Editing Satellite (section)

== Environmental impact ==
The environmental impact of satellites is not currently well understood as they were previously assumed to be benign due to the rarity of satellite launches. However, the exponential increase and projected growth of satellite launches are bringing the issue into consideration. The main issues are resource use and the release of pollutants into the atmosphere which can happen at different stages of a satellite's lifetime.

=== Resource use ===
Resource use is difficult to monitor and quantify for satellites and [[launch vehicle]]s due to their commercially sensitive nature. However, [[aluminium]] is a preferred metal in satellite construction due to its lightweight and relative cheapness and typically constitutes around 40% of a satellite's mass.<ref name="schulz">{{cite journal |last1=Schulz |first1=Leonard |last2=Glassmeier |first2=Karl-Heinz |title=On the anthropogenic and natural injection of matter into Earth's atmosphere |journal=Advances in Space Research |date=2021 |volume=67 |issue=3 |pages=1002–1025 |doi=10.1016/j.asr.2020.10.036 |arxiv=2008.13032 |bibcode=2021AdSpR..67.1002S}}</ref> Through mining and refining, aluminium has numerous negative environmental impacts and is one of the most carbon-intensive metals.<ref>{{cite journal |last1=Farjana |first1=Shahjadi Hisan |last2=Huda |first2=Nazmul |last3=Mahmud |first3=M.A. Parvez |title=Impacts of aluminum production: A cradle to gate investigation using life-cycle assessment |journal=Science of the Total Environment |date=2019 |volume=663 |pages=958–970 |doi=10.1016/j.scitotenv.2019.01.400 |pmid=30739864 |bibcode=2019ScTEn.663..958F}}</ref> Satellite manufacturing also requires rare elements such as [[lithium]], [[gold]], and [[gallium]], some of which have significant environmental consequences linked to their mining and processing and/or are in limited supply.<ref name="Gaston">{{cite journal |last1=Gaston |first1=Kevin |last2=Anderson |first2=Karen |last3=Shutler |first3=Jamie |last4=Brewin |first4=Robert |last5=Yan |first5=Xiaoyu |title=Environmental impacts of increasing numbers of artificial space objects |journal=Frontiers in Ecology and the Environment |date=2023 |volume=21 |issue=6 |pages=289–296 |doi=10.1002/fee.2624 |bibcode=2023FrEE...21..289G |hdl=10871/132935 |hdl-access=free}}</ref><ref>{{cite journal |last1=Norgate |first1=Terry |last2=Haque |first2=Nawshad |title=Using life cycle assessment to evaluate some environmental impacts of gold production |journal=Journal of Cleaner Production |date=2012 |volume=29 |pages=53–63 |doi=10.1016/j.jclepro.2012.01.042 |bibcode=2012JCPro..29...53N}}</ref><ref>{{cite journal |last1=Flexer |first1=Victoria |last2=Baspineiro |first2=Celso |last3=Galli |first3=Claudia |title=Lithium recovery from brines: A vital raw material for green energies with a potential environmental impact in its mining and processing |journal=Science of the Total Environment |date=2018 |volume=639 |pages=1188–1204 |doi=10.1016/j.scitotenv.2018.05.223 |pmid=29929287 |bibcode=2018ScTEn.639.1188F |hdl=11336/91034 |hdl-access=free}}</ref> Launch vehicles require larger amounts of raw materials to manufacture and the [[Booster (rocketry)|booster]] stages are usually dropped into the ocean after fuel exhaustion. They are not normally recovered.<ref name="Gaston" /> Two empty boosters used for [[Ariane 5]], which were composed mainly of steel, weighed around 38 tons each,<ref>{{cite web |title=Boosters (EAP) |url=https://www.esa.int/Enabling_Support/Space_Transportation/Launch_vehicles/Boosters_EAP |website=The European Space Agency |access-date=10 April 2024 |archive-date=6 March 2023 |archive-url=https://web.archive.org/web/20230306132210/https://www.esa.int/Enabling_Support/Space_Transportation/Launch_vehicles/Boosters_EAP |url-status=live }}</ref> to give an idea of the quantity of materials that are often left in the ocean.

=== Launches ===
Rocket launches release numerous pollutants into every layer of the atmosphere, especially affecting the atmosphere above the [[tropopause]] where the byproducts of combustion can reside for extended periods.<ref name="Durrieu">{{cite journal |last1=Durrieu |first1=Sylvie |last2=Nelson |first2=Ross |title=Earth observation from space – The issue of environmental sustainability |journal=Space Policy |date=2013 |volume=29 |issue=4 |pages=238–250 |doi=10.1016/j.spacepol.2013.07.003 |doi-access=free |bibcode=2013SpPol..29..238D}}</ref> These pollutants can include [[black carbon]], [[Carbon dioxide|CO<sub>2</sub>]], [[NOx|nitrogen oxides]] (NO<sub>x</sub>), [[aluminium]] and [[water vapour]], but the mix of pollutants is dependent on rocket design and fuel type.<ref>{{cite journal |last1=Dallas |first1=J. A. |last2=Raval |first2=S. |last3=Gaitan |first3=J. P. A. |last4=Saydam |first4=S. |last5=Dempster |first5=A. G. |date=2020 |title=The environmental impact of emissions from space launches: A comprehensive review |journal=Journal of Cleaner Production |volume=255 |bibcode=2020JCPro.25520209D |doi=10.1016/j.jclepro.2020.120209}}</ref> The amount of [[Greenhouse gas|green house gases]] emitted by rockets is considered trivial as it contributes significantly less, around 0.01%,<ref>{{cite journal |last1=Miraux |first1=Lois |title=Environmental limits to the space sector's growth |journal=Science of the Total Environment |date=2022 |volume=806 |issue=4 |doi=10.1016/j.scitotenv.2021.150862 |pmid=34637875 |bibcode=2022ScTEn.80650862M}}</ref> than the aviation industry yearly which itself accounts for 2-3% of the total global greenhouse gas emissions.<ref name= "Durrieu" />

Rocket emissions in the [[stratosphere]] and their effects are only beginning to be studied and it is likely that the impacts will be more critical than emissions in the troposphere.<ref name="Gaston" /> The stratosphere includes the [[ozone layer]] and pollutants emitted from rockets can contribute to [[ozone depletion]] in a number of ways. [[Radical (chemistry)|Radicals]] such as NO<sub>x</sub>, HO<sub>x</sub>, and ClO<sub>x</sub> deplete stratospheric O<sub>3</sub> through intermolecular reactions and can have huge impacts in trace amounts.<ref name= "Durrieu" /> However, it is currently understood that launch rates would need to increase by ten times to match the impact of regulated ozone-depleting substances.<ref name="Ryan">{{cite journal |last1=Ryan |first1=Robert |last2=Marais |first2=Eloise |last3=Balhatchet |first3=Chloe |last4=Eastham |first4=Sebastian |title=Impact of Rocket Launch and Space Debris Air Pollutant Emissions on Stratospheric Ozone and Global Climate |journal=Earth's Future |date=2022 |volume=10 |issue=6 |pages=e2021EF002612 |doi=10.1029/2021EF002612 |pmid=35865359 |pmc=9287058 |bibcode=2022EaFut..1002612R}}</ref><ref name="Ross">{{cite journal |last1=Ross |first1=Martin |last2=Toohey |first2=Darin |last3=Peinemann |first3=Manfred |last4=Ross |first4=Patrick |title=Limits on the Space Launch Market Related to Stratospheric Ozone Depletion |journal=Astropolitics |date=2009 |volume=7 |issue=1 |pages=50–82 |doi=10.1080/14777620902768867 |bibcode=2009AstPo...7...50R}}</ref> Whilst emissions of water vapour are largely deemed as inert, H<sub>2</sub>O is the source gas for HO<sub>x</sub> and can also contribute to ozone loss through the formation of ice particles.<ref name="Ryan" /> Black carbon particles emitted by rockets can absorb solar radiation in the stratosphere and cause warming in the surrounding air which can then impact the circulatory dynamics of the stratosphere.<ref>{{cite journal |last1=Maloney |first1=Christopher |last2=Portmann |first2=Robert |last3=Ross |first3=Martin |last4=Rosenlof |first4=Karen |title=The Climate and Ozone Impacts of Black Carbon Emissions From Global Rocket Launches |journal= Journal of Geophysical Research: Atmospheres|date=2022 |volume=127 |issue=12 |doi=10.1029/2021JD036373 |bibcode=2022JGRD..12736373M |url=https://repository.library.noaa.gov/view/noaa/53971 |access-date=19 May 2024 |archive-date=18 June 2024 |archive-url=https://web.archive.org/web/20240618175407/https://repository.library.noaa.gov/view/noaa/53971 |url-status=live }}</ref> Both warming and changes in circulation can then cause depletion of the ozone layer.

=== Operational ===
==== Low earth orbit satellites ====
Several pollutants are released in the upper atmospheric layers during the orbital lifetime of [[Low Earth orbit|LEO satellites.]] [[Orbital decay]] is caused by atmospheric drag and to keep the satellite in the correct orbit the platform occasionally needs repositioning. To do this nozzle-based systems use a chemical propellant to create thrust. In most cases [[hydrazine]] is the chemical propellant used which then releases [[ammonia]], [[hydrogen]] and [[nitrogen]] as gas into the upper atmosphere.<ref name="Durrieu" /> Also, the environment of the outer atmosphere causes the degradation of exterior materials. The atomic oxygen in the upper atmosphere oxidises hydrocarbon-based polymers like [[Kapton]], [[Teflon]] and [[BoPET|Mylar]] that are used to insulate and protect the satellite which then emits gasses like CO<sub>2</sub> and CO into the atmosphere.<ref>{{cite book |last1=de Groh |first1=Kim |last2=Banks |first2=Bruce |last3=Miller |first3=Sharon |last4=Dever |first4=Joyce |date=2018 |chapter=Degradation of Spacecraft Materials |title=Handbook of Environmental Degradation of Materials |pages=601–645 |edition=Third |doi=10.1016/B978-0-323-52472-8.00029-0 |isbn=978-0-323-52472-8 |hdl-access=free |hdl=2060/20040112017}}</ref>

==== Night sky ====
Given the current surge in satellites in the sky, soon hundreds of satellites may be clearly visible to the human eye at dark sites. It is estimated that the overall levels of diffuse brightness of the night skies has increased by up to 10% above natural levels.<ref>{{cite journal |last1=Kocifaj |first1=M. |last2=Kundracik |first2=F. |last3=Barentine |first3=J. C. |last4=Bara |first4=S. |date=2021 |title=The proliferation of space objects is a rapidly increasing source of artificial night sky brightness |journal=Monthly Notices of the Royal Astronomical Society: Letters |volume=504 |issue=1 |pages=L40–L44 |arxiv=2103.17125 |doi=10.1093/mnrasl/slab030 |doi-access=free}}</ref> This has the potential to confuse organisms, like insects and night-migrating birds, that use celestial patterns for migration and orientation.<ref>{{cite journal |last1=Sutherland |first1=W. J. |last2=Atkinson |first2=P. W. |last3=Broad |first3=S. |last4=Brown |first4=S. |last5=Clout |first5=M. |last6=Dias |first6=M. P. |last7=Dicks |first7=L. V. |last8=Doran |first8=H. |last9=Fleishman |first9=E. |last10=Garratt |first10=E. L. |last11=Gaston |first11=K. J. |last12=Hughes |first12=A. C. |last13=Le Roux |first13=X. |last14=Lickorish |first14=F. A. |last15=Maggs |first15=L. |date=2021 |title=A 2021 Horizon Scan of Emerging Global Biological Conservation Issues |journal=Trends in Ecology & Evolution |volume=36 |issue=1 |pages=87–97 |bibcode=2021TEcoE..36...87S |doi=10.1016/j.tree.2020.10.014 |pmid=33213887 |hdl-access=free |last16=Palardy |first16=J. E. |last17=Peck |first17=L. S. |last18=Pettorelli |first18=N. |last19=Pretty |first19=J. |last20=Spalding |first20=M. D. |last21=Tonneijck |first21=F. H. |last22=Walpole |first22=M. |last23=Watson |first23=J. E. M. |last24=Wentworth |first24=J. |last25=Thornton |first25=A. |hdl=10400.12/8056}}</ref><ref>{{cite journal |last1=Foster |first1=J. |last2=Smolka |first2=J. |last3=Nilsson |first3=D.E. |last4=Dacke |first4=M. |title=How animals follow the stars |journal=Proceedings of the Royal Society B: Biological Sciences |date=2018 |volume=285 |issue=1871 |doi=10.1098/rspb.2017.2322 |pmid=29367394 |pmc=5805938}}</ref> The impact this might have is currently unclear. The visibility of man-made objects in the night sky may also impact people's linkages with the world, nature, and culture.<ref>{{cite journal |last1=Hamacher |first1=Duane |last2=Barsa |first2=John |last3=Passi |first3=Segar |last4=Tapim |first4=Alo |title=Indigenous use of stellar scintillation to predict weather and seasonal change |journal=Proceedings of the Royal Society of Victoria |date=2019 |volume=131 |issue=1 |page=24 |doi=10.1071/RS19003 |arxiv=1903.01060}}</ref>

==== Ground-based infrastructure ====
At all points of a satellite's lifetime, its movement and processes are monitored on the ground through a network of facilities. The environmental cost of the infrastructure as well as day-to-day operations is likely to be quite high,<ref name="Gaston" /> but quantification requires further investigation.

=== Degeneration ===
Particular threats arise from uncontrolled de-orbit. 

Some notable satellite failures that polluted and dispersed radioactive materials are [[Kosmos 954]], [[Kosmos 1402]] and the [[List of nuclear power systems in space|Transit 5-BN-3]].

When in a controlled manner satellites reach the end of life they are intentionally deorbited or moved to a [[graveyard orbit]] further away from Earth in order to reduce [[space debris]]. Physical collection or removal is not economical or even currently possible. Moving satellites out to a graveyard orbit is also unsustainable because they remain there for hundreds of years.<ref name="Gaston" /> It will lead to the further pollution of space and future issues with space debris. 
When satellites deorbit much of it is destroyed during re-entry into the atmosphere due to the heat. This introduces more material and pollutants into the atmosphere.<ref name="schulz" /><ref>{{cite journal |last1=Miraux |first1=Lois |last2=Willson |first2=Andrew |last3=Calabuig |first3=Guillermo |title=Environmental sustainability of future proposed space activities |journal=Acta Astronautica |date=2022 |volume=200 |issue=1 |pages=329–346 |doi=10.1016/j.actaastro.2022.07.034 |bibcode=2022AcAau.200..329M |url=https://strathprints.strath.ac.uk/82154/1/Miraux_etal_AA_2022_Environmental_sustainability_of_future_proposed_space_activities.pdf}}</ref> There have been concerns expressed about the potential damage to the ozone layer and the possibility of increasing the earth's [[albedo]], reducing warming but also resulting in accidental [[geoengineering]] of the earth's climate.<ref name="Gaston" /> After deorbiting 70% of satellites end up in the ocean and are rarely recovered.<ref name="Durrieu" />

===Mitigation===
Using wood as an alternative material has been posited in order to reduce pollution and debris from satellites that reenter the atmosphere.<ref>{{cite news |last=Harper |first=Justin |date=29 December 2020 |title=Japan developing wooden satellites to cut space junk |work=bbc.co.uk |url=https://www.bbc.co.uk/news/business-55463366 |access-date=29 December 2020 |archive-date=29 December 2020 |archive-url=https://web.archive.org/web/20201229014751/https://www.bbc.co.uk/news/business-55463366 |url-status=live}}</ref>