The U.S. National Aeronautical and Space Administration unveiled on Wednesday plans to build a $35 billion rocket called the Space Launch System to take man to Mars.

The rocket would be launched after 10 years, but unmanned tests launches from the Kennedy Space Center in Cape Canaveral, Fla., are expected in six years, NASA Administrator Charles Bolden told the U.S. Congress.

"We're investing in technologies to live and work in space, and it sets the stage for visiting asteroids and Mars," The New York Times quoted Bolden saying.

NASA Exploration and Operations Chief William Gerstenmaier said although the rocket will be difficult to build, it would be capable of going beyond low-Earth orbit. He said the early prototype would have 10 percent more thrust than the Saturn V used by the Apollo astronauts to reach the moon. The final version would be 20 percent more powerful with horsepower the equivalent of 208,000 Corvette engines.

Its aim is to fly to a nearby asteroid by around 2025 and head for Mars sometime in the 2030s. There could possibly be a short trip to the moon, but it is not the main goal.

But NASA' ambitious trajectory may be at a risk because of the large spending involved at a time when Washington is cutting corners and the country's deficit is counted in the trillions.

Some senators are in favor of the new technology despite the cost, but many observers doubt Congress would agree to the sky-high price tag.

"Will it be tough times going forward? Of course it is.... We are in an era in which we have to do more with less - all across the board - and the competition for the available dollars will be fierce. But what we have here now are the realistic costs," The Sydney Morning Herald quoted Sen. Bill Nelson, D-Fla.

Former Democratic congressional budget analyst Stan Collender calculated the odds of NASA getting the House's approval at only 50-50.

"In the current political environment, new spending is probably the most taboo thing in politics," he said.

The planned rocket will use liquid fuel, unlike previous space shuttles which relied heavily on twin solid rocket boosters to get off the ground.