The new space race Is Causing New Pollution Problems.

NY Times, Ed Friedman Tue, 30 Jan 2024

The high-altitude chase started over Cape Canaveral on Feb. 17, 2023, when a SpaceX Falcon 9 rocket launched. Thomas Parent, a NASA research pilot, was flying a WB-57 jet when the rocket ascended past the right wing — leaving him mesmerized before he hit the throttle to accelerate.

For roughly an hour, Mr. Parent dove in and out of the plume in the rocket’s wake while Tony Casey, the sensor equipment operator aboard the jet, monitored its 17 scientific instruments. Researchers hoped to use the data to prove they could catch a rocket’s plume and eventually characterize the environmental effects of a space launch.

In the past few years, the number of rocket launches has spiked as commercial companies — especially SpaceX, founded by Elon Musk — and government agencies have lofted thousands of satellites into low-Earth orbit. And it is only the beginning. Satellites could eventually total one million, requiring an even greater number of space launches that could yield escalating levels of emissions.

SpaceX declined to comment about pollution from rockets and satellites. Representatives for Amazon and Eutelsat OneWeb, two other companies working toward satellite mega-constellations, said they are committed to sustainable operations. But scientists worry that more launches will scatter more pollutants in pristine layers of Earth’s atmosphere. And regulators across the globe, who assess some risks of space launches, do not set rules related to pollution.

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The exhaust plume from a SpaceX Falcon 9 rocket taking off from Vandenberg Air Force Base in California in 2018,Credit…Matt Hartman/Associated Press

Experts say they do not want to limit the booming space economy. But they fear that the steady march of science will move slower than the new space race — meaning we may understand the consequences of pollution from rockets and spacecraft only when it is too late. Already, studies show that the higher reaches of the atmosphere are laced with metals from spacecraft that disintegrate as they fall back to Earth.

“We are changing the system faster than we can understand those changes,” said Aaron Boley, an astronomer at the University of British Columbia and co-director of the Outer Space Institute. “We never really appreciate our ability to affect the environment. And we do this time and time again.”

……………………………… By the time a rocket curves into orbit, it will have dumped in the middle and upper layers of the atmosphere as much as two-thirds of its exhaust, which scientists predict will rain down and collect in the lower layer of the middle atmosphere, the stratosphere.

The stratosphere is home to the ozone layer, which shields us from the sun’s harmful radiation. But it is extremely sensitive: Even the smallest of changes can have enormous effects on it — and the world below.

………………………….Just how rockets will affect that relatively clear top, the stratosphere, remains uncertain. But scientists are concerned that black carbon, or soot, that is released from current rockets will act like a continuous volcanic eruption, a change that could deplete the ozone layer and affect the Earth below.

……………………………………………… A Race Against the Space Race

As space companies set records for launches and satellites deployed, scientists are starting to quantify the potential effects.

In a paper published in 2022, soot from rockets was shown to be nearly 500 times as efficient at heating the atmosphere as soot released from sources like airplanes closer to the surface. It’s the muddy-barrel effect.

“That means that as we start to grow the space industry and launch more rockets, we’re going to start to see that effect magnify very quickly,” said Eloise Marais, an associate professor in physical geography at University College London and an author of the study.

That said, Dr. Maloney’s team did not quantify how much more radiation exposure could occur.

The exact amounts of soot emitted by different rocket engines used around the globe are also poorly understood. Most launched rockets currently use kerosene fuel, which some experts call “dirty” because it emits carbon dioxide, water vapor and soot directly into the atmosphere. But it might not be the predominant fuel of the future. SpaceX’s future rocket Starship, for example, uses a mix of liquid methane and liquid oxygen propellants.

Still, any hydrocarbon fuel produces some amount of soot. And even “green rockets,” propelled by liquid hydrogen, produce water vapor, which is a greenhouse gas at these dry high altitudes.

“You can’t take what’s green in the troposphere and necessarily think of it being green in the upper atmosphere,” Dr. Boley said. “There is no such thing as a totally neutral propellant. They all have different impacts.”

Smithereens of Satellites

What goes up must come down. Once satellites in low-Earth orbit reach the end of their operational lifetimes, they plunge through the atmosphere and disintegrate, leaving a stream of pollutants in their wake. Although scientists do not yet know how this will influence Earth’s environment, Dr. Ross thinks that it will be the most significant impact from spaceflight.

A study published in October found that the stratosphere is already littered with metals from re-entering spacecraft. It used the same NASA WB-57 jet that chased the SpaceX rocket plume last year, studying the stratosphere over Alaska and much of the continental U.S.

When the researchers began analyzing the data, they saw particles that didn’t belong. Niobium and hafnium, for example, do not occur naturally but are used in rocket boosters. Yet these metals, along with other distinct elements from spacecraft, were embedded within roughly 10 percent of the most common particles in the stratosphere.

The findings validate earlier theoretical work, and Dr. Boley, who was not involved in the study, argues that the percentage will only increase given that humanity is at the beginning of the new satellite race.

Of course, researchers cannot yet say how these metals will affect the stratosphere.

“That’s a big question that we have to answer moving forward, but we can’t presume that it won’t matter,” Dr. Boley said.

…………………………………..scientists argue, satellite operators and rocket companies need regulations. Few are currently in place.

“Space launch falls into a gray area,” said Gavin Schmidt, director of the NASA Goddard Institute for Space Studies, who has been involved in a working group on this research. “It falls between the cracks of all the regulatory authorities.”

The Montreal Protocol, for instance, is a treaty that successfully set limits on chemicals known to harm the ozone layer. But it does not address rocket emissions or satellites.

In the United States, the Environmental Protection Agency is not responsible for analyzing rocket launches. The Federal Communications Commission licenses large constellations of satellites but does not consider their potential harm to the environment. (The Government Accountability Office called for changes to that F.C.C. policy in 2022, but they have yet to occur.) And the Federal Aviation Administration assesses environmental impacts of rocket launches on the ground, but not in the atmosphere or space.

That could put the stratosphere’s future in the hands of Elon Musk, Jeff Bezos and other private space company executives — which is particularly worrying to Dr. Boley, who says the space industry does not want to slow down.

“Unless it immediately affects their bottom line, they’re simply not interested,” he said. “The environmental impact is an inconvenience.”………  https://www.nytimes.com/2024/01/09/science/astronomy-telescopes-satellites-spacex-starlink.html?action=click&module=RelatedLinks&pgtype=Article—

February 3, 2024 Posted by Christina Macpherson | environment, space travel | 2 Comments