Pluto up close

NASA on Wednesday revealed images from the New Horizons spacecraft that flew by Pluto one day earlier.

By Amanda Barnett and Ben Brumfield

"Yesterday, America's space program took another historic leap for humankind. Today, the New Horizons team is bringing what was previously a blurred point of light into focus," spokesman Dwayne Brown said.

Pluto up close

The images the craft took and transmitted back to Earth are from the closest point the probe came to the dwarf planet as it made its milestone in space exploration history.

The Pluto mission completes the reconnaissance of the classical solar system, and it makes the United States the first nation to send a space probe to every planet from Mercury to Pluto.

The flyby came 50 years after the Mariner 4 probe accomplished the first flyby of Mars, which sent back the first photos of another planet taken close up from space.

"I think it's fitting that on that 50th anniversary, we complete the initial reconnaissance of the planets with the exploration of Pluto," said Alan Stern, the mission's principal investigator.

With Wednesday's photos, New Horizons is also sending a banquet of knowledge to scientists.

Charon

In the weeks that New Horizons was homing in on Pluto, NASA and its partner, the Johns Hopkins University Applied Physics Laboratory, published a barrage of images. First, they showed blurry spots that grew larger.

By Tuesday, clear photos revealed the contours of the planet's surface and of its largest moon, Charon. Wednesday images and information are just the beginning of 16 months' worth of data the probe will send back to Earth.

It wasn't a sure bet that New Horizons would survive to send the images, after passing by projectiles racing through Pluto's gravitational field.

Collisions with dust particles could have ripped through the probe like shotgun blasts, since the spacecraft moves about 8.5 miles per second. That's about 40 times as fast as a bullet exiting a gun barrel.

New Horizons went incommunicado for 12 hours as it passed Pluto, and mission managers packed into mission control held their breaths. The radio silence was planned, while the craft collected data on Pluto and its five moons, but it was during that most dangerous phase.