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Science Notes / Astronomy, archaeology

NASA to launch 2 probes to moon

Many space enthusiasts are mourning the end of the shuttle program, but NASA is still going to the moon. The space agency plans to launch two unmanned probes on Sept. 8 that will orbit our nearest celestial neighbor simultaneously. The mission is intended to help answer questions about how the moon and the Earth came into being, the temperature conditions at various points in the history of the solar system, and the composition of the moon, from crust to core.

Like much of NASA's work, the GRAIL mission -- named for the Gravity Recovery and Interior Laboratory probes -- is all about gravity. Here's how it's supposed to work: The spacecraft will leave Earth together on a 125-foot-tall Delta 2 rocket. Once they're carried away from the pull of Earth, the two GRAILs will be released. The craft each weigh about 500 pounds, and NASA describes them as about the size of a washing machine.

The GRAIL twins will take the long way to the moon -- about three or four months, compared with the four days it took Neil Armstrong et al. in 1969 on the Apollo 11 mission. GRAIL A will enter lunar orbit on New Year's Eve, with GRAIL B doing the same on New Year's Day. The key to the mission is maintaining the distance between the two spacecraft. As GRAIL A and B whip around the moon over the following 82 days, small variations in the moon's gravitational field will change the speed of each craft, causing them to drift slightly closer together or farther apart.

The slight changes in the moon's gravity at different points indicate what's going on inside the moon itself.

"We are testing the giant-impact theory of the moon -- the idea that the moon formed very early in Earth history due to impact with a Mars-sized body," says Zuber. "The impact threw off material that coalesced to form the moon." The mapping of the moon's interior will help reveal both the internal composition and the temperature changes the moon experienced over time.

Washington Post

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Human ancestors went to sea

Early manlike creatures may have been smarter than we think. Recent archaeological finds from the Mediterranean show that human ancestors traveled the high seas.

A team of researchers that included a North Carolina State University geologist found evidence that our ancestors were crossing open water at least 130,000 years ago. That's more than 100,000 years earlier than scientists had previously thought.

Their evidence is based on stone tools from the island of Crete. Because Crete has been an island for eons, any prehistoric people who left tools behind would have had to cross open water to get there.

The tools the team found are so old that they predate the human species, said Thomas Strasser, an archaeologist from Providence College who led the team. Instead of being made by our species, Homo sapiens, the tools were made by our ancestors, Homo erectus.

The tools are very different from any others found on Crete, Strasser said. They're most similar to early stone-age tools from Africa that are about 700,000 years old, he said.

-- Raleigh News & Observer