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August 7, 2008 Vol. 1, Issue 7


On August 8, 1978, Pioneer Venus Multiprobe (also known as Pioneer Venus 2) was launched from Cape Canaveral.

The NASA Pioneer Missions were designed to explore the solar system. In 1978, both the Pioneer Venus Orbiter and Pioneer Venus Multiprobe were launched to learn more about the structure and composition of the atmosphere around Venus.

Pioneer Venus 2’s Multiprobe Bus carried four probes to measure the chemical composition, pressure, density and temperature of the Venus atmosphere.

The larger 1.5-meter diameter probe carried seven instruments to perform science experiments: a neutral mass spectrometer, a gas chromatograph, a solar flux radiometer, an infrared radiometer, a cloud particle size spectrometer, a nephelometer, and temperature, pressure, and acceleration sensors.

The three identical smaller probes, only 0.8 meters in diameter, each carried a nephelometer, temperature, pressure, and acceleration sensors, and a net flux radiometer.

The trip to Venus took 123 days. All probes entered the atmosphere on December 9, 1978. The parachute-equipped large probe entered near the equator of Venus. Its battery-powered instruments recorded information over the 1.5 hours before impact. The three smaller probes were each targeted at a different location: the northern hemisphere, the daylight side, and the night side. Without parachutes, they reached the surface within 75 minutes. Although none of the probes was designed to withstand impact, the small day-side probe did, transmitting temperature data from the surface of Venus for 67 minutes before its batteries expired.

The Pioneer Venus Bus itself also carried two instruments to examine the composition of the atmosphere. Without heat shield or parachute, the Bus only survived to about 11 km altitude before disintegrating. In doing so, it provided our only direct view of the upper atmosphere of Venus.

Read more about Pioneer Venus Multiprobe Mission.

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