Pioneer 10’s tryst with Jupiter

For a breakthrough mission that achieved a series of firsts, the primary objective of Pioneer 10 was to fly by Jupiter. On December 4, 1973, Pioneer 10 achieved its closest approach to Jupiter. A.S.Ganesh takes a look at Pioneer 10’s encounter with the largest planet of our solar system…

The space race between the U.S. and the Soviet Union made immense progress possible in the field. Reaching our moon first drove most of the competition, won eventually by the U.S. when astronauts of the Apollo 11 mission set foot on the moon.

Once that had been achieved, human beings dared to look further to the outer planets and even beyond. Pioneer 10 was the first NASA mission to the outer planets and its primary objective was to fly by Jupiter, the largest planet in the solar system.

Launched 50 years ago on March 2, 1972, Pioneer 10 had notched up a number of firsts even before its encounter with Jupiter. As the first spacecraft to use all-nuclear electrical power, Pioneer 10 carried four plutonium generators. The first spacecraft to be placed on a trajectory to escape into interstellar space, Pioneer 10 became the first spacecraft to fly beyond Mars and the first to fly through the main asteroid belt on its way to Jupiter.

Pioneer 10’s tryst with Jupiter began in November 1973, a little over one-and-a-half years from its launch. Even at a distance of 11 million km, the spacecraft began detecting intense radiation and it was revealed that Jupiter’s magnetosphere, much more stronger than that of Earth’s, extended 6.9 million km towards the sun.

The Great Red Spot, a storm on Jupiter that is wider than the Earth, came into Pioneer 10’s view as the spacecraft drew closer to the planet. Data from Pioneer 10 published in April 1974 suggested that the centuries old anticyclonic storm was likely a towering mass of clouds.

Pioneer 10 made its closest approach with the biggest planet in our solar system on December 4, 1973. Moving at a speed of 1,26,000 km/hour, the spacecraft whizzed by the giant planet at a distance of about 1,31,000 km.

The spacecraft, however, just managed to survive. Having absorbed radiation that is over a thousand times the lethal dose for a human, some of its transistor circuits were fried, optics were darkened, and there were other unwanted side effects too.