Permanent Human Settlement of the Earth, Space and Ocean Frontiers

Wednesday, May 10, 2006




Inflatables

Bigelow Aerospace
Ralph Buttigieg
Sydney, NSW
Australia

Space ships and space habitats have to be big. People need room to eat, sleep, work, exercise and to relax. The small Apollo capsule may have been good enough for a short Moon trip but you are going to need something larger for a Mars mission.

Bigger means more mass, which means a bigger more expensive rocket to launch it. Also rockets have limitations on the size of the payload they can launch which places an upper limit to the dimensions of the spacecraft. NASA is trying to address these issues by developing a Heavy Lift Launch Vehicle for its Moon/Mars missions.

Inflatable spacecraft have long been proposed as a solution to these problems. German-American rocket pioneer Werner Von Braun outlined an inflatable space station in the 1950's. It would have been a rotating torus providing the astronauts with artificial gravity and would have been large enough to have crew of 80.

In the late 80's the scientists at Lawrence Livermore National Laboratories came up with a grandiose plan for interplanetary exploration based on inflatable modules. They wanted o Moon and Mars bases, orbiting Earth bases and Gas Stations all assembled from inflatables. At the time LLNL was also developing a missile defense system called Brilliant Pebbles so humorist dubbed the scheme “Brilliant Condoms”

LLNL contracted space suit manufacturer ILC Dover to design the modules. The advantages of inflatables can be seen from the study. The module was 5 meter in diameter and 17 meters long. The hull mass was only 1523 kg. Compare that with tradition designs such as the Zubrin Mars Direct 5 meter by 5 meter habitat which has a hull mass of 5000 kg.

NASA did real work on inflatables in the late 90's. Transhab was an inflatable module for the Space Station. It could have provided roomy multi-level living quarters for the ISS astronauts. Transhab was no thin walled balloon either. As the NASA report said:

TransHab's inflatable shell consists of multiple layers of blanket insulation, protection from orbital and meteoroid debris, optimized restraint layer and a redundant bladder with a protective layer.

With almost two dozen layers, TransHab’s foot-thick inflatable shell is a marvel of innovative design. The layers are fashioned to break up particles of space debris and tiny meteorites that may hit the shell with a speed seven times as fast as a bullet. The outer layers protect multiple inner bladders, made of a material that holds in the module’s air. The shell also provides insulation from temperatures in space that can range from plus 121 degrees Celsius (plus 250 degrees Fahrenheit) in the Sun to minus 128 degrees Celsius (minus 200 degrees Fahrenheit) in the shade.

A test module was built and deployed bu NASA decided to go with a more traditional design.

Fortunately, the technology was rescued by the private sector. Hotelier Robert Bigelow brought exclusive development rights to the technology from NASA and access to former Transhab workers. His team has been developing the hardware and eventually plan to assemble a commercial space station. The module ,called Nautilus, will have 330 cubic meters of room. Before the Nautilus is launched a one third prototype will be orbited and tested. The test module, Genesis is due for launch this year. Bigelow Aerospace has already booked two flights on Russian Dnepr rockets.

The test flights are worth following. If he succeeds a revolutionary space technology would have been proved. Expect NASA to be very interested.

More information on Bigelow's plans here and here.