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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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Astronomers have detected another ‘planet killer’ asteroid. Could we miss one coming our way?

<p>If you surfed the web this morning, you may have seen news of the latest existential threat to humanity: a “planet killer” asteroid named 2022 AP7.</p> <p>Luckily for us 2022 AP7 “has no chance to hit the Earth currently”, <a href="https://www.theguardian.com/science/2022/nov/01/huge-planet-killer-asteroid-discovered-and-its-heading-our-way">according</a> to Scott Sheppard at the Carnegie Institution for Science. He and his international team of colleagues <a href="https://iopscience.iop.org/article/10.3847/1538-3881/ac8cff/pdf">observed 2022 AP7</a> in a trio of “rather large” asteroids obscured by the Sun’s glare (the other two don’t pose a risk).</p> <p>2022 AP7 orbits the Sun every five years, and currently crosses Earth’s orbit when Earth is on the other side of the Sun to it. Eventually its movement will sync with Earth’s and it will cross much closer by, but this will be centuries into the future.</p> <p>We simply don’t know enough about 2022 AP7 to precisely predict the danger it may pose centuries from now. At the same time, we suspect there could be other “planet killers” out there yet to be discovered. But how many? And what’s being done to find them?</p> <p><strong>What makes a planet killer?</strong></p> <p>Asteroid 2022 AP7 is the largest potentially hazardous asteroid (PHA) found in eight years, with a diameter between 1.1km and 2.3km. For context, an asteroid with a diameter more than 1km is enough to trigger a <a href="https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event">mass extinction event</a> on Earth.</p> <p>As well as having a diameter greater than 1km, an asteroid also needs to have an orbit that crosses Earth’s to be considered potentially dangerous. In the case of 2022 AP7, any threat is centuries down the track. The important point is it has been detected and can now be tracked. This is the best possible outcome.</p> <p>It is estimated we’ve already <a href="https://theconversation.com/in-a-world-first-nasas-dart-mission-is-about-to-smash-into-an-asteroid-what-will-we-learn-189391">discovered</a> about 95% of potentially hazardous asteroids, and that there are fewer than 1,000 of these. The work of Sheppard and colleagues highlights that hunting down the remaining 5% – some 50 asteroids – will be a massive effort.</p> <figure class="align-center "><img src="https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.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/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=304&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=304&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=304&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=382&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=382&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/492923/original/file-20221102-25180-74aqvo.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=382&amp;fit=crop&amp;dpr=3 2262w" alt="" /><figcaption><span class="caption">Statistically, there’s less of a chance of a larger asteroid colliding with Earth compared to a smaller one.</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure> <p><strong>What constitutes a near miss?</strong></p> <p>NASA <a href="https://www.jpl.nasa.gov/asteroid-watch">closely tracks</a> all known objects in the Solar System. But every now and again an object will catch us off guard.</p> <p>In 2021, we had a close call with an asteroid called <a href="https://en.wikipedia.org/wiki/2021_UA1">2021 UA1</a>. It came only a few thousand kilometres from Earth, over the Antarctic. In cosmic terms, this is uncomfortably close. However, 2021 UA1 was only two metres across, and therefore posed no substantial risk.</p> <p>There are likely hundreds of millions of objects of this size in our Solar System, and it’s not uncommon for them to impact Earth. In these cases, most of the object burns up in the atmosphere and creates a spectacular light show, with little risk to life.</p> <p>In 2019 another <a href="https://theconversation.com/an-asteroid-just-buzzed-past-earth-and-we-barely-noticed-in-time-120972">asteroid</a> with a 100m diameter passed Earth some 70,000km away. It was publicly announced mere hours before it flew past. While it wasn’t as close, it was of a much more concerning size.</p> <p>These near misses reiterate how important it is for us to speed up the search for near-Earth objects.</p> <p><strong>Blind spots</strong></p> <p>The reason we haven’t already found every object that could one day pass nearby Earth is largely because of observational blind spots, and the fact we can’t observe all parts of the sky all the time.</p> <p>To find 2022 AP7, Sheppard and colleagues used a telescope at twilight soon after the Sun had set. They had to do this because they were looking for asteroids in the vicinity of Venus and Earth. Venus is currently on the <a href="https://theskylive.com/where-is-venus">other side of the Sun</a> to Earth.</p> <p>Making observations close to the Sun is difficult. The Sun’s glare overwhelms the weak light reflected off small asteroids – presenting a blind spot. But just before and after sunset, there’s a small window in which the Sun’s glare no longer blocks the view.</p> <p>Right now there are only about 25 asteroids known to have well-determined orbits that lie entirely within Earth’s orbit. More are likely to be discovered, and these may contribute significantly to the missing 5% of potentially hazardous asteroids.</p> <p><strong>The Near-Earth Object Surveyor</strong></p> <p>A recent NASA mission spectacularly demonstrated that humans can purposefully change the trajectory of an asteroid. NASA’s DART (<a href="https://www.nasa.gov/planetarydefense/dart/dart-news">Double Asteroid Redirection Test</a>) mission collided a vending-machine-sized spacecraft into a 160m diameter minor-planet moon called Dimorphos.</p> <figure class="align-center "><img src="https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.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/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=338&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=338&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=338&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/492925/original/file-20221102-28436-f16d5x.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/492925/original/file-20221102-28436-f16d5x.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/492925/original/file-20221102-28436-f16d5x.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="" /><figcaption><span class="caption">The DART spacecraft successfully collided with Dimorphos, which itself was orbiting a larger asteroid named Didymos.</span> <span class="attribution"><span class="source">NASA/Johns Hopkins APL/Steve Gribben</span></span></figcaption></figure> <p>The collision altered Dimorphos’s 12-hour orbital period by more than 30 minutes, and was declared a resounding success. So it’s plausible for humans to redirect a hazardous asteroid if we find one.</p> <p>That said, we’d have to find it well in advance. Potentially hazardous asteroids are much larger than Dimorphos, so a bigger collision would be required with plenty of lead time.</p> <p>To do this, NASA has plans to survey for potentially hazardous objects using a telescope in space. Its <a href="https://www.jpl.nasa.gov/missions/near-earth-object-surveyor">Near-Earth Object (NEO) Surveyor</a>, scheduled to launch in 2026, will be able to survey the Solar System very efficiently – including within blind spots caused by the Sun.</p> <p>That’s because the glare we see while observing from Earth is caused by Earth’s atmosphere. But in space there’s no atmosphere to look through.</p> <figure class="align-center "><img src="https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.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/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=363&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=363&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=363&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=457&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=457&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/492932/original/file-20221102-26-zoxo13.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=457&amp;fit=crop&amp;dpr=3 2262w" alt="" /><figcaption><span class="caption">The NEO Surveyor spacecraft won’t have the issue of observational blind spots when hunting for asteroids.</span> <span class="attribution"><span class="source">NASA/JPL/University of Arizona</span></span></figcaption></figure> <p>It’s very likely the Near-Earth Object Surveyor will reveal new objects, and help us characterise a large number of objects to greatly improve our understanding of threats.</p> <p>The key is to find as many objects as possible, categorise them, track the risks, and plan a redirection mission as much in advance as possible. The fact that all of these elements of planetary defence are now a reality is an amazing feat of science and engineering. It is the first time in human history we have these capabilities.<!-- 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/193709/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 Steven Tingay. Republished with permission from <a href="https://theconversation.com/astronomers-have-detected-another-planet-killer-asteroid-could-we-miss-one-coming-our-way-193709" target="_blank" rel="noopener">The Conversation</a>.</em></p> <p><em>Image: </em><em>DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA/J. da Silva/Spaceengine</em></p>

Technology

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We steered a spacecraft into an asteroid

<p dir="ltr">From seeing further into space than ever before to viewing our neighbouring planets in brand new detail, it’s safe to say more of us are talking about the skies above than in previous years.</p> <p dir="ltr">Now, NASA has made headlines for crashing a spacecraft into a distant asteroid in a historic first for humanity.</p> <p dir="ltr">After leaving Earth last November, the Double Asteroid Redirection Test (DART) spaceship travelled at a speedy 23,500 kilometres per hour for ten months to reach its target, an asteroid moonlet called Dimorphos.</p> <p dir="ltr">Dimorphos is a relatively small asteroid with a diameter of 160 metres - about the same size as the Great Pyramid of Giza - that orbits Didymos, a larger asteroid boasting a diameter of 780 metres.</p> <p><span id="docs-internal-guid-6fbbb56c-7fff-3b7c-bda5-0ec6342814cd"></span></p> <p dir="ltr">DART, meanwhile, is approximately the size of a refrigerator - but size isn’t everything.</p> <p dir="ltr"><img src="https://oversixtydev.blob.core.windows.net/media/2022/09/dart-collision0.jpg" alt="" width="1280" height="720" /></p> <p dir="ltr"><em>The Double Asteroid Redirection Test (DART) spacecraft is dwarfed by its target, Dimorphos, as well as Didymos, which Dimorphos orbits. Image: NASA / John Hopkins APL</em></p> <p dir="ltr">Located 11.2 million kilometres away from us, Dimorphus might not pose any risk to Earth, but it did serve as a suitable target for NASA to test whether a head-on collision from DART could cause the asteroid to change its orbit.</p> <p dir="ltr">This experiment, which uses a technique called kinetic impact to change the asteroid’s orbit, could determine whether it’s possible to prevent asteroids and other cosmic objects from colliding with Earth and avoid the devastating aftereffects of such a collision.</p> <p dir="ltr">NASA Administrator Bill Nelson explained that the experiment is part of the organisation’s overall planetary defence strategy.</p> <p dir="ltr">“At its core, DART represents an unprecedented success for planetary defence, but it is also a mission of unity with a real benefit for all humanity,” he said.</p> <p dir="ltr">“As NASA studies the cosmos and our home planet, we’re also working to protect that home, and this international collaboration turned science fiction into science fact, demonstrating one way to protect Earth.”</p> <p dir="ltr">Rebecca Allen, an astronomer at Swinburne University of Technology told the <em>ABC </em>that everything from the location of the impact, how fast DART travelled, and even its size are factors that could affect Dimorphos’ orbit.</p> <p dir="ltr"><span id="docs-internal-guid-15585374-7fff-10ba-cc0e-78c10d40f192"></span></p> <p dir="ltr">"This vending-sized machine spacecraft, will it have enough kinetic impact to drastically or really measurably change the orbit of this asteroid? That's what we're trying to learn,” she added.</p> <p dir="ltr"><img src="https://oversixtydev.blob.core.windows.net/media/2022/09/dart-collision1.jpg" alt="" width="1280" height="720" /></p> <p dir="ltr"><em>Shots taken from DART’s onboard camera showed asteroids Dimorphos and Didymos (left), and an up-close look at Dimorphos before DART crashed (right). Images: NASA / John Hopkins APL</em></p> <p dir="ltr"><strong>What happens now?</strong></p> <p dir="ltr">Though DART successfully collided with Dimorphus on Tuesday morning (AEST), we won’t know whether the collision actually resulted in a change in orbit.</p> <p dir="ltr">It will take anywhere from several days to weeks to determine whether it worked, and we can expect to learn more over the coming months.</p> <p dir="ltr">“Over the next two months we’re going to see more information from the investigation team on what what period change did we actually make,” Dr Elena Adams, a DART Mission Systems Engineer, said.</p> <p dir="ltr">“That’s our number two goal, number one was hit the asteroid, which we’ve done but now number two is really measure that period change and characterise how much we actually put out.”</p> <p dir="ltr">In a <a href="https://www.nasa.gov/press-release/nasa-s-dart-mission-hits-asteroid-in-first-ever-planetary-defense-test" target="_blank" rel="noopener">statement</a>, NASA said researchers are expecting the path Dimorphos takes around Didymos to shorten by just one percent, or about 10 minutes.</p> <p dir="ltr">But even this seemingly tiny change can have an impact over time, experts stress.</p> <p dir="ltr">"Just a small change in its speed is all we need to make a significant difference in the path an asteroid travels.” said Dr Thomas Zurbuchen, an associate administrator for the Science Mission Directorate at NASA’s Washington headquarters.</p> <p dir="ltr">The next few months will also see NASA use telescopes positioned on Earth and in space to observe the outcome of the collision, including measuring changes to Dimorphos’ orbit.</p> <p dir="ltr">Images will also be taken by LICIACube (Light Italian Cubesat for Imaging Asteroids), which deployed from DART fifteen days before the impact, with the European Space Agency’s Hera project scheduled to conduct surveys of Dimorphos and Didymos - with a focus on the crater created by the collision - in 2026.</p> <p dir="ltr">The images will add to the collection of photos taken by DRACO (Didymos Reconnaissance Camera for Optical navigation), which was onboard DART when it crashed. </p> <p dir="ltr"><span id="docs-internal-guid-2ace8485-7fff-36e0-9e45-208735e6bd71"></span></p> <p dir="ltr">As well as shots showing Didymos and Dimorphos, the images depict the rocky terrain of Dimorphos’ surface up close.</p> <p dir="ltr"><img src="https://oversixtydev.blob.core.windows.net/media/2022/09/dart-collision2.jpg" alt="" width="1280" height="720" /></p> <p dir="ltr"><em>DART’s onboard camera, DRACO, captured the final moments before the spacecraft crashed into the surface of Dimorphos. Images: NASA / John Hopkins APL</em></p> <p dir="ltr">The last photo, taken about one second before impact, was being transmitted to Earth when the craft crashed, resulting in a partial picture.</p> <p dir="ltr">“DART’s success provides a significant addition to the essential toolbox we must have to protect Earth from a devastating impact by an asteroid,” said Lindley Johnson, NASA’s Planetary Defense Officer. </p> <p dir="ltr"><span id="docs-internal-guid-3681f89e-7fff-545a-e424-65d63358e4f2"></span></p> <p dir="ltr">“This demonstrates we are no longer powerless to prevent this type of natural disaster.”</p> <p dir="ltr"><em>Image: NASA / John Hopkins APL</em></p>

Technology

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What a mass extinction is and what it means for you

<p>For more than 3.5 billion years, living organisms have thrived, multiplied and diversified to occupy every ecosystem on Earth. The flip side to this explosion of new species is that species extinctions have also always been part of the evolutionary life cycle.</p> <p>But these two processes are not always in step. When the loss of species rapidly outpaces the formation of new species, this balance can be tipped enough to elicit what are known as “mass extinction” events.</p> <p>A mass extinction is usually defined as a loss of about three quarters of all species in existence across the entire Earth over a “short” geological period of time. Given the vast amount of time since life first evolved on the planet, “short” is defined as anything less than 2.8 million years.</p> <p>Since at least the <a href="https://science.sciencemag.org/content/215/4539/1501">Cambrian period</a> <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev.earth.33.092203.122654">that began</a> around 540 million years ago when the diversity of life <a href="https://www.pnas.org/content/105/Supplement_1/11536">first exploded</a> into a vast array of forms, only five extinction events have definitively met these mass-extinction criteria.</p> <p>These so-called “Big Five” have become part of the scientific benchmark to determine whether human beings have today created the conditions for a sixth mass extinction.</p> <p><strong>The Big Five</strong></p> <p>These five mass extinctions have happened on average every 100 million years or so since the Cambrian, although there is no detectable pattern in their particular timing. Each event itself lasted between 50 thousand and 2.76 million years. The first mass extinction happened at the end of the Ordovician period about 443 million years ago and wiped out over 85% of all species.</p> <p>The Ordovician event <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/pala.12397">seems to have been the result</a> of two climate phenomena. First, a planetary-scale period of glaciation (a global-scale “ice age”), then a rapid warming period.</p> <p>The second mass extinction occurred during the Late Devonian period around 374 million years ago. This affected around 75% of all species, most of which were bottom-dwelling invertebrates in tropical seas at that time.</p> <p>This period in Earth’s past was characterised by high variation in sea levels, and rapidly alternating conditions of global cooling and warming. It was also the time when plants were starting to take over dry land, and there was a drop in global CO<sub>2</sub> concentration; all this was accompanied by soil transformation and periods of low oxygen.</p> <p>The third and most devastating of the Big Five occurred at the end of the Permian period around 250 million years ago. This wiped out more than 95% of all species in existence at the time.</p> <p>Some of the suggested <a href="https://www.sciencedirect.com/science/article/pii/S0031018216306915">causes</a> include an asteroid impact that filled the air with pulverised particle, creating unfavourable climate conditions for many species. These could have blocked the sun and generated intense acid rains. Some other possible causes are still debated, such as massive volcanic activity in what is today Siberia, increasing ocean toxicity caused by an increase in atmospheric CO₂, or the spread of oxygen-poor water in the deep ocean.</p> <p>Fifty million years after the great Permian extinction, about <a href="https://www.researchgate.net/publication/248289771_Triassic-Jurassic_boundary_events_Problems_progress_possibilities">80% of the world’s species</a> <a href="https://science.sciencemag.org/content/292/5519/1148">again went extinct</a> during the Triassic event. This was <a href="https://www.springer.com/gp/book/9783319680088">possibly caused</a> by some colossal geological activity in what is today the Atlantic Ocean that would have elevated atmospheric CO₂ concentrations, increased global temperatures, and acidified oceans.</p> <p>The last and probably most well-known of the mass-extinction events happened during the Cretaceous period, when an estimated 76% of all species went extinct, including the non-avian dinosaurs. The demise of the dinosaur super predators gave mammals a new opportunity to diversify and occupy new habitats, from which human beings eventually evolved.</p> <p>The <a href="https://science.sciencemag.org/content/350/6256/76">most likely cause</a> of the Cretaceous mass extinction was an extraterrestrial impact in the Yucatán of modern-day Mexico, a massive volcanic eruption in the Deccan Province of modern-day west-central India, or both in combination.<img src="https://images.theconversation.com/files/301159/original/file-20191111-178484-1e7unnm.png?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="" /><strong>Is today’s biodiversity crisis a sixth mass extinction?</strong></p> <p>The Earth is currently experiencing an extinction crisis largely due to the exploitation of the planet by people. But whether this constitutes a sixth mass extinction depends on whether today’s extinction rate is greater than the “normal” or “background” rate that occurs between mass extinctions.</p> <p>This background rate indicates how fast species would be expected to disappear in absence of human endeavour, and it’s mostly measured using the fossil record to count how many species died out between mass extinction events.</p> <p>The most accepted background rate estimated from the fossil record gives an average lifespan of about one million years for a species, or one species extinction per million species-years. But this estimated rate is highly uncertain, ranging between 0.1 and 2.0 extinctions per million species-years. Whether we are now indeed in a sixth mass extinction depends to some extent on the true value of this rate. Otherwise, it’s difficult to compare Earth’s situation today with the past.</p> <p>In contrast to the the Big Five, today’s species losses are driven by a <a href="http://assets.press.princeton.edu/chapters/s5_8879.pdf">mix of direct and indirect human activities</a>, such as the destruction and fragmentation of habitats, direct exploitation like fishing and hunting, chemical pollution, invasive species, and human-caused global warming.</p> <p>If we use the same approach to estimate today’s extinctions per million species-years, we come up with a rate that is between <a href="https://academic.oup.com/bioscience/article/66/9/785/1753703">ten and 10,000 times higher than the background rate</a>.</p> <p>Even considering a conservative background rate of <a href="https://advances.sciencemag.org/content/1/5/e1400253">two extinctions per million species-years</a>, the number of species that have gone extinct in the last century would have otherwise taken between 800 and 10,000 years to disappear if they were merely succumbing to the expected extinctions that happen at random. This alone supports the notion that the Earth is at least experiencing many more extinctions than expected from the background rate.</p> <p>It would <a href="https://www.nature.com/articles/nature11018">likely take several millions of years</a> of normal evolutionary diversification to “restore” the Earth’s species to what they were prior to human beings rapidly changing the planet. Among land vertebrates (species with an internal skeleton), <a href="https://science.sciencemag.org/content/345/6195/401">322 species have been recorded going extinct</a> since the year 1500, or about 1.2 species going extinction every two years.</p> <p>If this doesn’t sound like much, it’s important to remember extinction is always preceded by a loss in population abundance and shrinking distributions. Based on the number of decreasing vertebrate species listed in the International Union for Conservation of Nature’s <a href="https://www.iucnredlist.org/">Red List of Threatened Species</a>, 32% of all known species across all ecosystems and groups are decreasing in abundance and range. In fact, the Earth has lost about <a href="https://wwf.panda.org/knowledge_hub/all_publications/living_planet_index2/">60% of all vertebrate individuals since 1970</a>.</p> <p>Australia has one of the worst recent extinction records of any continent, with <a href="https://pdfs.semanticscholar.org/9ca4/f10e7349b6618dfbbfeb118a0954ab0643b8.pdf">more than 100 species of vertebrates going extinct</a> since the first people arrived over 50 thousand years ago. And more than 300 animal and 1,000 plant species are <a href="https://www.iucnredlist.org/">now considered threatened with imminent extinction</a>.</p> <p>Although biologists are still debating how much the current extinction rate exceeds the background rate, even the most conservative estimates reveal an exceptionally rapid loss of biodiversity typical of a mass extinction event.</p> <p>In fact, <a href="https://link.springer.com/article/10.1007/s12210-013-0258-9">some studies show</a> that the interacting conditions experienced today, such as accelerated <a href="http://doi.org/10.1038/s41598-018-35068-1">climate change</a>, changing atmospheric composition caused by human industry, and abnormal ecological stresses arising from human consumption of resources, define a perfect storm for extinctions. All these conditions together indicate that a sixth mass extinction is <a href="https://www.nature.com/articles/nature09678">already well under way</a>.</p> <p><em><a href="https://theconversation.com/profiles/frederik-saltre-220925">Frédérik Saltré</a>, Research Fellow in Ecology &amp; Associate Investigator for the ARC Centre of Excellence for Australian Biodiversity and Heritage, <a href="http://theconversation.com/institutions/flinders-university-972">Flinders University</a> and <a href="https://theconversation.com/profiles/corey-j-a-bradshaw-9183">Corey J. A. Bradshaw</a>, Matthew Flinders Fellow in Global Ecology and Models Theme Leader for the ARC Centre of Excellence for Australian Biodiversity and Heritage, <a href="http://theconversation.com/institutions/flinders-university-972">Flinders University</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/what-is-a-mass-extinction-and-are-we-in-one-now-122535">original article</a>.</em></p>

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Why dangerous asteroids heading to Earth are so hard to detect

<p>Earth is often in the firing line of fragments of asteroids and comets, most of which<span> </span><a href="https://theconversation.com/explainer-why-meteors-light-up-the-night-sky-35754">burn up</a>tens of kilometres above our heads. But occasionally, something larger gets through.</p> <p>That’s what happened off Russia’s east coast on December 18 last year. A<span> </span><a href="https://www.bbc.com/news/science-environment-47607696">giant explosion occurred above the Bering Sea</a><span> </span>when an asteroid some ten metres across detonated with an explosive energy ten times greater than the bomb dropped on Hiroshima.</p> <p>So why didn’t we see this asteroid coming? And why are we only hearing about its explosive arrival now?</p> <p><strong>Nobody saw it</strong></p> <p>Had the December explosion occurred near a city – as<span> </span><a href="https://www.theguardian.com/world/2013/feb/15/hundreds-injured-meteorite-russian-city-chelyabinsk">happened at Chelyabinsk in February 2013</a><span> </span>– we would have heard all about it at the time.</p> <p>But because it happened in a remote part of the world, it went unremarked for more than three months, until details were unveiled at the<span> </span><a href="https://www.hou.usra.edu/meetings/lpsc2019/">50th Lunar and Planetary Science Conference</a><span> </span>this week, based on<span> </span><a href="https://cneos.jpl.nasa.gov/fireballs/">NASA’s collection of fireball data</a>.</p> <p>So where did this asteroid come from?</p> <p><strong>At risk from space debris</strong></p> <p>The Solar system is littered with material left over from the formation of the planets. Most of it is locked up in stable reservoirs – the Asteroid belt, the Edgeworth-Kuiper belt and the Oort cloud – far from Earth.</p> <p>Those reservoirs continually leak objects into interplanetary space, injecting fresh debris into orbits that cross those of the planets. The inner Solar system is awash with debris, ranging from tiny flecks of dust to comets and asteroids many kilometres in diameter.</p> <p>The vast majority of the debris that collides with Earth is utterly harmless, but our planet still<span> </span><a href="https://theconversation.com/target-earth-how-asteroids-made-an-impact-on-australia-92836">bears the scars of collisions</a><span> </span>with much larger bodies.</p> <p>The largest, most devastating impacts (like that which<span> </span><a href="https://theconversation.com/how-the-dinosaurs-went-extinct-asteroid-collision-triggered-potentially-deadly-volcanic-eruptions-112134">helped to kill the dinosaurs</a><span> </span>65 million years ago) are the rarest. But smaller, more frequent collisions also pose a marked risk.</p> <p>In 1908, in Tunguska, Siberia, a<span> </span><a href="http://www.bbc.com/earth/story/20160706-in-siberia-in-1908-a-huge-explosion-came-out-of-nowhere">vast explosion</a><span> </span>levelled more than 2,000 square kilometres of forest. Due to the remote location, no deaths were recorded. Had the impact happened just two hours later, the city of St Petersburg could have been destroyed.</p> <p>In 2013, it was a 10,000-tonne asteroid that<span> </span><a href="https://earthsky.org/space/meteor-asteroid-chelyabinsk-russia-feb-15-2013">detonated above the Russian city of Chelyabinsk</a>. More than 1,500 people were injured and around 7,000 buildings were damaged, but amazingly nobody was killed.</p> <p>We’re still trying to work out how often events like this happen. Our information on the frequency of the larger impacts is pretty limited, so estimates can vary dramatically.</p> <p>Typically, people argue that Tunguska-sized impacts happen<span> </span><a href="https://academic.oup.com/astrogeo/article/50/1/1.18/201316">every few hundred years</a>, but that’s just based on a sample of one event. The truth is, we don’t really know.</p> <p><strong>What can we do about it?</strong></p> <p>Over the past couple of decades, a concerted effort has been made to search for potentially hazardous objects that pose a threat before they hit Earth. The result is the<span> </span><a href="https://cneos.jpl.nasa.gov/stats/totals.html">identification of thousands of near-Earth asteroids</a><span> </span>upwards of a few metres across.</p> <p>Once found, the orbits of those objects can be determined, and their paths<span> </span><a href="https://cneos.jpl.nasa.gov/ca/">predicted into the future</a>, to see whether an impact is possible or even likely. The longer we can observe a given object, the better that prediction becomes.</p> <p>But as we saw with Chelyabinsk in 2013, and again in December, we’re not there yet. While the catalogue of potentially hazardous objects continues to grow, many still remain undetected, waiting to catch us by surprise.</p> <p>If we discover a collision is pending in the coming days, we can work out where and when the collision will happen. That happened for the first time in 2008 when astronomers discovered the tiny<span> </span><a href="https://cneos.jpl.nasa.gov/news/2008tc3.html">asteroid 2008 TC3</a>, 19 hours before it hit Earth’s atmosphere over northern Sudan.</p> <p>For impacts predicted with a longer lead time, it will be possible to work out whether the object is truly dangerous, or would merely produce a spectacular but harmless fireball (like 2008 TC3).</p> <p>For any objects that truly pose a threat, the race will be on to deflect them – to turn a hit into a miss.</p> <p><strong>Searching the skies</strong></p> <p>Before we can quantify the threat an object poses, we first need to know that the object is there. But finding asteroids is hard.</p> <p>Surveys scour the skies,<span> </span><a href="https://spaceguardcentre.com/what-are-neos/finding-and-observing-asteroids/">looking for faint star-like points moving against the background stars</a>. A bigger asteroid will reflect more sunlight, and therefore appear brighter in the sky - at a given distance from Earth.</p> <p>As a result, the smaller the object, the closer it must be to Earth before we can spot it.</p> <p>Objects the size of the Chelyabinsk and Bering Sea events (about 20 and 10 metres diameter, respectively) are tiny. They can only be spotted when passing very close to our planet. The vast majority of the time they are simply undetectable.</p> <p>As a result, having impacts like these come out of the blue is really the norm, rather than the exception!</p> <p>The Chelyabinsk impact is a great example. Moving on its orbit around the Sun, it approached us in the daylight sky - totally hidden in the Sun’s glare.</p> <p>For larger objects, which impact much less frequently but would do far more damage, it is fair to expect we would receive some warning.</p> <p><strong>Why not move the asteroid?</strong></p> <p>While we need to keep searching for threatening objects, there is another way we could protect ourselves.</p> <p>Missions such as<span> </span><a href="https://solarsystem.nasa.gov/missions/hayabusa/in-depth/">Hayabusa</a>,<span> </span><a href="http://www.hayabusa2.jaxa.jp/en/">Hayabusa 2</a><span> </span>and<span> </span><a href="https://www.asteroidmission.org/">OSIRIS-REx</a><span> </span>have demonstrated the ability to travel to near-Earth asteroids, land on their surfaces, and move things around.</p> <p>From there, it is just a short hop to being able to deflect them – to change a potential collision into a near-miss.</p> <p>Interestingly, ideas of asteroid deflection dovetail nicely with the<span> </span><a href="https://theconversation.com/mining-asteroids-could-unlock-untold-wealth-heres-how-to-get-started-95675">possibility of asteroid mining</a>.</p> <p>The technology needed to extract material from an asteroid and send it back to Earth could equally be used to alter the orbit of that asteroid, moving it away from a potential collision with our planet.</p> <p>We’re not quite there yet, but for the first time in our history, we have the potential to truly control our own destiny.</p> <p><em>Written by Jonti Horner. Republished with permission of <a href="https://theconversation.com/why-dangerous-asteroids-heading-to-earth-are-so-hard-to-detect-113845">The Conversation.</a></em></p>

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NASA announces asteroid is headed for Earth this weekend

<p>In what seems like a scene out of a Hollywood movie, NASA has announced an asteroid up to 2.6 kilometres wide is set to pass the moon’s orbit over the weekend, narrowly missing Earth.</p> <p>NASA experts have been tracking Asteroid 86666 for 16 years and believe the giant rock, which is currently hurtling through space at 64,374km per hour, won’t come into contact with our planet.</p> <p>Asteroid 86666 has been classified by NASA as a potentially hazardous object, which is given to any asteroid or comet that is expected to come within 7,402,982km of the Earth’s surface. If a rock the size of this asteroid were to strike Earth it would potentially cause havoc, wreaking the ozone layer, creating tsunamis and potentially changing the planet’s climate.</p> <p>NASA will continue to monitor the progress of Asteroid 86666 using ground and space-based telescope as part of the Near-Earth Object Observations program and has stressed nothing is expected to impact Earth in the foreseeable future, stating on their website, “All known Potentially Hazardous Asteroids have less than a 0.01 per cent chance of impacting Earth in the next 100 years.” </p> <p><strong>Related links:</strong></p> <p><a href="/news/news/2015/10/nasa-announce-pluto-discovery/"><span style="text-decoration: underline;"><em><strong>What did NASA find on Pluto?</strong></em></span></a></p> <p><a href="/news/news/2015/09/nasa-announce-mars-discovery/"><span style="text-decoration: underline;"><em><strong>NASA reveals everything we know about Mars was wrong</strong></em></span></a></p> <p><a href="/news/news/2015/10/nasa-released-10000-photos/"><span style="text-decoration: underline;"><em><strong>NASA releases 10,000 never-before-seen photos of Apollo missions</strong></em></span></a></p>

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