https://www.bbc.com/future/article/20220713-how-to-make-rocket-launches-less-pollutingThe Kazakh Steppe is a vast area of grassland that stretches from northern Kazakhstan into Russia. It is home to the world's oldest spaceport, the Baikonur Cosmodrome. From its launchpads, both the world's first artificial satellite and the first human spaceflight, Sputnik 1 and Vostok 1, were launched.
The fuel used by many of the rockets that blasted off from Baikonur was UDMH (unsymmetrical dimethylhydrazine), a very useful propellant for the pioneering Soviet scientists. UDMH didn't need a source of ignition. It could be stored at room temperature, and it released a lot of energy. Yet it came to be dubbed "devil's venom" by the scientists who used it.
Devil's venom was highly carcinogenic to humans and it's blamed for turning a large area of the steppe into an ecological disaster zone. It's reported that UDMH rained down on the grasslands when it spilled out of the used first and second stages of Proton rockets and poisoned the soil for decades to come.
"Last year's number of missions was 144 worldwide," says William Pomerantz, vice president of special projects at Virgin Orbit, which launches small satellites horizontally from under the wing of a Boeing 747. Their rocket uses about 1/20th of the fuel of typical ground-launched, heavy-lift rockets, and recent launches include satellites now playing a key role in the collection of climate data. "Given this volume, the space launch industry remains a relatively small driver of atmospheric emissions compared with say, commercial aviation with more than 20 million flights worldwide, and other industries."
Eloise Marais, an associate professor in physical geography at University College London, and co-author of one of the recent research papers, thinks this comparison is "erroneous".
"When we compare the amount emitted from rocket launches to aircraft, it doesn't sound like a lot," she says. "But this comparison was always erroneous because aircraft released their pollutants within the troposphere and the lower stratosphere, whereas rockets are releasing their pollutants all the way from the surface of the Earth to the mesophere, and when pollution is released into those upper layers it lasts for a longer time than earthbound sources."