New horizons and the Pluto flyby: A flight control team's story

摘要

The New Horizons (NH) mission, part of NASA's New Frontiers Program, completed the first reconnaissance flyby of the Pluto system on July 14, 2015. NH successfully passed through the Pluto/Charon system taking hundreds of observations of never before seen worlds. To make this flyby successful, the Mission Operations Team carried numerous responsibilities. One part of the Mission Ops Team is the Flight Control Team, which handles real-time communications with the spacecraft. This paper will discuss the main Flight Controller tasks that were needed for success and how each was unique to the New Horizons mission. These include how the large Round Trip Light Time (RTLT), just under 9 hours at the time of the Pluto encounter, affected real-time operations. Other aspects affecting flight control included the separation of uplink and downlink tracks as the spacecraft began to perform more operations, spacecraft ranging, 2-Way to 3-Way mode transitions with the Deep Space Network (DSN), Critical Optical Navigation processing that team members needed to perform in a specific time window, and Solid State Recording (SSR) downlink maintenance. Also, many different unique DSN configurations needed to be tested and executed, including 2 TWTA dual-polarization downlink tracks, multiple antenna arraying tracks, and Radio science EXperiment (REX) uplinks. In the months leading up to closest approach, the number of shifts for the Flight Controllers (FCs) increased once the spacecraft left hibernation but shift times remained erratic per the DSN scheduling constraints with other missions. The team needed to make sure that people were given enough time to be rested and also that the correct information was being passed on to the next shift without a real-time handover. For the 9-day encounter sequence, we had near 24-hour antenna coverage. Outside of these 9 days, each shift consisted of a two-person crew. During the encounter period we used 3 people per shift on a staggered rotation- for smoother shift handovers and well rested controllers. The FC team also added two full-time interns that were trained before the encounter to help the team with schedule relief. The FCs used many tools to keep track of pertinent information, including an electronic console log, a command tracker spreadsheet for command verification after the 9 hour wait, and a status board for quick-glance information about the most recent contact with the spacecraft. The flyby was a success and the healthy spacecraft is now continuing through the Kuiper Belt. Amazing pictures are coming down now and will for many months to come, giving the scientists many years' worth of data for analysis.