On Thursday’s NewsHour…

VOLCANIC ASH GROUNDS FLIGHTS | A giant cloud of ash from a glacial volcano in Iceland grounded hundreds of flights across northern Europe on Thursday. Jim Lehrer gets a report from Independent Television News about when air traffic might resume.

CHANGING THE FUTURE OF NASA | President Obama defended his proposed cuts to NASA’s moon project in favor of investment in private space development, a plan whose critics include prominent former astronauts. Jeffrey Brown talks to former astronaut Harrison Schmitt and space activist Rick Tumlinson about the role of U.S. companies in the new space race.

TEA PARTY ACTIVISTS PROTEST TAX DAY | Jim Lehrer reports as Tea Party activists across the country used Thursday’s income tax filing deadline as a platform to voice disagreements over the growth of government spending.

SPOTLIGHT CITY: TAX DAY TOWN HALL | As part of a series spotlighting public opinion of government, Judy Woodruff gives a tax day report from the NewsHour’s town hall meeting in Tampa. Joining her are White House adviser Christina Romer, former Sen. Mel Martinez, Tampa Mayor Pam Iorio and Hillsborough County Commissioner Mark Sharpe.

U.K. ELECTION TV DEBATE | As Britain’s three candidates for prime minister wage heated campaigns ahead of the May election, Simon Marks reports from London on the politics behind the country’s very first American-style public debate.

Thursday’s anchors are Jim Lehrer and Judy Woodruff. Hari Sreenivasan will have the day’s other top news stories and a look at Web features, including more on Britain’s televised debate from GlobalPost corespondent Michael Goldfarb and a tax day reader’s guide with links to tips on filing.

Plus, our conversations with Pulitzer Prize winners continue on Art Beat.

We hope you join us.