NASA steps closer to nuclear power for moon base

NASA has made a series of critical strides in developing new nuclear reactors the size of a trash can that could power a human outpost on the moon or Mars. Three recent tests at different NASA centres and a national lab have successfully demonstrated key technologies required for compact fission-based nuclear power plants for human settlements on other worlds. "This recent string of technology development successes confirms that the fission surface power project is on the right path," said Don Palac, NASA's fission surface power project manager at the Glenn Research Centre in Cleveland, Ohio, in a statement. Power on the moon, NASA's current plan for human space exploration is to return astronauts to the moon by 2020 on sortie missions that could lead to a permanent outpost for exploring the lunar surface and testing technologies that could aid a manned mission to Mars. The space agency has been studying the feasibility of using nuclear fission power plants to support future moon bases. Engineers performed tests in recent weeks as part of a joint effort by NASA and the Department of Energy.

Nuclear fission power plants work by splitting the nuclei of atoms in a sustainable, controllable reaction that releases heat, which can then be funnelled through a power converter to transfer that energy into usable electricity. A small fission-based nuclear reactor coupled with a Sterling engine could provide up to 40 kilowatts of usable energy, enough to support a moon base or Mars outpost, project scientists said. That's about the same amount of power needed to supply eight houses on Earth, NASA officials have said. Key milestones in one of the recent tests, Palac's team subjected a lightweight radiator panel prototype to the vacuum conditions it would experience in space, as well as extreme cold (minus 125 degrees Celsius, or about minus 193 degrees Fahrenheit). The radiator is about six feet wide and nine feet long, and one of 20 that would be required to keep a lunar fission reactor cool, project officials said.

For comparison, the four giant solar arrays on the International Space Station can generate up to 120 kilowatts of usable power - about the equivalent to support 42 average-sized homes. They extend from a main truss as long as football field and make the space station easily visible at night on Earth to the unaided human eye.

A second fission power milestone included pumping molten liquid metal through a Sterling engine, an engine driven by heat, to simulate how heat from a nuclear reactor could be shunted to a converter to generate power. The test was carried out at NASA's Marshall Space Flight Centre in Huntsville.

The third test bombarded a Stirling engine alternator with radiation, up to 20 times the cumulative dose allowed for today's fission power plants on Earth, to see how it would hold up. It passed with flying colours, NASA officials said. Engineers performed the 26-hour endurance test at the Sandia National Laboratory in Los Alamos, N.M. "The pace of progress exhibited by these three achievements in the same time period is exciting," said Lee Mason, NASA's principal investigator for fission surface power at the Glenn Research Centre. "It has built the team's confidence and prepared them for challenges that lay ahead." The next step for NASA's fission power project is to combine its radiator, engine and alternator successes into a single non-nuclear power plant demonstration. That test is slated to begin in 2012, NASA officials said.

Courtesy: Space

Bird experiment shows Aesop's fable may be true

From the goose that laid the golden egg to the race between the tortoise and the hare, Aesop's fables are known for teaching moral lessons rather than literally being true. But a new study says at least one such tale might really have happened.

It's the fable about a thirsty crow. The bird comes across a pitcher with the water level too low for him to reach. The crow raises the water level by dropping stones into the pitcher. (Moral: Little by little does the trick, or in other retelling, necessity is the mother of invention.) Now, scientists report that some relatives of crows called rooks used the same stone-dropping strategy to get at a floating worm. Results of experiments with three birds were published online recently by the journal Current Biology.Rooks, like crows, had already been shown to use tools in previous experiments.Christopher Bird of Cambridge University and a colleague exposed the rooks to a 6-inch-tall clear plastic tube containing water, with a worm on its surface. The birds used the stone-dropping trick spontaneously and appeared to estimate how many stones they would need. They learned quickly that larger stones work better.In an accompanying commentary, Alex Taylor and Russell Gray of the University of Auckland in New Zealand noted that in an earlier experiment, the same birds had dropped a single stone into a tube to get food released at the bottom. So maybe they were just following that strategy again when they saw the tube in the new experiment, the scientists suggested.

But Bird's paper argued there's more to it: The rooks dropped multiple stones rather than just one before reaching for the worm, and they reached for it at the top of the tube rather than checking the bottom.The researchers also said Aesop's crow might have actually been a rook, since both kinds of birds were called crows in the past.

Courtesy: AP Science

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