{"id":130383,"date":"2025-10-18T15:27:14","date_gmt":"2025-10-18T15:27:14","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/130383\/"},"modified":"2025-10-18T15:27:14","modified_gmt":"2025-10-18T15:27:14","slug":"reflect-orbital-says-it-will-deliver-sunlight-on-demand","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/130383\/","title":{"rendered":"Reflect Orbital says it will deliver sunlight on demand"},"content":{"rendered":"<p><img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/sunlight-Marys-photos-Pixabay-e1760566549611.jpg\" alt=\"Reflect Orbital: A bright sun with rays bursting through past dark trees and landscape.\" width=\"800\" height=\"533\" class=\"size-full wp-image-524910\"\/><a href=\"https:\/\/www.reflectorbital.com\" rel=\"noopener nofollow\" target=\"_blank\">Reflect Orbital<\/a> promises sunlight on demand. What exactly does that mean and how would it affect astronomy? Image via Marys_fotos\/ <a href=\"https:\/\/pixabay.com\/photos\/sunlight-nature-outdoors-sunbeam-3130638\/\" rel=\"noopener nofollow\" target=\"_blank\">Pixabay<\/a>.<\/p>\n<p><a href=\"https:\/\/helpsupportearthsky.org\/2025-donation-campaign\/\" rel=\"noopener nofollow\" target=\"_blank\"><strong>We live in uncertain times. But things are always so much more peaceful, looking up.<\/strong> Please help EarthSky keep going!<\/a><\/p>\n<ul>\n<li><strong>Reflect Orbital is a startup company<\/strong> in the U.S. that wants to provide light for solar farms at night, among other uses.<\/li>\n<li><strong>The company suggested putting 250,000 satellites<\/strong> into space covered with mirrors in order to achieve their night-lighting goals.<\/li>\n<li><strong>Scientists said this plan could be dangerous<\/strong> for astronomers and others. Plus, it still would not adequately achieve the goals they are claiming.<\/li>\n<\/ul>\n<p>  By <a href=\"https:\/\/theconversation.com\/profiles\/michael-j-i-brown-113\" rel=\"noopener nofollow\" target=\"_blank\">Michael J. I. Brown<\/a>, <a href=\"https:\/\/theconversation.com\/institutions\/monash-university-1065\" rel=\"noopener nofollow\" target=\"_blank\">Monash University<\/a> and <a href=\"https:\/\/theconversation.com\/profiles\/matthew-kenworthy-1400515\" rel=\"noopener nofollow\" target=\"_blank\">Matthew Kenworthy<\/a>, <a href=\"https:\/\/theconversation.com\/institutions\/leiden-university-935\" rel=\"noopener nofollow\" target=\"_blank\">Leiden University<\/a><\/p>\n<p>What is Reflect Orbital?<\/p>\n<p>A proposed constellation of satellites has astronomers very worried. Unlike satellites that reflect sunlight and <a href=\"https:\/\/theconversation.com\/thousands-of-satellites-are-polluting-australian-skies-and-threatening-ancient-indigenous-astronomy-practices-173840\" rel=\"noopener nofollow\" target=\"_blank\">produce light pollution<\/a> as an unfortunate byproduct, the ones by U.S. startup <a href=\"https:\/\/www.reflectorbital.com\" rel=\"noopener nofollow\" target=\"_blank\">Reflect Orbital<\/a> would produce light pollution by design.<\/p>\n<p>The company promises to produce \u201csunlight on demand\u201d with mirrors that beam sunlight down to Earth so solar farms can <a href=\"https:\/\/www.reflectorbital.com\/energy\" rel=\"noopener nofollow\" target=\"_blank\">operate after sunset<\/a>. <\/p>\n<p>It plans to start with an 18-meter (60-foot) test satellite named Earendil-1, which the company has applied to <a href=\"https:\/\/communicationsdaily.com\/article\/2025\/08\/04\/fcc-approval-sought-for-sunreflecting-satellite-2508010001\" rel=\"noopener nofollow\" target=\"_blank\">launch in 2026<\/a>. It would eventually be followed by about 4,000 satellites in orbit by 2030, <a href=\"https:\/\/www.bloomberg.com\/news\/articles\/2025-10-06\/sequoia-backed-startup-faces-pushback-over-plan-to-reflect-sunlight-to-earth\" rel=\"noopener nofollow\" target=\"_blank\">according to the latest reports<\/a>.<\/p>\n<p>So, how bad would the light pollution be? And perhaps more importantly, can Reflect Orbital\u2019s satellites even work as advertised? <\/p>\n<p>Bouncing sunlight<\/p>\n<p>            <a href=\"https:\/\/images.theconversation.com\/files\/692811\/original\/file-20250925-56-r8riab.jpg?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" alt=\"A watch on somebody's hairy wrist with a small oblong of light on a wall next to it.\" src=\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/1760801232_371_file-20250925-56-r8riab.jpg\"  \/><\/a>Sunlight can be bounced off a wristwatch to produce a spot of light. Image via M. Brown\/ <a href=\"https:\/\/theconversation.com\/a-us-startup-plans-to-deliver-sunlight-on-demand-after-dark-can-it-work-and-would-we-want-it-to-264323\" rel=\"noopener nofollow\" target=\"_blank\">The Conversation<\/a>.<\/p>\n<p>In the same way you can bounce sunlight off a watch face to produce a spot of light, Reflect Orbital\u2019s satellites would use mirrors to beam light onto a patch of Earth.<\/p>\n<p>But the scale involved is vastly different. Reflect Orbital\u2019s satellites would orbit about 625 km (388 miles) above the ground. And they would eventually have mirrors <a href=\"https:\/\/www.youtube.com\/watch?v=yDV3v0Xb4ow&amp;t=1130\" rel=\"noopener nofollow\" target=\"_blank\">54 meters (177 feet) across<\/a>.<\/p>\n<p>When you bounce light off your watch onto a nearby wall, the spot of light can be very bright. But if you bounce it onto a distant wall, the spot becomes larger \u2026 and dimmer. <\/p>\n<p>This is because the sun is not a point of light, but spans half a <a href=\"https:\/\/earthsky.org\/astronomy-essentials\/sky-measurements-degrees-arc-minutes-arc-seconds\/\" rel=\"noopener nofollow\" target=\"_blank\">degree<\/a> in angle in the sky. This means that at large distances, a beam of sunlight reflected off a flat mirror spreads out with an angle of half a degree.  <\/p>\n<p>What does that mean in practice? Let\u2019s take a satellite reflecting sunlight over a distance of roughly 800 km (500 miles). That\u2019s because a 625-km-high (388-mile-high) satellite won\u2019t always be directly overhead, but beaming the sunlight at an angle. The illuminated patch of ground would be at least 7 km (4.3 miles) across.<\/p>\n<p>Even a curved mirror or a lens can\u2019t focus the sunlight into a tighter spot due to the distance and the half-degree angle of the sun in the sky. <\/p>\n<p>Would this reflected sunlight be bright or dim? Well, for a single 54-meter satellite, it will be 15,000 times fainter than the midday sun. But this is still far brighter than the full moon. <\/p>\n<p>            <a href=\"https:\/\/images.theconversation.com\/files\/689517\/original\/file-20250906-57-dgll9v.jpg?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" alt=\"Earth in space, with a large square foil reflector floating above it in orbit.\" src=\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/1760801233_470_file-20250906-57-dgll9v.jpg\"  \/><\/a>Mylar reflectors like these would unfold in orbit. Image via Josh Spradling\/ <a class=\"source\" href=\"https:\/\/www.planetary.org\/space-images\/ls2-earth\" rel=\"noopener nofollow\" target=\"_blank\">The Planetary Society<\/a> (<a class=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\" rel=\"noopener nofollow\" target=\"_blank\">CC BY-SA 3.0<\/a>).<br \/>\nThe balloon test<\/p>\n<p>Last year, Reflect Orbital\u2019s founder Ben Nowack <a href=\"https:\/\/www.youtube.com\/watch?v=4hUNCtDTIZc\" rel=\"noopener nofollow\" target=\"_blank\">posted a short video<\/a> that summarized a test with the \u201clast thing to build before moving into space.\u201d It was a reflector carried on a hot air balloon. <\/p>\n<p>In the test, a flat, square mirror roughly 2.5 meters (8.2 feet) across directs a beam of light down to solar panels and sensors. In one instance, the team measures 516 watts of light per square meter (11 sq ft) while the balloon is at a distance of 242 meters (794 feet). <\/p>\n<p>For comparison, the midday sun produces roughly 1,000 watts per square meter. So 516 watts per square meter is about half of that, which is enough to be useful.<\/p>\n<p>However, let\u2019s scale the balloon test to space. As we noted earlier, if the satellites were 800 km (500 miles) from the area of interest, the reflector would need to be 6.5km by 6.5km, or 42 square kilometers (16 square miles). It\u2019s not practical to build such a giant reflector, so the balloon test has some limitations.<\/p>\n<p>So what is Reflect Orbital planning to do?<\/p>\n<p>Reflect Orbital\u2019s plan is \u201csimple satellites in the right constellation shining on existing solar farms.\u201d And their goal is only <a href=\"https:\/\/monocle.com\/business\/aviation\/reflect-orbital-aerospace-startup\/\" rel=\"noopener nofollow\" target=\"_blank\">200 watts per square meter<\/a>, or 20% of the midday sun.<\/p>\n<p>Can smaller satellites deliver? If a single 54-meter satellite is 15,000 times fainter than the midday sun, you would need 3,000 of them to achieve 20% of the midday sun. That\u2019s a lot of satellites to illuminate one region.<\/p>\n<p>Another issue: satellites at a 625-km (390 mile) altitude move at 7.5 kilometers per second (16,800 mph). So a satellite will be within 1,000 km (621 miles) of a given location for no more than 3.5 minutes. <\/p>\n<p>This means 3,000 satellites would give you a few minutes of illumination. To provide even an hour, you\u2019d need thousands more.<\/p>\n<p>Reflect Orbital isn\u2019t lacking ambition. In one interview, Nowack suggested <a href=\"https:\/\/www.youtube.com\/watch?v=yDV3v0Xb4ow&amp;t=3000s\" rel=\"noopener nofollow\" target=\"_blank\">250,000 satellites<\/a> in 600-km-high (370-mile-high) orbits. That\u2019s more than <a href=\"https:\/\/sdup.esoc.esa.int\/discosweb\/statistics\/\" rel=\"noopener nofollow\" target=\"_blank\">all the currently cataloged satellites<\/a> and large pieces of space junk put together. <\/p>\n<p>And yet, that vast constellation would deliver only 20% of the midday sun to no more than 80 locations at once, based on our calculations above. In practice, even fewer locations would be illuminated due to cloudy weather. <\/p>\n<p>Additionally, given their altitude, the satellites could only deliver illumination to most locations near dusk and dawn, when the mirrors in low Earth orbit would be bathed in sunlight. Aware of this, Reflect Orbital plan for their constellation to encircle Earth <a href=\"https:\/\/youtu.be\/yDV3v0Xb4ow?si=trE6wIxVAdsHGDaE&amp;t=104\" rel=\"noopener nofollow\" target=\"_blank\">above the day-night line<\/a> in <a href=\"https:\/\/www.space.com\/orbiting-mirror-boost-solar-power-production\" rel=\"noopener nofollow\" target=\"_blank\">sun-synchronous orbits<\/a> to keep them continuously in sunlight. <\/p>\n<p>            <a href=\"https:\/\/images.theconversation.com\/files\/689496\/original\/file-20250906-64-ts6pk9.jpg?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" alt=\"A tall, narrow rocket launching on a pillar of fire, above billowing clouds of steam.\" src=\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/1760801233_830_file-20250906-64-ts6pk9.jpg\"  \/><\/a>Cheaper rockets have enabled the deployment of satellite constellations. Image via SpaceX\/ <a class=\"source\" href=\"https:\/\/www.flickr.com\/photos\/spacex\/16236321533\/\" rel=\"noopener nofollow\" target=\"_blank\">Flickr<\/a> (<a class=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/deed.en\" rel=\"noopener nofollow\" target=\"_blank\">CC BY-NC 2.0<\/a>).<br \/>\nBright lights<\/p>\n<p>So, are mirrored satellites a practical means to produce affordable solar power at night? Probably not. Could they produce <a href=\"https:\/\/theconversation.com\/satellites-are-making-the-night-sky-brighter-as-a-launch-site-nz-has-a-duty-to-combat-light-pollution-233784\" rel=\"noopener nofollow\" target=\"_blank\">devastating light pollution<\/a>? Absolutely.<\/p>\n<p>In the early evening it doesn\u2019t take long to spot satellites and space junk \u2026 and they\u2019re not deliberately designed to be bright. <a href=\"https:\/\/orbitaltoday.com\/2025\/07\/31\/startup-plans-to-beam-sunlight-to-earth-using-space-mirrors\" rel=\"noopener nofollow\" target=\"_blank\">With Reflect Orbital\u2019s plan<\/a>, even if just the test satellite works as planned, it will sometimes appear far brighter than the full moon.<\/p>\n<p>A constellation of such mirrors would be devastating to astronomy and dangerous to astronomers. To anyone looking through a telescope the surface of each mirror could be almost as bright as the surface of the sun, risking <a href=\"https:\/\/articles.adsabs.harvard.edu\/\/full\/2000JRASC..94..237L\/0000237.000.html\" rel=\"noopener nofollow\" target=\"_blank\">permanent eye damage<\/a>. <\/p>\n<p>The light pollution will hinder everyone\u2019s ability to see the cosmos, and light pollution is known to impact the <a href=\"https:\/\/theconversation.com\/8-ways-to-tone-down-the-christmas-lights-to-help-wildlife-and-why-we-should-218931\" rel=\"noopener nofollow\" target=\"_blank\">daily rhythms of animals<\/a> as well.<\/p>\n<p>Although Reflect Orbital aims to illuminate specific locations, the satellites\u2019 beams would also sweep across Earth when moving from one location to the next. The night sky could be lit up with flashes of light brighter than the moon.<\/p>\n<p>The company did not reply to The Conversation about these concerns within deadline. However, <a href=\"https:\/\/www.bloomberg.com\/news\/articles\/2025-10-06\/sequoia-backed-startup-faces-pushback-over-plan-to-reflect-sunlight-to-earth\" rel=\"noopener nofollow\" target=\"_blank\">it told Bloomberg this week<\/a> it plans to redirect sunlight in ways that are \u201cbrief, predictable and targeted,\u201d avoiding observatories and sharing the locations of the satellites so scientists can plan their work.<\/p>\n<p>The consequences would be dire<\/p>\n<p>It remains to be seen whether Reflect Orbital\u2019s project will get off the ground. The company may launch a test satellite, but it\u2019s a long way from that to getting 250,000 enormous mirrors constantly circling Earth to keep some solar farms ticking over for a few extra hours a day.<\/p>\n<p>Still, it\u2019s a project to watch. The consequences of success for astronomers \u2013 and anyone else who likes the night sky dark \u2013 would be dire. <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/1760062270_262_count.gif\" alt=\"The Conversation\" width=\"1\" height=\"1\" style=\"border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important\" referrerpolicy=\"no-referrer-when-downgrade\"\/><\/p>\n<p>            The number of satellites visible in the evening has skyrocketed.<\/p>\n<p><a href=\"https:\/\/theconversation.com\/profiles\/michael-j-i-brown-113\" rel=\"noopener nofollow\" target=\"_blank\">Michael J. I. Brown<\/a>, Associate Professor in Astronomy, <a href=\"https:\/\/theconversation.com\/institutions\/monash-university-1065\" rel=\"noopener nofollow\" target=\"_blank\">Monash University<\/a>, and <a href=\"https:\/\/theconversation.com\/profiles\/matthew-kenworthy-1400515\" rel=\"noopener nofollow\" target=\"_blank\">Matthew Kenworthy<\/a>, Associate Professor in Astronomy, <a href=\"https:\/\/theconversation.com\/institutions\/leiden-university-935\" rel=\"noopener nofollow\" target=\"_blank\">Leiden University<\/a><\/p>\n<p>This article is republished from <a href=\"https:\/\/theconversation.com\" rel=\"noopener nofollow\" target=\"_blank\">The Conversation<\/a> under a Creative Commons license. Read the <a href=\"https:\/\/theconversation.com\/a-us-startup-plans-to-deliver-sunlight-on-demand-after-dark-can-it-work-and-would-we-want-it-to-264323\" rel=\"noopener nofollow\" target=\"_blank\">original article<\/a>.<\/p>\n<p>Bottom line: The startup company Reflect Orbital has proposed putting hundreds of thousands of satellites with mirrors in space to illuminate areas of Earth at night. But can it be done? And should it be done?<\/p>\n<p><a href=\"https:\/\/earthsky.org\/space\/light-pollution-astronomy-around-the-globe\/\" rel=\"noopener nofollow\" target=\"_blank\">Read more: Light pollution is impacting astronomy around the globe<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Reflect Orbital promises sunlight on demand. What exactly does that mean and how would it affect astronomy? Image&hellip;\n","protected":false},"author":2,"featured_media":130384,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[270],"tags":[18,19,17,133,451,17563],"class_list":{"0":"post-130383","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-eire","9":"tag-ie","10":"tag-ireland","11":"tag-science","12":"tag-space","13":"tag-spaceflight"},"share_on_mastodon":{"url":"","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/130383","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=130383"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/130383\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/130384"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=130383"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=130383"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=130383"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}