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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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2.8-pound meteorite from space crashes roof of Canadian woman’s home, falls on bed – The Tribune India

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Tribune Web Desk

Chandigarh, October 16

Ruth Hamilton (66) had a disturbed awakening on October 3 when a large meteorite plunged from space, through her roof and landed in her bed.

Ruth, resident of Golden, British Columbia, woke up to the sound of a crash and her dog barking on October 3 around 11.35 pm.

Speaking with Canadian Press, she said: “I’ve never been so scared in my life, adding that, “I wasn’t sure what to do so I called 911 and, when I was speaking with the operator, I flipped over my pillow and saw that a rock had slipped between two pillows.”

She told CTV News: “I didn’t feel it.”

“It never touched me. I had debris on my face from the drywall, but not a single scratch.”

A police officer arrived on the scene, but suspected the object that landed in Hamilton’s bed was from a nearby construction site.

“He called the [construction site] and they said they hadn’t done a blast but that they had seen an explosion in the sky and, right then and there, we realised it was a meteorite,” she told the Canadian Press.

It turns out that the 2.8-pound space rock, about the size of a small cabbage, was part of a meteor shower identified by Alan Hildebrand, a planetary scientist in the Department of Geoscience at the University of Calgary, and his colleagues.

The group said the trajectory of the meteorite that hit Hamilton’s house would have made it visible throughout southeastern British Columbia and central and southern Alberta.

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NASA to launch first space probe to study Jupiter’s Trojan asteroids

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NASA is set on Saturday to launch a first-of-its kind mission, dubbed Lucy, to study Jupiter’s Trojan asteroids, two large clusters of space rocks that scientists believe are remnants of primordial material that formed the solar system’s outer planets.

The space probe, packed inside a special cargo capsule, is due for liftoff from Cape Canaveral Air Force Station in Florida at 5:34 a.m. EDT (0934 GMT), carried aloft by an Atlas V rocket from  United Launch Alliance (UAL), a joint venture of Boeing Co and Lockheed Martin Corp.

If all goes according to plan, Lucy will be hurled into space on a 12-year expedition to study a record number of asteroids. It will be the first to explore the Trojans, thousands of rocky objects orbiting the sun in two swarms – one ahead of the path of giant gas planet Jupiter and one behind it.

The largest known Trojan asteroids, named for the warriors of Greek mythology, are believed to measure as much as 225 kilometers (140 miles) in diameter.

Scientists hope Lucy’s close-up fly-by of seven Trojans will yield new clues to how the solar system’s planets came to be formed some 4.5 billion years ago and what shaped their present configuration.

Believed to be rich in carbon compounds, the asteroids may even provide new insights into the origin of organic materials and life on Earth, NASA said.

“The Trojan asteroids are leftovers from the early days of our solar system, effectively the fossils of planet formation,” principal mission investigator Harold Levison of the Southwest Research Institute in Boulder, Colorado, was quoted by NASA as saying.

No other single science mission has been designed to visit as many different objects independently orbiting the sun in the history of space exploration, NASA said.

As well as the Trojans, Lucy will do a fly-by of an asteroid in the solar system’s main asteroid belt, called DonaldJohanson in honor of the lead discoverer of the fossilized human ancestor known as Lucy, from which the NASA mission takes its name. The Lucy fossil, unearthed in Ethiopia in 1974, was in turn named for the Beatles hit “Lucy in the Sky with Diamonds.”

Lucy the asteroid probe will make spaceflight history in another way. Following a route that circles back to Earth three times for gravitational assists, it will be the first spacecraft ever to return to Earth’s vicinity from the outer solar system, according to NASA.

The probe will use rocket thrusters to maneuver in space and two rounded solar arrays, each the width of a school bus, to recharge batteries that will power the instruments contained in the much smaller central body of the spacecraft.

 

(Reporting by Steve Gorman in Los Angeles, Editing by Rosalba O’Brien)

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Darwin family microscope to be sold at auction

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A microscope Charles Darwin gave his son Leonard and which has remained in the family for nearly 200 years is headed for auction in December, and is expected to fetch up to $480,000.

The instrument was designed by Charles Gould for the firm Cary around 1825 and is one of six surviving microscopes associated with the British naturalist, according to auction house Christie’s.

The date of its manufacture coincides with the time when Darwin was studying zoophytes, organisms such as coral and sea anemone.

“It is just incredibly spine tingling to look through this and see the microscopic world that Darwin would have seen in the 1820s and 30s,” James Hyslop, Head of Department, Scientific Instruments, Globes & Natural History, at Christie’s, told Reuters.

“Later in his life in 1858, there’s a wonderful letter that he writes to his eldest son saying young Lenny was dissecting at his microscope and he said ‘Oh Papa, I should be so glad of this for my whole life’. It’s wonderful to have that family connexion of Charles Darwin just before he becomes internationally famous.”

Darwin published his groundbreaking work “On the Origin of Species” in 1859.

The microscope will be offered at Christie’s Valuable Books & Manuscripts auction on Dec. 15, and has a price estimate of 250,000 – 350,000 pounds ($343,050 – $480,270).

“Charles Darwin is one of the biggest names in the Science, and collectors for Darwiniana (relating to Darwin) are truly international in breadth,” Hyslop said.

($1 = 0.7288 pounds)

 

(Reporting by Marissa Davison; Writing by Marie-Louise Gumuchian; Editing by Mike Collett-White)

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