That Pretty Starship Explosion? A Lot of Pollution

The explosion of SpaceX's Starship didn't just cause damage to islands hit by falling debris. It also likely damaged the ocean and atmosphere, Space.com reports. The rocket's stainless-steel upper stage, which weighed 85 tons without propellant, broke up at an altitude of around 90 miles, according to space debris expert Jonathan McDowell. It's difficult to determine how much pollution was produced. But, according to atmospheric chemistry researcher Connor Barker's rough estimate, it may have generated 45.5 metric tons of metal oxides, which can harm ecosystems and human health, and 40 metric tons of nitrogen oxides, which contribute to particulate matter and can potentially damage the ozone layer.

While some viewers marveled at the beauty of the breakup, Moriba Jah, professor of aerospace engineering at the University of Texas at Austin, said that was akin to gazing admiringly at a nuclear bomb's mushroom cloud. "This stuff can harm ecosystems, can affect populations," he told the CBC, while also noting the risk to aircraft. "The extent of the debris field ... how much lethal debris—meaning how many chunks come down with a speed that can cause significant damage—that is stuff that is not well understood at this point," adds Aaron Boley, co-director at the Outer Space Institute, per the CBC.

McDowell predicted "many tons" of debris also reached the oceans, per Space.com. Little is known about how rocket debris affects the marine environment, but in 2016, a panel of experts identified a minor risk to ocean life with 10 launches—successful or not, each resulting in 40 metric tons of debris—a moderate risk with 100 launches, and a high risk with 1,000 launches. Jah therefore asks, "What are the sort of tests that we're going to require for people to successfully explore space, but not to the detriment of environmental sustainability?" The burn-up of satellites made from aluminum is another major concern, per Space.com, producing aluminum oxides known to accelerate the ozone's destruction. (More SpaceX stories.)