WASHINGTON — The top Republican on the U.S. Senate Judiciary Committee asked NASA Administrator Charles Bolden April 18 for a briefing on whistleblower allegations that foreign nationals obtained NASA secrets while visiting the agency’s Ames Research Center in Mountain View, Calif.

“Recently my office received serious allegations from whistleblowers regarding [NASA Ames] and its current director Simon P. Worden,” Sen. Charles Grassley (R-Iowa) wrote in a letter to Bolden, first obtained and reported by Science magazine. “These allegations came to my office from individuals who are concerned about the direction of [Ames] under Mr. Worden’s leadership.”

Worden and Ames spokesman Michael Mewhinney referred questions to NASA spokesman Michael Cabbage, who said that Bolden has received Grassley’s letter “and is in the process of reviewing it.”

According to Grassley, the whistleblowers allege that foreign nationals who were granted access to Ames by Worden “obtained NASA secrets and cutting edge technology while not possessing the proper clearance in violation of International Traffic in Arms Regulations,” or ITAR.

Grassley also told Bolden in the letter that he “has received information that federal law enforcement has opened investigations into several employees at [Ames], including Director Worden, the director of [Ames] programs Alan Weston, and foreign nationals.” The investigations, Grassley wrote, “apparently involve issues related to ITAR violations and national security.”

Grassley has asked for a briefing by April 27.

Worden, a retired Air Force brigadier general who has worked for the Defense Advanced Research Projects Agency and commanded Air Force Space Command’s 50th Space Wing, has been director of Ames since 2006.

Worden joined NASA following a stint as an adviser to Kansas Republican Sam Brownback, then serving as chairman of the Senate Commerce science, technology and space subcommittee.

Brian Berger is editor in chief of SpaceNews.com and the SpaceNews magazine. He joined SpaceNews.com in 1998, spending his first decade with the publication covering NASA. His reporting on the 2003 Space Shuttle Columbia accident was...