A space elevator would be cheaper and cleaner than using rockets
This is making space accessible to scientists, startups, and tourists who never could have afforded it previously, but the cheapest way to reach orbit might not be a rocket at all — it could be an elevator.
The space elevator
The seeds for a space elevator were first planted by Russian scientist Konstantin Tsiolkovsky in 1895, who, after visiting the 1,000-foot (305 m) Eiffel Tower, published a paper theorizing about the construction of a structure 22,000 miles (35,400 km) high.
This would provide access to geostationary orbit, an altitude where objects appear to remain fixed above Earth’s surface, but Tsiolkovsky conceded that no material could support the weight of such a tower.
We could then send electrically powered “climber” vehicles up and down the tether to deliver payloads to any Earth orbit.
In 1959, soon after Sputnik, Russian engineer Yuri N. Artsutanov proposed a way around this issue: instead of building a space elevator from the ground up, start at the top. More specifically, he suggested placing a satellite in geostationary orbit and dropping a tether from it down to Earth’s equator. As the tether descended, the satellite would ascend. Once attached to Earth’s surface, the tether would be kept taut, thanks to a combination of gravitational and centrifugal forces.
We could then send electrically powered “climber” vehicles up and down the tether to deliver payloads to any Earth orbit. According to physicist Bradley Edwards, who researched the concept for NASA about 20 years ago, it’d cost $10 billion and take 15 years to build a space elevator, but once operational, the cost of sending a payload to any Earth orbit could be as low as $100 per pound.
“Once you reduce the cost to almost a Fed-Ex kind of level, it opens the doors to lots of people, lots of countries, and lots of companies to get involved in space,” Edwards told Space.com in 2005.
In addition to the economic advantages, a space elevator would also be cleaner than using rockets — there’d be no burning of fuel, no harmful greenhouse emissions — and the new transport system wouldn’t contribute to the problem of space junk to the same degree that expendable rockets do.
So, why don’t we have one yet?
Tether troubles
Edwards wrote in his report for NASA that all of the technology needed to build a space elevator already existed except the material needed to build the tether, which needs to be light but also strong enough to withstand all the huge forces acting upon it.
The good news, according to the report, was that the perfect material — ultra-strong, ultra-tiny “nanotubes” of carbon — would be available in just two years.
“[S]teel is not strong enough, neither is Kevlar, carbon fiber, spider silk, or any other material other than carbon nanotubes,” wrote Edwards. “Fortunately for us, carbon nanotube research is extremely hot right now, and it is progressing quickly to commercial production.”Unfortunately, he misjudged how hard it would be to synthesize carbon nanotubes — to date, no one has been able to grow one longer than 21 inches (53 cm).
Further research into the material revealed that it tends to fray under extreme stress, too, meaning even if we could manufacture carbon nanotubes at the lengths needed, they’d be at risk of snapping, not only destroying the space elevator, but threatening lives on Earth.
Looking ahead
Carbon nanotubes might have been the early frontrunner as the tether material for space elevators, but there are other options, including graphene, an essentially two-dimensional form of carbon that is already easier to scale up than nanotubes (though still not easy).
Contrary to Edwards’ report, Johns Hopkins University researchers Sean Sun and Dan Popescu say Kevlar fibers could work — we would just need to constantly repair the tether, the same way the human body constantly repairs its tendons.
“Using sensors and artificially intelligent software, it would be possible to model the whole tether mathematically so as to predict when, where, and how the fibers would break,” the researchers wrote in Aeon in 2018.
“When they did, speedy robotic climbers patrolling up and down the tether would replace them, adjusting the rate of maintenance and repair as needed — mimicking the sensitivity of biological processes,” they continued.Astronomers from the University of Cambridge and Columbia University also think Kevlar could work for a space elevator — if we built it from the moon, rather than Earth.
They call their concept the Spaceline, and the idea is that a tether attached to the moon’s surface could extend toward Earth’s geostationary orbit, held taut by the pull of our planet’s gravity. We could then use rockets to deliver payloads — and potentially people — to solar-powered climber robots positioned at the end of this 200,000+ mile long tether. The bots could then travel up the line to the moon’s surface.
This wouldn’t eliminate the need for rockets to get into Earth’s orbit, but it would be a cheaper way to get to the moon. The forces acting on a lunar space elevator wouldn’t be as strong as one extending from Earth’s surface, either, according to the researchers, opening up more options for tether materials.
“[T]he necessary strength of the material is much lower than an Earth-based elevator — and thus it could be built from fibers that are already mass-produced … and relatively affordable,” they wrote in a paper shared on the preprint server arXiv.
After riding up the Earth-based space elevator, a capsule would fly to a space station attached to the tether of the moon-based one.
Electrically powered climber capsules could go up down the tether to deliver payloads to any Earth orbit.
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Some Chinese researchers, meanwhile, aren’t giving up on the idea of using carbon nanotubes for a space elevator — in 2018, a team from Tsinghua University revealed that they’d developed nanotubes that they say are strong enough for a tether.
The researchers are still working on the issue of scaling up production, but in 2021, state-owned news outlet Xinhua released a video depicting an in-development concept, called “Sky Ladder,” that would consist of space elevators above Earth and the moon.
After riding up the Earth-based space elevator, a capsule would fly to a space station attached to the tether of the moon-based one. If the project could be pulled off — a huge if — China predicts Sky Ladder could cut the cost of sending people and goods to the moon by 96 percent.
The bottom line
In the 120 years since Tsiolkovsky looked at the Eiffel Tower and thought way bigger, tremendous progress has been made developing materials with the properties needed for a space elevator. At this point, it seems likely we could one day have a material that can be manufactured at the scale needed for a tether — but by the time that happens, the need for a space elevator may have evaporated.
Several aerospace companies are making progress with their own reusable rockets, and as those join the market with SpaceX, competition could cause launch prices to fall further.
California startup SpinLaunch, meanwhile, is developing a massive centrifuge to fling payloads into space, where much smaller rockets can propel them into orbit. If the company succeeds (another one of those big ifs), it says the system would slash the amount of fuel needed to reach orbit by 70 percent.
Even if SpinLaunch doesn’t get off the ground, several groups are developing environmentally friendly rocket fuels that produce far fewer (or no) harmful emissions. More work is needed to efficiently scale up their production, but overcoming that hurdle will likely be far easier than building a 22,000-mile (35,400-km) elevator to space.
This article originally appeared on Big Think, home of the brightest minds and biggest ideas of all time.
Certain gases used for anesthesia are 3,000 times more damaging for the climate than CO2. Some anesthesiologists are pointing to other solutions.
On the whole, the medical sector is responsible for a disproportionally large percentage of greenhouse gas emissions, with the U.S. as the biggest culprit. According to a key paper published in 2020 in Health Affairs, the health industry “is among the most carbon-intensive service sectors in the industrialized world,” accounting for between 4.4 percent and 4.6 percent of greenhouse gas emissions. “It’s not just anesthesia but health care that has a problem,” says Jodi Sherman, anesthesiology professor and Medical Director of the Program on Healthcare Environmental Sustainability at Yale University as well as co-director of the Lancet Planetary Health Commission on Sustainable Healthcare. In the U.S., health care greenhouse gas emissions make up about 8.5 percent of domestic greenhouse gas emissions. They rose 6 percent from 2010 to 2018, to nearly 1,700 kilograms per person, more than in any other nation.
Of course, patients worry primarily about safety, not sustainability. Yet, Koch emphasizes that “as doctors, we have the responsibility to do no harm, and this includes making sure that we use resources as sustainably as possible.” Studies show that 2018 greenhouse gas and toxic air pollutant emissions resulted in the loss of 388,000 disability-adjusted life years in the U.S. alone. “Disease burden from health care pollution is of the same order of magnitude as deaths from preventable medical errors, and should be taken just as seriously,” Sherman cautions.
When Koch, the anesthesiologist, started discussing sustainable options with colleagues, the topic was immediately met with plenty of interest. Her experience is consistent with the latest representative poll of the nonprofit Foundation Health in Germany. Nine out of ten doctors were interested in urgently finding sustainable solutions for medical services but lacked knowhow and resources. For teaching purposes, Sherman and her team have developed the Yale Gassing Greener app that allows anesthesiologists to compare how much pollution they can avoid through choosing different anesthesia methods. Sherman also published professional guidelines intended to help her colleagues better understand how various methods affect carbon emissions.
Significant traces of inhalation gases have been found in Antarctica and the Himalayas, far from the vast majority of surgery rooms.
A solution espoused by both Sherman and Koch is comparatively simple: They stopped using desflurane, which is by far the most damaging of all inhalation gases to the climate. Its greenhouse effect is 2,590 times stronger than carbon dioxide. The Yale New Haven Hospital already stopped using desflurane in 2013, becoming the first known healthcare organization to eliminate a drug based on environmental grounds. Sherman points out that this resulted in saving more than $1.2 million in costs and 1,600 tons of CO2 equivalents, about the same as the exhaust from 360 passenger vehicles per year.
At the Charité, Koch claims that switching to other anesthesiology choices, such as propofol, has eliminated 90 percent of the climate gas emissions in the anesthesiology department since 2016. Young anesthesiologists are still taught to use desflurane as the standard because desflurane is absorbed less into the patients’ bodies, and they wake up faster. However, Koch who has worked as an anesthesiologist since 2006, says that with a little bit of experience, you can learn when to stop giving the propofol so it's timed just as well with a person’s wake-up process. In addition, “patients are less likely to feel nauseous after being given propofol,” Koch says. Intravenous drugs might require more skill, she adds, "but there is nothing unique to the drug desflurane that cannot be accomplished with other medications.”
Desflurane isn’t the only gas to be concerned about. Nitrous oxide is the second most damaging because it’s extremely long-lived in the environment, and it depletes the ozone layer. Climate-conscious anesthesiologists are phasing out this gas, too, or have implemented measures to decrease leaks.
Internationally, 192 governments agreed in the Kyoto protocol of 2005 to reduce halogenated hydrocarbons – resulting from inhalation gases, including desflurane and nitrous oxide – because of their immense climate-warming potential, and in 2016, they pledged to eliminate them by 2035. However, the use of inhalation anesthetics continues to increase worldwide, not least because more people access healthcare in developing countries, and because people in industrialized countries live longer and therefore need more surgeries. Significant traces of inhalation gases have been found in Antarctica and the Himalayas, far from the vast majority of surgery rooms.
Certain companies are now pushing new technology to capture inhalation gases before they are released into the atmosphere, but both Sherman and Koch believe marketing claims of 99 percent efficiency amount to greenwashing. After investigating the technology first-hand and visiting the company that is producing such filters in Germany, Koch concluded that such technology only reduces emissions by 25 percent. And Sherman believes such initiatives are akin to the fallacy of recycling plastic. In addition to questioning their efficiency, Sherman fears such technology “gives the illusion there is a magical solution that means I don’t need to change my behavior, reduce my waste and choose less harmful options.”
Financial interests are at play, too. “Desflurane is the most expensive inhalation gas, and some think, the most expensive must be the best,” Koch says. Both Koch and Sherman lament that efforts to increase sustainability in the medical sector are entirely voluntary in their countries and led by a few dedicated individual professionals while industry-wide standards and transparency are needed, a notion expressed in the American Hospital Association’s Sustainability Roadmap.
Susanne Koch, an anesthesiologist in Berlin, wants her colleagues to stop using a gas called desflurane, which is by far the most damaging of all inhalation gases to the climate.
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Other countries have done more. The European Union recommends reducing inhalation gases and even contemplated a ban of desflurane, except in medical emergencies. In 2008, the National Health Service (NHS) created a Sustainable Development Unit, which measures CO2 emissions in the U.K. health sector. NHS is the first national health service that pledged to reach net zero carbon by 2040. The carbon footprint of the NHS fell by 26 percent from 1990 to 2019, mostly due to reduced use of certain inhalers and the switch to renewable energy for heat and power. “The evidence that the climate emergency is a health emergency is overwhelming,” said Nick Watts, the NHS Chief Sustainability Officer, in a press release, “with health professionals already needing to manage its symptoms.”
Sherman is a leading voice in demanding action in the U.S. To her, comprehensive solutions start with the mandatory, transparent measurement of emissions in the health sector to tackle the biggest sources of pollution. While the Biden administration highlighted its efforts to reduce these kinds of emissions during the United Nations Climate Conference (COP27) in November 2022 and U.S. delegates announced that more than 100 health care organizations signed the voluntary Health Sector Climate Pledge, with the aim to reduce emissions by 50 percent in the next eight years, Sherman is convinced that voluntary pledges are not enough. “Voluntary measures are insufficient,” she testified in congress. “The vast majority of U.S. health care organizations remain uncommitted to timely action. Those that are committed lack policies and knowledge to support necessary changes; even worse, existing policies drive inappropriate consumption of resources and pollution.”
Both Sherman and Koch look at the larger picture. “Health care organizations have an obligation to their communities to protect public health,” Sherman says. “We must lead by example. That includes setting ambitious, science-based carbon reduction targets to achieve net zero emissions before 2050. We must quantify current emissions and their sources, particularly throughout the health care supply chains.”
