When the towering SpaceX Starship met its watery demise in the Indian Ocean during a test flight last month, it sparked a wave of concern among environmentalists. The crash of the 165-foot vessel, potentially releasing hundreds of kilograms of residual fuel, raised questions about its impact on marine ecosystems. Fortunately, the type of fuel used by Starship, comprising liquid oxygen and liquid methane, ranks among the most environmentally benign in aerospace technology. That’s the good news. The bad news is that the rocket’s environmental credentials are far from unblemished.
“Debris and fuel [from the latest Starship launch] are a drop in the ocean,” explained Tommaso Sgobba, executive director of the International Association for the Advancement of Space Safety.
While the Raptor engines of Starship utilize non-toxic propellants, the practice of discharging debris into the ocean remains controversial. Space agencies have historically deposited remnants in the seas, a practice that continues to draw criticism for its environmental implications.
“The stuff actually dumped is similar to other industrial materials contributed by shipping and fishing,” noted space sustainability researcher Vitali Braun. He pointed out the contradiction with international agreements, stating, “Theoretically, the United Nations Convention on the Law of the Sea binds all states ‘to protect and preserve the marine environment in all zones of the sea.’ So, effectively, states dumping their trash into the ocean is a violation of this treaty.”
The Sky is Not the Limit: The Consequences of Increased Launches
The ambitions of SpaceX to increase Starship launches to possibly hundreds annually present another layer of environmental concern. The proliferation of satellites, which inevitably re-enter Earth’s atmosphere, poses a significant and escalating risk.
As satellites and rocket debris return to Earth, they disintegrate and leave behind a trail of metallic ash. This residue could potentially harm the protective ozone layer or interfere with Earth’s magnetic field. The persistence of these particles in the upper atmosphere, possibly forever, is only adding to the concerns.
Methane: A Double-Edged Sword
Starship’s propulsion may utilize one of the cleaner fossil fuels, but methane’s environmental impact is nuanced. When burned, methane transforms into carbon dioxide and water vapor—both greenhouse gases, albeit with a lower impact than burning oil or coal. Still, methane contributes to global warming, a critical issue that humanity is striving to mitigate.
Andrew Wilson, assistant professor in environmental management at Glasgow Caledonian University, provided some stark figures: “One Starship launch produces 76,000 metric tons of carbon dioxide equivalent,” he explained. This emission level is significantly higher than that of SpaceX’s smaller Falcon 9 launches, yet lower per ton than the Falcon Heavy, which uses a more polluting oil-based fuel.
To put that number in perspective, 76,000 metric tons of CO2 is about the equivalent of the average energy use from 7,000 American homes each year.
The Bigger Picture: Carbon Footprint and Atmospheric Impact
Beyond carbon emissions, Starship’s environmental impact includes the release of water vapor and soot into the upper atmosphere. These substances can have warming effects due to radiative forcing. Moreover, methane leakage from storage and transportation adds to the environmental toll.
The overall carbon footprint of Starship is further complicated by the emissions associated with its production at SpaceX’s Starbase facility in South Texas, a figure difficult to accurately quantify. And SpaceX has chosen not to disclose their emissions, to the surprise of no one.
Long-term Environmental Concerns
Wilson warns that the increasing scale of Starship launches could dramatically increase its environmental footprint. “Historically, the space sector has been granted a lot of exemptions from different legislations, and, as a result, they have essentially been able to get away with doing what they want,” Wilson pointed out. “And Starship, because it’s the biggest rocket ever built, is also one of the dirtiest.”
Despite the minimal current impact of spaceflight emissions compared to other sectors, such as aviation, the rapid increase in space activities raises concerns about their cumulative effect on our planet.
Conclusion: Innovation at an Environmental Cost?
As SpaceX forges ahead with plans for Mars colonization and revolutionizing intercontinental travel via space, the environmental implications of such advancements loom large. While these innovations promise to redefine boundaries and reduce travel times on Earth, they come at a potential environmental cost that could contravene global climate goals, such as those set by the Paris Agreement.
“We are in a climate crisis — we already saw warming that is close to the targets of the Paris Agreement — and here we go, creating a massive launcher which is going to just add more carbon dioxide into the atmosphere,” Wilson concluded, highlighting the stark contrast between technological progress and environmental stewardship.