How environmentally friendly is SpaceX’s spaceship?

When the 50-meter-high upper stage of the SpaceX spaceship crashed into the Indian Ocean last week during its third test flight, environmentally conscious observers wondered whether the stainless steel vehicle, which may have contained hundreds of pounds of residual fuel, could endanger marine life . The good news is: not really. Starship uses one of the most environmentally friendly fuel combinations available. Still, sustainability experts warn that the rocket is not without problems.

‘Debris and fuel [from the latest Starship launch] are a drop in the ocean,” Tommaso Sgobba, executive director of the International Association for the Advancement of Space Safety, told

From a starship Raptor engines burn liquid oxygen and liquid methane, neither of which, fortunately, are toxic to the environment.

Related: Relive SpaceX Starship’s third flight test in breathtaking photos

Still, dumping waste into the ocean isn’t the most respectable behavior, even though the world’s space agencies and launch operators have been doing it for decades.

“The stuff that’s actually being dumped is similar to other industrial materials contributed by shipping and fishing,” space researcher Vitali Braun told “Theoretically, the United Nations Convention on the Law of the Sea obliges all states ‘to protect and preserve the marine environment in all zones of the sea’. So in effect, dumping waste into the ocean is a violation of this convention .”

What worries Braun most are Elon Musk’s plans to increase the frequency Starship launches to perhaps hundreds per year. Each of these flights could lift more than 100 tons of satellites into space. These satellites will not only rise, but at some point also fall back down.

“Those numbers are insane,” Braun said. ‘We have already seen an exponential increase re-entering satellites and rocket stages During the past years. With that perspective, I’m quite concerned about the consequences.”

Satellites and old rockets burn up as they spin back to Earth and leave them behind metallic ash, the composition of which raises concerns. Some researchers think these satellite burn remnants might damage to the Earth’s protective ozone layer or even influence the planet’s magnetic field. Most of the re-entering material evaporates about 75 to 50 miles above the Earth’s surface. At these altitudes, the ash particles can essentially last forever, meaning their concentrations will only continue to rise.

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Green or not green?

But there are other concerns about the frequent spaceship launches. Methane, while not toxic, is a gas that is commonly found in nature and is used to power everything from district heating to electricity generation and transportation. When burned it is converted into carbon dioxide and water vapour. Although the overall greenhouse gas emissions from burning methane are lower than those from burning oil or coal, the gas still contributes to global warming. greenhouse effect which humanity is currently working hard to thwart.

According to Andrew Wilson, assistant professor of environmental management at Glasgow Caledonian University in Scotland, one Starship launch produces 76,000 tons of carbon dioxide equivalent (a measure that combines several types of greenhouse gases into one unit). That’s 2.72 times more emissions than those produced by a single one SpaceX Falcon 9 launch, but only 0.96 of the emissions produced by a Falcon Heavy launch. Both the Falcon 9 and the Falcon heavy burn the much dirtier oil-based rocket fuel RP-1, making their carbon footprint per ton launched much higher. The Falcon 9for example, has less than one-sixth the payload of Starship.

Carbon emissions aren’t Starship’s only contribution to global warming. Water vapor is also a powerful greenhouse gas. The higher layers of the Earth’s atmosphere contain very little of it, of course, and scientists don’t know what water vapor produced by high-altitude rocket exhaust might do to the planet. In addition, spacecraft emissions contain soot, which spreads through the upper atmosphere and absorbs the incoming heat. This effect, known as radiative forcing, can contribute to additional warming. And let’s not forget that methane itself is a greenhouse gas that traps heat in the atmosphere up to 90 times more powerfully than carbon dioxide. Methane leaks from processing and storage facilities and gas pipelines are known to contribute significantly to global greenhouse gas emissions.

A full accounting of atmospheric impacts would also include the greenhouse gases generated by Starship vehicle production, which takes place at SpaceX’s Starbase facility in South Texas. But that’s an even harder number to determine.

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Carbon footprint

Wilson warns that Starship’s enormous size and the frequency with which SpaceX plans to launch it mean that the giant rocket’s long-term carbon footprint is unlikely to remain just a drop in the ocean.

“Historically, the space industry has been given a lot of exemptions from various pieces of legislation, and as a result they’ve essentially gotten away with doing whatever they want,” Wilson said. “And Starship, because it is the largest rocket ever built, is also one of the dirtiest.”

Currently, the total amount of greenhouse gas emissions from space travel is negligible, equivalent to 1% or 2% of the carbon footprint of aviation, which itself accounts for about 2.5% of total global greenhouse gas emissions. But the number of rocket launches has risen sharply in recent years. In 2023, a record number of 223 space flights will be made worldwide. according to astronomer and space age historian Jonathan McDowell. That is more than double the 85 attempts made in 2016. SpaceX alone launched a record 96 orbital rockets last year and is aiming for nearly 150 by 2024. SpaceX’s bold ambitions worry scientists like Wilson.

“If it scales up and SpaceX launches Starship more and more, as they say they will, then there will be an accumulation of those impacts on our environment,” Wilson said.

Except that it allows humanity to colonize Marsas Elon Musk In his vision, Starship is also envisioned as a next-generation intercontinental travel tool that could shorten the duration of the longest journeys here on Earth to just an hour.

“The amount of pollution this would cause compared to airplanes is a big difference,” Wilson said.

While engineers in most industries are scratching their heads wondering how to decarbonize by mid-century as required by international climate protection pledges, Musk and company are developing a carbon-intensive business with uncertain environmental consequences, Wilson suggests.

The Paris Agreement, signed at the 2015 United Nations Climate Change Conference in the French capital, commits countries to limiting global warming to 2.7 degrees Fahrenheit (1.5 degrees Celsius) compared to pre-industrial times. So far, that goal seems to be slipping through our fingers. In 2023, the global temperature even exceeded the 2.7 degrees Celsius threshold on 50% of days. according to the European Copernicus Climate Change Service.

“We are in a climate crisis – we have already seen warming close to the Paris Agreement targets – and here we go, creating a massive launch vehicle that will only put more carbon dioxide into the atmosphere,” Wilson concluded.

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