in an episode of Star Trek: The Next Generation, a pair of outspoken scientists have revealed how warp drives — the show’s ubiquitous propulsion system used to keep travelers swimming through space — wreak havoc on the environment. Since then, the characters have been careful to limit their spaceflight damage.
Can a similar scenario play out in the real universe now, minus the hyperdrive? Atmospheric scientist Christopher Maloney believes so. In a new study, he and his colleagues modeled how black carbon ejected from rocket launches around the world might gradually warm parts of the middle atmosphere and deplete the ozone layer.on June 1st journal of geophysical research: atmosphere.
“There’s a lot of momentum right now in terms of rocket launches and rising satellite constellations, so it’s really important to start looking at this to look at the impact we might see,” said Maloney of the National Oceanic and Atmospheric Administration (NOAA) Bo, Colorado. German’s Chemical Science Laboratory.
Maloney and his colleagues’ model starts with a typical launch trajectory, in which a rocket ejects tiny particles called aerosols from an engine nozzle. The most dangerous exhaust components are black carbon or soot. Rockets release large amounts of these tiny particles in the stratosphere, especially 15 to 40 kilometers above the ground, where planes fly. Modern jet engines also emit black carbon, but in much lesser amounts. Falling defunct satellites also release aerosols as they burn up in the stratosphere. Because these particles persist in the stratosphere for about four years, they can accumulate, especially in areas where space traffic is concentrated.
Maloney and his team used high-resolution climate models to predict the impact of this pollution on the atmosphere, studying how aerosols of different sizes heat or cool regions of space at different latitudes, longitudes and altitudes. They found that over two decades, temperatures in parts of the stratosphere could rise by 1.5 degrees Celsius or 2.7 degrees Fahrenheit, while the ozone layer in the northern hemisphere could thin slightly. They generally conclude that more rockets means more warming and more ozone loss, which can be problematic, especially since humans, wildlife and crops need the ozone layer to protect them from UV radiation.
In total, each year rocket launches emit about 1 gigagram or 1,000 metric tons of black carbon into the stratosphere, according to their calculations. In 20 years, this could easily reach 10 gigs or more, due to the increase in the number of rocket launches. The researchers considered multiple black carbon emission scenarios, including reaching levels of 30 and 100 gigagrams, which, while extreme, could happen within decades if rocket engine technology and trends don’t change much. They focused their analysis on widely used kerosene-burning rocket engines, such as the SpaceX Falcon, Rocket Lab Electron, and the first-stage booster of Russian Soyuz rockets.
They expect as many as 1,000 hydrocarbon rocket launches per year by the 2040s, as the global launch rate climbs by about 8 percent per year. That’s thanks in part to falling launch costs and a booming commercial space industry, as well as the rockets needed to launch growing satellite networks like SpaceX’s Starlink, Amazon’s Project Kuiper and OneWeb. Suborbital spaceflights, like those of Blue Origin and Virgin Galactic, can also penetrate the stratosphere.
