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Environmental Protection Agency chief Mike Leavitt signed new regulations Tuesday aimed at cutting pollutants from diesel engines in off-road vehicles such as farming and construction equipment by 90 percent over the next eight years.

The commission Congress created to investigate the security of electronic voting machines said the software is not reliable enough for use in the 2004 presidential election. Spencer Michels looks at the controversy in California over electronic voting methods.

Since 1990, the Hubble Space Telescope has been supplying scientists with reams of information about our universe. Tom Bearden reports that, despite its successes, safety concerns may prevent NASA from making the necessary repairs to the telescope.

NASA announced Tuesday the discovery of evidence that water once existed on the surface of Mars, creating conditions that may have supported life. NASA scientist Jim Garvin explains the findings and implications.

The Spirit rover drove into a Martian hollow, while halfway around the planet, its twin dug a trench with one wheel to investigate the soil's content. Ray Suarez discusses the latest findings with Steve Squyres of Cornell University, principle investigator…

Dr. Elias Zerhouni, director of the N.I.H., is spearheading efforts to speed up the time it takes for laboratory discoveries to be translated into new medical treatments and drugs. Susan Dentzer talks to Zerhouni and other researchers about the proposed…

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