An Australian farmer stands next to a ball of twisted metal, purported to be fallen space junk. | REUTERS
Out in the depths of snowy Hokkaido, where bears and foxes lurk, there is a material that Japanese scientists believe could transform the space industry: magnolia wood.
The natural resource, which is used for everything from knife handles to chopsticks, has a new cutting-edge application in the form of space satellites.
Koji Murata, a Kyoto University professor who specializes in wooden materials and agriculture, jokes that the frigid conditions of Hokkaido prepare the trees for low temperatures, although “outer space is an even more severe temperature.”
The project is more than just an idea. Back in 2022, Kyoto scientists sent wooden samples — cherry, birch and magnolia — into space. Magnolia, which is a hardwood, is relatively light and has dimensional stability that is superior to other species, Murata says, making it a winning candidate for the project.
In addition to testing wooden materials, the scientists have developed a wooden prototype satellite called the LingoSat with the support of the Japan Aerospace Exploration Agency and NASA. The device is contained in an aluminum frame that is only 10 cubic centimeters, while the wooden panel is less than 10 millimeters thick.
An early prototype of a LignoSat satellite made with cherry wood. The Kyoto University scientists who developed the device have ultimately settled on magnolia wood as the preferred material. | KOJI MURATA / KYOTO UNIVERSITY
Sending wooden materials into space may seem strange — something the scientists concede — but amid growing concern about metal space clutter and a brewing space race, particularly between Asian nations, those working on the project hope that it will help combat space clutter and show the way forward for less environmentally detrimental space activity.
Scientists have also raised the alarm about increased rocket launches damaging the ozone layer — which absorbs ultraviolet light, protecting life on Earth — and contributing to climate change.
Cosmic clutter
Space, despite its moniker, is far from empty. Planets, stars and cosmic dust are increasingly joined by clutter and debris left behind by broken or partly decomposed satellites. At the same time, new satellite launches are being proposed with dizzying frequency, concerning scientists. And while stargazers have complained about the high volume of satellites impeding their view, the old adage of “what goes up must come down,” is weighing on the mind of environmentalists.
Typically, satellites at the end of their lifespan will burn up on reentry — although the Point Nemo “spacecraft cemetery” east of New Zealand is the place of rest for when larger bodies come crashing down to earth. There, the broken remains of hundreds of space objects lurk underwater, having broken into thousands of pieces.
Orbiting Now, a website that tracks satellites, recorded more than 9,000 satellites in orbit as of December — including 8,270 Low Earth Orbit satellites, which are destined to burn up on reentry.
This process leaves behind a trail. In October, scientists from the National Oceanic and Atmospheric Administration in the U.S. found that, alongside space dust, the upper atmosphere “is peppered with particles containing a variety of metals from satellites and spent rocket boosters vaporized by the intense heat of re-entry.”
The study focused in depth on aerosol particles in the stratosphere — a layer of the atmosphere that plays a critical role moderating the Earth’s climate and is also home to the protective ozone layer.
While researchers indicated that the present situation may not be dire, concerns remain around the growth of the industry.
Eloise Marais, who leads University College London’s Atmospheric Composition and Air Quality research group, agrees the picture could grow more sinister over time.
“If Elon Musk lives up to his three Starship launches a day, in the future there are some potentially severe consequences on the environment, because those Starship rockets are really large and they're burning the type of fuel that produces black carbon ... (which is) very efficient at warming the atmosphere,” Marais says.
Action underway
In order to address such concerns, space agencies and scientists are increasingly pushing a more environmentally conscious agenda.
For the Kyoto University team, wooden satellites would mitigate the increase of metal in the stratosphere and the risks from tumbling satellites at a time when the atmosphere is growing ever more crowded thanks to SpaceX’s launches of thousands of satellites and the expansion of its competitors such as Amazon.
The initial concept for wooden satellites was driven by Takao Doi, an astronaut and professor at Kyoto University, and began as a more general discussion about wood in space and its potential application for lunar bases, says Yosuke Yamashiki, professor at the university’s Graduate School of Advanced Integrated Studies in Human Survivability.
“I was shocked, but I thought it might be a very good idea,” Yamashiki says of his initial reaction, noting that it could be a revolutionary concept. But the success of the project will come down to whether the researchers can prove that it works and make a case for it commercially.
“We have to demonstrate some of the motivation to promote the wooden satellite” beyond it just being another material, Yamashiki says. “If the first one is successful, the advantage will be recognized.”
Meanwhile, the European Space Agency established its Clean Space initiative in 2012 targeting the environmental consequences of the entirety of space mission life cycles. The initiative focuses on environmentally conscious design, fostering green technologies, measures to minimize space debris, servicing spacecraft and removing debris.
Luisa Innocenti, head of the Clean Space effort, says space agencies and companies are growing increasingly concerned about environmental issues — both in space and the potential for on-Earth impact.
“Pollution in space, through the debris, can also disrupt satellite communications and navigation systems, affecting various sectors like telecommunications and agriculture,” Innocenti said, noting that there is “a growing sense of urgency and recognition that environmental sustainability is a priority in the space sector.”
Since 2022, the Clean Space initiative has pursued a “Zero Debris" approach, which aims to develop a roadmap that will form the basis of future policy. Under this, the group plans to limit debris in the Earth and Lunar orbits by 2030 through the implementation of disposal requirements as well as innovation and design that mitigates the risk of collisions.
The group is urging agencies to comply “with the most stringent of environmental legislations” throughout the design process, and to do so before they are enforced, while developing a framework that will guide design and engineering processes.
Growing damage
Another aspect is the burgeoning space tourism industry — Richard Branson’s Virgin Galactic and Jeff Bezos’ Blue Origin are among those enthusiastically pursuing commercial space travel — which has excited those wealthy enough to participate. The knock-on environmental effects are currently limited, given the sector’s small scale at the moment, but depending on its trajectory they could end up being significant.
“Currently, the impacts are quite marginal,” Marais says. But she notes that because of the speculation around the projected growth, “that marginal impact could increase really quickly.”
“It really is currently like the Wild West, there is so much speculation around growth,” Marais says.
Marais, along with research fellow Robert Ryan, has modeled the future impact of rocket launches based on calculations of air pollutant emissions from 2019 launches, and as part of that found that the climate impact of soot from rocket launches is up to 500 times more damaging than soot from earthbound sources.
Rockets, which release soot particles, leave behind a trail of this so-called black carbon in the upper layers of the atmosphere, and it remains there longer than in the lower atmosphere, where rain helps to wash these particles away. Meanwhile, chemical reactions caused by air pollutants produced by rockets, especially when they or other debris falls back to Earth, damage the ozone.
Despite these concerns, there aren’t yet cohesive regulations in place.
“There's nothing that says (SpaceX) can't launch a vehicle until some sort of environmental controls have been performed, at least related to the rocket launch pollution,” Marais says. She notes that pollution close to the ground is supposed to be regulated, but there are allegations that these rules have been breached.
Earlier this year, environmental groups in the U.S. sued the Federal Aviation Administration for failing to sufficiently carry out an environmental review prior to a SpaceX launch that damaged the launch pad, firing debris into the air and creating a plume of dust.
Not all companies are lagging on the issue — some smaller operations “are making an effort to improve sustainability,” Marais says — but discussion around the topic is fraught and complex.
The term “sustainability” doesn’t really account for the “pollution that's coming from rockets and the reentry of space junk,” she says. “It's a complicated issue — there are organizations and industries that are trying their best, but even the definition of sustainability is not robust.”
Innocenti also notes the need for regulation to drive industry-wide change.
“Establishing guidelines for debris removal and satellite servicing is crucial,” she says, noting that “to support environmentally friendly space exploration, regulatory changes should focus on stricter debris mitigation measures, incentivizing eco-design practices and promoting international collaboration for responsible space activities.”
Marais says the environmental impact needs to be given greater weight in the discussion and there needs to be consideration of what is actually necessary when it comes to space travel and exploration, given the potentially long-term consequences.
In Kyoto, Yamashiki says that regulation will likely come into place, making companies more conscious of the types of materials they send into space and how these are removed.
The aerosol particles currently produced by satellites as they fall to earth “disturb our sky and create a different environment — this is not good,” he says. But being able to market wooden materials for satellites to companies such as SpaceX will require evidence, he notes.
“We already have several advantages, but they should be proved in space,” he says.
