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Advanced Optics Could Help Us Find Earth 2.0
NASA has long been interested in building bigger and better space telescopes. Its Institute for Advanced Concepts (NIAC) has funded several methods for building and deploying novel types of telescopes for various purposes. Back in 2019, one of the projects they funded was the Dual Use Exoplanet Telescope (DUET), which would use an advanced form of optics to track down a potential Earth 2.0.
So far, the largest telescope launched into space is JWST, with a 6.5m primary mirror. However, even with that big of a mirror, it is difficult to differentiate exoplanets from their stars, which may be only a few milliarcseconds away from each other. Larger telescopes on the ground have slightly higher resolutions, but they suffer from other limitations, such as atmospheric distortion and cloud cover.
A larger telescope in space would solve many of those problems, but launching one that is simply a larger version of JWST is prohibitively expensive or just plain prohibited, depending on whether it would fit in a rocket fairing. Even Starship and other next-generation launch systems couldn’t fit a 10 m assembled primary mirror.
PI Tom Ditto gives a talk at the SETI Institute about the DUET telescope.Credit – SETI Institute YouTube Channel
So, researchers have started to turn to alternative optical techniques that could solve this problem. One commonly known optical phenomenon is diffraction. The best-known example is the famous “slit” experiment that many kids perform in physics class. Light bends when going around an edge, and engineers can take that principle, scale it up, and build something that bends the light from far-away stars.
That is the underlying principle of DUET – it uses a technique called primary objective grating (POG) to focus specific wavelengths that might be of interest – for example, that wavelength that would show oxygen in an exoplanet’s atmosphere. In particular, DUET uses a type of POG that results in a circular spectrogram. Although this idea is novel in astronomy, it has been used in other fields. Tom Ditto, the PI on the project, was originally an artist before converting into a technologist focusing on optics.
With the NIAC Phase I funding, Ditto and his team developed a bench-top experiment that proved the technology underlying DUET. It consists of a slatted first data collection stage that focuses the light from a star of interest on a secondary stage and, thereby, a collector, which captures the data that could be translated into a circular spectrograph.
Graphic of deployment of the slits in the outer primary of the DUET telescope.Credit – Ditto et al.
In particular, the researchers were interested in UV light, as Earth would appear like a bright candle from far away, at least compared to light in other spectra. They tested a violet laser on their bench setup and analyzed the resulting circular spectrograph. It showed great promise for detecting something with a spectrum like Earth’s from very far away.
But there are still hurdles to overcome. One of the bigger concerns was the efficiency of the grating structure used in the experiments. Its 20% efficiency would make it barely feasible to detect the kind of faint objects the telescope is designed for. The deployment mechanism for the grating, which requires the assistance of additional spacecraft separate from the telescope itself, would also be a challenge.
How would we build large telescopes in space? Fraser explains.That’s where the experiment stands, as NASA has not elected to support the project with a Phase II grant so far. Given the history of exoplanet discovery, it’s only a matter of time before we find Earth 2.0. What technology we will use to do so is up in the air.
Learn more:
Ditto et al. – DUET The Dual Use Exoplanet Telescope
UT – Building Space Telescopes… In Space
UT – Future Space Telescopes Could be 100 Meters Across, Constructed in Space, and Then Bent Into a Precise Shape
UT – Using Smart Materials To Deploy A Dark Age Explorer
Lead Image:
Graphic of the DUET Space Telescope Fully Deployed.
Credit – Ditto et al.
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Satellites are Going to Track Garbage Drifting Across the Oceans
We are all too aware of the pollution on planet Earth. There are increased amounts of plastic and garbage on the world’s beaches and debris littering the oceans. Until now, it was thought that satellites weren’t capable of tracking marine debris but a supercomputer algorithm challenges that. 300,000 images were taken every three days at a resolution of 10 metres and were able to identify large concentrations of debris.
Upper estimates of plastic in our oceans peak at around 200 million tons! Every day it is believed another 8 million pieces of plastic make their way into the marine environment. Now, a study led by a team at the Institut de Ciencies del Mar at the University of Cadiz believe it may be possible to study and track the surface debris in the oceans. Using supercomputers and advanced algorithms, the team have shown that satellites can indeed be used.
Using data from the European Copernicus Sentinel-2 satellite, a total of 300,000 images of the Mediterranean Sea were analysed. The images were taken every 3 days at a resolution of 10 metres. Typically of course, there is not much debris in the sea which is that big but accumulations of debris have grown to that size. The aggregations are known as ‘windrows’ and have built up as ocean currents and winds bring debris together to form large structures.
The output from the study reveals the most polluted areas of the Mediterranean and the main entry points from the mainland. It will help us to improve our understanding of the processes and mechanisms that transport debris across the ocean and even help us to perhaps predict movement. The results also show that the amount of debris in the Mediterranean covers around 95 square kilometres.
Eastern Mediterranean Sea Area June 1993Unfortunately the research does not help resolve the issue of pollution but it does help us understand the scale. The team propose future satellites should be equipped with detectors to monitor the debris. It would increase the ability to detect plastic in the open ocean by a factor of 20 and help to model the impact of marine pollution on first, tourism and the marine ecosystem.
One element of the studies conclusion is that population density, geography and rainfall patterns play an important part in the accumulation of marine litter. Dry arid lands like deserts that play host to cities seem to contribute much less to marine litter while those that are much more temperate with higher rainfall seem to contribute more.
It is also interesting to note that the majority of litter that originates from land masses seems to be confined to 15 kilometres form the coast and subsequently returns after a few days of months. The team conclude that satellite based monitoring is an essential element in our battle against litter in the ocean. The technology can also be used for the detection of other floating objects such as the loss of ships, oil spills and even search and rescue elements.
Source : Satellites to monitor marine debris from space
The post Satellites are Going to Track Garbage Drifting Across the Oceans appeared first on Universe Today.
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An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to discover gravitationally bound star clusters when the Universe was 460 million years old. This is the first discovery of star clusters in an infant galaxy less than 500 million years after the Big Bang.
