2007 Isaac Asimov Memorial Debate: The Pioneer Anomaly

Program cover for the 2007 Asimov Debate on the Pioneer Anomaly.

The 2007 Asimov Memorial Debate considered the Pioneer Anomaly.

The Pioneer mission included the probes named Pioneer 10 and Pioneer 11. They were the first two probes to pass through the asteroid belt and Pioneer 10 was the first to visit Jupiter while Pioneer 11 was the first to visit Saturn. Ultimately, they escaped the solar system and will continue to drift into interstellar space.

However, as they grew more distant from Earth on their way out of the solar system, scientists noticed they were slowing down when compared to their predictive trajectories. This resulted in the probes being thousands of miles closer to Earth each year. This became known as the Pioneer Anomaly.

Our panel debated the possible theories for this discrepancy in their speeds and positions. What is this force dragging on the spacecraft's acceleration? Is it caused by some unforeseen aspect of the spacecraft's design? Does it reveal that we do not yet completely understand gravity?

Our experts included John D. Anderson, Ed Belbruno, Gary Kinsella, Irwin Shapiro, Slava Turyshev, and the debate was hosted and moderated by Neil deGrasse Tyson.