4 December 1978 - The Pioneer Venus Orbiter Enters Venus Orbit

Atlas Centaur with Pioneer Venus Orbiter
Image credit: NASA

On 4 December 1978, the Pioneer Venus Orbiter entered Venus Orbit.

In 1975, two Venus landers Venera 9 and 10 had already transmitted images from the surface of Venus.

So the goal of the Pioneer Venus Orbiter, also known as  Pioneer Venus 1 or Pioneer 12, was to characterise the atmosphere and surface of Venus.

It launched in May 1978 on top of a Atlas-Centaur rocket from the Launch Complex 36A at the Cape Canaveral, Florida.

Here is an artist impression of what that would have looked like:

Pioneer Venus Orbiter

Onboard Experiments

The Pioneer Venus Orbiter carried 17 experiments with a total mass of 45 kilograms. A list from Wikipedia:

  • a cloud photo-polarimeter (OCPP) to measure the vertical distribution of the clouds.
  • a surface radar mapper (ORAD) to determine topography and surface characteristics.
  • an infrared radiometer (OIR) to measure IR emissions from Venus' atmosphere
  • an airglow ultraviolet spectrometer (OUVS) to measure scattered and emitted UV light
  • a neutral mass spectrometer (ONMS) to determine the composition of the upper atmosphere
  • a solar wind plasma analyzer (OPA) to measure properties of the solar wind
  • a magnetometer (OMAG) to characterize the magnetic field at Venus
  • an electric field detector (OEFD) to study the solar wind and its interactions
  • an electron temperature (OETP) to study the thermal properties of the ionosphere
  • an ion mass spectrometer (OIMS) to characterize the ionospheric ion population
  • a charged particle retarding potential analyzer (ORPA) to study ionospheric particles
  • two radio science experiments to determine the gravity field of Venus
  • a radio occultation experiment to characterize the atmosphere
  • an atmospheric drag experiment to study the upper atmosphere
  • a radio science atmospheric and solar wind turbulence experiment
  • a gamma ray burst (OGBD) detector to record gamma ray burst events

As part of the experiments, it was able to produce a map a Venus like the one below:

Venus project orbiter surface map with labels

Here is an image of Venus that the Pioneer Venus Orbit captured in ultraviolet light: 

Venus clouds seen by Pioneer Venus Orbiter

The Pioneer Venus Orbiter was operational and continued to send data back to Earth till October 1992, when it ran out of fuel. It's orbit than degraded and it was destroyed as it entered the atmosphere.

The Pioneer Venus Orbiter  together with the Pioneer Venus Multiprobe were part of the Pioneer Venus project.

Cool fact: In February 1986, the Pioneer Venus Orbiter was able to observe Halley's Comet when it was unobservable from Earth because it was too close to the Sun.

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