Photograph by NASA/APL/SwRI
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A false-color image of Pluto and Charon exaggerates differences to make features easier to see. Filters on a New Horizons instrument called Ralph reveal areas within the heart-shaped region that vary in color.


Photograph by NASA/APL/SwRI

Spacecraft Sails By Pluto, Phones Home

Scientists rejoiced when New Horizons sent a signal confirming its safe passage past Pluto, setting the stage for amazing photos expected from the flyby.

It was just a trickle of 1s and 0s, but the string of numbers had sped across the solar system at the speed of light for 4.5 hours. Then, at 8:52 p.m. EDT, that signal collided with an antenna on Earth. 

In the control center, New Horizons mission operation manager Alice Bowman ran through a series of checks. Every system on board the spacecraft reported back healthy. The expected amount of data had been collected. No safe mode events had occurred. Then, Bowman recited the words everyone had been waiting to hear: “We have a healthy spacecraft, we’ve recorded data from the Pluto system, and we’re outbound from Pluto.”

The place erupted.

New Horizons had survived its trip through the Pluto system—a journey that could have ended catastrophically had New Horizons slammed into a single grain of dust.

Now, those fears can be laid to rest.

New Horizons principal investigator Alan Stern had a simple, three-word message for his team: "We did it."

And they definitely had.

“This is absolutely as good as it could have gone. Every system reported healthy and as expected,” says team member Alex Parker of the Southwest Research Institute. “That was really amazing.”

For the first time, New Horizons is on the other side of Pluto, and it’s hurtling into the unknown, laden with an enormous pile of data. Because the spacecraft is so far away, the complete data set will take 16 months to arrive at Earth. And like the signal received tonight, those data will travel across the solar system to rendezvous with Earth, passing the orbits of Neptune, Uranus, Saturn, Jupiter and Mars on the way.  (Learn more about the historic mission to Pluto on the National Geographic Channel.)

“The enormity of the effort to get here feels a little surreal, unusual, bizarre,” says team member Ivan Linscott of Stanford University.

Now that champagne-colored Pluto and its five known moons are shimmering in the spacecraft’s rear view mirror, the team is ready to start digging into the pile of data gathered during the Pluto encounter. Those observations include incredibly close-up images of Pluto’s and Charon’s surfaces, as well as images of the four smaller moons: Nix, Hydra, Kerberos, and Styx.

Instruments on board the spacecraft also studied the composition of those faraway worlds and the charged particles that surrounded them. What's more, New Horizons looked back after passing Pluto to make two special observations of the planet’s atmosphere, collecting the sunlight filtered through the planet’s atmosphere as well as a barrage of radio waves fired from Earth early this morning.

Last, New Horizons swiveled to look at the south pole of Pluto, a hemisphere deep in the throes of winter. Normally shrouded in darkness, it was lit by a glimmer of sunlight reflected off Charon, Pluto’s mega-moon.

In other words, as New Horizons left Pluto behind, it turned to see the planet, illuminated in the underworldly glow of Charonshine.

Follow Nadia Drake on Twitter and on her blog at National Geographic's Phenomena.