Stephen Granade Pioneer Anomaly Engineering Colloquium

Goddard Space Flight Center, Greenbelt, Maryland 20771

ENGINEERING COLLOQUIUM

Monday, April 11, 2016 / 3:30 PM, Building 3 Auditorium

Stephen Granade

"The Pioneer Anomaly"

ABSTRACT -- As Pioneer 10 and 11 passed beyond Saturn and crossed Uranus's orbit, NASA navigators noticed something odd. The satellites weren't where they were supposed to be. They were slowing down more than could be explained by the Sun's gravitational pull. And that discrepancy built up over time, apparently never changing. Pioneer 10 and 11 were exhibiting an anomalous and unexplained deceleration.

When the "Pioneer Anomaly" was announced in a 1998 journal article, some scientists began proposing new theories of physics to explain it. The cause turned out to be much more mundane. But solving the Pioneer Anomaly involved many years of simulation, refinement, and a heroic effort to recover data from the 1970s and 1980s. Data were stashed in a Pioneer project engineer's garage, under staircases at JPL, and in one remarkable instance, rescued two weeks before they were to be thrown into dumpsters. We'll discuss gravity, spacecraft motion, data forensics, scientific modelling, and how hard it is to keep data around in a readable format.

SPEAKER -- Stephen Granade is a physicist specializing in lasers and robotic sensors. His sensors have read fingerprints from ten feet away, controlled robot helicopters, and guided the shuttle to Hubble. He’s the host of NASA's "No Small Steps" YouTube series and is the Science Track director at Dragon Con, a science fiction convention. His PhD in physics is from Duke University.

Engineering Colloquium home page: https://ecolloq.gsfc.nasa.gov