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Two satellites just avoided a head-on smash. How close did they come to disaster? – The Conversation AU

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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, with potentially devastating consequences.

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

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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.




Read more:
You, me and debris: Australia should help clear ‘space junk’


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 83kg, it is much smaller than IRAS, but it has a very unusual and unfortunate shape. It has an 18m 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 13-87m. 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?




Read more:
Trash or treasure? A lot of space debris is junk, but some is precious heritage


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.

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NASA posts high-resolution images of Orion’s final lunar flyby

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Orion just made its final pass around the moon on its way to Earth, and NASA has released some of the spacecraft’s best photos so far. Taken by a high-resolution camera (actually a heavily modified GoPro Hero 4) mounted on the tip of Orion’s solar arrays, they show the spacecraft rounding the Moon then getting a closeup shot of the far side.

The photos Orion snapped on its first near pass to the Moon were rather grainy and blown out, likely because they were captured with Orion’s Optical Navigation Camera rather than the solar array-mounted GoPros. Other GoPro shots were a touch overexposed, but NASA appears to have nailed the settings with its latest series of shots.

Space photos were obviously not the primary goal of the Artemis I mission, but they’re important for public relations, as NASA learned many moons ago. It was a bit surprising that NASA didn’t show some high-resolution closeups of the Moon’s surface when it passed by the first time, but better late than never.

Orion’s performance so far has been “outstanding,” program manager Howard Hu told reporters last week. It launched on November 15th as part of the Artemis 1 mission atop NASA’s mighty Space Launch System. Days ago, the craft completed a three and a half minute engine burn (the longest on the trip so far) to set it on course for a splashdown on December 11th.

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The next mission, Artemis II, is scheduled in 2024 to carry astronauts on a similar path to Artemis I without landing on the moon. Then, humans will finally set foot on the lunar surface again with Artemis III, slated for launch in 2025.

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Biosignatures: Discovery Of Earth’s Oldest DNA Breaks Record By One Million Years

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Taxonomic profiles of the plant assemblage found in the metagenomes. Taxa in bold are genera only found as DNA and not as macrofossil or pollen. Asterisks indicate those that are found at other Pliocene Arctic sites. Extinct species as identified by either macrofossils or phylogenetic placements are marked with a dagger. Reads classified as Pyrus and Malus are marked with a pound symbol, and are probably over-classified DNA sequences belonging to another species within Rosaceae that are not present as a reference genome. — University of Cambridge

Two-million-year-old DNA has been identified for the first time – opening a ‘game-changing’ new chapter in the history of evolution.

 

Microscopic fragments of environmental DNA were found in Ice Age sediment in northern Greenland. Using cutting-edge technology, researchers discovered the fragments are one million years older than the previous record for DNA sampled from a Siberian mammoth bone.

The ancient DNA has been used to map a two-million-year-old ecosystem which weathered extreme climate change. Researchers hope the results could help to predict the long-term environmental toll of today’s global warming.

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The discovery was made by a team of scientists led by Professor Eske Willerslev and Professor Kurt H. Kjær. Professor Willerslev is a Fellow of St John’s College, University of Cambridge, and Director of the Lundbeck Foundation GeoGenetics Centre at the University of Copenhagen where Professor Kjær, a geology expert, is also based.

The results of the 41 usable samples found hidden in clay and quartz are published today (7 DECEMBER 2022) in Nature.

Professor Willerslev said: “A new chapter spanning one million extra years of history has finally been opened and for the first time we can look directly at the DNA of a past ecosystem that far back in time..

“DNA can degrade quickly but we’ve shown that under the right circumstances, we can now go back further in time than anyone could have dared imagine.”

Professor Kjær said: “The ancient DNA samples were found buried deep in sediment that had built-up over 20,000 years. The sediment was eventually preserved in ice or permafrost and, crucially, not disturbed by humans for two million years.”

The incomplete samples, a few millionths of a millimetre long, were taken from the København Formation, a sediment deposit almost 100 metres thick tucked in the mouth of a fjord in the Arctic Ocean in Greenland’s northernmost point. The climate in Greenland at the time varied between Arctic and temperate and was between 10-17C warmer than Greenland is today. The sediment built up metre by metre in a shallow bay.

Scientists discovered evidence of animals, plants and microorganisms including reindeer, hares, lemmings, birch and poplar trees. Researchers even found that Mastodon, an Ice Age mammal, roamed as far as Greenland before later becoming extinct. Previously it was thought the range of the elephant-like animals did not extend as far as Greenland from its known origins of North and Central America.

Detective work by 40 researchers from Denmark, the UK, France, Sweden, Norway, the USA and Germany, unlocked the secrets of the fragments of DNA. The process was painstaking – first they needed to establish whether there was DNA hidden in the clay and quartz, and if there was, could they successfully detach the DNA from the sediment to examine it? The answer, eventually, was yes. The researchers compared every single DNA fragment with extensive libraries of DNA collected from present-day animals, plants and microorganisms. A picture began to emerge of the DNA from trees, bushes, birds, animals and microorganisms.

Some of the DNA fragments were easy to classify as predecessors to present-day species, others could only be linked at genus level, and some originated from species impossible to place in the DNA libraries of animals, plants and microorganisms still living in the 21st century.

The two-million-year-old samples also help academics build a picture of a previously unknown stage in the evolution of the DNA of a range of species still in existence today.

Professor Kjær said: “Expeditions are expensive and many of the samples were taken back in 2006 when the team were in Greenland for another project, they have been stored ever since.

“It wasn’t until a new generation of DNA extraction and sequencing equipment was developed that we’ve been able to locate and identify extremely small and damaged fragments of DNA in the sediment samples. It meant we were finally able to map a two-million-year-old ecosystem.”

Assistant Professor Mikkel W. Pedersen, co-first author on the paper and also based at the Lundbeck Foundation GeoGenetics Centre, said: “The Kap København ecosystem, which has no present-day equivalent, existed at considerably higher temperatures than we have today – and because, on the face of it, the climate seems to have been similar to the climate we expect on our planet in the future due to global warming.

“One of the key factors here is to what degree species will be able to adapt to the change in conditions arising from a significant increase in temperature. The data suggests that more species can evolve and adapt to wildly varying temperatures than previously thought. But, crucially, these results show they need time to do this. The speed of today’s global warming means organisms and species do not have that time so the climate emergency remains a huge threat to biodiversity and the world – extinction is on the horizon for some species including plants and trees.”

While reviewing the ancient DNA from the Kap København Formation, the researchers also found DNA from a wide range of microorganisms, including bacteria and fungi, which they are continuing to map. A detailed description of how the interaction – between animals, plants and single-cell organisms – within the former ecosystem at Greenland’s northernmost point worked biologically will be presented in a future research paper.

It is now hoped that some of the ‘tricks’ of the two-million-year-old plant DNA discovered may be used to help make some endangered species more resistant to a warming climate.

Professor Kjær said: “It is possible that genetic engineering could mimic the strategy developed by plants and trees two million years ago to survive in a climate characterised by rising temperatures and prevent the extinction of some species, plants and trees. This is one of the reasons this scientific advance is so significant because it could reveal how to attempt to counteract the devastating impact of global warming.”

The findings from the Kap København Formation in Greenland have opened up a whole new period in DNA detection.

Professor Willerslev explained: “DNA generally survives best in cold, dry conditions such as those that prevailed during most of the period since the material was deposited at Kap København. Now that we have successfully extracted ancient DNA from clay and quartz, it may be possible that clay may have preserved ancient DNA in warm, humid environments in sites found in Africa.

“If we can begin to explore ancient DNA in clay grains from Africa, we may be able to gather ground-breaking information about the origin of many different species – perhaps even new knowledge about the first humans and their ancestors – the possibilities are endless.”

 

Astrobiology

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How you can watch Mars disappear behind the full moon tonight

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If you happen to have clear skies on Wednesday night, you’ll be able to catch a planet disappearing behind the moon.

The event occurs at a special time for Mars. On Wednesday night, Mars will be directly opposite the sun’s position in the sky, rising as the sun sets and setting as the sun rises. This is called an opposition and is when Mars is at its brightest in the night sky.

“Having the moon hide a bright planet is rare,” said Alan Dyer, an amateur astronomer and accomplished astrophotographer who will watch the event from his home near Strathmore, Alta.

“Having it do so on the very night a planet is at its brightest, as Mars now is, is very unusual. And with the objects so well-placed high in our sky. Fabulous!”

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When a planet or a star disappears behind another object, it’s called an occultation. The next time this happens between the moon and Mars will be in January 2025, although it will be two days before opposition.

When and where to look

Canada is in a prime location for the event.

Elaina Hyde, director of the Allan I. Carswell Observatory at York University’s department of physics and astronomy in Toronto, is also looking forward to Wednesday night’s occultation.

“Tonight, the occultation of Mars by our moon requires a ‘just right’ alignment,” she said. “In fact, not everyone on Earth will even be able to see this one.”

If you want to watch Mars blink out behind the moon, you just need clear skies. However, binoculars will provide a better view (though, be warned: a full moon is quite bright with binoculars or a telescope).

Because the occultation is between the moon, which is super bright, and Mars, which is at its brightest, they’re easy to find.

All you have to do is look east to find the moon. Mars will appear at the left or lower left, depending on your location.

People across North America in the shaded areas on the map will enjoy the the sight of the moon eclipsing Mars on Wednesday night. (Gregg Dinderman/Sky & Telescope)

You can gradually watch the event unfold right after sunset, when the pair will be farther apart. Over the next few hours, the pair will gradually appear to get closer and closer. The moon will seem to move to the left as they rise in the sky, eventually overtaking Mars.

How long Mars will stay eclipsed behind the moon depends on your location: it could be several minutes or about an hour. This is because it depends on how much of the moon’s disc Mars will need to traverse.

For example, in Toronto, Mars will only cross a small fraction of the moon’s lower disc, beginning at 10:29 p.m. ET and re-emerging roughly 45 minutes later. In Edmonton, it will take more than an hour for the entire event.

Here are the approximate times when Mars will disappear behind the moon. All times are local:

  • Vancouver: 6:55 p.m.
  • Edmonton: 8:04 p.m.
  • Calgary: 7:59 p.m.
  • Regina: 9:01 p.m.
  • Saskatoon: 9:03 p.m.
  • Winnipeg: 9:05 p.m.
  • Toronto: 10:29 p.m.
  • Ottawa: 10:36 p.m.
  • Montreal: 10:40 p.m.
  • Iqaluit: 9:50 p.m.
  • Whitehorse: 8:25 p.m.
  • Yellowknife: 8:23 p.m.

Thursday:

  • Halifax: 12:15 a.m.
  • Charlottetown: 12:07 a.m.
  • Moncton: 12:04 a.m.
  • St. John’s: 12:25 a.m.

You can find more locations here.

Remember, the event occurs all night, so you can take a peek outside once in a while leading up to the occultation and afterwards as it progresses.

You may also notice a bright red star not too far away from the moon and Mars, but to the right. That’s Aldebaran, the brightest star in the constellation Taurus.

This red giant lies near one of the most beautiful open star clusters in the northern sky, Hyades. In a few days’ time, once the moon moves away from that area of the sky, try using a pair of binoculars to check out the cluster.

Also, since you’re outside on Wednesday night, why not take a peak to the southwest where Jupiter will be quite apparent as the brightest object in the sky (aside from the moon). A pair of binoculars will also reveal four of its brightest moons, Io, Callisto, Ganymede and Europa.

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