Washington (Agencies): President Barack Obama has proposed restriction in expenses at NASA, sending a 2012 budget blueprint to Congress that calls for a five-year freeze on expending levels at the US space agency.

Obama would limit NASA's budget to last year's levels, USD18.7 billion yearly through fiscal 2016. The figure represents a 1.6-per cent decrease from the spending total the agency had sought for fiscal 2011, which ends in September.

NASA Administrator Charles Bolden wanted to put a brave face on the budget limitations, saying the administration's proposal "maintains our commitment to human spaceflight" and research.

"It should not compromise what NASA wants to do but it certainly would slow it down," said John Logsdon, a former director of the Space Policy Institute in Washington and an independent consultant to the Obama administration.

The move comes just as the United States winds down its space shuttle programme, and struggles to move forward on a replacement for the vaunted vessels that have carried hundreds of astronauts into space.

Nearly half of Obama's proposed 2012 NASA budget, and for the next five years, is dedicated to space operations and exploration systems.

Seven billion dollars have been allocated for work aimed at making the new heavy launcher operational by 2016. It will be important for sending astronauts beyond low Earth orbit to an asteroid and to Mars.

Obama's budget would persist to drive for commercial partnerships to develop reliable access to the space station and lessen the reliance on Russia, whose Soyuz spacecraft will be carrying US astronauts to the ISS until a shuttle successor is developed.

The draft budget proposes 850 million dollars in 2012 as seed money to help companies like SpaceX, which has already successfully launched a prototype space capsule into orbit.