On January 19, 2006, the New Horizons probe set sail from Earth at the record-breaking launch speed of 36,000 miles per hour. Its destination was Pluto—that previously unseen dwarf planet, sitting three billion miles away, at the very edge of our solar system. Now, nearly ten years later, it has finally reached its destination.
At 7:49 a.m. on Tuesday, while traveling at 31,000 miles per hour (or just under nine miles per second), the probe reached its closest distance to the dwarf planet—an approximate 7,750 miles away from the surface. It surpassed the planet after only three triumphant minutes, during which it accumulated images and mapped the surface structure and composition with visible and near-infrared light. It then sped closer to Charon, Pluto’s largest moon, and will now continue traveling through the Kuiper belt, the region of the solar system beyond Neptune’s orbit.
The New Horizons project team was unsure if the flyby was successful until they received a scheduled transmission at 9:00 p.m. It was a moment that brought much joy and relief. Even though the probability of the probe being struck by debris was estimated at less than one in 10,000, it would only take a small speck of dust to jeopardize the precise trajectory needed to accomplish the mission. Even worse, as Dr. Alan Stern, principal investigator on the project, told the New York Times: “If the spacecraft were hit by something even the size of a rice pellet, it could pierce into the spacecraft and potentially cause the stop function. It would be like colliding with a brick at 60 miles per hour.”
NASA released teaser close-ups of Pluto on Instagram ahead of receiving the first images from the flyby, which revealed a surprisingly charming heart-shaped region on the planet’s surface. The images were significantly clearer than the photos of Pluto previously captured by the Hubble Space Telescope, and even those were outdone yesterday when NASA released the astounding first collection of photos taken only 7,750 miles away from the surface. The resolution of those pictures, according to Dr. Stern, allows for something akin to counting the ponds in Central Park from space. “You can see wharfs on the Hudson. That’s the resolution that we will have on Pluto,” he explained. The data accumulated by New Horizons will take up to sixteen months to transmit to Earth because of the speed of transmission (2,000 bits per second) and the amount of high-resolution data gathered—not to mention the four-and-a-half-hour lag time before sent data signals reach Earth.
Sixteen months to look at pictures doesn’t seem like much, however, when you consider how long it took to get them. After a decade-long mission, we have finally reached the outer realms of our solar system and are looking to go even further. The New Horizon probe has enough fuel left to thrust it towards one more Kuiper belt object, and NASA has indicated that they will select that object by August. But for now, we can sit back, enjoy pictures like these, and celebrate their accomplishment—and maybe give some much-deserved attention to Pluto in the process.
In honor of our oft-forgotten planetary sibling, here are some fun facts about Pluto:
- Pluto was named by a twelve-year-old British girl named Venetia Burney. It was submitted, through her grandfather’s connections, to the Lowell Observatory and won the vote. Other possible names included Minerva and Cronus.
- Pluto was discovered in 1930 by a twenty-four-year-old “farm boy” and recreational astronomer who happened to make his own telescopes. He was also a Unitarian Universalist who founded a UU church in New Mexico. His ashes are the first to be sent into space—appropriately aboard the New Horizons probe.
- Other Earth souvenirs are also onboard the New Horizons probe. As reported by the New York Times: “New Horizons is carrying sentimental mementos from Earth, including some ashes of Mr. Tombaugh, who died in 1997; a CD-ROM with 434,000 names of people who responded to a “Send Your Name to Pluto” request; and a couple of coins—the state quarters of Maryland (where the spacecraft was built) and Florida (where it was launched).”
- Unfortunately for Dr. Stern and his staff, Pluto was demoted to dwarf planet status just a few months after New Horizons was launched. This came after Dr. Michael E. Brown’s discovery of Eris, a slightly larger object in the Kuiper belt. Brown says he has no regrets, but admits that Pluto’s demotion is most difficult for the New Horizons’ team: “They want Pluto to be a planet because they want to be flying to a planet. They would be far better off embracing the reality that it is not a planet and being excited about the fact that they are going to a new type of object in the outer solar system,” he told BBC.
For the most comprehensive live updates on the Pluto Flyby, check out science writer Jacob Aron’s live blog on New Scientist.