Mercury outlasts moon when it comes to craters
Source: Agencies |
April 1, 2011, Friday
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THINK the moon has many craters? New photos from the first spacecraft to orbit Mercury show the tiny inner planet has far more impressive battle scars from regular high-speed peltings by space rocks.
NASA's Messenger spacecraft, which began orbiting the planet less than two weeks ago, reveals a pock-marked planet full of craters from pieces of asteroids and comets.
"Mercury has had an exposed surface for at least 3.5 to 4 billion years and some of those surfaces are extremely cratered to the point where there are so many craters they start to obscure one another," said mission chief scientist Sean Solomon.
He said it was surprising how many secondary craters there are. Those are craters created by the falling soil kicked up from space rock collisions. Those initial space rock crashes "throw out a lot of material in the explosive process," he said.
One area of the far north of Mercury had never been seen by previous spacecraft on mere fly-bys.
The new images show scatterings of secondary craters, almost like a loaded pizza, but not the primary crater that was first carved out. The region is also so far north that the sun barely gets above the horizon and casts long shadows. "It's heavily cratered," Solomon said on Wednesday. "It may have happened on a particularly bad day."
Messenger has been circling Mercury only since March 17. In its first day of photo transmission, the space probe sent back 224 pictures, Solomon said. By the end of this week, NASA will have received more than 15,000 pictures from the US$446 million spacecraft.
The first image offered a glimpse of the planet's dark, frigid south pole, where scientists think there may be ice. But the photo isn't close enough to tell if radar images from Earth that hint at ice are correct, Solomon said. Photos of the poles are scheduled for later in the mission.
NASA's Messenger spacecraft, which began orbiting the planet less than two weeks ago, reveals a pock-marked planet full of craters from pieces of asteroids and comets.
"Mercury has had an exposed surface for at least 3.5 to 4 billion years and some of those surfaces are extremely cratered to the point where there are so many craters they start to obscure one another," said mission chief scientist Sean Solomon.
He said it was surprising how many secondary craters there are. Those are craters created by the falling soil kicked up from space rock collisions. Those initial space rock crashes "throw out a lot of material in the explosive process," he said.
One area of the far north of Mercury had never been seen by previous spacecraft on mere fly-bys.
The new images show scatterings of secondary craters, almost like a loaded pizza, but not the primary crater that was first carved out. The region is also so far north that the sun barely gets above the horizon and casts long shadows. "It's heavily cratered," Solomon said on Wednesday. "It may have happened on a particularly bad day."
Messenger has been circling Mercury only since March 17. In its first day of photo transmission, the space probe sent back 224 pictures, Solomon said. By the end of this week, NASA will have received more than 15,000 pictures from the US$446 million spacecraft.
The first image offered a glimpse of the planet's dark, frigid south pole, where scientists think there may be ice. But the photo isn't close enough to tell if radar images from Earth that hint at ice are correct, Solomon said. Photos of the poles are scheduled for later in the mission.
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