Orbital Laboratory-Stepping Stone to Interplanetary Flight

Abstract

An orbital laboratory is a necessary link in a manned spaceflight program leading to planetary exploration. Missions to the planets call for total flight times in excess of one year, while manned flights to date have been limited to total flight times of two weeks or less. Almost all of the technical and operational problems imposed by manned planetary flight, over and above those for lunar flight, are directly related to the major increase in mission duration. Experimental data on the exposure of humans to weightlessness is needed for these longer time periods to establish the medically and operationally acceptable levels of artificial gravity for interplanetary flight. Operating lifetimes for spacecraft subsystems need to be demonstrated. High reliability demands an onboard maintenance capability which will have to be proven feasible during earth orbit before being committed to an interplanetary trip. The main spacecraft of an interplanetary expedition performs essentially the same functions as an orbital laboratory. Each acts as a long-lifetime shelter, a laboratory, a supply depot, a docking station, and a repair facility. By proper choice of the interplanetary mission, the main spacecraft could actually be an orbital laboratory placed onto an interplanetary trajectory which makes a free-fall return to Earth after a flyby of one or more planets. It is possible to continue the interplanetary free-fall indefinitely with no propulsion required other than that needed to correct for guidance errors. A total, long-range program for manned spaceflight is outlined which proceeds from present accomplishments to a laboratory orbiting earth, thence to the simplest interplanetary flyby missions, on to the flyby/lander mode of interplanetary exploration, and ultimately to orbital laboratories on permanent free-fall trajectories between the planets. Each step of such a program would build logically on the accomplishments of the earlier missions. The development of an orbital laboratory as a durable, long-life facility is the key link in the overall program leading to manned planetary exploration.