Skeletons in Space

Says Ingber: "Mechanical restructuring of the cell and cytoskeleton apparently tells the cell what to do."

Very flat cells with taut cytoskeletons somehow sense that more cells are needed-to cover a cut, for example. Rounder, cramped cells might sense an overpopulation problem and decide it's time to die and make room for others. In either case, they are responding to a control system in which the shape-shifting cytoskeleton serves as a switching mechanism.

The potential implications of this research are vast - and not limited to space travel. It has already led to a prospective cancer treatment based on changes in cell shape. And it could provide new treatments for osteoporosis, cardiac disease, lung problems and developmental abnormalities. Every tissue in the body, says Ingber, has some disease that results from cells responding abnormally to mechanical forces.

"By pursuing the question of how cells sense gravity we've uncovered entirely new aspects of cell regulation."

Ingber believes that tensegrity is a core organising principle of the entire physical world. Self-stabilizing structures form spontaneously at every scale - cytoskeletons are merely one example. Another would be spherical carbon molecules called "BuckyBalls" that look like atomic soccer balls. Clay molecules also arrange themselves into tensegrity patterns that some researchers think harboured the first microscopic life forms on Earth. Even the universe itself, with its black holes (compression) and gravitationally linked galaxies (tension), may be a tensegrity structure.

"I gave a talk once at NASA on evolutionary biology," he recalls. "The last slide of my talk was a picture of the universe: super clusters of galaxies. Next to it was a one of capillary cells in a dish, formed into networks. The two pictures looked identical."