Putting up the Ritz

Although TransHab had already proven many aspects of the inflatable module technology, there was still much work to be done. For example, although the NASA team had begun working on how to incorporate windows, putting holes in the module walls to accommodate them complicated the engineering of the skin so much that they left windows out of the proposed ISS module design entirely.

But a space hotel without windows is an obvious nonstarter, so the Las Vegas team conducted many pressurization tests of different module designs and blew up—as in exploded , not just inflated —a lot of them. Often deliberately pushing designs beyond their limits to establish safety margins, the team followed NASA’s experience in doing the pressurization tests under water, in a large pool that damped down the explosive force when structures tore open. At one point they tried a fill-to-fail test in open air—and discovered why NASA hadn’t: the test module exploded with such force that, Schneider recalls, ”it almost moved the building off its foundation.” Noise complaints came in from kilometers away. Based on these and other tests, Genesis I ended up with a multilayer skin 15 cm thick with one 10-cm-wide window; the final version’s skin will be closer to 40 cm thick. But the engineering of the skin, as revolutionary as it was, was just the beginning, especially in this case—lacking a space station to connect to, Genesis I must function independently in orbit.

As a stand-alone orbiting capsule, the Genesis I is basically an entirely new spacecraft, with a new complement of power, control, communication, and other flight systems. Many of these were adapted from existing aerospace systems, according to chief engineer Haakonstad. ”We wanted low-cost, low-risk systems,” he explained. But he declined to give any further details about the technologies or their subcontractors, citing the highly competitive environment of commercial space development. Nevertheless, one employee did confide that ”there’s at least one component from Home Depot.”

To enhance reliability, Bigelow engineers made extensive use of a technique called ”dissimilar redundancy.” Genesis I is equipped with two different means of performing all critical functions, such as monitoring internal conditions or distributing electrical power from its solar panels. The engineering team decided early on that ”we are not just going to have backups,” said Haakonstad. ”We will have physically independent systems. The reasons are robustness, and to perform Product A versus Product B evaluations.”

In fact, as many as a third of the systems aboard Genesis I are there purely for evaluation for use on future test flights. As an example of redundancy, Genesis I has two communications systems, with nearly identical installations at each end of the spacecraft. With this setup, whichever end of the cylindrical spacecraft ends up pointing toward Earth will be the one having full communications capability. This redundancy was needed because Genesis I does not have a way to control its attitude in space, relying on gravity to torque it into a position with its long axis pointed toward the ground.

The Genesis I designers also had the unusual luxury of essentially no weight constraints—a dream for aerospace engineers, who must typically sweat out every last nonessential kilogram from their designs in order to meet strict launch limits. But because Bigelow Aerospace had chosen to launch Genesis I with the powerful Dnepr rocket—provided by Moscow-based, state-owned ISC Kosmotras—weight concerns were minimal.

The Dnepr is essentially an ICBM converted for use as a commercial lift vehicle, and the Genesis I launch weight of about 2000 kilograms (the exact figure has not been disclosed) used only half of the Dnepr’s capability. ”We were very heavy,” one engineer said, ”[but] we didn’t want to spend a lot of time fine-tuning the structure.” Major weight savings will be tested on the next prototype vehicle, he added.

Despite all the planning and the generous weight margin, some features had to be dropped, sometimes very late in the construction of the vehicle. Bigelow had planned to put his wife’s name—Diane—on the outside of the module in glowing LEDs. (”You need all the brownie points you can get,” he quips.) But ”for technical reasons, we had to take it off,” says Bigelow, who still managed to earn some points with his wife when the Russians wrote her name on the fairing of the rocket, next to the American flag.

Later this year Bigelow will launch the next in his series of prototypes, Genesis II. Ultimately, he plans to be launching test modules twice a year until he has the human-rated version perfected. ”We will be tasked with managing a lot of spacecraft,” Haakonstad explains, ”We may have up to five active vehicles” at a time in space.

Unlike NASA, Bigelow Aerospace does not track its spacecraft itself. Instead, it relies on the U.S. Department of Defense, which routinely observes and measures the orbits of thousands of near-Earth objects and then publishes the results. Bigelow Aerospace crunches these measurements using off-the-shelf orbital-prediction software to predict the 5- to 12-minute windows when Genesis I is within line of sight of the company’s ground stations in Las Vegas and Arlington, Va. Only during these windows can the control room receive telemetry and transmit commands. Two more ground stations that will provide more communications windows are due to come online this month in Alaska and Hawaii.

Each test module will be in orbit for a long time. ”We had aimed for an orbit with three to seven years of life,” says Haakonstad. In the end, he says Genesis I ended up in an orbit with a lifetime of ”seven to 13 years.” During that period, he went on, ”we will collect long-term data on the robustness of the system, the power system, and the integrity of the hull.” With the ability to rapidly deploy and test improvements in space, Bigelow Aerospace believes it can orbit a habitable module within three years.

Of course, a hotel is pointless if no one can afford to visit it. As a consequence, Bigelow Aerospace is closely watching the attempts of other private entrepreneurs to build low-cost spacecraft and boosters, such as those being encouraged by NASA’s program for private transportation to and from the ISS. Ultimately, though, despite all the cunning engineering in the world, it’s still impossible to say if Bigelow’s vision of a vibrant orbital economy will mature into reality—or become just another desert mirage.