Space station science officer Don Pettit always looks forward to
Saturday mornings.

\"It\'s when we have a bit of free time,\" he explains. Some of the crew
read books, play musical instruments or watch movies. \"I prefer to do
\'Saturday Morning Science\'\--fun experiments of my own design.\"

A few Saturdays ago, Pettit had his heart set on bubbles. \"We have a
copy of C. V. Boys book, Soap Bubbles, here on the ISS,\" says Pettit.
\"It was published in 1911 and it\'s still a wonderful treatise on thin
films. Every space station should have a copy,\" he laughed. \"We wanted
to see what thin films and bubbles might do in zero-g and felt it was a
topic ripe for discovery.\"

Pettit prepared a solution of water, soap, and glycerin and fashioned a
wand from thin stainless-steel wire. \"The wand was a loop that could be
re-sized from 35 mm to more than 150 mm in diameter,\" he explains. The
experiment was about to begin. \"But first,\" says Petit, \"we decided
to try a \'dry run\' with only water\--no soap.\"

He inserted the wand into a \"zero-g beaker\"\--a plastic bag full of
drinking water\--and pulled it out again. \"To my amazement,\" he says,
\"when the 2-inch loop was withdrawn, a thin film of water clung
tenaciously to the loop. I\'ve never before witnessed such a large-scale
film of water.\"

To appreciate Pettit\'s amazement, try the same experiment in your own
kitchen on Earth. Fill a bowl with drinking water and fashion an
adjustable loop of wire. No matter how hard you try, it\'s impossible to
make water stretch across a loop wider than about 1 cm. Any film you do
make, furthermore, will be fragile. A gentle breath of air will cause it
to burst.

Don Pettit\'s films, on the other hand, were 5 to 10 cm in diameter and
were remarkably sturdy. He could shake them, blow on them \... even
paint on them. After all that abuse they remained intact. \"They were
like little sheets of rubber,\" he marvelled. \"The films could
withstand all sorts of mechanical torture.\"

Water can f

Let\'s say you\'re on Earth and you have a thin film of water held
parallel to the ground. The film sags in the middle\--a result of
gravity. Water flows downhill from the periphery of the loop to the A
little pool of water forms there. It\'s heavy and the film sags more.
The pool gets bigger and bigger until its weight rips the film apart.

If you\'re in Earth orbit, however, the film would be in free fall.
Weightless. That pool never forms. The resulting film is quite tough\--a
natural result of water\'s high surface tension. \"Some of our films
lasted longer than 12 hours,\" notes Pettit.

What do you do with a tough thin film of water?

\"I wonder what someone like Matisse could do with this ephemeral
medium? Eventually, all the colors blended together yielding a rather
dull looking green, perhaps the true color of the universe?\"

\"We never got to the soap solution because we were diverted by water.
The soap bubbles will have to wait for another time.\"

\"Observations of nature, no matter how seemingly arcane, are like
peeling off one more layer on the great onion of knowledge, tickling
your imagination with what you have found but always revealing yet
another tantalizing layer underneath. I hope we never get to the core.\"