(CNN) -- NASA plans to capture an asteroid and start sending astronauts aloft again by 2017, even with a tighter budget, the U.S. space agency announced Wednesday.
The Obama administration is asking Congress for just over $17.7 billion in 2014, down a little more than 1% from the nearly $17.9 billion currently devoted to space exploration, aeronautics and other science.
The request includes $105 million to boost the study of asteroids, both to reduce the risk of one hitting Earth and to start planning for a mission to "identify, capture, redirect, and sample" a small one. The plan is to send an unmanned probe out to seize the asteroid and tow it into orbit around the moon, where astronauts would study it.
"This mission allows us to better develop our technology and systems to explore farther than we ever have before ... to places humanity has dreamed of for as long as I've been alive," NASA Administrator Charles Bolden told reporters.
The Obama administration has said before that it wants to send astronauts to explore an asteroid by 2025 and to Mars by 2030.
Wednesday's budget request would include another $20 billion to study near-Earth asteroids -- doubling the current spending on that effort. The funding is aimed not only at finding a suitable asteroid to explore, but also at "protecting the planet," Bolden said.
That concern got new attention after February, when a nearly 150-foot asteroid passed within 18,000 miles of Earth. That one was expected -- but the same day, an unrelated, 45-foot space rock plunged into the atmosphere and exploded high over southwestern Russia, injuring an estimated 1,200 people.
White House science adviser John Holdren told a congressional committee in March that as few as 10% of asteroids more than 150 yards wide -- which he called "potential city killers" -- have been detected.
NASA's budget request includes $822 million for the agency's Commercial Crew Program, its push to resume U.S. space flights through private companies by 2017. Bolden called that the "bottom-line" figure, warning that any cuts would mean delays. NASA has already hired the unmanned SpaceX Dragon to deliver cargo to the International Space Station, though no commercial manned missions are currently under way.
While putting money into renewed human space flight efforts, the proposal cuts scientific research, particularly the study of the other planets in our solar system. Planetary science takes a nearly $300 million hit compared to 2012, the last year detailed figures were available.
NASA officials defended the cut, saying major projects like the Mars rover Curiosity and the upcoming MAVEN probe to study the Martian upper atmosphere are already past their most expensive phases.
"But of course we'll be ramping up again as we approach 2020 and the next Mars rover," said Beth Robinson, the agency's chief financial officer.
Bolden said NASA's Mars research is the biggest part of the planetary science budget.