He "made headlines for trying to keep agency missions on schedule and under budget" but faced "internal battles over funding". He was credited with making "significant changes that have helped restore the importance of science in NASA's mission". On March 26, 2008 it was announced that Stern had resigned his position the previous day, effective April 11. He was replaced by Ed Weiler, who was to serve his second stint in the position. The resignation occurred on the same day that NASA Chief Michael D. Griffin overruled a decrease in funding for the Mars Exploration Rovers and Mars Odyssey missions that was intended to free up funds needed for the upcoming Mars Science Laboratory. NASA officials would neither confirm nor deny a connection between the two events. Stern left to avoid cutting healthy programs and basic research in order to cover cost overruns. He believed that cost overruns in the Mars program should be accommodated from within the Mars program, and not taken from other NASA programs. Michael D. Griffin became upset with Stern for making major decisions without consulting him, while Stern was frustrated by Griffin's refusal to allow him to cut or delay politically sensitive projects. Griffin favored cutting "less popular parts" of the budget, including basic research, and Stern's refusal to do so led to his resignation. Casting doubt on the theory that Stern resigned due to conflict with former Administrator Griffin is his statement of March 25, 2009 at spacepolitics.com: On November 23, 2008, in an op-ed in The New York Times, Stern criticized NASA's inability to keep its spending under control. Stern said that, during his own time at NASA, "when I articulated this problem... and consistently curtailed cost increases, I found myself eventually admonished and then neutered by still higher ups, precipitating my resignation earlier this year." While complimenting NASA Administrator Michael D. Griffin, Stern suggested that Griffin's decision to again bail out an over-budget mission was motivated by fear "that any move to cancel the Mars mission would be rebuffed by members of Congress protecting local jobs". Since leaving NASA, Stern has made constructive criticisms of the budgetary process and has advocated for revamping its public appeal. Planetary classification Stern has become particularly involved in the debate surrounding the 2006 definition of planet by the IAU. After the IAU's decision was made he was quoted as saying "It's an awful definition; it's sloppy