NASA says it has found proof that water shaped the rocks on the left, in a photograph taken by the Mars rover Curiosity (left). For comparison, the agency released an image of rocks from the Earth (right).
<strong>Pathfinder, 1997: </strong>The first mission to land a rover on Mars, Pathfinder touched down in Ares Vallis, an ancient flood plain in the planet's northern hemisphere. Among the 2.3 billion bits of data sent back by the lander and its rover, Sojourner, were 15 chemical analyses of rocks and soil, which suggested Mars had once had liquid water and a thicker atmosphere.
<strong>Spirit, 2010:</strong> When NASA's Spirit rover got stuck in Martian sand, it proved to be a lucky break: The spinning wheel churned up soil that provided evidence of rocks formed in the presence of water.
<strong>Opportunity, 2004: </strong>Opportunity discovered tiny mineral spheres — nicknamed blueberries — poking out of rocks that were likely formed by water. Researchers using Opportunity's science instruments identified them as concretions rich in the mineral hematite, deposited by water saturating the bedrock.
<strong>Curiosity 2012:</strong> A wider view of the outcrop of a former streambed shows bedrock that scientists believe was likely exposed by meteorites striking the surface of Mars.
<strong>Curiosity, 2012:</strong> NASA says that water shaped the rocks on the left, in a photograph taken by the Mars rover Curiosity. For comparison, the agency released an image of rocks from the Earth (right).
NASA's Curiosity rover has found definitive proof that water once ran across the surface of Mars, the agency announced today. NASA scientists say new photos from the rover show rocks that were smoothed and rounded by water. The rocks are in a large canyon and nearby channels that were cut by flowing water, making up an alluvial fan.
"You had water transporting these gravels to the downslope of the fan," NASA researchers say. The gravel then formed into a conglomerate rock, which was in turn likely covered before being exposed again.
This week, we've been taking time to listen to several world leaders address the U.N. General Assembly in New York with special emphasis on the looming crisis over Iran's nuclear ambitions. We heard from President Obama and Republican presidential nominee Mitt Romney on Tuesday, from Iranian President Mahmoud Ahmadinejad yesterday. Today, Israeli Prime Minister Benjamin Netanyahu addressed the gathering and outlined the situation in stark terms. He warned that Iran will have enough enriched uranium to make a nuclear bomb by next summer.
This is TALK OF THE NATION. I'm Neal Conan in Washington. More than 38 million kids get their lunches through the National School Lunch Program, and with more than a third of the nation's youngsters overweight or obese, the cafeteria has become a battleground.