U.S. President Barack Obama lauded NASA’s final space shuttle launch July 8, saying that the blastoff marks the end of one chapter of human spaceflight, but also the start of a new one.

“Today’s launch may mark the final flight of the Space Shuttle, but it propels us into the next era of our never-ending adventure to push the very frontiers of exploration and discovery in space,” Obama said in a statement.

Atlantis launched into space at 11:29 a.m. EDT (1529 GMT) from the Kennedy Space Center in Florida, marking the final flight of the space shuttle program, which NASA is shutting down after 30 years of spaceflight. The shuttle is carrying four astronauts on a 12-day delivery mission to the international space station.

“Behind Atlantis and her crew of brave astronauts stand thousands of dedicated workers who have poured their hearts and souls into America’s Space Shuttle program over the past three decades,” said Obama, who did not attend the launch but did tour Atlantis with his family before launch.

“To them and all of NASA’s incredible work force, I want to express my sincere gratitude. You helped our country lead the space age and you continue to inspire us each day.”

NASA is retiring its space shuttle fleet to make way for a new exploration program aimed at deep space missions. Thousands of contractors are expected to lose their jobs once the program is no more.

Previously, the agency planned to replace the shuttle program with a new one aimed at returning astronauts to the Moon. But Obama canceled that plan and gave NASA a new directive for deep space exploration, including a crewed asteroid mission by 2025.

“And I have tasked the men and women of NASA with an ambitious new mission: to break new boundaries in space exploration, ultimately sending Americans to Mars. I know they are up to the challenge — and I plan to be around to see it,” Obama said.

NASA currently plans to use a new space capsule, called the Multi-Purpose Crew Vehicle, for future deep space missions. The vehicle is based on work for the agency’s Orion spacecraft developed for the previous Moon plan.

The heavy-lift rocket for the new program is called the Space Launch System, but the details of the booster are not yet final. NASA officials have said they plan to settle on a design for the new rocket by the end of summer.

NASA’s space exploration plan will lead to new advances in science and technology, as well as spur education, innovation and economic growth, the president said.

A major hurdle to Obama’s deep space exploration vision is NASA’s budget, which is mired in a maze of congressional battles over cutbacks.