Unprecedented: Voyager 2 Reaches Neptune’s Influence, Prompts Prediction Pool among JPL Science Teams

We eagerly anticipated the moment when Voyager 2 would reach the edge of Neptune’s influence in the solar wind. To make things more exciting, we organized a prediction pool among the science teams at the Jet Propulsion Laboratory. A chalkboard was used to record the entries, with predictions based on when the spacecraft would encounter the “bow shock” of Neptune’s magnetosphere in PDT-ERT (Pacific Daylight Time-Earth Received Time).

There were only five predictions to choose from, starting on Day of Year 235, which corresponds to August 23rd in non-leap years. The one-way light time from the spacecraft was 4 hours and 6 minutes, and the spacecraft event time (SCET) was typically given in Greenwich Mean Time (GMT). To convert from PDT-ERT to GMT-SCET, 7 hours needed to be added to get to GMT, followed by a subtraction of 4 hours and 6 minutes to adjust for the event occurring on the spacecraft earlier. This resulted in a 2-hour and 54-minute difference.

As for myself, my prediction was set for exactly at noon on DOY 236, which fell on August 24th at precisely 1454 GMT-SCET. To my surprise, just moments before my predicted time slot, the Plasma Science experiment detected a bow shock at around approximately 1438. While I was not exactly spot on with my prediction, I couldn’t help but feel proud of having been close!

What truly stood out about this whole ordeal was how meticulously documented this entire process had been. Not only did we have records of our predictions and calculations available for reviewing later on, but we also had photographs capturing this historic moment in history still intact today!