Polluting Air and Space

Ethan Wong

September 20, 2024

I published an article on space debris years ago that overviews space junk and the Kessler Syndrome. If interested in some basic information regarding such topics, you can read it here: 

Back in August, China’s Long March 6A rocket broke apart in space, scattering debris everywhere. In the process of carrying a satellite, its upper stage was torn apart in Low-Earth Orbit (LEO), contributing to the growing threat of space junk surrounding Earth. But this is nothing compared to a previous space debris event: the Fengyun-1C Anti-Satellite missile test. This launch back in 2007 was self-destroyed in space and set a record 3531 pieces of space debris. Over 2700 pieces of space debris still litter Earth’s orbit, extending all around and occupying Low-Earth orbit. This outpour of debris even knocked out another satellite, specifically a 1999 weather satellite, creating more debris. 

The intention of the Long March 6 launch was to further develop the Qianfan “Thousand Sails” mega constellation project currently in the works by China, hoping to position over 15000 satellites to improve communication quality with better network coverage. Sound familiar? Elon Musk’s SpaceX has been doing the same thing with Starlink. As of now, SpaceX has launched over 6000 satellites into LEO, hoping to be a global coverage prodiver, especially in areas that lack internet service providers. Starlink works by placing clusters of satellites in orbit to decrease network latency of internet services that are made between satellites and devices on Earth; these satellites are launched in groups of 50+ and ejected randomly into space, equipped with solar panels and ion thrusters. One interesting development on the Starlink satellites a few years back was the launch of DarkSats, which are light-absorbing. Additionally, the satellites were equipped with solar panels that had antireflective coatings; in combination with DarkSats, the Starlink satellites have a reduced light output when seen from Earth. But why is this important?

As more Starlink satellites were launched into orbit, the astronomy community became frustrated with the intense light pollution in the sky caused by these vehicles. While a telescope’s view might be obstructed by the bright lights, potentially hiding discoveries or astronomical objects, large observatory telescopes face similar challenges: false alarms of detection. And while radio telescopes don’t rely on visible light, Starlink satellites transmit powerful radio signals that interfere with these telescopes.

But the satellites aren’t only blocking views for astronomers. As some of the Starlink satellites, and other satellites/spacecraft in general, return to Earth, the Earth’s environment is put at great risk by “descending space debris.” According to a study by José P. Ferreira, Joseph Wang and Ken-ichi Nomura, titled “Preliminary assessment of the environmental impact of space debris demise during atmospheric reentry,” aluminum-built spacecraft and satellites returning into Earth’s atmosphere can pollute Earth’s stratosphere’s air quality with traces of aluminum and the aluminum oxides. Their research studied the interactions of aluminum with oxygen, and how re-entry conditions created aluminum-oxygen bonds while allowing excess non-oxidized aluminum particles to cluster and mesh into the atmosphere. After simulation runs, the team’s findings stated that aluminum was twice as abundant in Earth’s atmosphere on a yearly basis than before the space age, with the descent of rockets and satellites accumulating around 87% of the total amount of aluminum typically deposited into the atmosphere by natural sources like meteoroids. Aluminum oxides in growing amounts can damage the atmosphere’s ozone layer, leading to increased UV radiation and higher chance of cancer and eye damage.

Their research is important to recognizing the costs of orbital missions on the environment, even if it isn’t from spewing chemical propulsion caused by rocket launches. Any spacecraft or satellite put into orbit will likely be disposed of into the oceans, if not burning up in the atmosphere. NASA has even planned to descend the ISS down to Earth, which I covered in a previous article. This can lead to debris effects in the atmosphere. The oceans have also been a heated debate, in which space debris, metal hardware, and previously propellant-filled chambers are disposed; while people advocate for the safety of marine life and ocean pollution, space companies argue that sending spacecraft and satellites–most of which burn up in the atmosphere–into the ocean is the safest and easiest approach. I will cover spacecraft ocean pollution in a future article given the length of this already, along with proposed and current solutions that have been implemented to reduce spacejunk and debris pollution. 

But satellites in orbit also contribute heavily to Earth, helping monitor the environment and actively providing data reports for scientists studying climate change. One example is the Orbiting Carbon Observatory 2 (OCO-2), a satellite that actively monitors the carbon dioxide levels in Earth’s atmosphere, informing scientists of peaks (CO2 is emitted into the atmosphere by human activities, etc) or dips (carbon levels fall due to decrease in CO2) in the overall data to obtain more information on climate change. The satellite helps scientists understand human activities or other things that might increase harm of climate change with carbon peaks, and can make predictions or issue statements to discourage carbon pollution, or even remedy solutions that aren’t widely recognized. Another satellite is the ICESat-2, which can help scientists keep account of melting ice such as glacier formation changes which could impact rising ocean levels. This is also important because there is less ice to reflect light, causing ocean and other water bodies to heat up more which affects marine life and communities dependent on this life to survive. The last out of many satellites I’ll mention is TEMPO, another satellite currently reporting ozone, aerosol levels, and other factors that could pollute the Earth’s atmosphere to scientists, ensuring proper air quality hourly. All of these, and more, are still active today. 

In the end, the satellite situation is a win-lose for Earth and the environment. Space debris, debris upon descent, and further moving Earth toward an orbit-less future is not ideal; however, satellites also bring lots of important information into society, such as helping the environment or providing better network connections worldwide. But in looking toward a future where climate change continues plaguing the Earth, and humans become increasingly dependent on technology, is there even a solution for this?