Launch Date February 4, 1961
Launch Site Baikonur Cosmodrome, Kazakhstan, Russia ​
Destination Venus
Type Impact
Status Unsuccessful
Nation USSR
Alternate Names Sputnik 4


Plunge into Venus' thick atmosphere and send back data for as long as possible.


Reached Earth orbit as planned, but the rocket that was to propel it to Venus did not fire. The probe re-entered Earth's atmosphere after 22 days in orbit.

This mission was the first attempt to send a spacecraft to Venus. Original intentions had been to send the 1V spacecraft to take pictures of the Venusian surface, but this proved to be far too ambitious a goal. Engineers instead downgraded the mission and used the 1VA spacecraft for a simple Venus atmospheric entry. The 1VA was essentially a modified 1M spacecraft used for Martian exploration.

The spacecraft contained a small globe containing various souvenirs and medals commemorating the mission. This flight was also the first occasion on which the Soviets used an intermediate Earth orbit to launch a spacecraft into interplanetary space.

Although the booster successfully placed the probe into Earth orbit, the fourth stage (the Blok L) never fired to send the spacecraft to Venus. A subsequent investigation showed that there had been a failure in the PT-200 DC transformer that ensured power supply to the Blok L guidance system. The system had evidently not been designed to work in a vacuum. The spacecraft + upper-stage stack reentered Earth's atmosphere on Feb. 26, 1961. The Soviets announced the total weight of the combination as 14,293 pounds (6,483 kilograms).


Launch Vehicle: 8K78 (no. L1-7)

Spacecraft Mass: 6,483 kilograms

Spacecraft Instruments:

  1. Magnetometer
  2. Variometer
  3. Charged-Particle Traps


Selected References

Siddiqi, Asif A. Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Monographs in Aerospace History No. 24. NASA, 2002.​

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