Early Monday morning, the space shuttle Endeavor lit up the heavens as it climbed toward the sky, en route to the International Space Station for its second-to-last flight. Endeavor and Atlantis each have one more mission; Discovery has two. By October, the shuttle will never fly again.

With the shuttle out of commission, the U.S. will not have a vehicle to launch humans into space. A replacement dubbed “Constellation” was introduced in 2004, but quickly encountered funding shortages; its maiden voyage was delayed beyond 2014. President Obama’s NASA budget proposal for 2011 scraps the program, instead redirecting billions of dollars to engine research, robotics and commercial space contracts.

“It’s the kind of thing that I wanted to see happen years ago, but [NASA] went in a different direction,” said Scott Hubbard, professor of aeronautics and astronautics. “I think NASA is returning to its roots in terms of building advanced work.”

With the space shuttle’s retirement and the Constellation program’s cancellation, Hubbard says shifting NASA from a launch system developer to a launch system purchaser will free up funding to focus on cutting edge technologies. His lab is focusing on astrobiology, concentrating on technologies for obtaining and returning samples from Mars to Earth.

NASA has the budget for “building one-of-a-kind things that are not commercially viable at all,” Hubbard said.

With the budget increase, he hopes some dollars will return to Stanford.

Annual NASA research spending at Stanford peaked at $98,383,000 during fiscal year 2004. It has steadily declined, reaching $24,850,000 in 2009.

“It doesn’t play near as big a part for Stanford as it used to,” said Barbara Cole, director of the Office of Sponsored Research.

Since the budget hasn’t been finalized and no grant proposals have been written, “it’s too soon to tell just how it’s going to impact us in what area,” Cole said.

Juan Alonso, professor of aeronautics and aerospace, predicts Stanford robotics, rocket research and aerospace design will see NASA funding in the near future.

“Putting people in space, and trying to either colonize or visit other planets or the moon or Mars — it’s motivated by the exploration drive that humans have had from discovering new countries or new continents to now discovering other worlds,” Alonso said.

Alonso’s lab focuses on aerospace systems, developing design models for hypersonic aircraft, efficient engine technologies and passenger load that one day could form the basis for orbital aircraft.

The budget will “make NASA more like what it should be, the pointy end of the spear, out there doing the kinds of things that nobody else would do, and leaving the more routine launch services to the commercial sector,” Hubbard said.

“The traditional role of government is to invest in things that aren’t ready for commercial business, and that’s what NASA’s going to be doing,” Hubbard said. “[It will] buy those things that the commercial sector is producing as a service.”

“There are a lot of analogies to the early days of aviation,” Hubbard said. “I always use the analogy to 1916-1920, when the government offered or said they would buy mail services. This is where Bill Boeing got his start, this is where the Loughead brothers, which became Lockheed, got going. These early mail routes that got purchased by the government moved aviation from just barnstorming drill figures to a real, commercially viable, routine business. I think we’re in a transition mode for launch services for NASA in the same way, now in the 21st century, and I think that’s exactly the right thing to do.”

Before suborbital tourism emerged, for years companies independently developed and built rockets and satellites. Hubbard said more money is spent in the commercial space industry today than in the government sector. As a result, he predicts that five years from now, commercial providers will transport cargo to the International Space Station on behalf of NASA.

And over the next two decades, Hubbard anticipates even greater international collaboration on space exploration. He expects robots will return surface samples from Mars and Titan, scientists will find evidence of more Earthlike planets nearby and satellites will capture a clear picture of climate change on Earth. In the meantime, he supports a “flexible path,” where human exploration gradually escapes Earth’s orbit to visit an asteroid, which is less expensive than landing on the moon.

In twenty years, he expects humans will almost be ready for a trip to Mars.

“The moon might be a stepping stone — maybe we partner with the Chinese or other nations,” Hubbard said. “But Mars is the human target that I think is the most interesting.”

Until then, a quick jaunt to space is available for $200,000 from Virgin Galactic. By the time astronauts are preparing to leave for Mars, he expects daily launches of suborbital and orbital commercial spacecraft, some en route to private orbiting space stations both for research and tourism.

“We’ll have set up some kind of, instead of air traffic management, space traffic management,” Hubbard said.

Alonso expects the gap in American spaceflight to be more significant. He predicts the private sector will catch up to NASA’s current spaceflight capabilities given enough investment and time, but doubts it will happen more quickly than if the Constellation Program were continued. With budget shortfalls, Alonso expected it would be delayed to 2015 or 2016, but doesn’t expect commercial companies to develop human-rated orbital spacecraft for six to ten years.

But is a ten-year hiatus from human space travel a problem?

“Probably not,” Alonso said.

He cautions that if NASA temporarily avoids direct involvement in human spaceflight, the “greater goal” — human exploration of the solar system — could slide to the backburner.

On the other hand, he says, a lot of space exploration can be accomplished without humans. Robotic exploration has come a long way, and if it improves significantly we may be able to do many more things that were reserved to astronauts with robots.

“So my opinion is that you need a balanced approach between the two. And at the moment, the plans seem to sort of focus on robotic exploration and developing technologies that may one day enable human exploration,” Alonso said.

In his view, establishing a lunar base is a good first step for humans.

“It’s closer to Earth such that humans can learn how to live in a different ‘planet,” Alonso said. “It’s far enough to learn how to live in a different planet, but its close enough in case we don’t learn very quickly, stumble and fall a few times, and need to recover gracefully.”

Alonso agrees with Hubbard that the budget will have a positive impact on research at universities and private companies, because work that was going into a rocket will now proceed to develop more advanced technology.

But there is an earthly catch.

“It’s an expensive proposition, all of this space exploration,” Alonso said. “And it’s actually hard to justify some of these efforts when the nation is embroiled in economic crisis and budget deficit and various other things that more directly impact people who live here on Earth.”

But regardless of the price tag, Hubbard and Alonso are excited for the Obama budget’s potential benefits to aerospace.

“With the shift back to technology, I think that you’re going to see a lot more opportunities,” Hubbard said.

CORRECTION: In an earlier version of this story, The Daily incorrectly reported that NASA research spending at Stanford reached $98,383 during fiscal year 2004 and $24,850 in 2009. The actual numbers are $98,383,000 and $24,850,000, respectively.