As we eagerly awaited the arrival of Voyager 2 at Neptune’s boundary, we decided to add a touch of excitement to the occasion. To do this, we organized a prediction pool among the science teams at the Jet Propulsion Laboratory. We used a chalkboard to record the entries, with each prediction based on when the spacecraft would encounter Neptune’s magnetosphere’s “bow shock” in PDT-ERT (Pacific Daylight Time-Earth Received Time).
There were only five predictions available, ranging from 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, we added 7 hours to get GMT and then subtracted 4 hours and 6 minutes to account for the event occurring earlier on the spacecraft. This resulted in a difference of 2 hours and 54 minutes.
My prediction was set for noon on DOY 236, which is August 24th at 1454 GMT-SCET. Unfortunately, my guess was not entirely accurate as the Plasma Science experiment detected the bow shock on August 24th at around 1:08 PM GMT-SCET. However, what stood out most about this prediction pool was its documentation and how it brought us closer together as a team while we waited for this historic moment. Additionally, it was fascinating that a photo capturing this event still exists today.