How Commercial Satellites Could Track Spy Balloons and Other UFOs

It turns out that you don’t need the Men in Black to spot unidentified anomalous phenomena, which are also known as UAPs, unidentified flying objects or UFOs. Researchers have shown how the task of detecting aerial objects in motion could be done by analyzing Earth imagery from commercial satellites.

They say they demonstrated the technique using one of the most notorious UAP incidents of recent times: last year’s flight of a Chinese spy balloon over the U.S., which ended in a shootdown by an Air Force fighter jet above the Atlantic Ocean. They also analyzed imagery of a different spy balloon that passed over Colombia at about the same time.

“Our proposed method appears to be successful and allows the measurement of the apparent velocity of moving objects,” the researchers report.

In a 2023 video, CBS News recaps lessons learned from the Chinese spy balloon’s flight:

The demonstration is described in a research paper written by Harvard University’s Eric Keto and Wellesley College’s Wesley Andres Watters, who proposed their image analysis technique in an earlier study. The new study was posted to the ArXiv pre-print server last week and has been submitted to the Journal of Astronomical Instrumentation for review.

Keto and Watters started out with multispectral imagery captured by Planet’s SuperDove satellites during last year’s balloon flights. Such imagery isn’t captured all at once. Instead, the satellite’s sensors record a succession of exposures that reflect different spectral bands. That means an aerial object would be seen at a slightly different location in each of the images that are combined to produce a multispectral view, due to the parallax effect created by a moving satellite.

The researchers said the spy balloons were ideal subjects for their study. “High-altitude balloons are advantageous targets, because the motion of the balloon itself can be ignored in the analysis,” they said.

The aim of their study was to create a baseline for interpreting spectral-band images. The researchers conducted a detailed analysis of imagery that was acquired over British Columbia, Missouri and Colombia — and made a few educated guesses about the relative velocities involved. They took a variety of factors into account, including shifts in the background terrain and the potential effects of atmospheric distortion. (The British Columbia imagery wasn’t that useful, because snow and ice covered up the features that would typically be used for ground reference.)

The analysis not only provided a baseline for tracking moving objects using SuperDove satellite imagery, but also made it possible for the researchers to provid estimates for the altitudes of the balloons. They said one balloon flew over Missouri at a height of about 21,200 meters (69,500 feet), while the other balloon’s altitude was about 21,500 meters (70,000 feet) when it was spotted over Colombia.

Keto and Watters aren’t the only ones looking into how commercial satellite data could be used to track anomalous aerial objects. A team of researchers at RAIC Labs (formerly known as Synthetaic) used Planet’s data archive and RAIC Labs’ AI-based image analysis program to trace the infamous Chinese balloon’s route backward from the U.S. to its point of origin near Hainan.

A 2023 video focuses on how Planet and Synthetaic / RAIC Labs tracked the Chinese balloon:

Such techniques could be used to detect phenomena that are even more exotic than Chinese spy balloons: The study conducted by Keto and Watters is part of Harvard University’s Galileo Project, which is aimed at finding ways to collect high-quality data that could be useful in the search for objects of extraterrestrial origin.

Harvard astronomer Avi Loeb, who heads up the Galileo Project, said last year in a blog posting that his team has been searching through Planet’s data archive for signs of unusual objects.

“Extraterrestrial equipment can be distinguished from a terrestrial object, not just by resolving unusual bolts or labels imprinted on its hardware but also based on its motion,” Loeb explained. “As mentioned in the DNI [Director of National Intelligence] reports in 2021 and 2022, unusual flight characteristics can serve as an indicator of an extraterrestrial origin.”

Will satellite data analysis become a standard tool for detecting anomalous aerial phenomena? Stay tuned: We’ve reached out to Loeb, Keto and Watters, and we’ll update this report with any additional information we can pass along.

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Saturn’s Energy is Out of Balance

Earth releases about as much energy out into space as it absorbs, arriving at a thermal equilibrium. This means it will reach an average temperature as is the case with most planets. Saturn however, is a little different as recent observations show the planet’s energy is out of balance. It seems that in addition to the energy it receives from the Sun, there must also be an internal source of heat, perhaps driven by its highly elliptical orbit. 

Saturn is the sixth planet from the Sun and is most well known for its stunning ring system. It was the first celestial object I saw through a telescope and like many others, captured my imagination. Of all the planets Jupiter is the largest followed by Saturn which has an equatorial diameter (not including the rings) of 116,460 kilometres. 

The Cassini spacecraft began its journey to Saturn in 1997. After a seven year journey it arrived in 2004 and until 2017 studied the ringed planet. It carried an array of scientific instruments including high resolution cameras to capture stunning detail of the planet and its rings. It also explored some of Saturn’s moons and made many discoveries such as the confirmation of the subsurface ocean on Enceladus and the hydrocarbon lakes on Titan. 

Artist impression of Cassini Space Probe

It was using the data form Cassini that Xinyue Wang, a third year doctoral student from the Natural Sciences and Mathematics department of University of Houston made their fascinating discovery. They found an imbalance in the planets atmospheric energy levels that seemed to vary on a seasonal cycle. Just like Earth, every other planet gets energy from the Sun. This solar radiation is absorbed and then re-emitted as thermal radiation. Wang reported ‘Saturn, like the other gas giants, has another energy input in the form of deep internal heat affecting its thermal structure and climate.’

The team conclude that the imbalance which recurs on a seasonable basis must have ben due to it’s large orbital eccentricity by nearly 20%. This refers to the elliptical orbit of Saturn which takes it closer to the Sun and then further away on a regular basis. As it gets closer to the Sun it experiences a massive increase in incoming solar radiation and less as it slowly drifts further away. Conversely, Earth which has a much smaller orbital eccentricity does not experience changes in the magnitude of incoming solar radiation.

Understanding the increased incoming radiation (which takes place for a number of years)  before slowly dropping again) is key to understanding the dynamics of the planet’s atmosphere. The development of giant storms is one effect as these are more prominent when there is an increase in incoming radiation. Studying these changes may help us to develop a better understanding of Earth’s atmospheric processes too. 

A giant storm rages on Saturn. Credit: NASA/JPL-Caltech/SSI

Until now we believed that there was no energy imbalance. This recent study revealed that this is not the case and it now requires further study to assess and develop the models. Along with further studies of the Saturnian energy imbalance, the team now wish to study the other gas giant planets and expect they will find similar imbalances. 

Source :  UH Scientists Discover Massive Energy Imbalance on Saturn

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A Combination Drill and Gas Conveyor Could Simplify Asteroid Extraction

Collecting material from an asteroid seems like a simple task. In reality, it isn’t. Low gravity, high rotational speeds, lack of air, and other constraints make collecting material from any asteroid difficult. But that won’t stop engineers from trying. A team from Beijing Spacecrafts and the Guangdong University of Technology recently published a paper that described a novel system for doing so – using an ultrasonic drill and gas “conveyor belt.”

So far, three missions have successfully taken samples from an asteroid: Hayabusa-1 and -2 and OSIRIS-REx. Both Hayabusa missions used a projectile to impact the asteroid and collected the debris from that impact. OSIRIS-REx used a system called the Touch and Go Sample Acquisition Mechanism (TAGSAM), which touched down briefly on Bennu, the mission’s target asteroid, and then pulled away with a sample of its regolith.

Another mission, Rosetta, attempted a more involved sample collection process that involved anchoring to the asteroid itself. However, its lander, Philae, didn’t successfully attach to the asteroid and never managed to return samples to the Rosetta orbiter. Its collection mechanism known as the Sampling and Drilling Device (SD2) was the most similar to conventional sample collection here on Earth, and utilized a drill.

Fraser and Pamela discuss what all goes into a asteroid sample return mission.

That concept of drilling is at the heart of the new proposed system. It utilizes an ultrasonic drill to break up the regolith into small chunks. It’s pretty standard stuff and nothing to write home about, as robots have been doing so on celestial bodies for decades. However, in this case, the drill is surrounded by a system that utilizes gas to push the tiny grains of dust created by the drill up into a sample collection system.

In the paper, the researchers describe it as a “gas conveyor belt,” which pushes the small particles hard enough to allow them to float in the asteroid’s microgravity environment. According to the authors, the proposed system has several advantages. These include low cost, low power consumption, and adaptability to different sample collection site environments.

Another significant advantage is that the probe that utilizes it doesn’t need to be entirely securely anchored to the asteroid. This was the problem for Philae, but the physics of the ultrasonic drill made it possible for the probe to be lightly tethered to the asteroid without having the system for the probe away from the surface.

Visualization of how the gas and drill work together in the system.
Credit – Zhao et al.

In addition to the modeling and theory behind the development of the system, they also built a prototype. They tried it on various regolith simulants in a vacuum and under pressure. Since the experiment was only on a benchtop, they couldn’t test it in the microgravity environment. The ultrasonic drill, which has a “percussive” function similar to a hammer drill used in construction, made neatly drilled holes in a sample rock on the benchtop.

However, some work remains, including more comprehensive system testing, microgravity, and more theoretical modeling of the system’s efficacy. The authors believe this system could be integrated into China’s upcoming asteroid exploration and sample return missions, which they think will happen soon. If they do, they might get a chance to prove this novel piece of technology and move us one step closer to solving the technical challenge of asteroid sample return.

Learn More:
Zhao et al. – Gas-Driven Regolith-Sampling Strategy for Exploring Micro-Gravity Asteroids
UT – Finally, Let’s Look at the Asteroid Treasure Returned to Earth by OSIRIS-REx
UT – Asteroid Ryugu Contained Bonus Comet Particles
UT – OSIRIS-REx’s Final Haul: 121.6 Grams from Asteroid Bennu

Lead Image:
Images of the prototype drilling system in different test configurations.
Credit – Zhao et al.

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Simulating the Last Moments Before Neutron Stars Merge

When stars reach the end of their life cycle, they shed their outer layers in a supernova. What is left behind is a neutron star, a stellar remnant that is incredibly dense despite being relatively small and cold. When this happens in binary systems, the resulting neutron stars will eventually spiral inward and collide. When they finally merge, the process triggers the release of gravitational waves and can lead to the formation of a black hole. But what happens as the neutron stars begin merging, right down to the quantum level, is something scientists are eager to learn more about.

When the stars begin to merge, very high temperatures are generated, creating “hot neutrinos” that remain out of equilibrium with the cold cores of the merging stars. Ordinarily, these tiny, massless particles only interact with normal matter via weak nuclear forces and possibly gravity. However, according to new simulations led by Penn State University (PSU) physicists, these neutrinos can weakly interact with normal matter during this time. These findings could lead to new insights into these powerful events.

Pedro Luis Espino, a postdoctoral researcher at Penn State and the University of California, Berkeley, led the research. He was joined by fellow astrophysicists from PSU, the Theoretical Physics Institute at the Friedrich Schiller University Jena, the University of Trent, and the Trento Institute for Fundamental Physics and Applications (INFN-TIFPA). A paper describing their simulations, “Neutrino Trapping and Out-of-Equilibrium Effects in Binary Neutron-Star Merger Remnants,” recently appeared in the journal Physical Reviews Letters.

Artist’s conception of a neutron star merger. This process also creates heavy elements. Credit: Tohoku University

Originally predicted by Einstein’s Theory of General Relativity, gravitational waves (GW) are essentially ripples in spacetime caused by the collapse of stars or the merger of compact objects (such as neutron stars and black holes). Neutron stars are so named because their incredible density fuses protons and electrons together, creating stellar remnants composed almost entirely of neutrons. For years, astronomers have studied GW events to learn more about binary companions and what happens at the moment they merge. Said Pedro Luis Espino, a postdoctoral researcher at Penn State and the University of California, Berkeley, explained in a Penn State press release:

“For the first time in 2017, we observed here on Earth signals of various kinds, including gravitational waves, from a binary neutron star merger. This led to a huge surge of interest in binary neutron star astrophysics. There is no way to reproduce these events in a lab to study them experimentally, so the best window we have into understanding what happens during a binary neutron star merger is through simulations based on math that arises from Einstein’s theory of general relativity.”

While neutron stars are effectively cold, they can become extremely hot during a merger, especially at the interface (the point where the two stars are making contact). In this region, temperatures can reach the trillions of degrees Kelvin, but the stars’ density prevents photons from escaping to dissipate the heat. According to David Radice, an assistant professor of astronomy and astrophysics at the Eberly College of Science at Penn State and one of the team leaders, this heat may be dissipated by neutrinos, which are created during the collision as neutrons are smashed to form protons, electrons, and neutrinos.

“The period where the merging stars are out of equilibrium is only 2 to 3 milliseconds, but like temperature, time is relative here, the orbital period of the two stars before the merge can be as little as one millisecond,” he said. “This brief out-of-equilibrium phase is when the most interesting physics occurs, once the system returns to equilibrium, the physics is better understood.”

To investigate this, the research team created supercomputer simulations that modeled the merger and associated physics of binary neutron stars. Their simulations showed that even neutrinos can be trapped by the heat and density of the merger, that the hot neutrinos are out of equilibrium with the still cool cores, and can interact with the matter of the stars. Moreover, their simulations indicate that the physical conditions present during a merger can affect the resulting GW signals. Said Espino:

“How the neutrinos interact with the matter of the stars and eventually are emitted can impact the oscillations of the merged remnants of the two stars, which in turn can impact what the electromagnetic and gravitation wave signals of the merger look like when they reach us here on Earth. Next-generation gravitation-wave detectors could be designed to look for these kinds of signal differences. In this way, these simulations play a crucial role allowing us to get insight into these extreme events while informing future experiments and observations in a kind of feedback loop.”

This is certainly good news for gravitational wave astronomy and for scientists hoping to use GW events to probe the interiors of neutron stars. Knowing what conditions are present during mergers based on the type of GW signals produced could also provide new insight into supernovae, Gamma-ray Bursts, Fast Radio Bursts, and the nature of Dark Matter.

Further Reading: PSU, Physical Review Letters

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Growing Black Holes Have Much in Common With Baby Stars

First looks would tell most observers that supermassive black holes (SMBHs) and very young stars have nothing in common. But that’s not true. Astronomers have detected a supermassive black hole (SMBH) whose growth is regulated the same way a baby star’s is: by magnetic winds.

Supermassive Black Holes are so massive that comprehending them is difficult. They can be billions of times more massive than our Sun, a number so easy to say that it trivializes their true magnitude. They grow so large through two mechanisms: mergers and accretion.

Black holes can’t be seen directly, but their existence is confirmed by observing how they alter their surroundings. SMBHs are so massive that they alter the orbits and velocities of nearby stars, a phenomenon astronomers have clearly observed. SMBHs are also visible as active galactic nuclei when they’re actively accreting material. Lastly, when black holes merge, they release gravitational waves that we can detect with facilities like LIGO/Virgo.

But there are lots of unanswered questions about how black holes grow by accretion. To try to understand how an SMBH accretes gas and acquires mass, a team of researchers observed ESO320-G030, a nearby galaxy only 120 million light years away.

Their results are in a paper titled “A spectacular galactic scale magnetohydrodynamic powered wind in ESO 320-G030.” The paper is published in the journal Astronomy and Astrophysics, and the lead author is Mark Gorski, a postdoc at Northwestern University.

One outstanding issue in the study of SMBHs concerns black hole feedback. Not all of the material that enters an SMBH’s accretion disk falls into the hole. Some is released by astrophysical jets. This is part of a process called black hole feedback, and it shapes how the black hole grows and how quickly its galaxy forms new stars.

ESO 320-G030 is interesting not only because it hosts an SMBH but also because it’s forming new stars at a rapid rate, about ten times as fast as the Milky Way. To try to understand all the processes in the galaxy’s nucleus, a team of researchers used the Atacama Large Millimetre/submillimetre Array (ALMA) to observe molecules being transported from the galaxy’s center outward.

“How galaxies regulate nuclear growth through gas accretion by supermassive black holes (SMBHs) is one of the most fundamental questions in galaxy evolution,” the authors write in their research article. “One potential way to regulate nuclear growth is through a galactic wind that removes gas from the nucleus.”

ALMA’s strength lies in its ability to see through thick gas and dust and to observe light that straddles infrared light and radio waves. It can track cold molecules by the light they emit in these wavelengths. In this research, ALMA tracked HCN (hydrogen cyanide) as it travelled through ESO 320-G030’s nucleus.

“It is unclear whether galactic winds are powered by jets, mechanical winds, radiation, or via magnetohydrodynamic (MHD) processes,” the authors write. By using ALMA to observe HCN, the researchers hoped to bring clarity.

An artist’s conception of a supermassive black hole’s jets. Credit: NASA / Dana Berry / SkyWorks Digital

ESO 320-G030 is a particular type of galaxy. It’s a luminous infrared galaxy with a very compact nucleus obscured by dust. About 30% of these types of galaxies have extremely compact nuclei with growing SMBHs or unusual starbursts. There’s clearly a lot of action in the galaxy’s nucleus, so it’s a critical target for astrophysicists and astronomers.

“Since this galaxy is very luminous in the infrared, telescopes can resolve striking details in its centre,” said Susanne Aalto, Professor of Radio Astronomy at Chalmers University of Technology. “We wanted to measure light from molecules carried by winds from the galaxy’s core, hoping to trace how the winds are launched by a growing, or soon to be growing, supermassive black hole. By using ALMA, we were able to study light from behind thick layers of dust and gas.”

There’s a debate among astronomers over the nature of black hole feedback. Galaxies have AGN-driven outflows that inject gas back into a galaxy’s nucleus, but they can’t agree on the nature of the feedback. It could be jets, mechanical winds, or radiation. Observing ESO 320-G030 with ALMA’s molecule-observing ability is a chance to wade deeply into the debate.

ALMA was able to trace the behaviour of HCN due to excitational vibration. The observations result in maps of the molecule’s movement in the galaxy’s nucleus.

This figure from the research shows an intensity-weighted velocity field of HCN in ESO 320-G030’s nucleus. The authors write, “The rough location and direction of the outflow is indicated by the dashed arrows.” The contours in the figure show that the HCN-vib emission is “extended along the outflow and that the outflow is launched from similarly rotating sides of the nucleus.” Image Credit: Gorski et al. 2024

“We can see how the winds form a spiralling structure, billowing out from the galaxy’s centre. When we measured the rotation, mass, and velocity of the material flowing outwards, we were surprised to find that we could rule out many explanations for the power of the wind, star formation for example. Instead, the flow outwards may be powered by the inflow of gas and seems to be held together by magnetic fields,” said Aalto.

As the SMBH draws material into its rotating accretion disk, the rotation creates powerful magnetic fields. The magnetic fields lift matter away from the center, creating a spiralling MHD (magnetohydrodynamic) wind. As matter is removed by the wind, the disk rotation slows. Slower rotation allows more material to fall into the hole, letting the SMBH grow more massive.

Other winds and jets in the nucleus propel material away from black holes in galaxy nuclei, but this newly discovered wind feeds material into the black hole. “In this Letter, we present compelling evidence that the outflow in ESO 320-G030 is powered by a different mechanism, an MHD wind launched prior to the ignition of an AGN,” the authors write. Since an AGN is observed when an SMBH has accreted material into its disk and the material has been heated by rotation, the wind the researchers observed is likely responsible for feeding material into the black hole’s disk, some of which falls into the hole itself.

To the astronomers behind the work, the ALMA data images are a breathtaking new insight into the winds in ESO 320-G030’s galactic nucleus. “What is spectacular about the outflow morphology is that the launching regions are apparent and connected to the rotating nuclear structure in the innermost ~12 pc,” they write. The patterns revealed by ALMA hint at the presence of a magnetized rotating wind.

The wind’s rotating element is key. “The rotation of outflows is a strong indication of magnetic acceleration,” the authors explain. If magnetic acceleration is driving it, then the other phenomena astronomers debate—AGN, astrophysical jets, or radiation—can’t be responsible.

This newly discovered wind is similar to the winds around young protostars that are accreting material and actively growing.

Artist’s conception of a star being born within a protective shroud of gas and dust. New research shows that magnetic winds aid the growth of both protostars and SMBHs. Credit: NASA

“It is well-established that stars, in the first stages of their evolution, grow with the help of rotating winds – accelerated by magnetic fields, just like the wind in this galaxy. Our observations show that supermassive black holes and tiny stars can grow by similar processes, but on very different scales.” said lead author Gorski in a press release.

This could be a big step in understanding how SMBHs grow, but the authors know it’s only one step. They need to observe more SMBHs and gather more data before anything is conclusive.

“Far from all questions about this process are answered. In our observations we see clear evidence of a rotating wind that helps regulate the growth of the galaxy’s central black hole. Now that we know what to look for, the next step is to find out how common a phenomenon this is. And if this is a stage which all galaxies with supermassive black holes go through, what happens to them next?” asks lead author Gorski.

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NASA Doesn't Know When Starliner Will Return From Orbit

After helium leaks and thruster problems with Boeing’s Starliner capsule, NASA has been pushing back the return date from the International Space Station. On Friday, the agency announced they no longer had a planned return date. Instead, they will keep testing the capsule, trying to understand its issues, and seeing if they can make any fixes. Plenty of supplies are on the station, so there’s no urgent need to bring the two astronauts back to Earth.

NASA decided to cancel the planned departure of Wednesday, June 26 because of conflicting timelines with a series of planned spacewalks on the ISS, set for today (Monday, June 24), and Tuesday, July 2. The delay also allows mission teams time to review propulsion and system data.

Boeing’s CTS-100 Starliner taking off from Cape Canaveral, Florida, on June 5th, 2024. Credit: NASA

After years of delays and two recent scrubbed launch attempts, Starliner finally launched on June 5, 2024 with NASA astronauts Butch Wilmore and Suni Williams on board. Although two of the spacecraft’s thrusters failed during the flight, the spacecraft managed to reach the ISS and delivered 227 kg (500 lbs) of cargo. Additionally, five small leaks on the service module were also detected, and the crew and ground teams have been working through safety checks.

“We are taking our time and following our standard mission management team process,” said Steve Stich, manager of NASA’s Commercial Crew Program in a NASA blog post. “We are letting the data drive our decision making relative to managing the small helium system leaks and thruster performance we observed during rendezvous and docking. Additionally, given the duration of the mission, it is appropriate for us to complete an agency-level review, similar to what was done ahead of the NASA’s SpaceX Demo-2 return after two months on orbit, to document the agency’s formal acceptance on proceeding as planned.”

This first crewed flight of Starliner was supposed to validate the spacecraft as part of NASA’s Commercial Crew Program (CCP), with the hope of it working alongside SpaceX’s Crew Dragon to make regular deliveries of cargo and crew to the ISS. This mission is the second time the Starliner has flown to the ISS and the third flight test overall. During the first uncrewed test flight (OFT-1), which took place back in December 2019, the Starliner launched successfully but failed to make it to the ISS. After making 61 corrective actions recommended by NASA, another attempt was made (OFT-2) on May 22nd, 2022. That flight successfully docked to the ISS, staying there for four days before undocking and landing in the White Sands Missile Range in New Mexico.

The seven Expedition 71 crew members gather with the two Crew Flight Test members for a team portrait aboard the space station. In the front from left are, Suni Williams, Oleg Kononenko, and Butch Wilmore. Second row from left are, Alexander Grebenkin, Tracy C. Dyson, and Mike Barratt. In the back are, Nikolai Chub, Jeanette Epps, and Matthew Dominick. Photo credit: NASA

Wilmore and Williams are now  working with the Expedition 71 crew, assisting with station operations as needed and completing add-on in-flight objectives for NASA’s certification of Starliner.

Stich said that despite all the issues, Starliner is performing well in orbit while docked to the space station.

“We are strategically using the extra time to clear a path for some critical station activities while completing readiness for Butch and Suni’s return on Starliner,” he said, “and gaining valuable insight into the system upgrades we will want to make for post-certification missions.”

Mission managers will evaluate future return opportunities for Starliner and NASA said they will host a media telecon with mission leadership following a readiness review. NASA added that Starliner is actually cleared for return in case of an emergency on the space station that would require the crew to leave orbit and come back to Earth.

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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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