In the wake of the space shuttle Columbia accident, the search for the next generation of space transportation vehicle has taken on a greater sense of urgency and importance for NASA.

A debate now swirls around the space agency's latest effort to shuttle people to and from the International Space Station (ISS) -- without a space shuttle. NASA and industry teams have begun sketching out what they collectively feel is a safe, sane, arguably simple, and less-costly way to put people into Earth orbit.

The focus of NASA's Orbital Space Plane (OSP) program is to provide crew rescue capability from the ISS by 2010 and crew transfer capability to and from the orbiting outpost no later than 2012.

However the effort is already steeped in skepticism and controversy as designers, engineers and contractors choose sides between two possible designs: wings and wheels like the shuttle or Apollo-like space capsules.

Competing companies

The green light to move out on an Orbital Space Plane has caused a ripple effect through NASA.

The decision to extend use of the now-grounded space shuttle fleet from 2012 to at least the middle of the next decade was followed by the delaying of development of a reusable launch vehicle booster from 2006 to no earlier than 2009.

Last month, NASA shelled out some $135 million to competing aerospace groups to help steer the Orbital Space Plane into reality. The three groups are: The Boeing Company of Seal Beach, California; Lockheed Martin Corporation of Denver, Colorado; and a team including Orbital Sciences Corporation of Dulles, Virginia, and Northrop Grumman of El Segundo, California.

Each team is now deep into work on vehicle concepts, ground operations, and supporting technologies needed to fly to and from the ISS.

Obviously for contractors, there's big money in the billions down the road.

A decision by NASA on whether to proceed with the full-scale development of the OSP flight system is anticipated in September 2004. If a positive decision is made to proceed with full-scale development, contract awards will be made in late 2004.

Flight demonstrations

Each OSP team is already involved in flight demonstrator projects helpful to the OSP program.

The Demonstration of Autonomous Rendezvous Technology (DART) program is in progress at Orbital Sciences Corporation. It will prove the technologies required for spacecraft to locate and rendezvous with another spacecraft -- such as the space station -- without direct human guidance. DART is expected to be flying in a little over a year from now.

Lockheed Martin has a Pad Abort Demonstrator. The test program would assess crew escape technologies, drawing from the experience base of the Mercury, Gemini and Apollo programs. Launch pad abort trials are to begin in mid-year 2005.

Boeing's Phantom Works is working on the X-37. This vehicle can be ferried into orbit by the space shuttle or lobbed into space on an expendable launch vehicle. Sometime in 2006, X-37 will operate at speeds up to 25 times the speed of sound and test technologies in the harsh environments of space and atmospheric reentry.

KISS-and-tell tactics

For his part, NASA chief, Sean O'Keefe, has chided industry to adopt "KISS-and-tell" tactics in pressing forward on the OSP. Basically, Keep-It-Simple Stupid and tell NASA how best to build what it wants and needs.

"The level one requirements for OSP are on one piece of paper," O'Keefe said. "The space shuttle is an engineering achievement. There's no doubt about that. OSP is based on a different philosophy," he explained.

O'Keefe lists only three level one requirements that the space agency is after in the quest for an Orbital Space Plane. It has to be an operational asset that goes from Earth to space station to bring people. Secondly, NASA wants the OSP to show a level of maneuverability not available with shuttle. Thirdly, is a flexibility of launch, to eventually have a vehicle far less cumbersome to ready and fly into orbit than today's shuttle system.

"Let's not make this a degree of difficulty dive that's equivalent to a two-and-a-half gainer," O'Keefe told SPACE.com.

Back to the '60s

"Each of these shapes has competitive advantages and disadvantages that will be explored during the formulation studies," said Frederick Gregory, NASA Deputy Administrator, during recent congressional hearings. "We believe the OSP system will, in combination with other launch systems, provide the vital human transport capability necessary to retire the shuttle," he said in his written testimony.

Gregory noted that studies have been conducted on how best to accelerate the OSP building schedule.

Retro-firing back to the 1960s, Gregory explained that the Apollo capsule is a "potentially attractive solution." Its performance is well understood. The abort-and-recovery system was simple and safe. Indeed, an Apollo-derived vehicle could be available four to six years after a contractor go-ahead -- therefore, hardware could be ready-to-go one to three years sooner than present-day OSP plans, he said.

"Grin and bear it" voyagers

Yet recently, capsule travel to and from the ISS received a less-than-sterling endorsement following the May 4 return to Earth of a Soyuz TMA-1 carrying Russia’s Nikolai Budarin and U.S. astronauts Kenneth Bowersox and Donald Pettit.

After more than five months of microgravity exposure onboard the station, the reentering space travelers were subjected to far higher gravity loads than planned. Their craft apparently suffered a technical glitch, causing the capsule and its precious cargo to make a steep, ballistic descent to Earth.

The voyagers ended up several hundred miles distant from a pre-selected landing zone. Bewildered recovery teams in helicopters and planes took some two hours to find the trio.

If an attached capsule to the ISS is to provide a quick route home in an emergency health situation, the Soyuz TMA-1 incident raises eyebrows.

"In this case it was a happy ending. But obviously everyone is going to have to understand what caused the problem," said Marcia Smith, a space policy analyst for the Congressional Research Service in Washington, D.C.

"If this crew was returning because of a medical emergency, having a two-hour delay in getting medical support…that could have been a problem," Smith said. "So they need to understand what went wrong and fix it," she said.

Complexity level

Dale Myers, a former industry leader in building the Apollo Command and Service Module, led a study group on behalf of NASA that looked into an Apollo-derived ISS crew rescue and transfer vehicle. It was judged that the capsule approach has the potential of being less expensive to pursue than a winged vehicle due to its lower complexity level.

"It appears to me that the robust launch escape system of Apollo, which worked over a wide range from the launch pad to high altitude, will be hard to beat in a winged vehicle," Myers reported. "This Apollo based system, without aerodynamic controls, wings, and landing gear is clearly simpler," he said.

Myers noted, however, that landing with wings yields good atmospheric cross range. That means far more flexibility in when and where to land. Also, winged vehicles have less gravity load during reentry, relieving stress on an injured or ill crewmember.

"If all things were equal, I'd choose winged vehicles. Unfortunately, they are not known to be equal," Myers said. Looking into the future, he added that another advantage of choosing a capsule approach over wings is beating a path back to the Moon.

"The greatest risk is doing nothing," Myers said.

Apollo obsolescence

Putting capsule pluses aside, virtually every Apollo system would have to be redesigned. Furthermore, there are changes required to make such a craft compatible with the internal pressure of the International Space Station. In addition, Apollo hardware could not be used due to obsolescence, NASA's Gregory testified.

"I don't know if the drawings even exist," said Dennis Smith, Manager of the Orbital Space Plane Program at the Marshall Space Flight Center. "The tooling doesn't exist. All the materials are different. All of the subsystems that were on it…we would be crazy to fly them today. I'm pretty sure they didn't know what an integrated circuit was back then," he told SPACE.com.

On the other hand, Smith said, from an aerodynamic standpoint, an Apollo capsule is well understood. "We flew it to the Moon. It came back and landed. We fished it out of the ocean. We clearly know how it flies," he said.

Finding the right answer

Throughout the years, numerous shapes and sizes of winged spacecraft have been studied.

For example, the U.S. Air Force looked at the X-20, the Dyna Soar. Over a decade ago, NASA's Langley Research Center focused on the HL-20 lifting body as a possible "space taxi". Sometimes called the "Personnel Launch System," the HL-20 never made it beyond a showy mockup.

A more recent NASA/Lockheed Martin Skunk Works cooperative debacle was the X-33. That prototype suborbital test vehicle was supposed to lead to a beefier and better orbital plane, the commercial VentureStar. That entire effort dead-ended. Likewise, the NASA Johnson Space Center-led X-38 project -- a cheaper, better, approach to a crew rescue vehicle -- fell victim to budget cuts.

"You name it. There's a bunch of shapes that have been looked at. There is a lot of data available…a lot of great things that have been done in the past. You'd be crazy not to look at what applies to OSP and what doesn't," Smith said.

"For OSP, we need to find the right answer," Smith said. "Which overall is the safest, most effective, and cheapest way to go do this mission," he said.