The engineers and decision-makers involved in the project said the timeline is not much tighter than the one they faced in developing the first shuttle. Modest technological gains made during a series of failed X-vehicles gives them a head start.

But interviews with NASA managers, contractors and outside specialists, along with documents the Bush administration submitted to Congressional budget-writers and obtained by Florida Today, shed fresh light on everything that must go right to get the first plane off the drawing board and docked at the International Space Station by 2010.

"The time frames, we believe, are doable or else we would not have put them there," said Dan Dumbacher, deputy manager for the space-plane program at NASA's Marshall Space Flight Center, where the orbital space plane program is being coordinated as part of an overhauled Space Launch Initiative. "We're not starting from scratch here."

Just consider all that must happen, in parallel, for NASA to meet this challenge by the end of the decade:

• An agency that the General Accounting Office has deemed incapable of generating reliable cost estimates must set requirements for a brand new spacecraft and then come up with a credible price tag in three years.
• With those requirements in hand, NASA and its contractors plan to demonstrate and prove technologies needed for the plane by about 2006: approach and landing, autonomous rendezvous in space, re-entry into the atmosphere and, most important, a failsafe escape system that would save the crew from dying in a launch disaster.
• The space agency and two rocket-building companies must test and maybe modify new rockets built for launching satellites to make sure they are safe for launching people into orbit.
• Last, but definitely not least, NASA must go to a skeptical Congress in 2005 asking for a $10 billion or so boost in its budgets during the latter half of this decade. That would mark a major shift in a country that has steadily scaled back its commitment to space spending for decades.

Plane development

Contractors who will build the plane and NASA officials said the schedule is conservative, even beatable.

"Given adequate funding, we think we can meet NASA's timeline with very low risk," said Bill Rothschild, the space plane manager for The Boeing Co. "At this stage of the program, it pays to be somewhat conservative since every engineering project has its 'unknown unknowns' and challenges that can alter schedules."

But, he added, "We believe we might beat the current schedule dates by a lot."

The reason, according to Rothschild and his counterpart at competitor Lockheed Martin, is the space plane is based largely on existing technology or technology that already is very close to being tested.

"What they're trying to do is say, 'Hey let's not try to push the boundaries of technology,' " said Lockheed's Mike Coats, a former astronaut. " 'Let's come up with a vehicle that can get the job done safely and affordably and in a time frame that is reasonable.' " The contractors don't have specific requirements in hand.

For example, it may be early next year before they're told more about what the ship must do -- presumably carry some number of astronauts to and from space station. So far, all they've seen on paper is a "technical directive" that tells them NASA wants a craft that could carry at least three people. Lockheed's already been looking at a four-seater and Boeing a six-seater.

More specifics will come early next year, NASA said. The contractors are not waiting around. They are working with NASA managers to apply some of the technological gains made on mothballed space vehicle projects such as the HL-20, X-33, X-37 and X-38. They'll also apply work already done under Space Launch Initiative, which is now refocused on the new plane.

Just after NASA announced its new strategy, the agency awarded contracts to Boeing to use its X-37 test vehicle to demonstrate new advances such as thermal protection and landing and approach -- which could be used on a new space plane. Lockheed also has a contract in the works to develop an escape system to save the astronauts if the rocket failed during launch.

The X-37 is about half the size, for example, of what Boeing might build if it's awarded the space plane contract. But it can be used for testing of technologies. In April 2004, Boeing plans to drop the X-37 from a NASA B-52H at about 45,000 feet to test its ability to land without a pilot at Edwards Air Force Base in California. In about 2006, the vehicle could be flown unmanned in orbit to prove some new technologies needed for thermal protection during re-entry from space.

"While the OSP is a new vehicle, it draws on the legacy and knowledge of more than 40 years of human space flight," Rothschild said.

Rockets and safety

From that legacy, NASA and the contractors are resurrecting the idea of launching a spacecraft on expendable, or one-time-use, rockets. Lockheed, and others, began asking NASA to consider that very idea in 1999. But the agency did not warm to the concept until this year, when leaders realized they could not afford to build the reusable launchers that SLI was shooting for.

"Let's use that expendable launch vehicle that the government already has paid a huge amount of money for, and that both Boeing and Lockheed have made huge investments in," Coats said of Lockheed's proposals. "Why not? That seemed like a logical step to us."

Logical and cost-efficient, maybe, said observers. But NASA and its contractors said they realize there is work to be done. Boeing's Delta 4 and Lockheed's Atlas 5 have demonstrated one successful launch each so far. They're meant to boost satellites not people. The safety requirements for launching humans to space is different than launching multimillion-dollar hunks of metal.

Kennedy Space Center is leading preliminary efforts to determine what, if any, changes are required of the rockets.

"We actually have to go through the studies, but a good crew escape system buys you a tremendous amount in terms of capability to increase safety for the astronauts," Dumbacher said. "That may mean significantly less modifications to the launch vehicles."

First, the rockets must launch a few more times to prove they are highly reliable getting payloads to orbit. Then, NASA needs Lockheed Martin to come through on a contract to build a crew escape system that would all but guarantee that the space plane could separate from a failing rocket and deliver astronauts safely back to the ground.

If those things happen, NASA could be spared from having to collaborate with the contractors to completely re-engineer the two new rockets, Dumbacher said.

Budget boost

If all of that goes perfectly, and NASA decides in 2004 or 2005 to actually build space planes, the agency will still face its biggest hurdle: getting money out of Congress.

NASA is just beginning to re-establish fiscal credibility with the White House and Congress after going at least $5 billion over budget on its part of the International Space Station and scrapping several space vehicle projects after spending hundreds of millions of dollars without actually delivering functioning spacecraft.

"Budget is a wonderful limiting factor," Dumbacher said. "It forces efficiency."

There will be no estimates until NASA goes through the studies to determine exactly what it will build, Dumbacher said.

"A big part of our job in OSP is to go off and get reasonable confidence level cost estimates so that when we get to the mid-2005 time frame, we know within some confidence level what it is going to cost," Dumbacher said. "We are purposely not quoting numbers now because we want to go off and do the right homework to come up with that."

The agency so far has said it needs $2.4 billion, which it is getting by shuffling money in its existing budget, for development costs through 2007. That is not even close to the final price because it doesn't include building the ships.

The ultimate total could be between $9 billion and $13 billion, according to Congressional staffers and industry experts.

If that's true, NASA is going to be coming back to Congress asking for a substantial hike in its budget from 2007 to 2010 -- something that would depart from three decades of cuts tospace spending.

Experts who've watched closely as that happened said NASA is going to have to be prepared with evidence that:

• It can control spending on the shuttles and station, which will be operating in tandem with the new space plane.
• Outsiders concur NASA can build the planes for what it says and deliver them on schedule.

"NASA is trying to maintain financial credibility," said Brian Chase, a former aide to U.S. Rep. Dave Weldon, R-Melbourne, and the new head of the National Space Society. "They're saying, 'We want to pursue this project, but we need some time to make sure we know what it's going to cost.' They don't want to throw out a low number that is unrealistic or a number that is too high and gets it shot down too soon."

This is not the old days, when NASA got a blank check to get to the moon, said Marc Schlather, head of the advocacy group ProSpace.

"One of the challenges they will have with this space plane is they have not gotten rid of this legacy when they were a big huge organization that could do anything and they were getting 5 to 6 cents of every federal dollar," Schlather said. "They won't get those kind of resources."

Yet, Schlather said, NASA still would be expected to deliver the goods as though they were getting those resources.

O'Keefe and others at NASA say this plan has a better chance of being successful because it already has an early blessing from President Bush and key members of the Republican-led Congress.