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Here's What Really Happened to Those 2 Satellites Projected to Crash in Earth Orbit – ScienceAlert

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It appears we have missed another close call between two satellites – but how close did we really come to a catastrophic event in space?

It all began with a series of tweets from LeoLabs, a company that uses radar to track satellites and debris in space. It predicted that two obsolete satellites orbiting Earth had a 1 in 100 chance of an almost direct head-on collision at 9:39am AEST on 30 January (23:39 UTC, January 29) with potentially devastating consequences.

LeoLabs estimated that the satellites could pass within 15-30 meters (50-100 feet) of one another. Neither satellite could be controlled or moved. All we could do was watch whatever unfolded above us.

Collisions in space can be disastrous and can send high-speed debris in all directions. This endangers other satellites, future launches, and especially crewed space missions.

As a point of reference, NASA often moves the International Space Station when the risk of collision is just 1 in 100,000. Last year the European Space Agency moved one of its satellites when the likelihood of collision with a SpaceX satellite was estimated at 1 in 50,000.

However, this increased to 1 in 1,000 when the US Air Force, which maintains perhaps the most comprehensive catalogue of satellites, provided more detailed information.

Following LeoLabs’ warning, other organisations such as the Aerospace Corporation began to provide similarly worrying predictions. In contrast, calculations based on publicly available data were far more optimistic. Neither the US Air Force nor NASA issued any warning.

This was notable, as the United States had a role in the launch of both satellites involved in the near-miss. The first is the Infrared Astronomical Satellite (IRAS), a large space telescope weighing around a tonne and launched in 1983.

It successfully completed its mission later that year and has floated dormant ever since.

The second satellite has a slightly more intriguing story. Known as GGSE-4, it is a formerly secret government satellite launched in 1967. It was part of a much larger project to capture radar emissions from the Soviet Union. This particular satellite also contained an experiment to explore ways to stabilise satellites using gravity.

Weighing in at 83 kilograms (182 pounds), it is much smaller than IRAS, but it has a very unusual and unfortunate shape. It has an 18 meter (60 foot) protruding arm with a weight on the end, thus making it a much larger target.

Almost 24 hours later, LeoLabs tweeted again. It downgraded the chance of a collision to 1 in 1,000, and revised the predicted passing distance between the satellites to 13-87 meters (43-285 feet). Although still closer than usual, this was a decidedly smaller risk.

But less than 15 hours after that, the company tweeted yet again, raising the probability of collision back to 1 in 100, and then to a very alarming 1 in 20 after learning about the shape of GGSE-4.

The good news is that the two satellites appear to have missed one another. Although there were a handful of eyewitness accounts of the IRAS satellite appearing to pass unharmed through the predicted point of impact, it can still take a few hours for scientists to confirm that a collision did not take place.

LeoLabs has since confirmed it has not detected any new space debris.

But why did the predictions change so dramatically and so often? What happened?

Tricky situation

The real problem is that we don’t really know precisely where these satellites are. That requires us to be extremely conservative, especially given the cost and importance of most active satellites, and the dramatic consequences of high-speed collisions.

The tracking of objects in space is often called Space Situational Awareness, and it is a very difficult task. One of the best methods is radar, which is expensive to build and operate. Visual observation with telescopes is much cheaper but comes with other complications, such as weather and lots of moving parts that can break down.

Another difficulty is that our models for predicting satellites’ orbits don’t work well in lower orbits, where drag from Earth’s atmosphere can become a factor.

There is yet another problem. Whereas it is in the best interest of commercial satellites for everyone to know exactly where they are, this is not the case for military and spy satellites. Defence organisations do not share the full list of objects they are tracking.

This potential collision involved an ancient spy satellite from 1967. It is at least one that we can see. Given the difficulty of just tracking the satellites that we know about, how will we avoid satellites that are trying their hardest not to be seen?

In fact, much research has gone into building stealth satellites that are invisible from Earth. Even commercial industry is considering making satellites that are harder to see, partly in response to astronomers’ own concerns about objects blotting out their view of the heavens.

SpaceX is considering building “dark satellites” the reflect less light into telescopes on Earth, which will only make them harder to track.

What should we do?

The solution starts with developing better ways to track satellites and space debris. Removing the junk is an important next step, but we can only do that if we know exactly where it is.

Western Sydney University is developing biology-inspired cameras that can see satellites during the day, allowing them to work when other telescopes cannot. These sensors can also see satellites when they move in front of bright objects like the Moon.

There is also no clear international space law or policy, but a strong need for one. Unfortunately, such laws will be impossible to enforce if we cannot do a better job of figuring out what is happening in orbit around our planet.

Gregory Cohen, Associate Professor, Western Sydney University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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How to spot a Starlink satellite in the night sky – Trading U

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There are hundreds of SpaceX satellites in the sky. A successful sighting just requires a bit of luck, writes Abigail Beall

Space


16 September 2020

Denise Taylor/Getty Images

What you need

The Find Starlink website or something similar

A spot of sky viewed away from light pollution

OUR skies are filling up with satellites. Starting in May 2019, the firm SpaceX has deployed around 700 Starlink satellites into Earth orbit over 11 launches. SpaceX plans to deploy 12,000, and perhaps later 42,000, satellites with the aim of providing internet access to the entire world.

These satellites have the potential to change the way that the night sky looks. For comparison, there are only around 2600 satellites currently orbiting Earth. These days, …

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Australian stinging tree could pave way for novel painkillers – News-Medical.Net

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Australia is well known for having many of the world’s most venomous creatures, ranging from snakes, spiders, jellyfish, centipedes, fish, ticks, bees, and ants. 21 of the 25 most venomous snakes in the world are all from Australia. The country is also home to dangerous plants, like the Australian stinging tree.

Close up of the heart-shaped leaf of the most toxic of the Australian species of stinging trees Dendrocnide moroides, also known as the stinging brush, gympie stinger, moonlight plant among others. Image Credit: Victoria Tucholka / Shutterstock

Now, a team of researchers at the University of Queensland in Brisbane examined the toxins produced by two species of Australian stinging trees- the shrub-sized Gympie-Gympie (Dendrocnide moroides) and the giant Australian stinging tree (Dendrocnide excelsa).

Leaves of the fearsome giant stinging tree, Dendrocnide excelsa. Image Credit: Lakeview Images

Leaves of the fearsome giant stinging tree, Dendrocnide excelsa. Image Credit: Lakeview Images

The Gympie-Gympie stinging tree is one of the world’s most toxic plants and may cause excruciating long-lasting pain. From these plants, the researchers found a new family of toxins, which they called “gympietides” after the name of the tree. Usually, these trees are found in the Northern Rivers region of New South Wales and at the tip of the Cape York Peninsula.

“Our research on the venom of Australian stinging trees, found in the country’s northeast, shows these dangerous plants can inject unwary wanderers with chemicals much like those found in the stings of scorpions, spiders and cone snails,” the researchers said.

Long-lasting pain

The Australian stinging tree is covered with hollow needle-like hairs called trichomes, which are bolstered with silica. Like common nettles, the hairs contain toxins and substances, which can induce extreme pain.

The scientists reported that stinging trees produce extremely persistent and painful stings upon contact of their trichomes with mammalian skin. The pain typically lasts for several hours, and intermittent painful flares may occur for days and weeks.

“The Australian stinging tree species are particularly notorious for producing an excruciatingly painful sting, which unlike those of their European and North American relatives can cause symptoms that last for days or weeks,” Irina Vetter, associate professor at the UQ’s Institute for Molecular Bioscience, said.

“Like other stinging plants such as nettles, the giant stinging tree is covered in needle-like appendages called trichomes that are around five millimeters in length—the trichomes look like fine hairs, but act like hypodermic needles that inject toxins when they make contact with skin,” she added.

The team reported that the pain and stinging sensation might be tied to small-molecule neurotransmitters and inflammatory mediators. However, these compounds cannot explain the observed sensory effects.

In the study, published in the journal Science Advances, the team demonstrated that the venoms of the stinging trees contain unknown pain-inducing peptides.

Discovering gympietides

To arrive at the study findings, the team studied the stinging hairs from the giant Australian stinging tree, obtaining an extract from them. They separate them into their singular molecular contents. The substances produced extreme pain responses when they were tested in the laboratory.

The team discovered that the extract contains a small family of mini-proteins. Further, the team examined the genes that are found in the leaves of the Gympie-Gympie to find out which one could produce the toxin. From there, the team revealed molecules that can reproduce the pain response even when developed synthetically in the laboratory.

Gympietides contain an intricate three-dimensional structure maintained by links within the molecule that forms a knotted shape. Hence, the toxin is kept stable, which stays intact for a long time once it gets injected into the victim. The structure of the gympietides is similar to the toxins from the cone snail, scorpion, and spider venom, which affect ion channels in nerve cells that are known as mediators of pain.

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“The 3D structure of these gympietides is reminiscent of animal venom toxins targeting the same receptors, thus representing a remarkable case of inter-kingdom convergent evolution of animal and plant venoms,” the researchers wrote in the paper.

“Our work clarifies the molecular basis for the pain caused by these plants while enabling structure-activity and convergent evolution studies to define how ancestrally distinct peptides in venoms may elicit the same response at pain receptors,” they added.

The researchers hope that the toxins will provide new information on how pain-sensing nerves function, paving the way for the development of novel painkillers.

Journal reference:

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How to watch historic SpaceX rocket launch more Starlink satellites Friday – CNET

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The Falcon 9 rocket booster that sent NASA astronauts to the International Space Station in May is scheduled to get recycled again Friday, when SpaceX plans to send 60 more Starlink satellites to orbit atop its column of fire. 

Elon Musk’s trademark reusable rocket will be making its third flight when it lifts off from Florida’s Kennedy Space Center at 10:57 a.m. PT (1:57 p.m. ET). This specific unit sent astronauts Doug Hurley and Bob Behnken to orbit in May and then launched a South Korean satellite in July. So far, SpaceX has managed to launch and land the same rocket up to six times

The launch was originally scheduled for Thursday, but it got scrubbed and pushed back a day due to a “recovery issue.” It could be that SpaceX didn’t like the look of the weather in the Atlantic where the first stage and the fairing were set to be recovered. 

One half of the nose cone, or fairing, atop the rocket has also seen two previous flights, both of them earlier Starlink missions. 

This should be a fairly routine launch. It will be the 13th Starlink mission so far, and SpaceX is ultimately planning on dozens more as it grows its broadband mega-constellation.


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Following the launch and separation of the rocket’s second stage and payload, the first-stage booster will again return to Earth to land on a droneship in the Atlantic. 

SpaceX will stream the entire thing via the feed above, starting at about 10 minutes before launch.

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