NASA spacecraft set to pull back curtain on dwarf planet Pluto



Pluto, reveal thyself, and Earthlings, enjoy the show.

On Tuesday, NASA’s New Horizons spacecraft will sweep past Pluto and present the previously unexplored world in all its icy glory.

It promises to be the biggest planetary unveiling in a quarter-century. The curtain has not been pulled back like this since NASA’s Voyager 2 shed light on Neptune in 1989.

Now it’s little Pluto’s turn to shine way out on the frigid fringes of our solar system.

New Horizons has traveled 3 billion miles (4.8 billion km) over 9½ years to get to this historic point. The fastest spacecraft ever launched, it carries the most powerful suite of science instruments ever sent on a scouting and reconnaissance mission of a new, unfamiliar world.

Guarantees principal scientist Alan Stern, “We’re going to knock your socks off.”

The size of a baby grand piano, the spacecraft will come closest to Pluto on Tuesday morning — at 7:49 a.m. EDT (1149 GMT). That is when New Horizons is predicted to pass within 7,767 miles (12,500 km) of Pluto. Fourteen minutes later, the spacecraft will zoom within 17,931 miles (28,856 km) of Charon, Pluto’s jumbo moon.

It will be cause to celebrate for those gathered at the operations center at Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland. The lab designed and built the spacecraft for the National Aeronautics and Space Administration, and has been managing its roundabout route through the solar system.

“What NASA’s doing with New Horizons is unprecedented in our time . . . the last picture show, for a very, very long time,” says Stern, a planetary scientist with the Southwest Research Institute in Boulder, Colorado.

It is the last stop in NASA’s quest to explore every planet in our solar system, starting with Venus in 1962. And in a cosmic coincidence, the Pluto visit falls on the 50th anniversary of the first-ever flyby of Mars, by Mariner 4.

Yes, we all know Pluto is no longer an official planet, merely a dwarf, but it still enjoyed full planet status when New Horizons rocketed from Cape Canaveral, Florida, on Jan. 19, 2006. Pluto’s demotion came just seven months later, a sore subject still for many.

The sneak peeks of Pluto in recent weeks are getting “juicier and juicier,” says Johns Hopkins project scientist Hal Weaver. “The science team is just drooling over these pictures.”

The Hubble Space Telescope previously captured the best pictures of Pluto. If the pixelated blobs of pictures had been of Earth, though, not even the continents would have been visible.

The New Horizons team is turning “a point of light into a planet,” Stern says.

An image released last week shows a copper-colored Pluto bearing, a large, bright spot in the shape of a heart.

Scientists expect image resolution to improve dramatically by Tuesday.

New Horizons, weighing less than 1,000 pounds (450 kg) including fuel, has seven instruments that will be going full force during the encounter. It’s expected to collect 5,000 times as much data, for instance, as Mariner 4.

“We’re going to rewrite the book,” Weaver says. “This is it — this is our once-in-a-lifetime opportunity to see it.”

The team gets one crack at this.

“We’re trying to hit a very small box, relatively speaking,” says Mark Holdridge, the encounter mission manager. “It’s 60 by 90 miles (96.5 by 145 km), and we’re going 30,000 mph (48,000 kph), and we’re trying to hit that box within a plus or minus 100 seconds.”

The only planet in our solar system discovered by an American, Pluto actually is a mini solar system unto itself. Pluto — just two-thirds the size of our own moon — has big moon Charon that’s just over half its size, as well as baby moons Styx, Nix, Hydra and Kerberos. The names are associated with the underworld in which the mythological god, Pluto, reigned. New Horizons will observe each known moon and keep a lookout for more.

Scientists involved in the $700 million effort want to get a good look at Pluto and Charon, and get a handle on their surfaces and chemical composition. They also plan to measure the temperature and pressure in Pluto’s nitrogen-rich atmosphere and determine how much gas is escaping into space. Temperatures can plunge to nearly minus-400 degrees Fahrenheit.

Bill McKinnon, a New Horizons team member from Washington University in St. Louis, expects to see craters and possible volcanic remnants. A liquid ocean and a rocky core may lie beneath the icy shell.

“Anybody who thinks that when we go to Pluto, we’re going to find cold, dead ice balls is in for a rude shock,” McKinnon says. “I’m really hoping to see a very active and dynamic world.”

Pluto has tantalized astronomers since its 1930 discovery by Clyde Tombaugh using the Lowell Observatory in Flagstaff, Arizona. Some of Tombaugh’s ashes are aboard New Horizons. His two children, now in their 70s, plan to be at Johns Hopkins for the encounter.

With its tilted, elongated 248-year orbit, Pluto has made it only a third of the way around the sun since its discovery. The amount of sunlight that reaches Pluto is so dim that at high noon it looks like twilight here on Earth. The massive surrounding Kuiper Belt, in fact, is called the Twilight Zone. The New Horizons team has its eyes on a few much smaller objects in the Kuiper Belt, and is hoping for a mission extension as the spacecraft continues toward the solar system exit on the heels of NASA’s Voyagers 1 and 2 and Pioneers 10 and 11.

For now, signals take 4½ hours to travel one-way between New Horizons and flight controllers in Maryland.

New Horizons’ science instruments will be cranked up to collect maximum data Tuesday, leaving no time to send back data. In fact, scientists won’t be absolutely certain of success until Tuesday night, 13 hours following New Horizons’ closest approach, when it “phones home.”

It will be Wednesday before the closest of Pluto’s close-ups are available for release. And it will be well into next year — October 2016 — before all the anticipated data are transmitted to Earth.

Come Tuesday, Clyde Tombaugh will pass within 7,800 miles (12,550 km) of the icy world he discovered 85 years ago.

His ashes are flying on NASA’s New Horizons spacecraft on humanity’s first journey to Pluto.

New Horizons also is carrying a 1991 U.S. postage stamp that’s about to become obsolete — it trumpets “Pluto Not Yet Explored” — as well as two state quarters, one representing Florida, home of the launch site, and the other Maryland, headquarters for the spacecraft’s developers and flight control.

In all, nine small mementos are tucked aboard New Horizons.

There’s a good reason there are nine.

When New Horizons rocketed away from Cape Canaveral on Jan. 19, 2006, Pluto was the ninth planet in our solar system. It was demoted to a dwarf planet a scant seven months later.

Tombaugh’s widow and two children offered up an ounce of his ashes for the journey to Pluto. The ashes of the farm boy-turned-astronomer are in a 2-inch (5-cm) aluminum capsule inscribed with these words:

“Interred herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system’s ‘third zone.’ Adelle and Muron’s boy, Patricia’s husband, Annette and Alden’s father, astronomer, teacher, punster, and friend: Clyde Tombaugh (1906-1997)”

Annette Tombaugh-Sitze and her younger brother, Alden, now in their 70s, plan to be at the flight operation base at Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, for Tuesday’s historic encounter. Their mother died in 2012 at age 99.

“I think my dad would be thrilled with the New Horizons. I mean, who wouldn’t be?” Annette said in a NASA interview posted online. “When he looked at Pluto, it was just a speck of light.”

As for the 29-cent stowaway stamp, Pluto is depicted as grayish with orange flecks, an artist’s rendering based on what NASA knew about the tiny orb prior to 1991, which wasn’t much.

New Horizons’ better and better views reveal a copper-colored, icy bright world.

“No stamp has ever traveled this far!” Mark Saunders, a spokesman for the U.S. Postal Service, said in an email last week.

A small cutout of SpaceShipOne is attached to New Horizons; the first manned private space plane achieved suborbital flights in 2004 and won the $10 million Ansari X Prize.

Also on the spacecraft are two U.S. flags as well as two CDs.

One contains the photos of team members.

The other contains 434,738 names of people who signed up online in advance.