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By NASA
5 min read
Ultra-low-noise Infrared Detectors for Exoplanet Imaging
A linear-mode avalanche photodiode array in the test dewar. The detector is the dark square in the center. Michael Bottom, University of Hawai’i One of the ultimate goals in astrophysics is the discovery of Earth-like planets that are capable of hosting life. While thousands of planets have been discovered around other stars, the vast majority of these detections have been made via indirect methods, that is, by detecting the effect of the planet on the star’s light, rather than detecting the planet’s light directly. For example, when a planet passes in front of its host star, the brightness of the star decreases slightly.
However, indirect methods do not allow for characterization of the planet itself, including its temperature, pressure, gravity, and atmospheric composition. Planetary atmospheres may include “biosignature” gases like oxygen, water vapor, carbon dioxide, etc., which are known to be key ingredients needed to support life as we know it. As such, direct imaging of a planet and characterization of its atmosphere are key to understanding its potential habitability.
But the technical challenges involved in imaging Earth-like extrasolar planets are extreme. First such planets are detected only by observing light they reflect from their parent star, and so they typically appear fainter than the stars they orbit by factors of about 10 billion. Furthermore, at the cosmic distances involved, the planets appear right next to the stars. A popular expression is that exoplanet imaging is like trying to detect a firefly three feet from a searchlight from a distance of 300 miles.
Tremendous effort has gone into developing starlight suppression technologies to block the bright glare of the star, but detecting the light of the planet is challenging in its own right, as planets are incredibly faint. One way to quantify the faintness of planetary light is to understand the photon flux rate. A photon is an indivisible particle of light, that is, the minimum detectable amount of light. On a sunny day, approximately 10 thousand trillion photons enter your eye every second. The rate of photons entering your eye from an Earth-like exoplanet around a nearby star would be around 10 to 100 per year. Telescopes with large mirrors can help collect as much of this light as possible, but ultra-sensitive detectors are also needed, particularly for infrared light, where the biosignature gases have their strongest effects. Unfortunately, state-of-the-art infrared detectors are far too noisy to detect the low level of light emitted from exoplanets.
With support from NASA’s Astrophysics Division and industrial partners, researchers at the University of Hawai’i are developing a promising detector technology to meet these stringent sensitivity requirements. These detectors, known as avalanche photodiode arrays, are constructed out of the same semiconductor material as conventional infrared sensors. However, these new sensors employ an extra “avalanche” layer that takes the signal from a single photon and multiplies it, much like an avalanche can start with a single snowball and quickly grow it to the size of a boulder. This signal amplification occurs before any noise from the detector is introduced, so the effective noise is proportionally reduced. However, at high avalanche levels, photodiodes start to behave badly, with noise exponentially increasing, which negates any benefits of the signal amplification. Late University of Hawai’i faculty member Donald Hall, who was a key figure in driving technology for infrared astronomy, realized the potential use of avalanche photodiodes for ultra-low-noise infrared astronomy with some modifications to the material properties.
University of Hawai’i team members with cryogenic dewar used to test the sensors. From left to right, Angelu Ramos, Michael Bottom, Shane Jacobson, Charles-Antoine Claveau. Michael Bottom, University of Hawai’i The most recent sensors benefit from a new design including a graded semiconductor bandgap that allows for excellent noise performance at moderate amplification, a mesa pixel geometry to reduce electronic crosstalk, and a read-out integrated circuit to allow for short readout times. “It was actually challenging figuring out just how sensitive these detectors are,” said Michael Bottom, associate professor at the University of Hawai’i and lead of development effort. “Our ‘light-tight’ test chamber, which was designed to evaluate the infrared sensors on the James Webb Space Telescope, was supposed to be completely dark. But when we put these avalanche photodiodes in the chamber, we started seeing light leaks at the level of a photon an hour, which you would never be able to detect using the previous generation of sensors.”
The new designs have a format of one megapixel, more than ten times larger than the previous iteration of sensors, and circuitry that allows for tracking and subtracting any electronic drifts. Additionally, the pixel size and control electronics are such that these new sensors could be drop-in replacements for the most common infrared sensors used on the ground, which would give new capabilities to existing instruments.
Image of the Palomar-2 globular cluster located in the constellation of Auriga, taken with the linear-mode avalanche photodiode arrays, taken from the first on-sky testing of the sensors using the University of Hawai’i’s 2.2 meter telescope. Michael Bottom, University of Hawai’i Last year, the team took the first on-sky images from the detectors, using the University of Hawai’i’s 2.2-meter telescope. “It was impressive to see the avalanche process on sky. When we turned up the gain, we could see more stars appear,” said Guillaume Huber, a graduate student working on the project. “The on-sky demonstration was important to prove the detectors could perform well in an operational environment,” added Michael Bottom.
According to the research team, while the current sensors are a major step forward, the megapixel format is still too small for many science applications, particularly those involving spectroscopy. Further tasks include improving detector uniformity and decreasing persistence. The next generation of sensors will be four times larger, meeting the size requirements for the Habitable Worlds Observatory, NASA’s next envisioned flagship mission, with the goals of imaging and characterizing Earth-like exoplanets.
Project Lead: Dr. Michael Bottom, University of Hawai’i
Sponsoring Organization: NASA Strategic Astrophysics Technology (SAT) Program
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Last Updated Feb 18, 2025 Related Terms
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By NASA
1 Min Read Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR)
The SBIR/STTR programs provide an opportunity for small, high technology companies and research institutions (RI) to participate in Government sponsored research and development (R&D) efforts in key technology areas. NASA SBIR Phase I contracts have a period of performance for 6 months with a maximum funding of $125,000, and Phase II contracts have a period of performance up to 24 months with a maximum funding of $750,000. The STTR Phase I contracts last for 13 months with a maximum funding of $125,000, and Phase II contracts last for 24 months with the maximum contract value of $750,000.
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By European Space Agency
In a world first, ESA and Telesat have successfully connected a Low Earth Orbit (LEO) satellite to the ground using 5G Non-Terrestrial Network (NTN) technology in the Ka-band frequency range, marking a crucial step towards making space-based connections as simple as using a mobile phone.
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
With a shared commitment to fostering U.S. economic growth that benefits the American public, NASA’s Space Technology Mission Directorate and the Department of Commerce’s U.S. Patent and Trademark Office (USPTO) have signed a memorandum of understanding to strengthen collaboration in transferring federally-developed technology into the private sector, known as tech transfer.
“NASA has to invent new technology every day to carry out audacious missions like building an outpost on the Moon or looking for signs of life on the frozen moons of distant planets,” said Clayton Turner, associate administrator of the agency’s Space Technology Mission Directorate. “That is one of our greatest strengths. And with the help of the U.S. Patent and Trademark Office, we’re streamlining the process of getting those inventions into the hands of the public, boosting the economy, and benefiting everyone on Earth along the way.”
The agency’s Space Technology Mission Directorate and USPTO have been working together to share information and cooperate in mutual areas of interest, find ways to advance both agencies’ technology transfer missions, identify barriers to technology transfer, and coordinate initiatives to overcome those barriers. By combining expertise, both agencies are driving inclusive innovation and adoption of best practices, which will advance commercialization of the space agency’s most cutting-edge technology.
As part of the new agreement, NASA and USPTO are conducting an extensive study of technology transfer best practices across university and federal labs. The effort will increase opportunities for learning and growth in the technology transfer community.
“NASA’s Technology Transfer program and the U.S. Patent and Trademark Office had candid conversations with dozens of tech transfer experts about what we could do better,” said Dan Lockney, executive for NASA’s Technology Transfer program. “I can’t wait to share what we’ve learned with the entire tech transfer community nationwide. We look forward to addressing common challenges, and this paper will offer some assurance that we are on a solid, strong path to transferring technologies effectively.”
The two agencies will publish a detailed study of their findings, which will be shared at the Federal Laboratory Consortium for Technology Transfer’s national meeting in the spring. The effort will increase opportunities for learning and growth in the technology transfer community.
“We are excited to join NASA’s Space Technology Mission Directorate in publishing and sharing this insight with the larger tech transfer community, so that everyone can benefit from the successes and lessons learned from our study participants,” said Parikha Solanki, senior advisor at the U.S. Patent and Trademark Office. “We hope that the impact of this study will extend well beyond the paper, such that it might be a springboard for ongoing dialogue and knowledge sharing between tech transfer practitioners across institutions, ultimately for the benefit of the public at large.”
Learn more about NASA’s Technology Transfer Program:
https://go.nasa.gov/3VEZcmZ
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Last Updated Dec 19, 2024 Related Terms
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By USH
The ongoing mystery surrounding recent drone sightings has become increasingly complex, with conflicting reports making it difficult to draw definitive conclusions. However, a new and intriguing element has emerged alongside these drones sightings: numerous accounts of mysterious orbs, potentially of alien origin, flying at both low and high altitudes.
Reports of mysterious orbs have been increasing in recent weeks. These orbs have been sighted at both high altitudes and closer to urban areas.
Orb sighting over New Jersey on December 17, 2024Watch video UFO Sightings Daily
Pilots have reported encounters to air traffic control. Listen to conversations between pilots and traffic control.
And a passenger aboard United Airlines flight UA2359 from Chicago to Newark recently captured footage of these mysterious orbs. The video, shared online by the user “EasilyAmusedEE” on December 16, 2024, shows objects at altitudes between 40,000 and 50,000 feet—far beyond the capabilities of consumer drones. The footage was reportedly taken using an iPhone 16 Pro Max.
Video plane passenger films unknown orbs.
About the drone sightings: Meanwhile, eyewitness accounts describe these so-called drones as crafts that emit no noise, suggesting advanced technology. Additionally, there are claims that these crafts seem to intentionally draw attention, as they have reportedly interfered with cars (lamps flickering), electronics, streetlights (lamps flickering), and even fully charged batteries, which are said to be instantly drained in their presence.
Video shows among other (drone/orb) sightings, cars lamps flickering, streetlights lamps flickering, fully charged batteries drained.
This surge in Orb sightings raises more questions. Are these orbs extraterrestrial in origin? Could they be deliberately associated with the drone phenomena, or is their timing coincidental? Some suggest the possibility of a false flag operation, hinting at a deeper and potentially misleading agenda by the U.S. government.
Whether these drones and Orbs sightings point to advanced human technology, extraterrestrial activity, or a mix of both, one thing is clear: there is something significant going on.View the full article
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