WASHINGTON — As the administration of U.S. President Barack Obama prepares to propose changes to NASA’s human spaceflight program in the president’s 2011 budget request to lawmakers Feb. 1, an independent NASA safety advisory panel is warning the space agency against abandoning its current plans.

In an annual report issued Jan. 15, the Aerospace Safety Advisory Panel (ASAP) cautioned the United States against halting work on NASA’s Ares 1 rocket to fund unproven commercial alternatives.

“To abandon Ares 1 as a baseline vehicle for an alternative without demonstrated capability nor proven superiority (or even equivalence) is unwise and probably not cost-effective,” the report states.

Designed to launch the Orion Crew Exploration Vehicle into low Earth orbit, Ares 1 is a key element of Constellation, NASA’s 5-year-old effort to replace the space shuttle with rockets and spacecraft optimized for the Moon. NASA has invested several billion dollars in Ares 1 since 2005 and last October successfully launched a full-scale prototype of the rocket.

The Aerospace Safety Advisory Panel report lauds Ares 1 as a vehicle “designed from the beginning with a clear emphasis on safety” and notes approvingly “that Time magazine cited the Ares rocket as the ‘best invention of 2009.’”

The future of Ares 1, however, has been in doubt since Obama’s presidential transition team set up shop at NASA headquarters here shortly after the 2008 election and began asking what it would cost to scrap the rocket in favor of using human-rated versions of existing rockets to launch a scaled-back version of Orion. Ares 1 was dealt another political setback last year when a White House-appointed committee led by former Lockheed Martin chief Norm Augustine urged Obama to consider dropping Ares 1 in favor of paying commercial firms to transport astronauts to the international space station.

NASA awarded a pair of contracts totaling $3.5 billion in December 2008 to Dulles, Va.-based Orbital Sciences Corp. and Hawthorne, Calif.-based Space Exploration Technologies (SpaceX) to haul cargo to the space station aboard unmanned vehicles the companies say could evolve to carry people.

SpaceX, in particular, has been urging NASA to commit to fostering development of commercial crew launch services through the expansion of the Commercial Orbital Transportation Services (COTS) program the agency created in 2006 to subsidize development of new cargo delivery systems. SpaceX and Orbital stand to receive a combined $450 million under the COTS program for their competing unmanned systems by the time the two complete demonstration cargo flights.

While the Aerospace Safety Advisory Panel report notes satisfaction with the COTS program’s evolution, progress and demo-first approach, the panel expressed concerns about NASA expanding COTS in the absence of a clear human-rating process for commercial vehicles.

Specifically, it says NASA’s current procedures “were not specifically intended to establish requirements for vehicles produced by entities external to NASA, such as COTS firms or international programs.”

The panel recommends NASA accelerate its efforts to develop a human-rating process for would-be commercial providers.

“It is the Panel’s position that no COTS manufacturer is currently [human-rating-requirements] qualified, despite some claims and beliefs to the contrary,” the report states, noting that the panel has not evaluated the COTS concepts with regard to inherent safety issues. “Questions that must be answered are: What is the process for certifying that potential COTS vehicles are airworthy and capable of carrying astronauts into space safely? How is compliance assured over the life of the activity?”

SpaceX, for its part, says its Falcon 9 rocket and Dragon capsule were designed from the beginning to meet NASA human-rating standards.

“Much like Ares 1, our system was designed from day one to meet the human-rating requirements and we are confident that we can meet whatever [human-rating requirements] may be formally adopted for commercial systems,” said Lawrence Williams, SpaceX vice president of strategic relations. In May 2008, NASA modified its human safety requirements for Constellation, but the revision did not address requirements for commercial vehicles, a concern the ASAP has raised repeatedly, according to meeting minutes documents in the panel’s report. Williams said SpaceX eagerly awaits official human safety guidance from NASA for COTS vehicles, and the company will develop Falcon 9 and Dragon in accordance with any new guidelines that take effect. “SpaceX certainly agrees that time is of the essence here,” he said.

The Commercial Spaceflight Federation, an advocacy organization that counts SpaceX among its members, also took the safety advisory panel to task for asserting in its report that “no COTS manufacturer is currently [human-rating-requirements] qualified.” In the absence of such federal guidelines, the group said in a statement, “it is impossible for companies to meet standards that do not currently exist.”

In addition to NASA’s lack of formal safety requirements, the ASAP took issue with the Augustine committee’s support for outsourcing human spaceflight without having conducted a safety analysis of the commercial concepts SpaceX and others presented to the committee last summer.

“In making this recommendation, the [Augustine] committee also noted that while human safety never can be absolutely assured, safety was assumed to be a ‘given,’” the report says. “The Panel believes that this assumption is premature and oversimplifies a complex and challenging problem because there is not a ‘cookie-cutter approach’ to safety in space.”

The report points to the Ares 1 program as an example of the right way to go about ensuring astronaut safety.

“Its architecture was selected by NASA’s Exploration System Architecture Study (ESAS) team because of its potential to deliver at least 10 times the level of crew safety as the current shuttle,” the report says.

The panelists warn that switching from a “well-designed, safety optimized” system to commercially developed vehicles based on “nothing more than unsubstantiated claims would seem a poor choice,” according to the report. “Before any change is made to another architecture, the inherent safety of that approach must be assessed to ensure that it offers a level of safety equal to or greater than the program of record.”

The report also warned against extending the life of NASA’s fleet of aging space shuttle orbiters “significantly” beyond their planned September 2010 retirement absent the kind of thorough vehicle recertification effort recommended in the aftermath of the 2003 Space Shuttle Columbia disaster.

“With sufficient money, manpower, and recertification efforts, it is possible that the Shuttle could be extended,” the report states. “While we are aware of no major systems that are ‘on the knee of the curve’ of wear out, the funds needed to allow full recertification are substantial, and the probability of finding things that demand even more resources during recertification is very real.”

NASA plans to launch five more shuttle missions by October, and then shut down the program and transfer the three orbiters to museums and science centers.

Once the shuttles stop flying, NASA intends to buy rides for its astronauts on Russian Soyuz vehicles until a new service — either commercial or government — materializes.