Artificial gravity needed for future space missions


Before a manned mission to Mars is feasible, an effective means of creating artificial gravity is needed to help prevent physical deterioration astronauts suffer during long space flights, said Dr. Laurence R. Young, the first Apollo Program Professor of Astronautics, at a talk last week.

Dr. Young gave his talk, entitled "Humans in Space: The Next Steps," on Monday, Nov. 20, in recognition of his appointment to the chair. At the lecture, he also announced the establishment of two new student prizes. The Apollo Prize will go each year to the undergraduate with the best project on humans in space. It was established with gifts from Dr. Young and Lewis Nashner, who received the SB (1965), SM and ScD in aeronautics and astronautics. The Massachusetts Space Grant Consortium will also present an award each year through the Apollo Professorship to the Massachusetts high school senior with the best space-related state science fair project. Both prizes consist of cash and an invitation to a launch.

Although much space-related scientific knowledge can be gained using unmanned programs, a Mars mission should be undertaken to learn more about possible earlier life forms on that planet, said Dr. Young, co-founder of the Man-Vehicle Laboratory and an alternate payload specialist on a 1993 space shuttle mission. He quoted Daniel Goldin, administrator of NASA, who said that "our goal should be a sustained presence in Mars and the solar system, not a one-shot, feel-good spectacular."

The biggest problem that must be overcome for lengthy missions of that type is the harmful effects of weightlessness on the human body, Dr. Young noted. These effects include loss of bone mass and red blood cells, fluid shifting from the lower to upper body, deconditioning of circulation and muscles, and changes in the immune system. Such reactions by the body "are perfectly appropriate for zero-gravity flight but perfectly inappropriate for return to the surface of our planet or another planet," he said.

Despite in-flight exercise, most astronauts experience problems with balance and orientation, fainting, and risk of muscle tears and bone fractures for the first few days after landing. The purpose of a Mars mission "is not mere survival," Dr. Young said. "We cannot afford to have astronauts in a weak physical condition on any part of the mission." Such a mission can't be seriously considered until these problems can be overcome, he said.

Studies on Skylab in the 1970s and the space shuttle's Spacelab (including Dr. Young's studies of the neurovestibular system governing balance) have provided much information on the physical effects of weightlessness but have yet to result in a method of combating it while in zero-gravity environments, he said. Artificial gravity created by spinning the spacecraft, possibly in the manner depicted in the movie "2001," may be the answer, he said.

By varying factors such as the rate of rotation and the radius of the spinning segment, scientists can adjust the gravity experienced by the astronauts. Ideas being studied include having the facility spin only while the astronauts are asleep, or including a two-person centrifuge powered by a bicycle in the spacecraft. Dr. Young outlined his suggestion for a module eight meters in diameter and spinning at 10 rpm to achieve artificial gravity at the rim of 0.4-0.5 G. Studies of people confined to bed for long periods (and who therefore experience some of the same effects as astronauts) have shown that just one to two hours a day of walking in normal gravity are enough to counteract the symptoms, he said.

However, unlike the astronauts in "2001," those aboard a real-life spinning spacecraft would experience other effects of rotation. For example, gravity gets progressively lower toward the center, so objects would get lighter as they were lifted from the "floor" toward the center, Dr. Young said. Also, people walking in the direction of the spin would be heavier and those walking in the opposite direction would be lighter.

Variables such as optimum duration and level of artificial gravity, structural layout and habituation schedules need to be studied further, Dr. Young said. The planned international space station should provide an opportunity to pursue this research, since the space shuttle missions are too short to gather the necessary data, he added.

Moving forward with this research is vital, Dr. Young said, showing a drawing of astronauts exploring the mountainous red surface of Mars. "If we do so, we may very well see the fruits of our exploration of space in a scene like this, [which is] no more extraordinary at this time than the scene of people on the moon was to Arthur Clarke when he did his early writing."

A version of this article appeared in MIT Tech Talk on November 29, 1995.


Topics: Aeronautical and astronautical engineering, Faculty

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