Final destination T
For decades, Pluto seemed out of reach. Then two scientists found a way to pay it a visit
THEY called it the “first mission to the last planet.”
In 2006, a 224-foot-tall rocket lifted off from Cape Canaveral, Fla., carrying a tiny, thousand-pound probe named New Horizons. Its mission: to wing its way across billions of miles of cold, dark space for a rendezvous with the solar system’s most distant planet, Pluto.
The undertaking would finally close a chapter of space exploration, marking the last of the Milky Way’s planets to be probed.
The story of how a group of scientists pulled off this feat is told in “Chasing New Horizons: Inside the Epic First Mission to Pluto.”
It’s written by Alan Stern, a planetary scientist and the mission’s principal investigator, and David Grinspoon, an astrobiologist and science journalist.
Other planets had been visited decades ago. Pluto’s nearest neighbors, Neptune and Uranus, had been analyzed by the Voyager 2 probe in the 1980s. Pluto, however, remained frustratingly mysterious, a faint speck of light in telescopes.
“Pluto was the last game in town, the last train to Clarksville, the last first mission,” Stern tells The Post. “What could be a bigger contribution to the field than to get [a mission] started?”
Space had always interested Stern. He watched one of the early Apollo landings and marveled as newsman Walter Cronkite held up a copy of NASA’s thick flight plan. He later studied aerospace engineering.
The New Horizons mission was born in 1989 over pasta and mediocre cabernet. A group of planetary scientists, including Stern, had convened in Baltimore for a conference and began discussing the need for a mission to Pluto. That meeting launched a grassroots movement to convince NASA to plan — and most importantly fund — just such a mission.
“A debate erupted [at NASA] between the Pluto supporters, who were mostly younger scientists, and Pluto detractors, mostly older scientists,” the authors write.
The debate dragged on for more than a decade with numerous frustrating stops and starts. Time was of the essence.
Pluto had reached the closest point to the sun in 1989, and since then had been slipping farther away along its massive 248-year orbit. The farther away it got, the harder it would be to reach.
Scientists and Pluto fans launched a letter-writing and media campaign to get the mission restarted.
“I think we annoyed some people inside of NASA because we kept pushing,” Stern says.
Finally, in 2000, NASA relented.
Several teams of scientists offered proposals for a probe, but NASA ultimately selected one from Stern and his team at Johns Hopkins Applied Physics Laboratory and the Southwest Research Institute.
The downside was the craft had to be launched in just four to six years and the mission had to cost a fifth of that of its predecessor, Voyager. (The final bill was ultimately around $700 million.)
Pluto is too far from the sun for the spaceship to be powered by solar panels, so the team used a plutonium-powered battery.
The battery was tested in Idaho and when it was shipped to Florida for the launch, it was transported in a heavily armed convoy. NASA even sent decoy convoys to throw off anyone looking to steal or sabotage the plutonium.
On Jan. 19, 2006, “Go Atlas, Go Centaur, Go New Horizons,” crackled across the radio and the spacecraft blasted off.
It was loaded with sensitive instruments, including a long-range camera, a spectrometer and a dust counter. But its most special payload was ashes belonging to Clyde Tombaugh, the astronomer who had discovered Pluto in 1930.
Stern and his team celebrated the successful launch by ceremonially burning the emergency contingency plans they didn’t have to use.
With New Horizons away, now they’d have to wait. And wait. Even traveling at some 31,000 miles an hour, the craft would take nearly a decade to reach its target.
Then in August 2006, barely seven months after launch, strange news reached the team. A group of astronomers had made the head-scratching decree that Pluto would no longer be considered a proper planet but a “dwarf planet.”
The New Horizons team’s reaction to the decree ranged from “indifferent” to “bemused” to “seriously pissed off.” But in the end, they reasoned, “Dwarf planets are planets. End of argument.”
As the craft hurtled through space, the team stayed busy remotely checking its instruments, uploading new software and planning for the day when it would fly by Pluto.
After waiting nearly 10 years, the craft would only be able to study the planet for a few hours as it whizzed past.
New Horizons finally made it in July 2015. As it passed, it collected a treasure trove of scientific data. But because it was so far away and its transmitter so weak, sending all that data back to earth took more than a year.
But what was discovered “knocked our socks off,” says Stern, who was just 32 when he first discussed the mission back in 1989 but was nearly 50 when it became reality. The planet’s terrain was surprisingly diverse, with canyons and soaring mountains. It also turned out to be geologically active.
“That shouldn’t happen in a small planet,” Stern says. “It should cool off early in its history and quit evolving, not still be active 4 billion years after it formed. But I guess Pluto doesn’t read the textbooks, because it’s still active to this day.”
The probe also revealed a massive nitrogen glacier, shed light on the orbits of the body’s mysterious moons and hinted at a liquid water ocean inside Pluto today.
Today, the craft is another billion miles past Pluto, with enough power to run for decades. This New Year’s Day it’s expected to fly by an object in the Kuiper belt, an orbiting collection of rocky bodies. It will be the most distant subject ever studied. New horizon, indeed.