NASA Brings Out The Big Gun For Asteroid Impact Science
Just before he gets ready to fire a projectile down the 14-foot barrel of a vertical gun, planetary scientist Peter Schultz turns to me and gives an apologetic smile.
“There’s something you have to do,” he says, as his graduate student snickers. “You have to assume the Gault position.”
The Gault position, it turns out, involves crossing your index finger over your middle, your ring finger over your pinkie, then crossing your two arms over one another and finally crossing your legs (while standing).
Schultz assumes it, explaining that it serves as a good luck measure, as does his graduate student and the other engineers in the gun control room.
“We’re armed,” someone calls. “Voltage looks good.” A klaxon buzzes and, seconds later, there’s the sound of a powerful explosion from the next room over.
A burst of flame and sand appears on the computer screen in front of us and, just like that, the NASA Ames Vertical Gun range has provided a new data point for science.
The gun is a fantastic tool for studying the effects of meteorite impacts on different places in the solar system. You see, Earth is something of an anomaly.
Most other rocky bodies are covered in countless craters ranging from the size of continents down to the size of sand grains.
The active tectonics of our planet recycle its crust, erasing the long-term scars that come from living in a solar system full of debris.
But just about every other terrestrial planet, moon, asteroid, and comet is coated in pockmarks, a testament to how pervasive and important impacts have been in our solar system’s history.
Over the course of its nearly 50-year career, the gun range been used to figure out why the scars of an impact look different on Mars than they do on Venus.
It has helped explain how the man on the moon could have gotten his face. And it has provided key data for many NASA missions, in particular the Deep Impact spacecraft, which shot a projectile into an asteroid.
Peter Schultz, who teaches geoscience at Brown University, has done much of this research. He’s worked at the gun range for 33 years, becoming its principal investigator in 2012, and he knows a great deal about its history and lore.
Though it’s called a gun, the facility doesn’t look much like any firearm you’ve ever seen. The main chassis is a long metal barrel as thick as a cannon mounted on an enormous red pole that forks at the end into two legs.
The red pole was once used to hold MIM-14 Nike-Hercules missiles that served as an anti-ballistic defense against Soviet nuclear warheads, Schultz explains.
This complex is pointed at a huge rotund cylinder and can be moved up and down in 15-degree increments to simulate a meteorite strike at different angles.
The entire machine is housed in a 3-story industrial building here at NASA’s Ames campus.
At the far end of the barrel, a gunpowder explosion is used to compress hydrogen gas to as much as 1 million times atmospheric pressure.
The compressed gas gets released and sent down the launch tube, firing a projectile pellet at speeds between 7,000 and 15,000 mph.
The shot enters the cylinder, in which low pressure or even a vacuum is maintained, and hits a dish filled with different material that simulates whatever planetary body researchers are studying.
High-speed cameras mounted on windows around the cylinder record the impact aftermath at up to 1 million frames per second.
Using data from the gun, Gault helped figure out that the Apollo astronauts weren’t going to die by lunar quicksand.
After NASA finished its goal of safely landing and returning astronauts, Gault continued using the gun range to study the formation of craters on the moon.
When he retired, NASA planned to mothball the gun but an outcry from the planetary science community re-opened the firing range as a national facility.
It was during this time that Schultz, who had worked with Gault as a post-doc, was hired to take over as science coordinator for the gun range.
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