In orbit, water makes the stretch

It’s well known that water behaves differently in the near-zero gravity of a spacecraft than on Earth. Yet scientist-astronaut Donald R. Pettit, now aboard the International Space Station, was startled recently when he watched this most familiar of liquids stretch across a large metal hoop.

SPACEY WATER. Vigorously shaken, a water film aboard the International Space Station sheds a droplet without breaking. Pettit

The odd behavior showed up just as Pettit was about to do some just-for-fun experiments with soap bubbles in his off-duty hours.

Using a wire twisted into a bubble wand, Pettit dipped the loop first into plain water to see what would happen. To his surprise, the wand’s loop emerged holding a glistening film. On Earth, such unsupported water membranes break as soon as they form. Pettit found he could make the films as large as saucers.

What’s more, the films were able to withstand strong shaking–though a drop or two might fly off–and could last up to half a day. Pettit attributes their tenacity to ordinary surface tension no longer being overpowered by the tug of gravity.

Besides being amusing, Pettit’s observations of films, as well as of floating water droplets, may be relevant to theories of fluid turbulence, says physicist Francis H. Harlow, one of Pettit’s former colleagues at Los Alamos (N.M.) National Laboratory. Harlow has been in e-mail contact with Pettit about the odd water structures.

NASA spotlighted Pettit’s unpublished findings recently in its Web-zine (


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