One million satellites in the sky: Light contamination on space telescopes

One million satellites in the sky: Light contamination on space telescopes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Physical Sciences - Article One million satellites in the sky: Light contamination on space telescopes Alejandro Borlaff, Pamela Marcum, Steve Howell This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6414845/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Dec, 2025 Read the published version in Nature → Version 1 posted You are reading this latest preprint version Abstract Rapidly growing satellite mega-constellations have raised strong concerns among the scientific community. Reflections from satellites are visible to the human eye and extremely bright for professional telescopes. These trails already affect astronomical observations across the complete electromagnetic spectrum, with a noticeable cost for operations and mitigation efforts. Despite the common misconception, satellite trails affect not only ground-based observatories, but also space observatories, like Hubble . However, the current number of satellites is only a fraction (<10%) of those to be launched in the next decade. Here we show a forecast of the satellite trail contamination levels for a series of international low earth orbit telescopes, based on the proposed telecommunication industry constellations. Our results show that if these constellations are completed, one fourth ofHubble's images will be contaminated, while the space telescopes SPHEREx, ARRAKIHS, and Xuntian will have 94% of their exposures affected, with 5.9 +0.6 -0.6 , 32 +17 -13 and 86 +20 -19 trails per exposure respectively, with an average surface brightness of μ = 18+-2 mag arcsec -2 . Our results demonstrate that light contamination is a growing threat for space-telescope operations. We propose a series of mitigation measures to minimize their impact, allowing researchers to predict, model, and correct unwanted satellite light pollution from science observations. Physical sciences/Astronomy and planetary science/Astronomy and astrophysics/Astronomical instrumentation Physical sciences/Astronomy and planetary science/Space physics/Astronomical instrumentation Earth and environmental sciences/Space physics/Astronomical instrumentation Space telescopes (1547) Artificial satellites (68) Light pollution (2318) Hubble Space Telescope (761) Space observatories (1543) Interdisciplinary astronomy(804) Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Published Journal Publication published 03 Dec, 2025 Read the published version in Nature → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6414845","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":444405544,"identity":"376f8c51-81ec-4ea1-96cf-2bac17eb0fe5","order_by":0,"name":"Alejandro Borlaff","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3UlEQVRIie3RMQrCMBSA4ciDuLySNaC0V0gR3MSrVArOBRdBKZ3qIrp29yKRQFx6g4JWBC8gOIqpmyBRN8H8EMiQj5cQQlyuHw3M6hLYHuuvCBIa98TXpM8/Os6ydg3JdI8sBzpL5mlA2EZbLZcooCgnyDXQqtAqzPh5bB8nkYCXR0gOa10hla2Ml/ZHBdJcrCGBmTLBWzp8S4Qk4kGEIWYDo4wtw9pGQoVCFWWEoQboeCsV55yOrMTfLY6nZBr5vobWBa/pYM2UlDbSfMrzAcojK3gVs89wuVyu/+sOYDA/4jPgR6MAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0003-3249-4431","institution":"NASA Ames Research Center","correspondingAuthor":true,"prefix":"","firstName":"Alejandro","middleName":"","lastName":"Borlaff","suffix":""},{"id":444405545,"identity":"8880a989-5ed1-4117-a37e-9f22f54e82e0","order_by":1,"name":"Pamela Marcum","email":"","orcid":"","institution":"NASA Ames Research Center","correspondingAuthor":false,"prefix":"","firstName":"Pamela","middleName":"","lastName":"Marcum","suffix":""},{"id":444405546,"identity":"13f5c06e-0afb-4042-b72e-378a90d1db95","order_by":2,"name":"Steve Howell","email":"","orcid":"","institution":"NASA","correspondingAuthor":false,"prefix":"","firstName":"Steve","middleName":"","lastName":"Howell","suffix":""}],"badges":[],"createdAt":"2025-04-09 21:30:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6414845/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6414845/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41586-025-09759-5","type":"published","date":"2025-12-03T05:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":97419590,"identity":"057e783f-b160-431a-922f-b21302af4f76","added_by":"auto","created_at":"2025-12-04 08:18:38","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3368015,"visible":true,"origin":"","legend":"Article File","description":"","filename":"OMSITSBorlaff2025Nature.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6414845/v1_covered_afe75352-6a5a-4893-8ae0-e64a1c650b43.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"One million satellites in the sky: Light contamination on space telescopes","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Space telescopes (1547), Artificial satellites (68), Light pollution (2318), Hubble Space Telescope (761), Space observatories (1543), Interdisciplinary astronomy(804)","lastPublishedDoi":"10.21203/rs.3.rs-6414845/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6414845/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eRapidly growing satellite mega-constellations have raised strong concerns among the scientific community. Reflections from satellites are visible to the human eye and extremely bright for professional telescopes. These trails already affect astronomical observations across the complete electromagnetic spectrum, with a noticeable cost for operations and mitigation efforts. Despite the common misconception, satellite trails affect not only ground-based observatories, but also space observatories, like \u003cem\u003eHubble\u003c/em\u003e. However, the current number of satellites is only a fraction (\u0026lt;10%) of those to be launched in the next decade. Here we show a forecast of the satellite trail contamination levels for a series of international low earth orbit telescopes, based on the proposed telecommunication industry constellations. Our results show that if these constellations are completed, one fourth ofHubble's images will be contaminated, while the space telescopes SPHEREx, ARRAKIHS, and Xuntian will have \u003cstrong\u003e94%\u003c/strong\u003e of their exposures affected, with \u003cstrong\u003e5.9\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e+0.6 \u003c/strong\u003e\u003c/sup\u003e\u003csup\u003e\u003csub\u003e\u003cstrong\u003e-0.6\u003c/strong\u003e\u003c/sub\u003e\u003c/sup\u003e, \u003cstrong\u003e32\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e+17\u003c/strong\u003e\u003c/sup\u003e\u003csub\u003e\u003cstrong\u003e-13\u003c/strong\u003e\u003c/sub\u003e and \u003cstrong\u003e86\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e+20\u003c/strong\u003e\u003c/sup\u003e\u003csub\u003e\u003cstrong\u003e-19\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e \u003c/strong\u003e\u0026nbsp;trails per exposure respectively, with an average surface brightness of \u003cstrong\u003eμ = 18+-2\u003c/strong\u003e mag arcsec\u003csup\u003e\u003cstrong\u003e-2\u003c/strong\u003e\u003c/sup\u003e. Our results demonstrate that light contamination is a growing threat for space-telescope operations. We propose a series of mitigation measures to minimize their impact, allowing researchers to predict, model, and correct unwanted satellite light pollution from science observations.\u003c/p\u003e","manuscriptTitle":"One million satellites in the sky: Light contamination on space telescopes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-18 03:31:55","doi":"10.21203/rs.3.rs-6414845/v1","editorialEvents":[],"status":"published","journal":{"display":false,"email":"[email protected]","identity":"nature","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"nature","sideBox":"Learn more about [Nature](http://www.nature.com/nature/)","snPcode":"","submissionUrl":"","title":"Nature","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"241d9d39-7635-47fd-a712-a15098ebb750","owner":[],"postedDate":"April 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":47314121,"name":"Physical sciences/Astronomy and planetary science/Astronomy and astrophysics/Astronomical instrumentation"},{"id":47314122,"name":"Physical sciences/Astronomy and planetary science/Space physics/Astronomical instrumentation"},{"id":47314123,"name":"Earth and environmental sciences/Space physics/Astronomical instrumentation"}],"tags":[],"updatedAt":"2025-12-04T08:18:29+00:00","versionOfRecord":{"articleIdentity":"rs-6414845","link":"https://doi.org/10.1038/s41586-025-09759-5","journal":{"identity":"nature","isVorOnly":false,"title":"Nature"},"publishedOn":"2025-12-03 05:00:00","publishedOnDateReadable":"December 3rd, 2025"},"versionCreatedAt":"2025-04-18 03:31:55","video":"","vorDoi":"10.1038/s41586-025-09759-5","vorDoiUrl":"https://doi.org/10.1038/s41586-025-09759-5","workflowStages":[]},"version":"v1","identity":"rs-6414845","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6414845","identity":"rs-6414845","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}