Unknown Universe, The by Clark Stuart

Author:Clark, Stuart [Clark, Stuart]
Language: eng
Format: epub
ISBN: 9781781855737
Publisher: Head of Zeus

NASA launched Pioneer 10 and 11 on 2 March 1972 and 5 April 1973. They were the first robotic scouts sent to the outer Solar System, and relied on the fact that they were spinning to keep them stable, in the same way that a child’s spinning top stays upright when it is rotating. The spin meant that the mission scientists hardly ever needed to fire the spacecraft’s thrusters, and so for many months at a time, the Pioneers would be moving solely under the influence of the Solar System’s gravitational field.

After they encountered the giant planets Jupiter and Saturn, returning the first close-up images and data from these worlds, they sailed on into the inky depths. Unwilling simply to terminate communications with two perfectly good spacecraft, NASA cast around for ideas of what to do with them.

John Anderson at NASA’s Jet Propulsion Laboratory (JPL) and others came up with an objective. They would analyse the trajectory of the Pioneers in the hopes of finding a previously undiscovered planet in the outer Solar System. They reasoned that the gravity of such a planet would pull the little spacecraft off course by a minute but noticeable amount.

By the end of the decade, they had a signal. It was equivalent to a force 10 billion times weaker than Earth’s gravity and it showed up in both spacecraft. But instead of pointing into the dark reaches of the outer Solar System, where they expected an undiscovered planet would lurk, the force pointed back towards the inner Solar System. It was as if the Sun’s gravity were tugging both spacecraft a little bit harder than expected.

By the time NASA lost contact with Pioneer 10 in 2003, it was some 400,000 kilometres off course. To find out once and for all what lay at the base of this anomaly, in 2005 another JPL scientist, Slava Turyshev, decided to track down the telemetry data from the spacecraft. This had been generated by 114 on board sensors and would tell him the state of the spacecraft and its instruments. He would correlate it with the tracking data to see exactly how and when the Pioneers had gone off course. The original analysis couldn’t determine whether it was changing with time or distance, whether it was always there or ramped up.

What Turyshev did, with a team of volunteers and some second-hand equipment that could read the decades-old data tapes, was virtually refly the mission inside a modern computer. This was no easy task. At the end of seven years’ worth of effort to do this, Turyshev made his announcement. Disappointingly for those seeking new physics, it was all a red herring.

The Pioneers had been powered by small radioactive samples of plutonium. The virtual refly showed that the anomaly correlated with the stray heat generated by the isotope that escaped into space. Tucked behind the main antenna dish, which was always pointed back towards the inner Solar System, the pressure of the escaping infrared radiation hit the underside of

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