Plastic Waste on our Beaches Now Visible from Space, Says New Study

According to the United Nations, the world produces about 430 million metric tons (267 U.S. tons) of plastic annually, two-thirds of which are only used for a short time and quickly become garbage. What’s more, plastics are the most harmful and persistent fraction of marine litter, accounting for at least 85% of total marine waste. This problem is easily recognizable due to the Great Pacific Garbage Patch and the amount of plastic waste that washes up on beaches and shores every year. Unless measures are taken to address this problem, the annual flow of plastic into the ocean could triple by 2040.

One way to address this problem is to improve the global tracking of plastic waste using Earth observation satellites. In a recent study, a team of Australian researchers developed a new method for spotting plastic rubbish on our beaches, which they successfully field-tested on a remote stretch of coastline. This satellite imagery tool distinguishes between sand, water, and plastics based on how they reflect light differently. It can detect plastics on shorelines from an altitude of more than 600 km (~375 mi) – higher than the International Space Station‘s (ISS) orbit.

The paper that describes their tool, “Beached Plastic Debris Index; a modern index for detecting plastics on beaches,” was recently published by the Marine Pollution Bulletin. The research team was led by Jenna Guffogg, a researcher at the Royal Melbourne Institute of Technology University (RMIT) and the Faculty of Geo-Information Science and Earth Observation (ITC) at the University of Twente. She was joined by multiple colleagues from both institutions. The study was part of Dr. Guffogg’s joint PhD research with the support of an Australian Government Research Training Program (RTP) scholarship.

Dr Jenna Guffogg said plastic on beaches can have severe impacts on wildlife and their habitats, just as it does in open waters. Credit: BPDI

According to current estimates, humans dump well over 10 million metric tons (11 million U.S. tons) of plastic waste into our oceans annually. Since plastic production continues to increase worldwide, these numbers are projected to increase dramatically. What ends up on our beaches can severely impact wildlife and marine habitats, just like the impact it has in open waters. If these plastics are not removed, they will inevitably fragment into micro and nano plastics, another major environmental hazard. Said Dr. Guffogg in a recent RMIT University press release:

“Plastics can be mistaken for food; larger animals become entangled, and smaller ones, like hermit crabs, become trapped inside items such as plastic containers. Remote island beaches have some of the highest recorded densities of plastics in the world, and we’re also seeing increasing volumes of plastics and derelict fishing gear on the remote shorelines of northern Australia.

“While the impacts of these ocean plastics on the environment, fishing and, tourism are well documented, methods for measuring the exact scale of the issue or targeting clean-up operations, sometimes most needed in remote locations, have been held back by technological limitations.”

Satellite technology is already used to track plastic garbage floating around the world’s oceans. This includes relatively small drifts containing thousands of plastic bottles, bags, and fishing nets, but also gigantic floating trash islands like the Great Pacific Garbage Patch. As of 2018, this garbage patch measured about 1.6 million km² (620,000 mi²) and consisted of 45,000–129,000 metric tons (50,000–142,000 U.S. tons). However, the technology used to locate plastic waste in the ocean is largely ineffective at spotting plastic on beaches.

Geospatial scientists have found a way to detect plastic waste on remote beaches, bringing us closer to global monitoring options. Credit: RMIT

Much of the problem is that plastic can be mistaken for patches of sand when viewed from space. The Beached Plastic Debris Index (BPDI) developed by Dr. Guffogg and her colleagues circumvents this by employing a spectral index – a mathematical formula that analyzes patterns of reflected light. The BPDI is specially designed to map plastic debris in coastal areas using high-definition data from the WorldView-3 satellite, a commercial Earth observation satellite (owned by Maxar Technologies) that has been in operation since 2014.

Thanks to their efforts, scientists now have an effective way to monitor plastic on beaches, which could assist in clean-up operations. As part of the remote sensing team at RMIT, Dr. Guffogg and her colleagues have developed similar tools for monitoring forests and mapping bushfires from space. To validate the BPDI, the team field-tested it by placing 14 plastic targets on a beach in southern Gippsland, about 200 km (125 mi) southeast of Melbourne. Each target was made of a different type of plastic and measured two square meters (21.5 square feet) – smaller than the satellite’s pixel size of about three square meters.

The resulting images were compared to three other indices, two designed for detecting plastics on land and one for detecting plastics in aquatic settings. The BPDI outperformed all three as the others struggled to differentiate between plastics and sand or misclassified shadows and water as plastic. As study author Dr. Mariela Soto-Berelov explained, this makes the BPDI far more useful for environments where water and plastic-contaminated pixels are likely to coexist.  

“This is incredibly exciting, as up to now we have not had a tool for detecting plastics in coastal environments from space. The beauty of satellite imagery is that it can capture large and remote areas at regular intervals. Detection is a key step needed for understanding where plastic debris is accumulating and planning clean-up operations, which aligns with several Sustainable Development Goals, such as Protecting Seas and Oceans.”  

The next step is to test the BPDI tool in real-life scenarios, which will consist of the team partnering with various organizations dedicated to monitoring and addressing the plastic waste problem.

Further Reading: RMIT, Marine Pollution Bulletin

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Future Space Telescopes Could be Made From Thin Membranes, Unrolled in Space to Enormous Size

Space-based telescopes are remarkable. Their view isn’t obscured by the weather in our atmosphere, and so they can capture incredibly detailed images of the heavens. Unfortunately, they are quite limited in mirror size. As amazing as the James Webb Space Telescope is, its primary mirror is only 6.5 meters in diameter. Even then, the mirror had to have foldable components to fit into the launch rocket. In contrast, the Extremely Large Telescope currently under construction in northern Chile will have a mirror more than 39 meters across. If only we could launch such a large mirror into space! A new study looks at how that might be done.

As the study points out, when it comes to telescope mirrors, all you really need is a reflective surface. It doesn’t need to be coated onto a thick piece of glass, nor does it need a big, rigid support structure. All that is just needed to hold the shape of the mirror against its own weight. As far as starlight is concerned, the shiny surface is all that matters. So why not just use a thin sheet of reflective material? You could just roll it up and put it in your launch vehicle. We could, for example, easily launch a 40-meter roll of aluminum foil into space.

Of course, things aren’t quite that simple. You would still need to unroll your membrane telescope back into its proper shape. You would also need a detector to focus the image upon, and you’d need a way to keep that detector in the correct alignment with the broadsheet mirror. In principle, you could do that with a thin support structure, which wouldn’t add an excessive bulk to your telescope. But even if we assume all of those engineering problems could be solved, you’d still have a problem. Even in the vacuum of space, the shape of such a thin mirror would deform over time. Solving this problem is the main focus of this new paper.

Once launched into space and unfurled, the membrane mirror wouldn’t deform significantly. But to capture sharp images, the mirror would have to maintain focus on the order of visible light. When the Hubble was launched, its mirror shape was off by less than the thickness of a human hair, and it took correcting lenses and an entire shuttle mission to fix. Any shifts on that scale would render our membrane telescope useless. So the authors look to a well-used trick of astronomers known as adaptive optics.

How radiative adaptive optics might work. Credit: Rabien, et al

Adaptive optics is used on large ground-based telescopes as a way to correct for atmospheric distortion. Actuators behind the mirror distort the mirror’s shape in real time to counteract the twinkles of the atmosphere. Essentially, it makes the shape of the mirror imperfect to account for our imperfect view of the sky. A similar trick could be used for a membrane telescope, but if we had to launch a complex actuator system for the mirror, we might as well go back to launching rigid telescopes. But what if we simply use laser projection instead?

By shining a laser projection onto the mirror, we could alter its shape through radiative recoil. Since it is simply a thin membrane, the shape would be significant enough to create optical corrections, and it could be modified in real time to maintain the mirror’s focus. The authors call this technique radiative adaptive optics, and through a series of lab experiments have demonstrated that it could work.

Doing this in deep space is much more complicated than doing it in the lab, but the work shows the approach is worth exploring. Perhaps in the coming decades we might build an entire array of such telescopes, which would allow us to see details in the distant heavens we can now only imagine.

Reference: Rabien, S., et al. “Membrane space telescope: active surface control with radiative adaptive optics.” Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave. Vol. 13092. SPIE, 2024.

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Voyager 1 is Forced to Rely on its Low Power Radio

Voyager 1 was launched waaaaaay back in 1977. I would have been 4 years old then! It’s an incredible achievement that technology that was built THAT long ago is still working. Yet here we are in 2024, Voyager 1 and 2 are getting older. Earlier this week, NASA had to turn off one of the radio transmitters on Voyager 1. This forced communication to rely upon the low-power radio. Alas technology around 50 years old does sometimes glitch and this was the result of a command to turn on a heater. The result was that Voyager 1 tripped into fault protection mode and switch communications! Oops. 

Voyager 1 is a NASA space probe launched on September 5, 1977, as part of the Voyager program to study the outer planets and beyond. Initially, Voyager 1’s mission focused on flybys of Jupiter and Saturn, capturing incredible images before traveling outward. In 2012, it became the first human-made object to enter interstellar space, crossing the heliopause—the boundary between the influence of the Sun and interstellar space. It now continues to  to send data back to Earth from over 22 billion km  away, helping scientists learn about the interstellar medium. There is also a “Golden Record” onboard which contains sounds and images of life on Earth, Voyager 1 serves as a time capsule, intended to articulate the story of our world to any alien civilizations that may encounter it.

The Ringed Planet Saturn

Just a few days ago on 24 October, NASA had to reconnect to Voyager 1 on its outward journey because one of its radio transmitters had been turned off! Alien intervention perhaps! Exciting though that would be, alas not. 

The transmitter seems to have been turned off as a result of one of the spacecraft fault protection systems. Any time there is an issue with onboard systems the computer will flip the systems into protection mode to protect any further damage. If the spacecraft draws too much power from the batteries, the same system will turn off less critical systems to conserve power. When the fault protection system kicks in, it’s then the job of engineers on the ground fixing the fault.

Artist rendition of Voyager 1 entering interstellar space. (Credit: NASA/JPL-Caltech)

There are challenges here though. Due to the immense distance to Voyager 1, now about 24 billion km away, any communications to or from takes almost 23 hours to arrive. A request for data for example means a delay of 46 hours before the request arrives and the data returned! Undaunted, the team sent commands to Voyager 1 on the 16 October to turn on a heater but, whilst the probe should have had enough power, the command triggered the system to turn off a radio transmitter to conserve power. This was discovered on 18 October when the Deep Space Network was no longer able to detect the usual ping from the spacecraft. 

The engineers correctly identified the likely cause of the problem and found Voyager pinging away on a different frequency using the alternate radio transmitte. This one hadn’t been used since the early 19080’s! With the fault identified, the team did not switch immediately back to the original transmitter just yet in case the fault triggered again. Instead,they are now working to understand the fault before switching back. 

Until then, Voyager 1 will continue to communicate with Earth using the lower power transmitter as it continues its exploration out into interstellar space. 

Source : After Pause, NASA’s Voyager 1 Communicating With Mission Team

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China Trains Next Batch of Taikonauts

China has a fabulously rich history when it comes to space travel and was among the first to experiment in rocket technology. The invention of the rocket is often attributed to the Sung Dynasty (AD 960-1279.) Since then, China has been keen to develop and build its own space industry. The Chinese National Space Administration has already successfully landed probes on the Moon but is preparing for their first human landers. Chinese astronauts are sometimes known as taikonauts and CNSA has just confirmed their fourth batch of taikonauts are set for a lunar landing. 

The Chinese National Space Administration (CNSA) is China’s equivalent to NASA. It was founded in 1993 to oversee the country’s space aspirations. Amazing results have been achieved over the last twenty years including the landmark Chang’e lunar missions. In 2019 Chang’e-4 landed on the far side of the Moon, the first lunar lander to do so and in 2021 became the third country to land a rover on Mars. In 2021 the first modules for CNSA’s Tiangong space station were launched, it’s now operational and working with other space agencies, is working on a number of scientific research projects. 

China has announced that it successfully completed its latest selection process in May. The CNSA are striving to expand their team of taikonauts. Ten were chosen from all the applicants including 8 experienced space pilots and two payload specialists. The team will now begin their program of training in August covering over 200 subject areas designed to prepare them for future missions to the Moon and other Chinese space initiatives. 

The training covers an extensive range of skills It will include training for living and working in microgravity, to learn about physical and mental health in space and specialist training in extravehicular activities. They will also learn maintenance techniques for advanced spacecraft systems and in hands-on training for undertaking experiments in microgravity. 

On her 2007 mission aboard the International Space Station, NASA astronaut Peggy Whitson, Expedition 16 commander, worked on the Capillary Flow Experiment (CFE), which observes the flow of fluid, in particular capillary phenomena, in microgravity. Credits: NASA

The program is designed to expand and fine tune the skills of the taikonauts in preparation for future crewed lunar missions. Specialist training for lunar landings include piloting spacecraft under different gravitational conditions, manoeuvring lunar rovers, training in celestial navigation and stellar identification. 

Not only will they learn about space operations but they will have to learn skills to support scientific objectives too. This will include how to conduct geological surveys and how to operate tools and manoeuvre in the micro-gravitational environments. 

Source : China’s fourth batch of taikonauts set for lunar landings

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NASA Focusses in on Artemis III Landing Sites.

It was 1969 that humans first set foot on the Moon. Back then, the Apollo mission was the focus of the attempts to land on the Moon but now, over 50 years on, it looks like we are set to head back. The Artemis project is the program that hopes to take us back to the Moon again and it’s going from strength to strength. The plan is to get humans back on the Moon by 2025 as part of Artemis III. As a prelude to this, NASA is now turning its attention to the possible landing sites. 

The Artemis Project is NASA’s program aimed at returning humans to the Moon and establishing a permanent base there. Ultimately with a view to paving the way for missions to Mars. With the first launch in 2017, Artemis intends to land “the first woman and the next man” on the lunar surface by 2025.  The program began with Artemis I and an uncrewed mission which orbited the Moon. Arte is II will take astronauts on an orbit of the Moon and finally Artemis III will land humans back on the Moon by 2025. At the heart of the program is the giant Space Launch System (SLS) rocket and the Orion spacecraft. 

NASA’s Space Launch System rocket carrying the Orion spacecraft launches on the Artemis I flight test, Wednesday, Nov. 16, 2022, from Launch Complex 39B at NASA’s Kennedy Space Center in Florida. Credit: NASA/Joel Kowsky.

As the plans ramp up for the first crewed landing, NASA are now analysing possible landing sites and have identified nine potential spots. They are all near the South Pole of the Moon and will provide Artemis III with landing sites near to potentially useful resources. Further investigations will be required to further assess them for their suitability. 

The team working upon the analysis is the Cross Agency Site Selection Analysis team and they will work with other science and industry partners. The teams will explore each possible site for science value and suitability for the mission including the availability of water ice. The final list so far, and in no particular order, are;

• Peak near Cabeus B
• Haworth
• Malapert Massif
• Mons Mouton Plateau
• Mons Mouton
• Nobile Rim 1
• Nobile Rim 2
• de Gerlache Rim 2
• Slater Plain

The South Polar region was chosen as a region was chosen chiefly because it has water locked up deep in the shadowed craters. The Apollo missions never visited that region of the Moon either so it is a great opportunity for humans to explore this aged region of the lunar surface. To settle on these 9 areas, the team assessed various regions of the south polar region using potential launch window suitability, terrain suitability, communication capability and even lighting levels. The geology team also looked at the landing sites to assess their scientific value 

Apollo 17 astronaut Harrison Schmitt collecting a soil sample, his spacesuit coated with dust. Credit: NASA

NASA will finally settle on the appropriate landing site based upon the decision for the launch date. Once that has been confirmed it will determine the transfer trajectories to the Moon, the orbital paths and the surface environment. 

Source : NASA Provides Update on Artemis III Moon Landing Regions

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The Connection Between Black Holes and Dark Energy is Getting Stronger

The discovery of the accelerated expansion of the Universe has often been attributed to the force known as dark energy. An intriguing new theory was put forward last year to explain this mysterious force; black holes could be the cause of dark energy! The theory goes on to suggest as more black holes form in the Universe, the stronger the pressure from dark energy. A survey from the Dark Energy Spectroscopic Instrument (DESI) seems to support the theory. The data from the first year of operation shows the density of dark energy increases over time and seems to correlate with the number and mass of black holes! 

Cast your mind back 4 billion years to the beginning of the Universe. Just after the Big Bang, the moment when the Universe popped into existence, there was a brief period when the Universe expanded faster than the speed of light. Before you argue that nothing can travel faster than the speed of light we are talking of the very fabric of space and time expanding faster than the speed of light. The speed of light limit relates to travel through the fabric of space, not the fabric of space itself! This was the inflationary period. 

This illustration shows the “arrow of time” from the Big Bang to the present cosmological epoch. Credit: NASA

The energy that drove the expansion in the early Universe shared similarities with dark energy, the repulsive force that seems to permeate the Universe and is driving the current day accelerated expansion of the Universe.

What is dark energy though? It is thought to make up around 68% of the Universe and, unlike normal matter and energy seems to have a repulsive force rather than attractive. The repulsive nature was first inferred from observations in the late 1990’s when astronomers deduced the rate of acceleration when observing distant supernova. As to the nature of dark energy, no-one really knows what it is or what it comes from, that is, until now. 

Artist’s illustration of a bright and powerful supernova explosion. (Credit: NASA/CXC/M.Weiss)

A team of researchers from the University of Michigan and other institutions have published a paper in the Journal of Cosmology and Astroparticle Physics. In their paper they propose that black holes are the source of dark energy. Professor Gregory Tarle said ‘Where in the later Universe do we see gravity as strong as it was at the beginning of the Universe?’ The answer, Tarle goes on to describe is the centre of black holes. Tarle and team propose that what happened during the inflation period runs in reverse during the collapse of a massive star. When this happens, the matter could conceivably become dark energy. 

The team have used data from the Dark Energy Spectroscopic Instrument (DESI) which is mounted upon the 4m Mayall telescope at Kitt Peak National Observatory. The instrument is essentially 5,000 computer controlled fibre optics which cover an area of the sky equal to about 8 square degrees. The evidence of dark energy is achieved by studying tens of millions of galaxies. The galaxies are so far way their light takes billions of years to reach us. We can use the information to determine how fast the Universe is expanding with unprecedented precision. 

Stu Harris works on assembling the focal plane for the Dark Energy Spectroscopic Instrument (DESI), which involves hundreds of thousands of parts, at Lawrence Berkeley National Laboratory on Wednesday, 6 December, 2017 in Berkeley, Calif.

The data shows evidence that dark energy has increased with time. This is not perhaps in itself surprising but it seems to accurately mirror the increase in black holes over time too. Now that DESI is operational, more observations are required to hunt down the black holes and try to quantify their growth over time to see if there really is merit in this new exciting hypothesis. 

Source : Evidence mounts for dark energy from black holes

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Will Advanced Civilizations Build Habitable Planets or Dyson Spheres

If there are alien civilizations in the Universe, some of them could be super advanced. So advanced that they can rip apart planets and create vast shells surrounding a star to capture all its energy. These Dyson spheres should be detectable by modern telescopes. Occasionally astronomers find an object that resembles such an alien megastructure, but so far, they’ve all turned out to be natural objects. As best we can tell, there are no Dyson spheres out there.

And when you think about it, building a Dyson sphere is the cosmic endgame of a capitalist dystopia. In the never-ending quest to capture and consume every last bit of energy, your civilization rips worlds asunder, moving heaven and earth to create an orbitally unstable, unlivable engine. If you can traverse light-years and transform planets, why not just move Earth-like planets and moons into a star’s habitable zone and have a nice cluster of comfy planets to live on? If this kind of stellar-punk civilization is out there, could astronomers detect it? This is the question behind a study on the arXiv.

The authors begin by noting that when Freeman Dyson proposed the idea in 1960, our solar system was the only known planetary system. Star systems were thought to be rare at the time, but now we know better. Most stars have planets, and even our solar system has a dozen water-rich moons that could be made habitable with a shift of their orbits and a bit of terraforming. Since this would be much easier than building a Dyson sphere, the authors argue that modified systems should be much more common. The only question is how to detect them.

One way would be to look for planetary systems that don’t seem to have formed naturally. For example, if you find a system with a dozen worlds in a star’s habitable zone and few other planets, that isn’t likely to have happened by chance. Less obvious would be to look for systems that are orbitally unusual. Perhaps the planets have orbital resonances that aren’t stable in the long term, or have unusually perfect orbits. Maybe the chemical composition of some worlds don’t match that of the system as a whole. Anything that stands out might be worth a closer look.

Using lasers to change a planet’s orbit. Credit: Narasimha, et al

Another way would be to look for signs of systems under construction. The authors note that planets could be moved or captured slowly over time using high-power directional lasers to accelerate them. Stray light from those lasers would be visible across light years. If we detect monochromatic laser light coming from a potentially habitable star, it could be aliens building a better home.

It’s not likely that we’ll find this kind of evidence, but the idea is no stranger than those of giant alien megastructures. Besides, it’s fun to think about just how many habitable planets you could pack into a single star system. It turns out to be quite a lot!

Reference: Narasimha, Raghav, Margarita Safonova, and C. Sivaram. “Making Habitable Worlds: Planets Versus Megastructures.” arXiv preprint arXiv:2309.06562 (2023).

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