The field of horses charges down the stretch in the seventh race at Churchill Downs in Louisville, Ky., on June 19, 2009. The day marked the first night racing at the storied track in its 135-year history. Track superintendent Butch Lehr is retiring after Saturday's race. He's been maintaining the track since 1982.
Credit Ed Reinke / AP
Lehr rolls in a section of a mosquito trap which is set up near the turf course at the track Aug. 13, 2002, in Louisville, Ky.
The surface on which Kentucky Derby horses will race Saturday is a special piece of real estate, built for high performance and safety. The track is generically described as dirt, but is actually a careful mixture of river sand, silt and clay.
Egyptian presidential candidate Abdel Moneim Aboul Fotouh is welcomed by supporters upon his arrival at a meeting north of Cairo, on April 26. He was formerly a leader of the Muslim Brotherhood, but was kicked out of the organization.
Credit Amr Nabil / AP
Mohammed Morsi is the candidate for the Muslim Brotherhood, the group that got the most votes in parliamentary elections. He's shown here at a campaign rally in Cairo on April 30.
In this photograph of a courtroom sketch, Khalid Sheikh Mohammed, charged with orchestrating the Sept. 11 attacks, attends a court hearing at Guantanamo in 2008. He's expected to appear in a military court Saturday.
Khalid Sheikh Mohammed and four other men charged in the Sept. 11 attacks were supposed to be tried six years ago in a military tribunal created by the Bush administration.
But that system — which allowed hearsay evidence, among other things — faced questions about its fundamental fairness. When President Obama came into office, he put all the proceedings at Guantanamo on hold and asked that the commission system be revamped.
Since then, there has been an effort to make sure the trials at Guantanamo are credible, with both Congress and the Supreme Court weighing in.
The Obama administration today released a new set of rules for oil and gas drilling on public land. As NPR's Elizabeth Shogren reports, the rules are meant to keep companies from polluting water when they use the engineering technique known as fracking.
ELIZABETH SHOGREN, BYLINE: Hydraulic fracturing is what made the current drilling booms possible. Companies force hundreds of thousands of gallons of water, sand, and chemicals deep underground to open up cracks in the rock and make the oil or natural gas flow faster.