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Venera 4

Launched on June 12^th, 1967, Venera 4 was the first Russian probe to reach Venus still working. The previous 3 probes failed prior to arrival. Venera 4 had 2 sections:

Main Bus

The main bus, weighing 723kg, was to fly right at Venus and scan it's atmosphere, magnetic field, hydrogen halo and the solar wind using the following instruments:

• Triaxial Fluxgate Magnetometer
• 4 Ion Traps
• STS-5 Gas-Discharge Counter
• 2 Silicon Solid-State Radiation Detectors
• Windowed SBT-9 Gas-Discharge Counter
• Lyman-α Atomic Hydrogen & Oxygen Spectrometers

After it hit the atmosphere, October 18^th, 1967, the bus was to drop the capsule and disintegrate. All went according to plan and the probe discovered that Venus has a weak magnetic field (3000x < Earth), no radiation field and a weak hydrogen corona (1000x < Earth).

Capsule

The capsule weighing 383kg was dropped into the atmosphere upon arrival and measured the atmosphere with these instruments:

• Altimeter
• Thermal Control (to keep capsule at -8°C)
• Parachute
• Thermometer
• Barometer
• Hydrometer
• Set of gas analysis instruments.

The parachute deployed at 52km above the surface where it read a little less than 1 atmosphere and 33°C. The transmissions stopped at about 26km above the surface where it read 22 atmospheres and 262°C. The probe found that the atmosphere contained almost no Hydrogen or Oxygen (0.4-0.8%), very little Nitrogen (7%) and mostly Carbon Dioxide (90-93%). The altimeter malfunctioned reading the capsule 26km lower than it actually was.

The capsule also included durable penants on the spacecraft (above right). It was kind of like putting a flag on Venus.