WASHINGTON – NASA said Monday it’s not giving up on Mars, but it’ll have to get there later and at a lower price.

Earlier this month, the president’s budget canceled joint U.S.-European robotic missions to Mars in 2016 and 2018. Now top science officials say they are scrambling to come up with a plan by the end of the summer for a cut-rate journey to the red planet in 2018.

NASA sciences chief John Grunsfeld said he thinks there’s a better than even chance that NASA will not miss the 2018 opportunity. That’s when Mars passes closest to Earth, something that only happens once every 15 years. It offers a chance at fuel cost-savings.

Agency officials who met with upset scientists on Monday seemed intent on salvaging a program that took some of the deepest science spending hits in the president’s budget. Until this month, NASA had been ramping up its Martian ambitions.

Meanwhile, this summer, the most high-tech rover ever, Curiosity, will land near the Martian equator in search of the chemical building blocks of life. The more scientists study Mars, the closer they get to answering whether microbial life once existed there, a clue to the ultimate question: Are we alone?

Two years ago, President Barack Obama stood at Kennedy Space Center and said it was more of a priority than going to the moon.

But the two upcoming missions were then canceled along with the most ambitious Mars flight yet – one the National Academy of Sciences endorsed as the No. 1 solar system priority. That was a plan to grab Martian rocks and soil and bring them back to Earth.

Mars researcher Steve Squyres of Cornell University, who headed the national academy panel said if NASA couldn’t make progress on a Mars sample return, the space agency should think about moving on to the next priorities, such as visiting Jupiter’s moon Europa.