets asked Jodrell Bank to listen for telemetry, and sent a team to England to assist, but nothing was heard. Attempts by Yevpatoria on March 4 and 5 also failed to receive any signal. Due to the inability to conduct a midcourse maneuver. Venera 1 flew silently past the planet at 100,000 km distance. In case it was silently continuing its mission, commands were sent on May 20. 1961. the day of the encounter, without result.

It was later determined that the altitude control system failure was due to the Sun sensor overheating. The thermal control design had only considered the average temperature for the instrument, and not the localized temperature at an unpressuri/ed sensitive clement. The lack of response after February 17 was attributed to a failure of the sequencer for the communications system. There was also evidence that the motorized thermal control shutters were not operating properly.

The flight of Venera 1 was followed worldwide as the first mission to another planet – another coup for the Soviet Union. But failure followed quickly. Radio Moscow announced the loss on March 2, noting that an investigation was underway and that sabotage was not excluded. The window closed on February 1 5, before the third 1VA could be launched.

Results:

None for Venus. Results were obtained from the Venera 1 instruments during its short cruise period. A faint interplanetary magnetic field on the order of 3.5 nT was reported and the solar wind plasma flow discovered by Luna 1 to 3 was found to be present beyond the Earth’s magnetopause in deep space. Venera 1 marked the first flight of a true interplanetary spacecraft with all the capabilities necessary for such a mission, including flexible attitude stabilization modes and midcourse maneuvering.