A Tour of NASA's Mars Wind Tunnel
NASA's Ames Research Center is dotted with monolithic structures from early in NASA's history (or even preceding it). Some facilities are still used for their original purposes, such as the wind tunnels. Other equipment and buildings have been significantly repurposed as NASA's mission has evolved. An interesting example of the latter is the Mars Wind Tunnel (or more formally, the Planetary Aeolian Laboratory). The facility was originally constructed to test how rockets would behave after takeoff by using a huge vacuum chamber, but is now used to simulate soil behavior in the low pressure atmosphere of Mars.
Beginning operations in 1965, the building was originally the Structural Dynamics Laboratory, a facility for simulating upper atmosphere conditions for rockets like Titan and Atlas. To accommodate these tall launch vehicles, the interior is about 100 feet tall.
Marvin the Martian helpfully guides visitors to the wind tunnel.
A vertical panorama of the interior shows that the building is actually five sided. The Mars Wind Tunnel (bottom right) is dwarfed by the huge structure. Surprisingly, it is more cost efficient to pump the air out of this entire room rather than build a new ceiling to create a smaller space more fitting for the short tunnel.
The Mars Wind Tunnel is situated across the floor of the facility. There are cameras situated around to observe low pressure experiments when the a vacuum is pulled.
The Tunnel is only a couple of feet tall, making the testing of large objects, such as potential Martian space suits, difficult.
The fan is used at atmospheric pressure to simulate wind, but at low pressure (like on Mars), the fan won't really move any air and can overheat due to a lack of convective cooling. Researches use pressurized air jets to simulate wind in those sorts of conditions.
To simulate different soils, they keep a collection of rocks, pebbles, and sand of varying sizes in the lab.
The neighboring Arc Jet complex provides the vacuum to create the low pressure environment for the Mars Wind Tunnel. It is actually very expensive to pull a vacuum, so the Mars Wind Tunnel essentially borrows the vacuum created for running other tests and experiments. The Arc Jet is another cool, 1960's era piece of Ames — it essentially uses bottled lightning to help recreate re-entry conditions to test NASA's heat shields.
Situated across from the low pressure Mars Wind Tunnel is the smaller Titan Wind Tunnel. This piece of equipment is pressurized to simulate the atmosphere in places like Saturn's moon Titan or Venus, back when NASA was more interested in the second rock from the sun.
Authors note: I've just begun work as a researcher at NASA's Ames Research Center, which affords me the privilege of seeing some pretty neat stuff. I just thought I'd share.