A concept of the European Space Agency's ExoMars Rover. Credit: European Space Agency/AOES Medialab artist's concept

Scientists briefed on U.S. President Barack Obama’s proposed NASA budget say it would reduce funding for planetary science by $300 million next year with further cuts over the next five years, The Washington Post reports.

NASA’s Mars exploration program would take a big hit under the plan, which severs the U.S. partnership with the European Space Agency on the ExoMars program to send probes to Mars in 2016 and 2018. “The impact of the cuts … will be to immediately terminate the Mars deal with the Europeans,” G. Scott Hubbard, a Stanford University and former NASA planetary scientist, said. “It’s a scientific tragedy and a national embarrassment.”

U.S. Rep. John Abney Culberson (R-Texas) said the Obama cuts “absolutely will not fly” with the House committee that oversees NASA. “You don’t cut spending for critical scientific research endeavors that have immeasurable benefit to the nation and inspire the human spirit of exploration we all have,” Culberson said.

The budget is set to be released Feb. 13.