New Horizons Phones Home
One by one, to escalating waves of fist-pumping and relief, the chain of indicators that New Horizons was healthy and successful in its exploration reverberated through the Mission Operations Center at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland on Tuesday evening, and on out to audiences on campus and around the world.
"Lock with carrier," reported Alice Bowman, Mission Operations Manager. The Deep Space Network station at Madrid had just reported to her the acquisition of New Horizon's downlink signal, sent from the spacecraft four and a half hours prior.
"Symbols lock." Computers at the MOC recognized the headers that delineated packets of information carried by the signal.
"Telemetry lock." Computers at the MOC recognized the signal as a valid sequence of correctly formatted data from the spacecraft.
These three handshakes complete, mission controllers began parsing vital bits of information about the status of the spacecraft.
"No autonomy rules have fired,"a voice reported to Bowman over the communications loop. None of the spacecraft's pre-programmed "rules" --constraints placed on various pieces of telemetry that, if exceeded, would indicate a problem -- had been triggered.
"SSR pointers as expected," reported another. The spacecraft's solid state recorder, the storage for all of the mission's critical science data, had recorded the exact amount of data that the planned observations required, meaning they'd all been carried out successfully.
Steadily, the remaining reports came in. GNC nominal. Propulsion nominal. Thruster counts correct. Thermal nominal. All temperatures green. With all of her team's reports in hand, Bowman addressed Principal Investigator Alan Stern over the loop:
P.I., this is MOM on Pluto-1. We have a healthy spacecraft, we recorded data on the Pluto system, and we are outbound from Pluto.
After 22 hours out of contact, the spacecraft had turned its high gain antenna to Earth and began reporting that it had performed the mission to perfection. 15 minutes later, it ceased transmission and continued its survey of Pluto and its moons, now well on the system's opposite side. But that short burst was all the team had designed, a quick check-in for the sanity of the engineers. It was, in fact, a small concession from the science team, who would otherwise have been happy to leave the spacecraft to its data gathering. There was a planned observation in the sequence that just happened to leave the high-gain antenna pointing roughly in the direction of Earth, which was tweaked during the design phase to allow the status report. To nobody's surprise, it became the mission's "Eagle has landed."
"You have a lot of faith in your children," Bowman said, "but sometimes they don't do exactly what you expect them to do." With Tuesday night's downlink signal, unceremoniously dubbed "E Health 2," the New Horizons team knew that theirs had.
Minutes later, Bowman and the entire team from the MOC entered a nearby auditorium full of media, mission staff, and friends and family, to riotous applause and a standing ovation. Looking mostly exhausted, they stood dutifully by while, among others, NASA administrator Charles Bolden sang their praises. Cheers of "ALICE! ALICE!" erupted from the crowd when Bowman was asked to speak briefly on the success. When they died down, she began: "Oh, gee."
Mission Operations Manager Alice Bowman discusses the successful "phone home" signal on Tuesday night. Credit: NASA, screen grab by @ferwen
"I can't express how it feels to have achieved a childhood dream of space exploration," Bowman told the audience. "I'm pretty overwhelmed at this moment. Do something because you want to. Give yourself that challenge."
That sentiment was a powerful undercurrent at the Applied Physics Laboratory Tuesday evening, for mission scientists and engineers who'd spent many years of their lives shepherding the little probe through the solar system, to Alan Stern, who advocated and directed a Pluto mission for decades, to the children of Clyde Tombaugh, the astronomer who discovered Pluto 85 years ago, who were present for the night's events. It was an atmosphere first laced with anticipation, and then thick with jubilation, relief, and more than a little exhaustion.
Instead of replenishing the bounty of sleep lost since the 4 July safe mode event that threatened the mission, scientists and engineers will be back in the MOC on 5 AM Wednesday morning, for the "First Look A" uplink, which Stern has called the "New York Times dataset." It will contain compositional data, color information, and what promise to be incredibly detailed high resolution images, up to one hundred times better in resolution than the image that grabbed top billing on Tuesday morning. John Grunsfeld, NASA's Associate Administrator for the Science Mission Directorate, compared the phone home signal to the landing of the Mars Curiosity rover: though a major technical mission milestone had been achieved, the science rewards had yet to come, in a sense making it the beginning of the mission. It will be a full 16 months before the entirety of those rewards are returned to Earth from the spacecraft, and possibly many years before they're all brought to bear on our effort to fully understand the complicated story of Pluto.
But all of that can wait, at least until morning. In the meantime, New Horizons will continue intensive observations of the opposite side of the Pluto system, free from the inquisitive meddling of its worried parents. Triumphant mission engineers and scientists can see to celebrations and well-earned sleep. And the last chapter of humanity's first journey to visit the worlds circling its star can be confidently closed. With a little luck, the exultant scene at the Johns Hopkins Applied Physics Laboratory on Tuesday night will inspire its children to begin writing a new volume.