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Pioneer 10’s twisting path through space poses an overwhelming puzzle for physicists

Pioneer 10's twisting path through space poses an overwhelming puzzle for physicists

On March 2, 1972, on a balmy Thursday on Florida’s humid Cape Canaveral Peninsula, NASA’s 570-pound Atlas Centaur rocket named Pioneer 10 lifted off. Over the next 10 years, Pioneer sent back stunning reports from the far reaches of the solar system, carrying out its mission with great success.

Then, instead of becoming silent as expected, Pioneer continued sending signals back to Earth. Its tiny nuclear generator kept powering the 70 watts of power needed to maintain a radio link with the Jet Propulsion Laboratory in Pasadena, California, and this lasted for decades longer than anyone thought. Communications continued on a daily basis until January 23, 2003, more than thirty years after the mission began. By then, the probe was about twice as far from the Sun as Neptune and Pluto, and Pioneer became the first human-made object ever to leave the Sun’s gravitational grasp forever.

The Pioneer story would have been an important chapter in the history of science had it ended there, but it didn’t. Experimental physics is full of examples of science projects designed to study one phenomenon while revealing unexpected truths about something else entirely, and the really interesting part of the Pioneer 10 story is one such example. Although it carried out its robotic exploration of Jupiter and Saturn with skill and perseverance well above the call of duty (if one could apply such language to a robot), by the time it crossed the outer limits of the planetary system, it was clear to NASA that it was hundreds of thousands of miles away from where its computer tracking programs said it should be. How was that possible?

The way objects move in space, whether they are planets the size of Jupiter or a small craft like Pioneer, is governed by well-known laws of physics that give precise answers about location that can be measured in centimeters, even on the scale of the solar system. It simply could not have been that Pioneer was hundreds of thousands of miles off course. No matter how it was treated, the problem wouldn’t go away, and it soon became apparent that something really strange was going on. NASA scientists have given Pioneer an odd name; They called it “anomaly”.

“Leading Investigators: Did a Distant Spacecraft Prove Einstein and Newton Wrong?” A newly released “Kindle Single” by Konstantin Kakais, a talented journalist and writer who studied physics as an undergraduate at Harvard University, explores the tantalizing clues unearthed by scientists in their quest to explain the divergence of pioneers. The deeper they dig, the less they seem to understand. Immersed in the daily tracking records of the 30-year-old space probe, startling and perhaps revolutionary questions began to emerge: Was the spacecraft’s false trajectory evidence of some new and unknown wrinkle in the fundamental laws of physics?

A slightly off-course spacecraft might seem like an unlikely subject for deep speculation about the fundamental nature of the universe, but obvious solutions to the Pioneer flight aberration weren’t forthcoming. However, this was a matter of “black letter” physics, and errors of this kind and of such magnitude could not occur.

What could be the cause of the “anomaly”? NASA investigators didn’t seem to agree, though the list of possible culprits was long and intimidating: dark matter? Attraction of a scalar vector tensor? Collision with a graviton? Fundamental error in Einstein’s equations?

One thing that is clear about the questions posed by Pioneer and “The Anomaly” is that potential groundbreaking discoveries are in the offing for those brave and smart enough to successfully tackle them. This is the area that young scientists call “the new physics” – an unexamined land where sometimes the new Nobel prizes are also found.

Writing in clear, sharp prose devoid of technical language, science writer and former Mexico City bureau chief for The Economist Constantin Cacais gives us a science detective story, tracing the mental processes and groups of those committed to untangling this high-stakes scientific mystery. Kakaes draws on extensive interviews and archival research, following the story from “The Anomaly’s” initial discovery through decades of relentless research, to its final conclusion. Pioneering Investigators is a definitive and riveting account not only of the oddities of the pioneers but also of how scientific knowledge is made and dismantled, as scientists sometimes put their reputations and livelihoods on the line in pursuit of cosmic truths.

This was a great read that kept me up very late at night. Highly recommended.

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