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Huge satellite BlueWalker-3 has now unfurled – and yes it’s very bright

<p>If you look at the sky near Jupiter just after sunset, you might notice a bright new star, travelling fast across the sky.</p> <p>This star is no planet or far-flung galaxy – it’s the largest commercial communications satellite in low-Earth orbit, the BlueWalker 3 satellite which has now unfurled its solar panels.</p> <p>The apartment-sized satellite is a prototype from American company AST SpaceMobile, whose goal is to create a space-based mobile broadband network. This is only one of multiple satellites planned for the SpaceMobile constellation – some of which will be even bigger than BlueWalker 3.</p> <p>Amateur astronomers have been reporting sightings of BlueWalker 3 over the last few weeks, many with an approximate brightness of 2<sup>nd</sup> or 3<sup>rd</sup> magnitude. This is moderately bright, but not as bright as Sirius <a href="https://earthsky.org/astronomy-essentials/what-is-stellar-magnitude/" target="_blank" rel="noopener">– the brightest star in the night sky.</a></p> <figure class="wp-block-embed aligncenter is-type-rich is-provider-twitter wp-block-embed-twitter"> <div class="wp-block-embed__wrapper"> <div class="entry-content-asset"> <div class="embed-wrapper"> <div class="inner"> <div class="twitter-tweet twitter-tweet-rendered spai-bg-prepared" style="display: flex; max-width: 500px; width: 100%; margin-top: 10px; margin-bottom: 10px;"><iframe id="twitter-widget-0" class="spai-bg-prepared" style="position: static; visibility: visible; width: 400px; height: 550px; display: block; flex-grow: 1;" title="Twitter Tweet" src="https://platform.twitter.com/embed/Tweet.html?creatorScreenName=cosmosmagazine&dnt=true&embedId=twitter-widget-0&features=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&frame=false&hideCard=false&hideThread=false&id=1591249397953998849&lang=en&origin=https%3A%2F%2Fcosmosmagazine.com%2Fspace%2Fbluewalker-3-unfurlled-ast-space-x-elon-musk%2F&sessionId=96d02fb5de79caae06b83ca7b911f2ac94853601&siteScreenName=cosmosmagazine&theme=light&widgetsVersion=a3525f077c700%3A1667415560940&width=500px" frameborder="0" scrolling="no" allowfullscreen="allowfullscreen" data-tweet-id="1591249397953998849"></iframe></div> </div> </div> </div> </div> </figure> <p>This means that some astronomers prediction that it “could outshine all stars and planets in the night sky” hasn’t come to pass.</p> <p>However, <a href="https://en.wikipedia.org/wiki/List_of_brightest_stars" target="_blank" rel="noopener">a magnitude of 2 would put it in the rank of top 50</a> brightest stars.</p> <p>If you wanted to track it for yourself, <a href="https://heavens-above.com/" target="_blank" rel="noopener">website Heavens Above</a> has just created a new tool <a href="https://www.orbtrack.org/#/?satName=BLUEWALKER%203" target="_blank" rel="noreferrer noopener">to track the satellite.</a> <a href="https://in-the-sky.org/satpasses.php?gotosat=53807" target="_blank" rel="noreferrer noopener">You can also use In The Sky and note your location.</a> Note that it can only be seen just after the Sun has gone down, as the Sun from below the horizon reflects onto the satellite, and makes it bright.</p> <figure class="wp-block-embed aligncenter is-type-rich is-provider-twitter wp-block-embed-twitter"> <div class="wp-block-embed__wrapper"> <div class="entry-content-asset"> <div class="embed-wrapper"> <div class="inner"> <div class="twitter-tweet twitter-tweet-rendered spai-bg-prepared" style="display: flex; max-width: 500px; width: 100%; margin-top: 10px; margin-bottom: 10px;"><iframe id="twitter-widget-1" class="spai-bg-prepared" style="position: static; visibility: visible; width: 400px; height: 675px; display: block; flex-grow: 1;" title="Twitter Tweet" src="https://platform.twitter.com/embed/Tweet.html?creatorScreenName=cosmosmagazine&dnt=true&embedId=twitter-widget-1&features=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&frame=false&hideCard=false&hideThread=false&id=1594885656370909186&lang=en&origin=https%3A%2F%2Fcosmosmagazine.com%2Fspace%2Fbluewalker-3-unfurlled-ast-space-x-elon-musk%2F&sessionId=96d02fb5de79caae06b83ca7b911f2ac94853601&siteScreenName=cosmosmagazine&theme=light&widgetsVersion=a3525f077c700%3A1667415560940&width=500px" frameborder="0" scrolling="no" allowfullscreen="allowfullscreen" data-tweet-id="1594885656370909186"></iframe></div> </div> </div> </div> </div> </figure> <p>The goal with AST SpaceMobile is to create cellular broadband anywhere on the globe. Similar to Space X’s Starlink, many satellites are required to create full coverage around the world.</p> <p>Astronomers and satellite operators are currently at odds over these satellite constellations. The more there, the more interference is likely for both optical and radio astronomy.</p> <p>There’s also the question of what we – as humans – are comfortable with. Having 100s of these satellites in the sky at any one time would mean that when we look up, many of the bright lights in the sky would not be stars but satellites instead.</p> <figure class="wp-block-embed aligncenter is-type-rich is-provider-twitter wp-block-embed-twitter"> <div class="wp-block-embed__wrapper"> <div class="entry-content-asset"> <div class="embed-wrapper"> <div class="inner"> <div class="twitter-tweet twitter-tweet-rendered spai-bg-prepared" style="display: flex; max-width: 500px; width: 100%; margin-top: 10px; margin-bottom: 10px;"><iframe id="twitter-widget-2" class="spai-bg-prepared" style="position: static; visibility: visible; width: 400px; height: 699px; display: block; flex-grow: 1;" title="Twitter Tweet" src="https://platform.twitter.com/embed/Tweet.html?creatorScreenName=cosmosmagazine&dnt=true&embedId=twitter-widget-2&features=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&frame=false&hideCard=false&hideThread=false&id=1595568298414215168&lang=en&origin=https%3A%2F%2Fcosmosmagazine.com%2Fspace%2Fbluewalker-3-unfurlled-ast-space-x-elon-musk%2F&sessionId=96d02fb5de79caae06b83ca7b911f2ac94853601&siteScreenName=cosmosmagazine&theme=light&widgetsVersion=a3525f077c700%3A1667415560940&width=500px" frameborder="0" scrolling="no" allowfullscreen="allowfullscreen" data-tweet-id="1595568298414215168"></iframe></div> </div> </div> </div> </div> </figure> <p>There’s also potentially issues about collisions in orbit <a href="https://arstechnica.com/science/2020/11/nasa-objects-to-new-megaconstellation-citing-risk-of-catastrophic-collison/" target="_blank" rel="noopener">making our skies unsafe.</a></p> <p>There’s currently discussions happening between astronomers, satellite operators and the United Nations Committee on Peaceful Uses of Outer Space (COPUOS) about what is reasonable for satellites to be able to do in the night sky. The next meeting <a href="https://www.skatelescope.org/news/un-body-to-continue-deliberating-on-how-to-protect-dark-quiet-skies/" target="_blank" rel="noopener">will occur in 2023</a>.</p> <p>“States are generally supportive, and we succeeded in ensuring that the radio and optical interference effects of large satellite constellations on astronomy are considered by the subcommittee,” Head of Assurance at the SKAO, Tim Stevenson said after the last meeting in February.</p> <p>“We are looking forward to preparing and sustaining our case in COPUOS, which is the paramount forum in the world to deal with this issue.”</p> <p><!-- Start of tracking content syndication. Please do not remove this section as it allows us to keep track of republished articles --></p> <p><img id="cosmos-post-tracker" style="opacity: 0; height: 1px!important; width: 1px!important; border: 0!important; position: absolute!important; z-index: -1!important;" src="https://syndication.cosmosmagazine.com/?id=226135&title=Huge+satellite+BlueWalker-3+has+now+unfurled+%E2%80%93+and+yes+it%E2%80%99s+very+bright" width="1" height="1" data-spai-target="src" data-spai-orig="" data-spai-exclude="nocdn" /></p> <p><!-- End of tracking content syndication --></p> <div id="contributors"> <p><em><a href="https://cosmosmagazine.com/space/bluewalker-3-unfurlled-ast-space-x-elon-musk/" target="_blank" rel="noopener">This article</a> was originally published on Cosmos Magazine and was written by Jacinta Bowler. </em></p> <p><em>Image: AST</em></p> </div>

Technology

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How satellites, radar and drones are tracking meteorites and aiding Earth’s asteroid defence

<p>On July 31 2013 a <a href="https://cneos.jpl.nasa.gov/fireballs/" target="_blank" rel="noopener">constellation of US defence satellites</a> saw a streak of light over South Australia as a rock from outer space burned through Earth’s atmosphere on its way to crash into the ground below.</p> <p>The impact created an explosion equivalent to about 220 tonnes of TNT. More than 1,500km away, in Tasmania, the bang was heard by detectors normally used to listen for <a href="https://www.dfat.gov.au/international-relations/security/asno/Pages/australian-ims-stations" target="_blank" rel="noopener">extremely low-frequency sounds</a> from illegal tests of nuclear weapons.</p> <p>These were two excellent indications that there should be a patch of ground covered in meteorites somewhere north of Port Augusta. But how could we track them down?</p> <p>My colleagues and I who work on the <a href="https://dfn.gfo.rocks/" target="_blank" rel="noopener">Desert Fireball Network (DFN)</a>, which tracks incoming asteroids and <a href="https://dfn.gfo.rocks/meteorites.html" target="_blank" rel="noopener">the resulting meteorites</a>, had a couple of ideas: weather radar and drones.</p> <p><strong>Eyes in space</strong></p> <p>Finding meteorites is not an easy task. There is a network of high-quality ground-based sensors called the <a href="https://gfo.rocks/" target="_blank" rel="noopener">Global Fireball Observatory</a>, but it only covers about 1% of the planet.</p> <p>The <a href="https://cneos.jpl.nasa.gov/fireballs/" target="_blank" rel="noopener">US satellite data</a> published by NASA covers a much larger area than ground-based detectors, but it only picks up the biggest fireballs. What’s more, they <a href="https://academic.oup.com/mnras/article/483/4/5166/5256650" target="_blank" rel="noopener">don’t always give an accurate idea of the meteor’s trajectory</a>.</p> <p>So, to have any chance to find a meteorite from these data, you need a little outside help.</p> <p><strong>Weather radars</strong></p> <p>In 2019, Australia’s Bureau of Meteorology started making its weather radar data <a href="https://www.openradar.io/" target="_blank" rel="noopener">openly available</a> to researchers and the public. I saw this as an opportunity to complete the puzzle.</p> <p>I combed through the record of events from the Desert Fireball Network and NASA, and cross-matched them with nearby weather radars. Then I looked for unusual radar signatures that could indicate the presence of falling meteorites.</p> <figure class="align-center zoomable"><a href="https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=334&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=334&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=334&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=420&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=420&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/496384/original/file-20221121-22-iwtkve.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=420&amp;fit=crop&amp;dpr=3 2262w" alt="An annoyed aerial photo showing the locations of the Woomera radar station and the falling meteorites." /></a><figcaption><span class="caption">The Woomera weather radar station captured reflections from the falling meteorites.</span> <span class="attribution"><span class="source">Curtin University</span>, <span class="license">Author provided</span></span></figcaption></figure> <p>And bingo, the 2013 event was not too far from the Woomera radar station. The weather was clear, and the radar record showed some small reflections at about the right place and time.</p> <p>Next, I had to use the weather data to figure out how the wind would have pushed the meteorites around on their way down to Earth.</p> <p>If I got the calculations right, I would have a treasure map showing the location of a rich haul of meteorites. If I got them wrong, I would end up sending my team to wander around in the desert for two weeks for nothing.</p> <p><strong>The search</strong></p> <p>I gave what I hoped was an accurate treasure map to my colleague Andy Tomkins from Monash University. In September this year, he happened to be driving past the site on his way back from an expedition in the Nullarbor.</p> <p>Thankfully, Andy found the first meteorite within 10 minutes of looking. In the following two hours, his team found nine more.</p> <figure class="align-center "><img src="https://images.theconversation.com/files/496385/original/file-20221121-16-he3p7h.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/496385/original/file-20221121-16-he3p7h.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/496385/original/file-20221121-16-he3p7h.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/496385/original/file-20221121-16-he3p7h.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/496385/original/file-20221121-16-he3p7h.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/496385/original/file-20221121-16-he3p7h.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/496385/original/file-20221121-16-he3p7h.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" alt="Photo of several people walking through a desert field looking at the ground." /><figcaption><span class="caption">A field team from Monash University searched for meteorites in the strewn field.</span> <span class="attribution"><span class="source">Monash University</span>, <span class="license">Author provided</span></span></figcaption></figure> <p>The technique of finding meteorites with weather radars <a href="https://ares.jsc.nasa.gov/meteorite-falls/how-to-find-meteorites/" target="_blank" rel="noopener">was pioneered</a> by my colleague Marc Fries in the US. However, this is the first time it has been done outside the US NEXRAD radar network. (When it comes to monitoring airspace, the US has more powerful and more densely packed tech than anyone else.)</p> <p>This first search confirmed there were lots of meteorites on the ground. But how were we going to find them all?</p> <p>That’s where the drones come in. We used a method developed by my colleague Seamus Anderson to <a href="https://gfo.rocks/blog/2022/03/14/First_Meteorite_Found_with_Drone.html" target="_blank" rel="noopener">automatically detect meteorites from drone images</a>.</p> <p>In the end we collected 44 meteorites, weighing a bit over 4kg in total. Together they form what we call a “strewn field”.</p> <figure class="align-center zoomable"><a href="https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/496386/original/file-20221121-13-qssltc.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" alt="An aerial view of a desert field with a black dot (a meteorite) highlighted by a yellow square." /></a><figcaption><span class="caption">A machine-learning algorithm identified meteorites from drone photos.</span> <span class="attribution"><span class="source">Curtin Uni</span>, <span class="license">Author provided</span></span></figcaption></figure> <p>Strewn fields <a href="https://onlinelibrary.wiley.com/doi/10.1111/maps.13892" target="_blank" rel="noopener">tell us a lot</a> about how an asteroid fragments in our atmosphere.</p> <p>That’s quite important to know, because the energy of these things is comparable to that of nuclear weapons. For example, the 17-metre asteroid that exploded over Chelyabinsk in Russia in 2013 produced an explosion 30 times the size of the bomb dropped on Hiroshima in 1945.</p> <p>So when the next big one is about to hit, it may be useful to predict how it will deposit its energy in our atmosphere.</p> <p>With new telescopes and better technology, we are starting to see some asteroids <a href="https://skymapper.anu.edu.au/news/great-balls-fire/" target="_blank" rel="noopener">before they hit Earth</a>. We will see even more when projects such as the <a href="https://www.lsst.org" target="_blank" rel="noopener">Vera Rubin Observatory</a> and the <a href="https://atlas.fallingstar.com" target="_blank" rel="noopener">Asteroid Terrestrial-impact Last Alert System (ATLAS)</a> are up and running.</p> <p>These systems might give us as much as a few days’ notice that an asteroid is heading for Earth. This would be too late to make any effort to deflect it – but plenty of time for preparation and damage control on the ground.</p> <p><strong>The value of open data</strong></p> <p>This find was only made possible by the free availability of crucial data – and the people who made it available.</p> <p>The US satellites that detected the fireball are presumably there to detect missile and rocket launches. However, somebody (I don’t know who) must have figured out how to publish some of the satellite data without giving away too much about their capabilities, and then lobbied hard to get the data released.</p> <p>Likewise, the find would not have happened without the work of Joshua Soderholm at Australia’s Bureau of Meteorology, who worked to make low-level weather radar data openly accessible for other uses. Soderholm went to the trouble to make the radar data <a href="https://www.go-fair.org/fair-principles/" target="_blank" rel="noopener">readily available and easy to use</a>, which goes well beyond the vague formulations you can read at the bottom of scientific papers like “data available upon reasonable request”.</p> <p>There is no shortage of fireballs to track down. Right now, we’re on the hunt for a meteorite that was spotted in space last weekend before <a href="https://www.nytimes.com/2022/11/19/science/fireball-asteroid-toronto-new-york.html" target="_blank" rel="noopener">blazing through the sky over Ontario, Canada</a>.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img 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;" src="https://counter.theconversation.com/content/194997/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: https://theconversation.com/republishing-guidelines --></p> <p><em>Writen by Hadrien Devillepoix. Republished with permission from <a href="https://theconversation.com/how-satellites-radar-and-drones-are-tracking-meteorites-and-aiding-earths-asteroid-defence-194997" target="_blank" rel="noopener">The Conversation</a>.</em></p> <p><em>Image: NASA</em></p>

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Satellites interfere with Indigenous astronomy

<p>Since time immemorial, Indigenous peoples worldwide have observed, tracked and memorised all the visible objects in the night sky.</p> <p>This ancient star knowledge was meticulously ingrained with practical knowledge of the land, sky, waters, community and the Dreaming — and passed down through generations.</p> <p>One of the most well-known and celebrated Aboriginal constellations is the Emu in the Sky, which appears in the southern sky early in the year. It is an example of a dark constellation, which means it’s characterised by particularly dark patches in the sky, rather than stars.</p> <p>Conversely, space technology companies such as Starlink are increasingly competing to dominate the skies, and potentially change them forever.</p> <p>The modern-day space race has led to thousands of satellites being scattered through Earth’s outer orbits. If left unchallenged, these companies risk overpopulating an already crowded space environment – potentially pushing dark skies to extinction.</p> <p><strong>Mega-constellations</strong></p> <p>Mega-constellations are groupings of satellites that communicate and work together as they orbit Earth.</p> <p>Since 2018, the Starlink project, run by Elon Musk’s SpaceX, has launched about 1,700 satellites into low Earth orbit. The company plans to launch another <a href="https://www.cnbc.com/2021/08/19/spacex-starlink-satellite-internet-new-capabilities-starship-launch.html" target="_blank" rel="noopener">30,000 over the next decade</a>.</p> <p>British company OneWeb has launched nearly 150 satellites, with plans <a href="https://www.spaceconnectonline.com.au/launch/5111-oneweb-to-deploy-over-half-its-constellation-satellites-this-month" target="_blank" rel="noopener">for another 6,000</a>. And Amazon intends to launch an additional <a href="https://www.cnbc.com/2021/11/01/amazons-project-kuiper-launching-first-internet-satellites-in-q4-2022.html" target="_blank" rel="noopener">3,000 satellites</a> into multiple orbits.</p> <figure class="align-center "><em><img src="https://images.theconversation.com/files/458059/original/file-20220414-20-rmk6kw.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/458059/original/file-20220414-20-rmk6kw.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=337&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/458059/original/file-20220414-20-rmk6kw.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=337&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/458059/original/file-20220414-20-rmk6kw.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=337&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/458059/original/file-20220414-20-rmk6kw.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=424&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/458059/original/file-20220414-20-rmk6kw.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=424&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/458059/original/file-20220414-20-rmk6kw.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=424&amp;fit=crop&amp;dpr=3 2262w" alt="A satellite hovering in orbit above Earth." /></em><figcaption><em><span class="caption">A growing number of Starlink satellites can be found in low orbit around Earth.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/minsk-minskiy-district-belarus-19-january-2110892792" target="_blank" rel="noopener">Shutterstock</a></span></em></figcaption></figure> <p>Each of these companies is taking to the skies to increase internet access across the globe. But even if they deliver on this, sky gazers — and especially Indigenous peoples — are left to wonder: at what cost?</p> <p><strong>Streaks in the night</strong></p> <p>People across the globe began noticing streaks across our skies not long after the first Starlink launch in May 2019. They were unlike anything anyone had seen before.</p> <p>Astronomers are very used to viewing the sky and dealing with interference, often originating from aircraft or the occasional satellite. However, the goal of mega-constellations is to engulf the entire planet, <a href="https://spacenews.com/spacex-launches-another-set-of-starlink-satellites-as-it-nears-global-coverage/" target="_blank" rel="noopener">leaving no place untouched</a>. Mega-constellations alter our collective view of the stars. And there is currently no known way to remove them.</p> <p>One mega-constellation has been observed to <a href="https://www.vox.com/science-and-health/2020/1/7/21003272/space-x-starlink-astronomy-light-pollution" target="_blank" rel="noopener">produce up to 19 parallel streaks</a> across the sky. These streaks disturb astronomical observations, and a significant amount of scientific data can be lost as a result.</p> <figure class="align-center "><img src="https://images.theconversation.com/files/458060/original/file-20220414-17-8ym1fy.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/458060/original/file-20220414-17-8ym1fy.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/458060/original/file-20220414-17-8ym1fy.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/458060/original/file-20220414-17-8ym1fy.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/458060/original/file-20220414-17-8ym1fy.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/458060/original/file-20220414-17-8ym1fy.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/458060/original/file-20220414-17-8ym1fy.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" alt="Satellites leaving streaks in the night sky." /><figcaption><em><span class="caption">Satellites can leave streaks in the night sky.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/starlink-satellites-summer-night-sky-1753118759" target="_blank" rel="noopener">Shutterstock</a></span></em></figcaption></figure> <p>As they travel across the entire sky, scattering the Sun’s light, dark constellations become even fainter — further desecrating Indigenous knowledge and kinship with the environment.</p> <p><a href="https://academic.oup.com/mnrasl/article/504/1/L40/6188393" target="_blank" rel="noopener">Further research</a> on the impacts of mega-constellations have found that as they orbit Earth, the Sun’s rays are reflected off them and scattered into the atmosphere.</p> <p>The authors of that study conclude we are collectively experiencing a new type of “skyglow” as a result: a phenomenon in which the brightness of the sky increases due to human-made light pollution.</p> <p>Initial calculations indicate this new source of light pollution has increased the brightness of night skies globally by about 10%, compared with the natural skyglow measured in the 1960s.</p> <p>Currently, the upper limit of light pollution tolerable at observatories <a href="https://www-cambridge-org.virtual.anu.edu.au/core/journals/transactions-of-the-international-astronomical-union/article/commission-50-identification-and-protection-of-existing-or-potential-observatory-sites-identification-et-protection-des-sites-dobservatoires-existants-ou-potentiels/5483EC52C57F73B2246AF593513A2D9D" target="_blank" rel="noopener">is 10% above the natural skyglow</a>, which suggests we have already reached the limit.</p> <p>In other words, scientific observations of the sky are already at risk of being rendered redundant. If this excess skyglow increases even more, observatories are at serious risk.</p> <p><strong>Indigenous sky sovereignty</strong></p> <p>Indigenous knowledge systems and oral traditions teach us about the intricate and complex relationships Indigenous peoples have with the environment, including the sky.</p> <p>For example, many Aboriginal and Torres Strait Islander cultures have no concept of “outer space”. They only have a continuous and connected reality where coexistence with all things is paramount.</p> <p>As captured by the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0962629818304086?via%3Dihub" target="_blank" rel="noopener">Bawaka Country</a> group, based in northeast Arnhem Land:</p> <blockquote> <p>…to hurt Sky Country, to try and possess it, is an ongoing colonisation of the plural lifeworlds of all those who have ongoing connections with and beyond the sky.</p> </blockquote> <p>Desecrating the sky impacts Indigenous sovereignty as it limits access to their knowledge system, in the same ways desecrating the land has removed First Peoples from their countries, cultures and ways of life.</p> <p>For example, the Gamilaraay and Wiradjuri peoples of New South Wales observe the Emu in the Sky to gauge when it is time to hunt for emu eggs — and most importantly, when it is time to stop. How would the Gamilaraay know when to stop collecting eggs, or when to conduct annual ceremonies signalled by the Celestial Emu, if it was no longer visible?</p> <p>Similarly, important parts of the Jukurrpa, or Dreaming of the Martu people of Western Australia is embedded in the Seven Sisters constellation. How would they keep this knowledge safe if they can’t locate any of the Sisters?</p> <p>Indigenous histories teach us about the devastating consequences of colonialism, and how the impacts of the colonial agenda can be mitigated through prioritising the health of country and community.</p> <p>In the words of <a href="https://www.nature.com/articles/s41550-020-01238-3" target="_blank" rel="noopener">astronomer Aparna Venkatesan and colleagues</a>:</p> <blockquote> <p>…the manner and pace of ‘occupying’ near-Earth space raise the risk of repeating the mistakes of colonisation on a cosmic scale.</p> </blockquote> <p>Active Indigenous sky sovereignty acknowledges the interconnected nature between land and sky, and that caring for country includes sky country. By doing so, it challenges <a href="https://digitalrepository.unm.edu/amst_etds/81/" target="_blank" rel="noopener">the otherwise unimpeded authority</a> of technology corporations.</p> <p><strong>Harming fauna, harming ourselves</strong></p> <p>By understanding that the world (and indeed the Universe) is interconnected, we see that no living creature is immune to the consequences of polluting the skies.</p> <p>Currently, native fauna such as the tammar wallaby, magpie, bogong moth and marine turtles are experiencing a <a href="https://www.awe.gov.au/sites/default/files/documents/national-light-pollution-guidelines-wildlife.pdf" target="_blank" rel="noopener">reduction in populations and quality of life</a> due to the impacts of light-pollution.</p> <figure class="align-center "><em><img src="https://images.theconversation.com/files/458063/original/file-20220414-30327-7xnlx8.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/458063/original/file-20220414-30327-7xnlx8.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/458063/original/file-20220414-30327-7xnlx8.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/458063/original/file-20220414-30327-7xnlx8.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/458063/original/file-20220414-30327-7xnlx8.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/458063/original/file-20220414-30327-7xnlx8.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/458063/original/file-20220414-30327-7xnlx8.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" alt="A tammar wallaby with young in its pouch." /></em><figcaption><em><span class="caption">The tammar wallaby is just one Australian species affected by light pollution.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/wallaby-young-animal-pouch-undergrowth-1840354798" target="_blank" rel="noopener">Shutterstock</a></span></em></figcaption></figure> <p>Migratory species are particularly affected by light pollution, which can result in them losing access to their migratory route. This is a crisis Australia’s fauna has faced since before the introduction of mega-constellations.</p> <p>With more skyglow and light pollution, positive outcomes for native fauna and migratory species diminish.</p> <p><strong>Going forward</strong></p> <p>Several companies have made attempts to reduce the impact of mega-constellations on skyglow.</p> <p>For example, OneWeb has opted to rollout fewer satellites than initially proposed, and has designed them to be positioned at a higher altitude. This means <a href="https://arxiv.org/ftp/arxiv/papers/2012/2012.05100.pdf" target="_blank" rel="noopener">they will produce less skyglow</a>, while also covering a larger area.</p> <p>Starlink, on the other hand, has not shown any public interest in operating at higher and less impactful altitudes, for fears it will <a href="https://arstechnica.com/tech-policy/2021/04/fcc-lets-spacex-cut-satellite-altitude-to-improve-starlink-speed-and-latency/" target="_blank" rel="noopener">impact the Starlink network’s speed and latency.</a></p> <p>That said, they have attempted to reduce their satellites’ luminosity by painting them with a novel anti-reflective coating. Coating techniques have demonstrated a reduction in reflected sunlight by up to 50%. Unfortunately, not all wavelengths of <a href="https://arxiv.org/abs/2010.04655" target="_blank" rel="noopener">light being scattered are reduced using this method</a>. So multi-wave astronomy, and different species of animals, are still at risk.</p> <p>We’ll need more solutions to navigate our increasingly polluted atmosphere, particularly if communication monopolies continue to rein over near-Earth space.</p> <p>Just as some companies have started considering tactics to avoid increasing skyglow, all space tech companies must be held responsible for adding to an already polluted space.</p> <p>Guidelines such as those set by the Inter-Agency Space Debris Coordination Committee offer solutions to this problem. They suggest lowering the height of a satellite’s orbit when it’s no longer needed, <a href="https://www.nature.com/articles/d41586-018-06170-1" target="_blank" rel="noopener">allowing it to disintegrate as it falls</a> down to Earth.</p> <p>However, these are international guidelines, so there’s no legal framework to enforce such practices.</p> <p>And given that near-miss collisions have already <a href="https://techcrunch.com/2019/09/03/near-miss-between-science-craft-and-starlink-satellite-shows-need-to-improve-orbital-coordination/" target="_blank" rel="noopener">taken place between some mega-constellations</a>, and an estimated 20,000 pieces of space debris already floating above, reducing orbital pollution must also now be a priority.</p> <p>Reducing air pollutants has also been shown to drastically <a href="https://doi.org/10.1093/mnrasl/slab030" target="_blank" rel="noopener">decrease natural sky brightness</a>, offering a potential solution for improving night sky visibility — not to mention cleaner breathing air for all.</p> <p>In valuing Indigenous knowledge systems, that value must be extended to the natural environment in which that knowledge is embedded and founded upon. In Australia, preserving dark skies is not just vital for the continuation of Indigenous knowledge and astronomers — it benefits us all.</p> <p>A major tenet of life for Indigenous peoples is valuing the sustainability of one’s actions. By adopting this at a larger scale, we could create a reality in which we’re not a threat to our own survival.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img 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;" src="https://counter.theconversation.com/content/173840/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: https://theconversation.com/republishing-guidelines --></p> <p><em><a href="https://theconversation.com/profiles/karlie-noon-1310291" target="_blank" rel="noopener">Karlie Noon</a>, Astronomer, <a href="https://theconversation.com/institutions/australian-national-university-877" target="_blank" rel="noopener">Australian National University</a></em></p> <p><em>This article is republished from <a href="https://theconversation.com" target="_blank" rel="noopener">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/thousands-of-satellites-are-polluting-australian-skies-and-threatening-ancient-indigenous-astronomy-practices-173840" target="_blank" rel="noopener">original article</a>.</em></p> <p><em>Image: Getty Images</em></p>

Domestic Travel

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How the use of lasers and small satellites helps information get through space

<p>Satellites are becoming increasingly important in our lives, as they help us meet a demand for more data, exchanged at higher speeds. This is why we are exploring new ways of improving satellite communication.</p> <p>Satellite technology is used to navigate, forecast the weather, monitor Earth from space, receive TV signals from space, and connect to remote places through tools such as satellite phones and <a href="https://www.nbnco.com.au/learn/network-technology/sky-muster-explained">NBN’s Sky Muster satellites</a>.</p> <p>All these communications use radio waves. These are electromagnetic waves that propagate through space and, to a certain degree, through obstacles such as walls.</p> <p>Each communication system uses a frequency band allocated for it, and each band makes up part of the <a href="https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html">electromagnetic spectrum</a> – which is the name given to the range of all types of electromagnetic radiation.</p> <p>But the electromagnetic spectrum we are able to use with current technology is a finite resource, and is now completely occupied. This means old services have to make room for new ones, or higher frequency bands have to be used.</p> <p>While this poses technological challenges, one promising way forward is optical communication.</p> <p><strong>Communication with lasers</strong></p> <p>Instead of using radio waves to carry the information, we can use light from lasers as the carrier. While technically still part of the electromagnetic spectrum, optical frequencies are significantly higher, which means we can use them to transfer data at higher speeds.</p> <p>However, one disadvantage is that a laser cannot propagate through walls, and can even be blocked by clouds. While this is problematic on Earth, and for communication between satellites and Earth, it’s no problem for communication between satellites.</p> <p>On Earth, optical communication via fibre optic cables connects continents and provides enormous data exchanges. This is the technology that allows <a href="https://www.vox.com/2015/4/30/11562024/too-embarrassed-to-ask-what-is-the-cloud-and-how-does-it-work">the cloud</a> to exist, and online services to be provided.</p> <p>Optical communication between satellites doesn’t use fibre optic cables, but involves light propagating through space. This is called “free space optical communication”, and can be used to not only deliver data from satellites to the ground, but also to connect satellites in space.</p> <p>In other words, free space optical communication will provide the same massive connectivity in space we already have on Earth.</p> <p>Some systems such as the <a href="https://artes.esa.int/edrs-global">European Data Relay System</a> are already operational, and others like SpaceX’s <a href="https://www.space.com/see-spacex-starlink-satellites-in-night-sky.html">Starlink</a> continue to be developed.</p> <p>But there are still many challenges to overcome, and we’re limited by current technology. My colleagues and I are working on making optical, as well as radio-frequency, data links even faster and more secure.</p> <p><strong>CubeSats</strong></p> <p>So far, a lot of effort has gone into the research and development of radio-frequency technology. This is how we know data rates are at their highest physical limit and can’t be further increased.</p> <p>While a single radio-frequency link can provide data rates of 10Gbps with large antennas, an optical link can achieve rates 10 to 100 times higher, using antennas that are 10 to 100 times smaller.</p> <p>These small antennas are in fact optical lenses, and their compact size allows them to be integrated into small satellites called CubeSats.</p> <p>CubeSats are not larger than a shoebox or toaster, but can employ high speed data links to other satellites or the ground.</p> <p>They are currently used for a wide range of tasks including earth observation, communications and scientific experiments in space. And while they’re not able to provide all services from space, they play an important role in current and future satellite systems.</p> <p>Another advantage of optical communication is increased security. The light from a laser forms a narrow beam, which has to be pointed from a sender to a receiver. Since this beam is very narrow, the communication doesn’t interfere with other receivers and it’s very hard, if not impossible, to eavesdrop on the communication. This makes optical systems more secure than radio electromagnetic systems.</p> <p>Optical communication can also be used for <a href="https://qt.eu/understand/underlying-principles/quantum-key-distribution-qkd/">Quantum Key Distribution</a>. This technology allows the absolute secure exchange of encryption keys for safe communications.</p> <p><strong>What can we expect from this?</strong></p> <p>While it’s exciting to develop systems for space, and to launch satellites, the real benefit of satellite systems is felt on Earth.</p> <p>High speed communication provided by optical data links will improve connectivity for all of us. Notably, remote areas which currently have relatively slow connections will experience better access to remote health and remote learning.</p> <p>Better data links will also let us deliver images and videos from space with less delay and higher resolution. This will improve the way we manage our resources, including <a href="https://www.ga.gov.au/scientific-topics/community-safety/flood/wofs">water</a>, agriculture and forestry.</p> <p>They will also <a href="https://www.ga.gov.au/scientific-topics/earth-obs/case-studies/mapping-bushfires">provide vital real-time information in disaster scenarios such as bushfires</a>. The potential applications of optical communication technology are vast.</p> <p><strong>Banding knowledge together</strong></p> <p>Working in optical satellite communication is challenging, as it combines many different fields and research areas including telecommunication, photonics and manufacturing.</p> <p>Currently, our technology is far from achieving what is theoretically possible, and there’s great room for improvement. This is why there’s a strong focus on collaboration.</p> <p>In Australia, there are two major programs facilitating this - the Australian Space Agency run by the federal government, and the <a href="https://smartsatcrc.com/">SmartSat Cooperative Research Centre</a> (CRC), also supported by the federal government.</p> <p>Through the SmartSat CRC program, my colleagues and I will spend the next seven years tackling a range of applied research problems in this area.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img 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; text-shadow: none !important;" src="https://counter.theconversation.com/content/126344/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: http://theconversation.com/republishing-guidelines --></p> <p><em><a href="https://theconversation.com/profiles/gottfried-lechner-877898">Gottfried Lechner</a>, Associate Professor and Director of the Institute for Telecommunications Research, University of South Australia, <a href="http://theconversation.com/institutions/university-of-south-australia-1180">University of South Australia</a></em></p> <p><em>This article is republished from <a href="http://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/were-using-lasers-and-toaster-sized-satellites-to-beam-information-faster-through-space-126344">original article</a>.</em></p>

Technology

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Satellite image of Uluru goes viral and sparks the world’s interest in the popular travel spot

<p>An image of Uluru taken by a satellite has sparked renewed interest in the iconic landmark around the world by going viral.</p><p>The stunning image, taken by the Korean Kompsat-2 satellite from an altitude of 685km, has been shared thousands of times since Tourism NT posted it on Twitter earlier this month.</p><p>Spokeswoman for Tourism NT, Kim Wheatley pointed out that the picture gives us a new perspective of Uluru. While aerial images from scenic flights have been published countless times, this new image is unique, giving “one of the world’s most iconic locations … a whole new perspective”.</p><p>The detail in the image is so great that the vertical layers, striations, are clearly visible as they carve striking lines across Uluru.</p><p>Tourism NT is encouraging visitors to post photos of their experiences in the NT with the hashtag #ntaustralia, hoping to build on the momentum created by the photo.</p><p><em>Image source: Tourism NT</em></p><p><strong>Related links:</strong></p><p><em><strong><span style="text-decoration: underline;"><a href="/news/news/2015/02/best-beaches-in-the-world/" target="_blank">Which Australian beach is considered one of the world’s very best?</a></span></strong></em></p><p><em><strong><span style="text-decoration: underline;"><a href="/news/news/2015/02/frozen-niagara-falls/" target="_blank">The stunning picture of a frozen Niagara Falls</a></span></strong></em></p><p><em><strong><span style="text-decoration: underline;"><a href="/news/news/2015/02/tourists-ruin-morning-glory/" target="_blank">Tourists have ruined this once pristine natural wonder</a></span></strong></em></p>

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