When NASA's Jet Propulsion Laboratory sent the Curiosity Rover to Mars, it went through an exceptionally complex process to get the damn thing on the ground.
One of the things used to slow it down through the thin atmosphere was the largest supersonic parachute it had ever built. Now it's building bigger ones to send people to the Red Planet, and that's a problem: it doesn't have a wind tunnel big enough to test it, so it build one with rocket sleds.
The parachute NASA used to decelerate the Curiosity Rover's descent stage involved using an indoor wind tunnel. A giant hall would become a hurricane alleyway as NASA threw its 16-metre supersonic parachute into it to test.
To send people to Mars, NASA needs a bigger craft, and therefore a bigger parachute to slow it down during the descent. The problem with that is the wind tunnel it has isn't big enough, nor is any other wind tunnel in the world the right size.
So NASA used its smarts to build one outdoors to replicate Mars-like conditions in the desert.
What it did was attach a parachute to a large silver bullet, and through a series of cables and pulleys, raise the bullet and the parachute up into the sky on a military helicopter.
Once the bullet made contact with a metal landing pad, a rocket sled kicked off and pulled it along the ground, replicating Mars like conditions.