EarthTalk: Questions and Answers About Our Environment

December 2020

Dear EarthTalk: Elon Musk plans to put thousands of new satellites into space to blanket Earth with high speed Internet. What are the environmental implications of this?   ~ M. C., Atlanta. GA

Putting satellites up into the ionosphere—the layer of our atmosphere extending from 50-600 miles above the surface where a high concentration of ions and free electrons facilitate the reflection of radio waves—isn’t anything new. The Soviets beat us to the punch when they launched the first satellite, Sputnik, in 1957, but these days there are over 9,000 satellites overhead, the majority from U.S. companies and government agencies. But with Elon Musk’s SpaceX poised to launch tens of thousands of new ones in the next few years, many people wonder whether putting all this technology overhead is such a good idea.

Some 9,000 satellites already orbit the ionosphere hundreds of miles above Earth’s surface, shedding parts that turn into hurtling “space junk.” Credit: Pixabay

One concern is that all this hardware eventually breaks down and shed parts. Peter Greenstreet of the Institute of Physics reports that this so-called “space junk” orbits at some 7.5 kilometers per second—so fast that even the tiniest pieces create a potential hazard for space stations and other man-made or natural objects making the same rounds. Greenstreet adds that space junk falling to Earth’s surface is less of a concern, given that most of it breaks down into tiny pieces due to the heat and friction encountered upon entry to our atmosphere and thus stands little to no chance of hurting any people or property below.

Another environmental issue with satellite proliferation is so-called “sky pollution.” By reflecting the light of the sun, satellites cause streaks of light across the sky where astronomers would prefer darkness for peering into the heavens and where everyday people will be robbed of their own views of a dark sky.

But despite these drawbacks, there are plenty of good reasons to like satellites if you care about the environment. “From the International Space Station (ISS) to hundreds of other observational satellites, remote sensing allows for climate and environmental monitoring,” reports Daisy Gill on “These imaging satellites are an incredible source of data for climate change research, enabling us to see the global changes on the planet that are happening more frequently, and with data freely available for anyone to view and use.”  Examples include tracking changing oceanic temperatures, currents and sea level.

Satellites are also key to understanding global and local precipitation and flooding patterns, how wildfires start and spread, the distribution of wildlife populations, and other indicators of environmental health. Satellites are also useful as early warning systems for natural disasters and extreme weather events.

If we can figure out ways to clean up space junk, we can use satellites with less guilt. NASA’s e.DeOrbit project is focusing on seeking out and removing satellite debris in the upper reaches of the ionosphere. Meanwhile, the European Space Agency is hard at work on its own “capture mechanisms” to pick up space debris such as nets, harpoons robotic arms and tentacles. Only time will tell if these technologies can help restore the heavens above—or at least the ionosphere—to a more pristine state.


“Outside Looking In: Satellites in the Climate Crisis,”;

“Space junk and the environment: It’s a very dark picture indeed,”

Dear EarthTalk: Is it true that wastes left over from mining operations could be used to absorb carbon dioxide and help solve the climate crisis?                        ~ D. Moore, Richmond, VA

Yes, mining wastes (“tailings”) could indeed be part of the solution to our climate woes. Researchers have shown that alkaline wastes—such as the slurries (semi-liquid mixtures), gravel and other industrial detritus that accumulate during and after mining projects—could be “reacted” with airborne carbon dioxide (CO2), which would not only sequester some of this most common of greenhouse gases but also neutralize the otherwise hazardous alkalinity of the waste itself.

Mine tailings like this could sequester lots of atmospheric carbon dioxide. Credit: wild trees, flickrCC

This is good news because tailings in and of themselves can be a major environmental nuisance and health threat for those living nearby. Since most of this mining waste comes in slurry form means it often ends up in or near water, which causes contamination issues and destroys aquatic life. And because tailings can be transported by wind and/or water, they can easily expand their realm of contamination, spreading into nearby waterways and destroying larger and larger swaths of wildlife habitat.

If we can turn our mine tailings into carbon sinks (absorbers) on a large scale, it’s a win-win. Researchers at Canada’s University of Alberta seem to think so: Their March 2019 study found that the minerals in tailings naturally capture atmospheric CO2 if exposed to them, and the findings are backed up by similar research elsewhere. Harnessing this carbon sequestration (capturing) tool on a global scale would do wonders for our collective carbon footprint.

Meanwhile, an ongoing research project at another Canadian college, the University of British Columbia (UBC), is looking into how to facilitate so-called “direct capture” of atmospheric CO2 into mine tailings with the goal of at least offsetting the greenhouse gases generated as a result of the extraction work.  In response to this challenge, UBC is identifying common traits among different types of mine tailings that excel at carbon sequestration in hopes of developing a set of protocols that mining operations anywhere in the world can call upon to reduce their impact and suck up at least the emissions their projects create.

“Incorporation of carbon sequestration activities into mine operations…will generate economic, corporate and societal advantages to mines and affiliated industries, including co-benefits such as tailings stabilization, dust mitigation and toxic metal immobilization,” they conclude. “Carrying this out on a global scale could trap between 310 million to 4 billion tons of carbon dioxide annually,” Robert F. Service reports in Nature. “That could provide the world with a much-needed means of lowering atmospheric carbon dioxide.”

It’s much easier said than done, and governments will need to offer incentives on a massive scale needed to make a dent in atmospheric carbon, Service says, adding: “And engineers will need to figure out how to harness the wastes while preventing the release of heavy metals and radioactivity locked in the material.”


“Revaluing mine waste rock for carbon capture and storage,”;

“Scientists identify new minerals for carbon capture,”


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