• NASA shares parting shots of Vesta

    NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

    This image mosaic synthesizes some of the best views that NASA's Dawn spacecraft obtained during more than a year in orbit around the asteroid Vesta. A towering mountain, rising more than twice the height of Mount Everest, sticks out from the south pole at the bottom of the image. A chain of three craters known as the "Snowman" can be seen at top left.

    By Alan Boyle, Science Editor, NBC News


    NASA's Dawn mission is saying Hasta la Vesta with a series of parting shots showing the asteroid Vesta, unveiled as the probe hightails it for the dwarf planet Ceres, the next stop on its eight-year, 3-billion-mile (5-billion-kilometer) itinerary.

    The newly released pictures were taken as the Dawn probe wound down more than a year's worth of observations while in orbit around Vesta, an acorn-shaped world in the main asteroid belt. Dawn's $466 million mission was launched in 2007 and is aimed at studying the composition of Vesta as well as Ceres, two huge asteroids that are thought to preserve a record of the solar system's earliest days.

    Dawn's data showed that Vesta has a chemically complex surface and an iron core. Based on its scars, the protoplanet appears to have suffered a mighty cosmic impact not just once, but twice in the past couple of billion years.

    If it weren't for Jupiter's disruptive gravitational influence, Vesta might well have grown to become a major planet. "We can now say with certainty that Vesta resembles a small planet more closely than a typical asteroid," UCLA's Christopher Russell, the mission's principal investigator, said last month.

    Dawn officially left Vesta's orbit during the night of Sept. 4-5, and its ion propulsion drive is gently pushing the probe toward a rendezvous with Ceres in 2015. Russell and his colleagues said today's images represent the last routine daily delivery from the mission during the three-year cruise, although other images may be highlighted as fresh findings are made.

    "Dawn has peeled back the veil on some of the mysteries surrounding Vesta, but we're still working hard on more analysis," Russell said in today's news release. "So while Vesta is now out of sight, it will not be out of mind."

    NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

    An elevation map from NASA's Dawn probe shows the topography of the northern and southern hemispheres of Vesta, updated with readings gathered during Dawn's last look back. Colors represent distance relative to Vesta's center, with lows in violet and highs in red.

    NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

    This image from NASA's Dawn mission, released Sept. 10, shows a shadowy view of the asteroid Vesta's northern hemisphere, using pictures obtained during Dawn's last look back. The mosaic is composed of five images obtained by Dawn's framing camera on Aug. 26, while the probe was at an altitude of 4,000 miles (6,000 kilometers).

    This video highlights Dawn's top accomplishments during its orbit around the giant asteroid Vesta.

    Researchers expect to see a markedly different world when Dawn gets to Ceres. Unlike 330-mile-wide (530-kilometer-wide) Vesta, 583-mile-wide (940-kilometer-wide) Ceres is so massive that its gravity has crushed the world into a basically spherical shape — which is why the International Astronomical Union classifies it as a dwarf planet. Ceres has a differentiated crust, icy mantle and core, and may have a higher water content than Earth.

    "Almost everything we see at Ceres will be a surprise, and totally different from Vesta," Russell said last week.

    Months after Dawn's arrival at Ceres, NASA's New Horizons probe will fly by my favorite dwarf planet, Pluto, and its brood of moons. How will Ceres and Pluto compare? Will we see polar frost caps on Ceres? Ice volcanoes on Pluto? Stay tuned for 2015, the year of the dwarf planets.

    More about Vesta and the dwarfs:

    Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

  • First views of Vesta from orbit

    NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

    NASA's Dawn spacecraft obtained this image with its framing camera on July 17. It was taken from a distance of about 9,500 miles from the asteroid Vesta.

    By Alan Boyle, Science Editor, NBC News

    Today NASA unveiled the first pictures of the asteroid Vesta as seen from an orbiting spacecraft. The pictures of the not-quite-round, 330-mile-wide (530-kilometer-wide) world were sent across a distance of 117 million miles (188 million kilometers). after the Dawn orbiter's successful weekend rendezvous.

    Dawn went into orbit around 1 a.m. ET Saturday, at a distance of about 9,900 miles (16,000 kilometers) from Vesta. The pockmarked space rock ranks as the asteroid belt's No. 1 object in brightness, No. 2 in mass (behind the dwarf planet Ceres) and No. 3 in diameter (behind Ceres and the asteroid Pallas).

    Size isn't everything: Scientists are interested in Vesta largely because it's thought to be made of the stuff that dominated the early solar system. Once upon a time, before they snowballed into the big planets we see today, most of the objects in our celestial neighborhood may well have looked like Vesta.

    "We are beginning the study of arguably the oldest extant primordial surface in the solar system," the $466 million Dawn mission's principal investigator, Christopher Russell of the University of California at Los Angeles, said in today's image advisory. "This region of space has been ignored for far too long. So far, the images received to date reveal a complex surface that seems to have preserved some of the earliest events in Vesta's history, as well as logging the onslaught that Vesta has suffered in the intervening eons."

    To me, Vesta's most interesting scar is the huge crater that was left on its southern end by an ancient impact. The crater is roughly the width of Ohio — so big that it looks more like a dent than a crater. The shattering impact threw off a large amount of debris. Astronomers estimate that about 6 percent of the meteorites that fall to Earth have come from the asteroid.

    This stereo view of Vesta looks at the south polar crater straight on, which explains why the picture looks so flat, even through red-blue glasses. The terrain seems to be smooshed in by Vesta's blast from the past:

    NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

    This anaglyph image of the south polar region of the asteroid Vesta was put together from two clear filter images, taken on July 9 by the framing camera instrument aboard NASA's Dawn spacecraft.The anaglyph image shows the rough topography in the south polar area, including a large mountain, impact craters, grooves and steep scarps in three dimensions. Use red-blue glasses to view in 3-D.

    Dawn's arrival at Vesta comes after nearly four years of cruising through deep space. "Dawn slipped gently into orbit with the same grace it has displayed during its years of ion thrusting through interplanetary space," said Marc Rayman, Dawn's chief engineer and mission manager at NASA's Jet Propulsion Laboratory. "It is fantastically exciting that we will begin providing humankind its first detailed view of one of the last unexplored worlds in the inner solar system."

    During the next three weeks, the probe will settle into orbit, look around the asteroid to see if it has any moons, and get ready for a yearlong stretch of scientific observations. In 2012, Dawn will leave Vesta behind and start making its way toward a 2015 rendezvous with Ceres, a 590-mile-wide (950-kilometer-wide) world that has enough bigness and roundness to qualify as a dwarf planet. To find out where Ceres and other worlds stand nowadays, check out our interactive look at "the new solar system."

    NASA / JPL-Caltech / JAXA / ESA

    This composite shows the comparative sizes of eight asteroids that have been spotted by space probes.

    More 3-D views from space:

    Got 3-D? NASA provides some suggestions for purchasing red-blue glasses via mail order, and you also may be able to find them at novelty stores. I've been known to send out 3-D glasses to Cosmic Log readers, and although I'm not quite ready for the next giveaway, you'll be the first to know if you "like" the Cosmic Log Facebook page. You can also connect with the Cosmic Log community by following @b0yle on Twitter. To learn even more about Ceres and other dwarf planets (including Pluto, my personal favorite), you can check out my book, "The Case for Pluto."