Headlines from earth yesterday heralded the Iranian Nuclear Deal, but some of us were looking skyward. On a small green campus tucked into suburban Maryland at the Johns Hopkins University Applied Physics Lab scientists, engineers, media, friends, family, faculty and board of Johns Hopkins University awaited the report back from Pluto. The New Horizons spacecraft, built by Hopkins APL engineers and scientists, had arrived at the outer planet three billion miles away after a nine and a half year journey. That evening the spacecraft was reporting in after 22 hours of silence while it gathered extensive data as it passed within 7750 miles of Pluto.
The spacecraft, which had been built in a record four years at APL, had traveled at a rate of a million miles/day (between 31,000-46,000mph depending on its orbit). The evening before it had started downloading data and taking pictures in a rapid collection of scientific information. It couldn’t do that job and call home at the same time so its progenitors waited anxiously at Mission Control, aware that any number of unpredictable events like a pebble size bit of detritus colliding could disrupt and destroy the mission.
“Stand by for telemetry….” Mission Operations Manager (MOM) Alice Bowman alerted. At 8:52:37pm—right on time—New Horizons called home. “We’re in lock with telemetry with the spacecraft,” she affirmed as one by one the systems managers reported: “MOM, propulsion is nominal…MOM, thermal is nominal…MOM, power is nominal…” Nominal meant normal. MOM meant Alice. The conclusion: “We have a healthy spacecraft and we’re outbound for Pluto!” The room at Mission Control and in the auditorium nearby burst into cheers and tears and gave a standing ovation. It was a remarkable moment and extraordinary achievement.
The mission had proceeded like clockwork. It had been a team effort over a decade and a half, occupying 2500 people. The very best scientists and engineers built the space craft, designed its scientific mission (including the first student-designed project on a NASA mission), programmed its course. The trajectory included an important scientific data-gathering pass of Jupiter, where the spacecraft received a needed gravity assist which sent it hurling on its way into deep space.
New Horizons arrived at the closest approach to the planet just 72 seconds early. That precision over nine years and three billion miles was almost impossible to comprehend except to the scientists and engineers who understood that precision was essential to accomplish the task. Even a small margin of error projected over that amount of time and space could be disastrous.
The mission exemplified a remarkable achievement of teamwork and partnerships among NASA, universities, and the U.S. Department of Energy which supplied the plutonium power source. The nuclear power it provided will allow the spacecraft to operate until 2030. The total power draw for the Pluto encounter was only 202 watts (about three and a half light bulbs). Each transmission draws only 28 watts (enough to power two small night lights.) Reception of these transmissions relies on super giant receivers—the Deep Space Network. There are only three in the world large enough—one in Madrid, Spain, one in Pasadena, CA in the US and one outside Canberra, Australia. The placement of them means that data can be received at any time as the earth spins on its axis. Last night’s transmissions were broadcast from Pluto four and a half hours before they were received, traveling at the speed of light and sent via the giant antenna dish in Madrid.
Alan Stern, the head of the New Horizons Mission and NASA’s chief investigator, told the gathering: “We did it! One small step for New Horizons, one giant leap for mankind.”
The audience included students who had been born almost ten years before on the day of the New Horizons launch. An elementary school boy asked, “Does this make Pluto a planet?” Fran Bagenal, NASA team leader for plasma investigations on the Mission, answered, “Yes! Of course Pluto is a planet!”
The Pluto mission began as a barroom bet by Alan Stern to prove Pluto was not just a dwarf planet but a full planet. The exploration was affirmed as a top priority by the National Academy of Science. In the audience last night were the grown children of Claude Tombaugh, the astronomer who originally discovered Pluto. Eighty-five years earlier their father told his senior astronomer, “I think I have found your planet X.”
Fifty years before to the day—July 14—humans first explored Mars with NASA’s Mariner 4. John Casani, special assistant to the director at NASA’s Jet Propulsion Laboratory (JPL) and one of the early engineers in the space program noted, “People developing spacecraft today know what they are doing. We didn’t know what we were doing. Back then the shoulders we were standing on were too narrow and our shoes were too big. We had only the technology for guided missiles.”
The scientists and engineers had to figure out, among other concepts, 3-axis stabilization. “Innovation was the key to making things work,” Dr. Casani said. “There was no book on 3-axis stabilization. We were all only a couple of years out of graduate school. We weren’t experienced enough to know that what they were asking us to do couldn’t be done.”
“You couldn’t go to the library and ask for a book,” added Norm Haynes, who was the trajectory engineer for the Mariner 4 Mission and also spent his career at NASA’s JPL. “There were no textbooks on how to build a spacecraft.”
There were no computers on board the first spacecrafts either. In 1962 the computer had only a 65,000-word vocabulary as opposed to the multiple gigabytes of memory today. The first computer was aboard Mariner 4 which delivered 22 pictures of Mars, each taking ten hours to send back. It took 60 hours to go to the Moon, 6,000 hours to go to Mars and now the New Horizons spacecraft can endure a nine and a half year journey to Pluto and still arrive in tact. The per mile cost of New Horizon was 25 cents/mile; the per mile cost of Columbus was $3000/mile and the per mile cost of Magellan was $5000/mile. On Mariner 4 in 1965 the spacecraft transmitted information at 8 1/3 bits / second; New Horizon transmits at 1000 bits/second and it is 60 times further away.
The scientists and engineers said the key to success was the willingness to imagine, to innovate and to be willing to fail. Considerable failures preceded this achievement.
Why is the exploration of Pluto important? It opens up our view of what is possible, of the universe and perhaps even of ourselves, suggesting larger horizons physical and metaphysical. It demonstrates the possibilities of human potential—of imagination and ingenuity empowered by cooperation, teamwork and a large goal. From a scientific point of view, from the point of view of NASA which has to secure the funding, it provides knowledge about the universe where we live and the universe beyond.
The data that will be gathered on the New Horizons’ close approach to Pluto is about 100 times more than can transmit before the spacecraft flies away. It will take 16 months to send all the scientific information home.
“We explore because we are human, but we want to know,” said noted physicist Stephen Hawking in a call-in message to the gathering.
If the next stage is funded, the New Horizons spacecraft will go off to explore the outer reaches of the Kuiper Belt, letting us know what lies beyond Pluto in the further reaches of space.
The spacecraft was built to last. Its power will endure until 2030, then it will not be sufficient to keep the instruments warm enough to operate, and the craft will drift into deep space. By 2030, the equipment on the spacecraft will be 40 years old and the innovations that will have developed by then we can now barely imagine.