Add another voice to the sea of experts weighing in on the upcoming White House decision on NASA's future.

A panel of independent safety specialists says abandoning NASA's besieged Ares 1 rocket is "unwise" because potential commercial space transportation providers are currently unable to meet stringent safety standards.

In a report released late Friday, the Aerospace Safety Advisory Panel discussed their opinions on commercial crew transportation to space, the Constellation moon program and the approaching retirement of the space shuttle fleet.

President Obama is expected to decide NASA's future trajectory in the coming weeks. Private companies are expected to take on a large slice of the human space program, and the agency's Ares 1 rocket may be canceled in favor of a new heavy-lift design for exploration.

NASA should only choose an alternative to the Ares 1 rocket and Orion spacecraft, called the "program-of-record" in policy parlance, if commercial vehicles offer equal or better safety, the panel said.

SpaceX, Orbital Sciences, United Launch Alliance and other companies have submitted preliminary proposals to NASA for study money on piloted spacecraft to carry astronauts to low Earth orbit. SpaceX and Orbital have already won more than $3 billion in contracts to supply cargo to the International Space Station with unmanned ships.

Under the COTS test program, SpaceX and Orbital will demonstrate their robotic Dragon and Cygnus spacecraft in 2010 and 2011, respectively. Those companies' human-rated proposals are based on variants of the unmanned versions of those craft.

A presidential commission led by former aerospace industry executive Norman Augustine presented options to the White House in October. Most of the alternatives involved scrapping the Ares 1 rocket and switching to commercial suppliers for astronaut transport, allowing NASA to focus on developing a heavy-lift rocket tailored for deep space exploration.

According to the advisory board, the Augustine committee made premature and oversimplified assumptions about safety in its work.

The safety panel, operating under a congressional mandate, said the ability of either COTS provider to close the gap in human spaceflight or provide safety equal to the program-of-record is "speculative."

"It is the panel's position that no COTS manufacturer is [human] qualified, despite some claims and beliefs to the contrary," the board said in its report.

If NASA chooses to procure human space transportation on commercial vehicles, the panel said the agency must foster a validation and certification process within the supplier's organization and conduct oversight during operations.

SpaceX officials have said they designed their Dragon capsule and Falcon 9 rocket with human passengers in mind. Company founder Elon Musk said both vehicles meet NASA's published human rating requirements, apart from an escape system.

The safety committee touted the Ares 1 design, saying the rocket was "designed from the beginning with a clear emphasis on safety." The panel specifically cited the reliability of the first stage motor and launch abort system.

"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 said.

The panel also discussed its findings on the safety of extending the space shuttle program to shorten the upcoming gap in human spaceflight, concluding it does not support adding many more flights to the shuttle manifest.

The Columbia Accident Investigation Board, convened after the loss of Columbia in 2003, recommended a comprehensive recertification effort if the shuttle flew beyond 2010.

"We are especially concerned over any kind of 'serial extension' where a few flights at a time might be added," the safety committee wrote. "The risk of continuing to fly the shuttle without a recertification and expending the resources to bring the vehicle up to modern standards is more than we should ask astronauts to shoulder."

Joseph Dyer, the panel chairman and a former naval officer, said in a letter attached to the report that the safety committee was unable to evaluate specific concepts being considered to replace the Ares and Orion architecture. The letter was addressed to NASA Administrator Charles Bolden, Vice President Biden and Speaker Nancy Pelosi.

"Significant issues include human rating requirements for potential commercial and international entities, extension of shuttle beyond the current manifest, workforce transition from the shuttle to the follow-on program, the need for candid public communications about the risks of human spaceflight, and the more aggressive use of robots to reduce the risk of human exploration," Dyer wrote.

Bolden provided the following statement on the panel's annual report.

"I would like to thank this year's members of the Aerospace Safety Advisory Panel for the 2009 annual report. The ASAP is an independent group of experts that has been evaluating NASA's safety performance and advising the agency since the panel was established in 1968."

"NASA appreciates the insight and will thoroughly review the report."