Our first-ever close-up look at Pluto is still six months away, but this week marks the official kickoff of observations for NASA's New Horizons mission — and sets the stage for a steady drumbeat of revelations about a little-known planetary frontier.
"It won't be much to write home about at the beginning here," project scientist Hal Weaver told NBC News from the mission's headquarters at Johns Hopkins University's Applied Physics Laboratory in Maryland. "But it'll be neat to watch the Pluto system expand as we get closer and closer."
New Horizons was launched from Cape Canaveral nine years ago — and during that time, the piano-sized spacecraft has traveled nearly 3 billion miles (4.8 billion kilometers) at the fastest clip ever recorded for an interplanetary probe. Also during that time, the International Astronomical Union put Pluto in a new pigeonhole reserved for "dwarf planets."
January 2006: Pluto Spacecraft Begins Long JourneyJan. 14, 200602:04
The $728 million mission is the first to study any of the icy dwarfs on the edge of the solar system's edge, and arguably the last one in the foreseeable future to visit a previously unexplored planetary realm. New Horizons' closest precedent is NASA's twin Voyager missions, which gave scientists their first up-close look at Uranus and Neptune.
"The last time anybody did anything like this was in 1989, with Voyager," said Alan Stern, a planetary scientist from the Southwest Research Institute who leads the New Horizons mission as principal investigator. "If you weren’t at least 6 years old in 1989, you probably don’t remember Voyager. So it turns out that about half the country has no recollection of a first-time planetary encounter like this."
Official start of observations
Thursday marks T-minus-180 days on the countdown to the close encounter with Pluto on July 14, and the official start of the observational campaign for the approach.
New Horizons is still more than 133 million miles (215 million kilometers) away, and Pluto still looks like a mere speck. Nevertheless, the mission team plans to start using the spacecraft's pictures of Pluto to guide the spacecraft rather than relying on radio tracking.
The spacecraft was roused from hibernation on Dec. 6, and since then the team has been checking out its systems and the seven scientific instruments on board. The parameters for one of those instruments, the Alice ultraviolet imaging spectrometer, had to be tweaked to adjust for a slower-than-expected warmup, but those adjustments were completed on Tuesday.
"Everything looks like it's working great," Weaver said.
The LORRI high-resolution camera is due to take the approach campaign's first pictures of Pluto and its moons on Jan. 25, and they'll be sent down to Earth a couple of days later.
At New Horizons' distance, it takes about four and a half hours for the spacecraft's signals to be received on Earth, due to the finite speed of light.
"The main purpose of those observations is for optical navigation, to make sure it's on course," Weaver said.
Pitter-patter of milestones
The mission team has planned a series of events leading up to the flyby: February marks the 109th birthday of Clyde Tombaugh, the late astronomer who discovered Pluto in 1930. March brings the 85th anniversary of the formal announcement of the discovery. April will feature a "T-minus-100 days" countdown. And May is the month when New Horizons' pictures start outdoing the Hubble Space Telescope's best view of Pluto.
Four documentary film crews are following the mission's progress for PBS' NOVA series, Japan's NHK network, the Discovery Channel and the BBC, Stern said.
"There's going to be a steady pitter-patter," he said.
On July 14, New Horizons will sail within about 8,500 miles (13,700 kilometers) of Pluto's surface. From that distance, the spacecraft's imagers should be able to map the dwarf planet's mottled surface in multiple wavelengths, and perhaps make out the clouds and ice volcanoes that scientists hope are there. Other instruments will study Pluto's whisper-thin atmosphere, tally up dust particles and measure the solar wind.
"People ask, 'What are the scientific questions you're going to answer?'" Stern said. "New Horizons doesn't have any of those, it's purely about raw exploration. ... We're not 'rewriting the textbook,' we're writing the textbook from scratch."
Because of the vast distances involved, New Horizons is designed to store data in the spacecraft's computer and feed it out at a relatively slow transmission rate. It's expected to take nine months to get all the readings from the Pluto encounter back to Earth.
Then it'll be time to plan out the next phase of New Horizons' mission: a rendezvous with another mini-world in the Kuiper Belt, the vast ring of icy material that lies beyond the orbit of Neptune. With Hubble's help, the New Horizons team has identified three potential targets and plans to propose the best option for NASA funding in late 2016.
If all proceeds according to plan, New Horizons' second act would reach its climax with a flyby roughly 4 billion miles (6.4 billion kilometers) from the sun in 2018 or 2019.
Update for 1:25 p.m. ET Jan. 15: After that 2018-2019 encounter, what happens? Stern says he's already thinking about potential encores — either a still more distant flyby of a "hot" object in the Kuiper Belt, or a Voyager-style study of the heliosphere's far frontiers.
"The spacecraft has power and fuel to run until about 2038," Stern said in an email. "Of course, a second NASA extended mission proposal would have to be approved."