Watching the Sparks Fly

by Susan Lee

May 26, 2000

I am old enough to remember before the Orbiter, or space shuttle, flew. While it was being built one of the developments I remember hearing about in the news was "shuttle" tiles. These are the special tiles on the bottom of the orbiter that protect the astronauts and the vehicle from the high temperatures generated as the orbiter flies back into Earth's atmosphere.

When I went on my first tour of NASA Ames Research Center I learned that a great deal of research on the development of these tiles was done here. The Space Technology Division has a facility called an arc jet testing facility that simulates the temperatures experienced in high altitude atmospheric flight.

When I heard I was going to get to see this facility I expected it would look like something on a Star Wars set, very futuristic and modern. I couldn't imagine where it was located at NASA Ames because I hadn't seen any buildings that had that look. I was very surprised to find out that I had driven right past this facility many hundreds of times without knowing what important things were happening inside.

From the outside it looks a lot like an old fashioned garage or gas station. Those of you who are tax payers will be glad to know that lots of expense was spared in the choice of materials for this building. Think corrugated metal. Little did I know that inside the boundaries of materials research were being pushed to the limit. The research done here is being applied to the X-33 and X-34.

I can't explain to you how an arc jet works, but I can tell you that it involves heat, electricity, pressure, and water cooling. I'll have to get back to you on this. Instead I'll tell you what it looks like when it's working. First I went into the control room. Everyone was getting ready for the test. This involved lots of radio communications, only one test facility can operate at a time because they need so much electricity.

Then the operators started flipping switches and checking dials on a long wall of instrument controls. I had to put on some special goggles and ear plugs. We left the control room and went out next to the arc jet which has a small window the size of your monitor screen you can look into. I was told things would happen very fast so I paid close attention.

There is a loud roaring sound when things start up and then an arm-like strut which holds the material sample swings up into view. All of a sudden an arc of light aimed at the sample appears and gets day glow bright. The tile lights up too. Sparks were flying. I felt very excited and scared but then the test was done. Computer sensors have recorded data about the test. The researchers were anxious to find their results. Hopefully they learned something about how to keep space travelers from burning up!

To learn more about the Thermal Protection Branch visit: http://spacetech.arc.nasa.gov