Journey to Pluto: 9.5 years, one amazing flyby

In this artist's rendering, Pluto's frozen southern pole is lit by its largest moon, Charon.

In this artist’s rendering, Pluto’s frozen southern pole is lit by its largest moon, Charon.


We are SO CLOSE!

After a journey of 9.5 years across 3 billion miles of space, NASA's New Horizons spacecraft is about to give humanity its first detailed look at Pluto and its large moon Charon.

At approximately 4:49 a.m. Pacific time on Tuesday, the spacecraft will fly within 7,800 miles of Pluto's surface, making its closest approach to the dwarf planet. It will be furiously collecting data as it zips past at 30,800 miles per hour.

By the end of the day, cameras aboard New Horizons will have resolved features on Pluto's surface as small as the ponds of Central Park or the runways of LAX.

If the distant Kuiper belt object has snow-capped mountains, steep crevasses and towering ice cliffs, as some scientists have predicted, New Horizons will see them.

INFOGRAPHIC: New Horizons' path to Pluto

At the same time, other instruments aboard the spacecraft will take measurements to determine what the dwarf planet is made of, create temperature maps of its multi-colored surface, and search for auroras in its thin atmosphere.

The first high-resolution images should be available to the public on Thursday or Friday, but New Horizons principal investigator Alan Stern said it will take more than a year for all the information New Horizons will gather to make it back to Earth.

Early in the mission planning stages, Stern and his colleagues decided that on the day of closest approach all the spacecraft's power should go toward gathering information, rather than beaming it across the solar system.

"On the day of the flyby only engineering data comes down," Stern said. "On the 15th the science data dump begins again."

"To work on this mission you have to really be into delayed gratification," he added.

But even in the days before closest approach, when New Horizons was still more than 5 million miles from the Pluto system, the spacecraft was already sending back intriguing hints of discoveries to come.

Pluto's mottled surface looks more complex then anyone anticipated, Stern said, and he was surprised to see that the Texas-sized moon Charon had dark poles --  something that has never been seen before in the solar system.

"It's almost an anti-polar cap," he said.

In addition, scientists can now say with certainty that Pluto does not have dust rings around it like its neighbor Neptune.

It also appears that Pluto does not have any additional moons beyond the five satellites Charon, Nix, Styx, Hydra, and Kerberos that had already been spotted by NASA'S Hubble Space Telescope.

The New Horizons team is not saying yet what these revelations might mean.

"No answers yet," said Richard Binzel, a planetary scientist at MIT and member of the New Horizons science team. "We are trying to take these interpretations very slowly and carefully, especially as new and closer data are arriving."

It may seem that 9.5 years is a long time to travel for a close flyby that will last for just a day, but Stern said that has always been NASA's plan.

"The first visit to every planet is a flyby," he said. "It's a simpler mission -- it costs less and you get the basic lay of the land.

In the meantime, the scientists, like the world, are just thrilled this moment has come at last.

"Alan [Stern] has been at this for a quarter of a century and I've been working on it for 15 years," said Glenn Fountain, New Horizons' project manager. "I'm excited that we are finally here, and I'm just waiting to see that next image."

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