This story was updated 11:35 a.m. EDT.

WASHINGTON — NASA is recalling Goddard Space Flight Center Director Ed Weiler to the U.S. space agency's headquarters here to take over the Science Mission Directorate in the wake of Alan Stern's resignation.

Stern, a seasoned planetary scientist who joined NASA in April 2007 to pursue a reform-minded agenda, informed colleagues in an e-mail March 26 that he would be leaving the agency in the month ahead.

In his e-mail, which he sent out at 8:34 a.m., according to the time stamp, Stern said that he offered his resignation March 25 and that NASA Administrator Mike Griffin "reluctantly accepted" it.

"I will remain at NASA for a few weeks," Stern wrote. "It's been my privilege to serve the NASA and scientific community and to work with you."

"I also want you to know," Stern continued, "that Mike and I remain on good terms. He remains in my eyes the best administrator NASA has ever had."

In a statement, Griffin commended Stern for his service and announced that Weiler, who served as NASA's space science chief from 1998 to 2004, would replace Stern on an interim basis.

"Alan has rendered invaluable service to NASA as the Principal Investigator for the Pluto/New Horizons mission, as a member of the NASA Advisory Council, and as the associate administrator of the Science Mission Directorate," Griffin said. "While I deeply regret his decision to leave NASA, I understand his reasons for doing so, and wish him all the best in his future endeavors."