This video shows a simple fluid experiment aboard NASA’s DC-9 Weightless Wonder aircraft.

[youtube=http://www.youtube.com/watch?v=gTqLQO3L4Ko&w=700]

In 1996, fluid mechanics scientist, Dr. Mark Weislogel, performed 50 water-balloon experiments during a four-day flight campaign aboard the DC-9 at NASA’s Glenn Research Center. More information on the experiments is available at http://spaceflightsystems.grc.nasa.gov/WaterBalloon and at http://microgravity.grc.nasa.gov/balloon/HS.HTM.

Although these flights are commonly described as “zero gravity,” that is not strictly accurate. Because of limitations on the precision of the parabolic trajectory, occupants do experience some residual gravity. The preferred term is “microgravity,” although that is not strictly accurate, either.

The residual gravity experienced on the best parabolic flights is typically +/-0.2g. So, technically, these should be called centigravity flights. No one uses that term, though, so don’t do it unless you want to sound like Sheldon on “Big Bang Theory.”

Because they fly above atmospheric disturbances, suborbital spacecraft will be able to achieve microgravity levels that are more than 100 times better.

Here’s another water-balloon video. This one was shot by astronaut Don Petit aboard the International Space Station:

[youtube=http://www.youtube.com/watch?v=3xWEN8O1oAs&w=700]