Economics Today 18th Edition by Roger LeRoy Miller

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Reducing the Fixed Costs of Space Exploration
Robert Bigelow, chief executive of Bigelow Aerospace, has dreamed of this day. He will now have a chance to see a newly designed spacecraft leave a launch pad, escape from the earth's gravitational influence, achieve orbit, and blow up. The blowing-up part of the flight will not be an explosion but instead will entail attaching Bigelow's new $17.8 million spacecraft to an air lock and inflating it with breathable air.
Bigelow Aerospace's "inflatable space pod" is a lightweight dwelling. Composed of soft materials that allow it to be folded for transport into space, the inflatable space pod weighs 3,000 pounds on the earth, twothirds less than a traditional spacecraft. Hence, the pod can be launched at a fraction of the cost. Once the pod is in orbit, many different crews will use it over time, so it will serve as a fixed input for space exploration. Furthermore, the nonmetallic walls of the pod will produce less of the heavy radiation that solar storms create when particles pass through metal walls of traditional spacecraft. In addition to providing crews with improved radiation protection, therefore, the inflatable space pod will better protect highly sensitive and expensive equipment from damage from solar storms. Hence, as spaceship makers in other nations, including European countries and Russia, have concluded, the pod promises lower fixed costs of orbital space exploration for years to come.
Are disposable rockets used to lift a spacecraft to earth orbit fixed or variable inputs? Explain your reasoning.