When an asteroid hit the earth at 11,000 mph (18,000 km / h), how much of the asteroid's water remains in the debris and how much cooks off in the intense heat of the collision?
Scientists at Brown University wanted to find out. So they did what each of us would do and built an asteroid cannon – with much help from NASA.
The resulting study, published on April 25 in the journal Science Advances, may sound ridiculous (or ridiculously ingenious), but it aims to answer some of the most persistent questions in the science of planet formation. How did initially bone-dry planets get their water in the earliest days of the solar system? Why were traces of water found in the mantle of the parched moon of the earth or near the massive Tycho lunar crater? Can ancient, carbon-based asteroids serve as a transgalactic taxi service transporting small pools of water from one part of the cosmos to the other? [When Space Attacks: The 6 Craziest Meteor Impacts]
If this latter theory is true, then mathematics is not on its side. "Impact models tell us that [asteroids] should degas completely at many of the solar system's common impact velocities, meaning that all the water they contain cooks up in the heat of impact," says co-author Peter Schultz, a professor in Brown's Department of Earth, environmental and planetary sciences, said in a statement. "But nature tends to be more interesting than our models, so we have to do experiments."
And for this experiment Schultz and his colleagues needed an asteroid cannon. So the team used the help of the NASA Vertical Gun Range at the Ames Research Center in California ̵
Without real asteroids, the team resorted to marble-sized cylinders of antigorite – a green mineral that is abundant in the oceanic crust and contains an average of 13 percent water – as projectiles. For their target, they used a tray of dry, powdery pumice to represent the loose layer of dusty minerals that covered the Earth's bedrock. Beneath the tray, they attached a plastic-lined fountain to catch the explosive debris released during their man-made impacts of asteroids.
Over several attempts, the researchers blew the fake asteroid at speeds in excess of 11,200 mph into the wrong Earth, a speed "comparable to the average impact velocity" in the asteroid belt, the researchers said. On impact, part of the rock melted and then quickly solidified again to glass. Other pieces of antigorite fused with the powder into breccias – jagged collages of debris stuck together during the heat of the impact.
When researchers analyzed these debris on water, they found far more than their models had shown: Up to 30 percent of the "asteroid" water remained trapped in the impact products. In other words, the theory that asteroids could serve as an intergalactic H20 delivery service appears to contain water.
"These new experiments raise the possibility that growing terrestrial planets absorb water inside them as they grow," the researchers wrote. "And it shows why experiments are so important," added Shultz, "because this is something models have missed."
In other words, please – let the scientists have their guns.
Originally published on Live Science.