On the Saturday afternoon of July 4, 2015, NASA’s New Horizons Pluto mission leader Alan Stern was in his office near the project Mission Control Center, working, when his cell phone rang.
He was aware of the Independence Day holiday but was much more focused on the fact that the date was “Pluto flyby minus 10 days.” New Horizons, the spacecraft mission that had been the central focus of his career for 14 years, was now just 10 days from its targeted encounter with the most distant planet ever explored.
Immersed in work that afternoon, Alan was busy preparing for the flyby. He was used to operating on little sleep during this final approach phase of the mission, but that day he’d gotten up in the middle of the night and gone into their Mission Operations Center (MOC) for the upload of the crucial, massive set of computer instructions to guide the spacecraft through its upcoming close flyby. That “command load” represented nearly a decade of work, and that morning it had been sent by radio transmission hurtling at the speed of light to reach New Horizons, then on its approach to Pluto.