It takes all kinds of spacecraft to reach orbit and a NASA contractor is working to build three more.

Houston, Texas-based Spacehab, known for its laboratory modules and other hardware that ride aboard NASA's space shuttles, is developing a trio of ever-larger vehicles to make up its Apex spacecraft family.

"Apex is our opportunity to have a full, end-to-end commercial [space] service," said Michael Bain, the firm's chief operating officer, in an interview.

Spacehab engineers are currently hammering out specifications for their Apex 100, 300 and 400 series spacecraft, which they hope will provide a flexible range of services for spaceflight customers and attract NASA's eye for space station resupply. Current plans call only for unmanned craft, but a human-rated version could be developed later if the market warrants it, they said.

"If that emerging market comes to bear, then we would have a system that has cut its teeth on unmanned flight," Spacehab's Apex program manager Jim Baker told SPACE.com, adding that an Apex spacecraft could be modified for manned operations if required. "We'll have proven its guidance, navigation...and recovery operations."

The aerospace firm built a spare parts stowage platform for the International Space Station (ISS), which Discovery's STS-114 astronaut crew delivered to the orbital laboratory during their July-August spaceflight. Spacehab officials announced their Apex plans in conjunction with that flight.

A tiered approach

While Spacehab engineers are starting small and working their way up, all of their Apex vehicles are expected to come in recoverable - in which payloads return to Earth - and non-recoverable varieties.

The smallest Apex vehicle, the 100 series, is currently expected to carry no more than 836 pounds (380 kilograms) in orbit on a one-way flight, though it could return a 572-pound (260-kilogram) payload back to Earth, Apex planners said.

While the 100-series Apex could launch atop a Falcon 1, Minotaur or Taurus booster, a mid-size version - the 300 series - would rely on a larger rocket, such as Boeing's Delta 2, according to Spacehab's mission plan.

"Our concept is to fly on existing or emerging vehicles," Baker said. "That gives us the ability to shift from one [launch] provider to another, so should any one of the vehicles have a failure, we'll still have access to space."

Under current plans, Spacehab's Apex 300 spacecraft would carry a maximum orbital load of about 8,818 pounds (4,000 kilograms), though smaller payloads of up to 4,850 pounds (2,200 kilograms) could be returned to Earth on recoverable flights.

Spacehab's Apex 400 series tops the spacecraft family's payload charts, with specification calling for loads up to 27,000 pounds (12,300 kilograms) for one-way flights and 18,959 pounds (8,600 kilograms) for returnable flights. The spacecraft could launch atop an Atlas 5 or Delta 4 rocket, Spacehab officials said.

"Strategically, it's vital that we have a broad base," Spacehab president and CEO Michael Kearney told SPACE.com, adding that growing interest in private space commerce is bringing the industry to a head. "We need to have a new vehicle...we want to be right there on that frontier."

Post-shuttle plans

With NASA's plan to retire its three remaining space shuttles by 2010, Spacehab and other private spaceflight firms are hoping to snag resupply rights for the ISS.

"To take what we've learned working with the shuttle and then remove our dependability on the shuttle, that seemed like a natural progression," Baker said of the Apex effort.

At a space conference earlier this year, NASA chief Michael Griffin said he hoped the space agency could purchase ISS resupply flights from commercial providers in the future. Private firms such as SpaceX, SpaceDev and Transformational Space (t/Space) among others have already expressed an interest.

"People tend to look at the spacecraft part of this, but there's much more," Kearney said, adding that he believes Spacehab's experience and existing infrastructure - such as clean rooms for hardware preparation - will prove vital assets in developing the Apex program.

Baker pointed out that space catering, in addition to satellite deployment and ISS resupply, may be an avenue Apex spacecraft could explore.

Space entrepreneur Robert Bigelow and his North Las Vegas, Nevada-based firm Bigelow Aerospace are working to develop inflatable orbital habitats that could serve as research platforms or hotels for future space tourists. A test version is slated to launch early next year.

"That thing's going to need clean towels and champagne brought up, there's that logistics issue there," Baker said.