Venera 1

• 1. Introduction

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  On the 19th of May 1961, the Soviet probe Venera 1 swept past Venus, and nothing it carried was able to tell Earth. No spacecraft had ever traveled so far. Venera 1 was the first to complete an interplanetary flight and the first to fly past another planet. Yet it did so in silence. The name means Venus 1 in Russian. Records also list it as Venera-1VA No.2, and in the West it was occasionally called Sputnik 8. It belonged to the Soviet Venera programme, and it had been meant to strike Venus as an impactor rather than coast by. How did a probe get that far and then go quiet? The answers begin with a winter launch.

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• 2. Launch Day

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  Venera-1VA No.1, the sister ship of Venera 1, never left Earth orbit because a power transformer failed. Engineers had wrapped that transformer in foil and painted it black and white to manage heat. Venera 1 was the second of the two Venus attempts in February 1961.

  At 00:34:36 GMT on the 12th of February 1961, Soviet experts launched Venera-1 on a Molniya carrier rocket from the Baikonur Cosmodrome. The vehicle, designated L1-6V, climbed downrange beneath a clear blue winter sky and reached orbit.

  The spacecraft and the rocket's Blok-L upper stage first settled into a low Earth orbit measuring 229 by 282 km. Then the upper stage fired again and pushed Venera 1 into a heliocentric orbit, meaning a path around the Sun, aimed at Venus.

  The 11D33 engine on that stage was the world's first staged-combustion-cycle rocket engine. It also marked the first time an ullage engine let a liquid-fuel rocket engine start in space. Once that burn finished, Venera 1 began its own life as a spacecraft rather than a payload.

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• 3. Anatomy of a Probe

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  Venera 1 weighed 643.5 kg and was built around a cylindrical body 1.05 m in diameter. A dome on top brought the total height to 2.035 m. The cylinder was pressurized to 1.2 atm with dry nitrogen, and internal fans spread the heat evenly. Motorized thermal shutters handled temperature control.

  Two solar panels extended from the cylinder and charged a bank of silver-zinc batteries. These panels also carried antennas, which brings the communications gear into view.

  A 2 m parabolic wire-mesh antenna was designed to send data from Venus to Earth on a frequency of 922.8 MHz. A 2.4 m boom carried a separate antenna for short-wave signals during the near-Earth phase. Semidirectional quadrupole antennas on the solar panels handled routine telemetry and commands on a circularly polarized decimetre radio band.

  Every one of those systems existed to serve a set of scientific instruments.

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• 4. Instruments Aboard

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  A flux-gate magnetometer was mounted on the antenna boom of Venera 1. This instrument measured magnetic fields along the route. Two ion traps sampled the solar wind, and micrometeorite detectors watched for tiny dust impacts.

  Geiger counter tubes and a sodium iodide scintillator measured cosmic radiation. One solar panel also held an experiment that tracked the temperatures of experimental coatings. Infrared and ultraviolet radiometers may have been included as well, though the record does not settle the question.

  Reading space well required keeping the sensors pointed correctly, and that demanded a way to steer.

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• 5. Steering by Stars

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  For most of its flight, Venera 1 stayed steady by spinning. It was also the first spacecraft designed to correct its course midway. To do that, it entered a mode of 3-axis stabilization, fixing on the Sun and the star Canopus. The KDU-414 engine inside the dome performed those mid-course corrections.

  A second 3-axis mode was reserved for Venus. Had the plan held, the probe would have fixed on the Sun and Earth. It would then have used a parabolic antenna for the first time to relay data.

  None of this orientation machinery would get its Venus test, because trouble with locking onto the Sun began during the very first telemetry session.

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• 6. Power Trouble

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  In that first telemetry session, Venera 1 failed to enter the constant solar orientation mode. The result was a shortage of electrical power on board. Controllers had planned for this case. The station was supposed to orient itself roughly toward the Sun and switch off its non-vital systems.

  The radio transmitters, however, had not been adequately designed for that situation. Communication was lost soon afterward.

  On the 17th of February, the signal came back. The probe still could not lock onto the Sun properly, so it again entered protective mode and shut off its transmitter. Even so, the probe was about to return its most lasting results.

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• 7. What It Measured

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  On the 19th of February 1961, Venera 1 reached a distance of 1,900,000 km from Earth and completed the last of three successful telemetry sessions. The first two had gathered solar-wind and cosmic-ray data near Earth and at the Earth's magnetopause. The third gathered the same kind of data far out in space.

  Luna 2 had already discovered the solar wind. Venera 1 supplied the first verification that this plasma is present uniformly in deep space.

  A week later, the next scheduled telemetry session did not take place.

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• 8. Silent Flyby

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  Venera 1 passed within 100,000 km of Venus without a word. Its only data came from interplanetary space, and none came from the planet itself.

  In June, the British radio telescope at Jodrell Bank may have picked up some weak signals from the probe. The record treats this detection as possible rather than certain.

  Soviet engineers believed that Venera 1 failed because a solar-direction sensor overheated, a small part behind a long silence.

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