Delicately but deliberately, NASA is closing down the Constellation program that was to replace the space shuttle and return astronauts to the moon.

President Obama wants to cancel NASA’s moon plans and shut down the program in October. But Congress has not agreed and says Constellation cannot be legally scrapped without its OK.

That leaves NASA caught in a tug of war. So engineers are building pieces of Constellation while at the same time NASA is turning off parts of the program that it never officially started with contracts.

The agency has pulled the plug on bidding to run ground operations for the program at Kennedy Space Center and decided not to award contracts for alternative designs of the Altair lander, which astronauts were to ride to the moon’s surface.

It advised contractors that “there will be no further evaluation of their proposals nor will there be an award” to develop the first phase of the Ares V cargo lifter. The Ares V, a giant rocket bigger than the Apollo era’s Saturn V, was going to launch Altair and all the extra fuel and gear astronauts would need to go back to the moon for long stays.

“In light of recent events and the uncertainty of future Ares V requirements for fiscal year 2011 and beyond, it is in NASA’s best interest to cancel the current solicitation,” Byron W. Butler, a NASA procurement officer, wrote to interested contractors March 11.

The recent events Butler referred to include Obama’s proposal to have the space agency rely on private rocket companies to ferry astronauts and cargo to the International Space Station on fixed-price contracts. Money now planned for Constellation would be spent on research and development of new technologies to one day take humans to the moon, nearby asteroids or Mars.

But as NASA slows down in some areas of Constellation, it is pressing ahead in others. It is conducting studies for more test flights at Kennedy Space Center of the behind-schedule and over-budget Ares I rocket that was supposed to take astronauts into orbit, where they would rendezvous with the cargo of the Ares V.

NASA also recently decided to give $34.5 million in stimulus funds to build part of the Ares I rocket. In an internal memo obtained by the Orlando Sentinel, NASA officials said the agency could justify the award for the Ares I Upper Stage Production Contract because “a portion of the work has relevance to future exploration needs.”

Congress is not pleased. Nearly 30 members wrote a letter to NASA Administrator Charles F. Bolden Jr. in February complaining about rumors of shutdown activities and pointing out that the Ares I rocket contracts required buying parts in advance and that any attempt to disrupt those purchases “can be viewed, with strong legitimacy, as a termination of the program.”

More recently, 16 members of Congress called on federal auditors at the Government Accountability Office to rule on whether NASA is on the right side of the law.

“To what extent can planned contracts be canceled, suspended, or slowed and the agency still be considered to have not terminated the program?” the lawmakers asked in a March 12 letter.

They asked the GAO for a quick decision -- in 60 days -- because they are worried that NASA’s efforts might terminate the program before Congress can save it.

“NASA is ignoring the will of Congress by taking steps to terminate the Constellation program. This effort sends the clear message that there are no loopholes, exclusions, or other routes the agency can use to kill the program,” Sen. George LeMieux (R-Fla.) said in a statement.

NASA said it was abiding by the law.

“NASA is fully complying with the provisions of the FY 2010 Consolidated Appropriations Act,” spokesman Mike Cabbage said in a statement. “However,” he added, quoting a recent letter to Congress from Bolden, “in general, the program will ‘refrain from initiating new work not currently under contract and also from expanding the scope of any work that currently is under contract.’ ”

rblock@orlandosentinel.com

mmatthews@orlandosentinel.com