Giant space telescopes could be made out of liquid

Hexbyte Glen Cove

Optical lens for the Large Synoptic Survey Telescope (LSST). Credit: Farrin Abbott/SLAC National Accelerator Laboratory

The Hubble space telescope has a primary mirror of 2.4 meters. The Nancy Grace Roman telescope also has a mirror measuring 2.4 meters, and the James Webb Space Telescope has a whopping 6.5 meter primary mirror. They get the job done that they were designed to do, but what if… we could have even bigger mirrors?

The larger the mirror, the more light is collected. This means that we can see farther back in time with bigger mirrors to observe star and galaxy formation, image exoplanets directly, and work out just what dark matter is.

But the process for creating a mirror is involved and takes time. There is casting the mirror blank to get the basic shape. Then you have to toughen the glass by heating and slow cooling. Grinding the glass down and polishing it into its perfect shape comes next followed by testing and coating the . This isn’t so bad for smaller lenses, but we want bigger. Much bigger.

Enter the idea for using fluids to create lenses in space that are 10x–100x bigger. And the time it would take to make them would be significantly less than a glass-based lens.

FLUTE, or the Fluidic Telescope Experiment is run by principal investigator Edward Balaban at Ames Research Center in California’s Silicon Valley. Collaborators on the experiment include researchers at Ames at the Goddard Space Flight Center in Greenbelt, Maryland, along with researchers from Technion, the Israeli Institute of Technology.

Their goal is to make possible the fabrication of fluid lenses in space that are not only bigger than their glass counterparts, but also just as high quality or better optically as making an earth-based lens. And this can be done in a fraction of the time.

In space, liquids eventually form a perfect spherical shape. In order to test the process first though, they stayed closer to home and used water as a medium to create fluid lenses. They had to make sure the water had the same density as the liquid polymers they were using to make the lenses so that the effects of gravity were effectively canceled out. Leaving out any mechanical processes, the polymers were injected into circular frames submerged in water and then solidified, creating comparable or better lenses than using standard techniques.

Next the team boarded two ZeroG parabolic flights to further test the process. Synthetic oils of varying viscosities were tested to determine which would work better. These oils were pumped into circular frames about the size of a dollar coin while the plane was in freefall, and again the researchers were able to make free-standing liquid lenses, though once the plane started lifting up again and the effects of gravity were felt the liquids lost their shape.

This experiment will be performed on the ISS (International Space Station) next and is already onboard, waiting for the arrival of Axiom-1 with Mission Specialist Eytan Stibbe slated to perform the experiment. There they will add the step of using either UV light or temperature to harden the liquid so that the lenses can be examined and tested by the researchers back at Ames on Earth.

A successful experiment will be the first time an optical component is made in space. If it succeeds, this will be the start of a new way to build telescopes, out in space. This would be a revolution in space-based manufacturing and the time needed to build one will be greatly reduced. And oh the sights we will see.

Giant space telescopes could be made out of liquid (2022, April 11)

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Hexbyte Glen Cove Unexpected hope for millions as bleached coral reefs continue to supply nutritious seafood

Hexbyte Glen Cove

A reef dominated by macroalgae. Credit: Professor Nick Graham, Lancaster University

Researchers studying coral reefs damaged by rising sea temperatures have discovered an unexpected ‘bright spot’ of hope for communities who depend upon them for food security.

Coral reef ecosystems support diverse small-scale fisheries—and the fish they catch are rich in micronutrients vital to the health of millions of people in the tropics, a new Lancaster University-led study reveals.

And, counter-intuitively, following bleaching events that kill off coral and can transform the composition of reef ecosystems, reef fisheries can remain rich sources of micronutrients, even increasing in nutritional value for some minerals.

The findings, published today in the journal One Earth, show that the availability of micronutrients from coral reef small-scale fisheries may be more resilient to climate change than previously thought. This increased understanding is critical as continued global warming means coral bleaching events are becoming more frequent and more severe, placing greater stress on these vulnerable ecosystems.

Dr. James Robinson, who led the study, said: “Our findings underline the continuing importance of these fisheries for vulnerable coastal communities, and the need to protect against over-fishing to ensure long-term sustainability of reef fisheries.”

Rabbit fish, Victoria Market, Seychelles. Credit: Dr James Robinson

The researchers also caution that while these fisheries have proved more resilient to climate change disturbance than expected, continued understanding of the long-term impacts of climate change to coral reef fisheries, and more data from other regions, are urgent priorities.

More than six million people work in small-scale fisheries that rely on tropical coral reefs. Their catches help to feed hundreds of millions of coastal people in regions with high prevalence of malnourishment, causing stunting, wasting and anemia. However, until now, the nutritional composition of coral reef fish catches, and how climate change might affect the nutrients available from reef fisheries, was not known.

This study, led by scientists from Lancaster University and involving an international team of researchers from the Seychelles, Australia, Canada and Mozambique, benefitted from more than 20 years of long-term monitoring data from the Seychelles, where tropical reefs were damaged by a large coral bleaching event in 1998, killing an estimated 90% of the corals.

Following the mass-bleaching event, around 60% of the recovered to a coral-dominated system, but around 40% were transformed to reefs dominated by seaweeds. These differences provided a natural experiment for the scientists to compare the micronutrients available from fisheries on reefs with different climate-driven ecosystem compositions.

A recovering coral reef, Seychelles. Credit: Professor Nick Graham

The scientists, who used a combination of experimental fishing, nutrient analysis, and visual surveys of fish communities in the Seychelles, calculated that reef fish are important sources of selenium and zinc, and contain levels of calcium, iron and omega-3 fatty acids comparable to other animal-based foods, such as chicken and pork.

They also found that iron and zinc are more concentrated in fish caught on reefs that have been transformed after coral bleaching and are now dominated by macroalgae such as Sargassum seaweeds. These seaweeds have high levels of minerals, which, researchers believe, is a key reason why the algal-feeding herbivorous fishes found in greater numbers on transformed reefs contain higher levels of iron and zinc.

Dr. Robinson said: “Coral reef fish contain high levels of essential dietary nutrients such as iron and zinc, so contribute to healthy diets in places with high fish consumption. We found that some micronutrient-rich reef species become more abundant after coral bleaching, enabling fisheries to supply nutritious food despite climate change impacts. Protecting catches from these local food systems should be a priority.”

The researchers believe the results underline the need for effective local management to protect the sustainability of reef fisheries, as well as policies that retain more of reef fish catches for local people and promote traditional fish-based diets. These can help reef fisheries to best contribute to healthy diets across the tropics.

Parrotfish, Seychelles. Credit: Dr James Robinson

Professor Christina Hicks, a co-author on the study, said: “Fish are now recognized as critical to alleviating malnutrition, particularly in the tropics where diets can lack up to 50% of the micronutrients needed for healthy growth. This work is promising because it suggests fisheries will continue to play a crucial role, even in the face of climate change, and highlights the vital importance of investing in sustainable fisheries management.”

The findings are outlined in the paper “Climate-induced increases in micronutrient availability for coral .”

The study’s authors include: James Robinson, Eva Maire, Nick Graham and Christina Hicks from Lancaster University; Nathalie Bodin from Seychelles Fishing Authority and Sustainable Ocean Seychelles; Tessa Hempson from James Cook University and Oceans Without Borders; Shaun Wilson from the Department of Biodiversity, Conservation and Attractions in Australia, and Oceans Institute, Australia; and Aaron MacNeil from Dalhousie University.

More information:
James P.W. Robinson, Climate-induced increases in micronutrient availability for coral reef fisheries, One Earth (2022). DOI: 10.1016/j.oneear.2021.12.005. … 2590-3322(21)00723-5

Unexpected hope for millions as bleached coral reefs continue to supply nutritious seafood (2022, January 6)
retrieved 6 January 2022

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