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By European Space Agency
Ice melting from glaciers around the world is depleting regional freshwater resources and driving global sea levels to rise at ever-faster rates.
According to new findings, through an international effort involving 35 research teams, glaciers have been losing an average of 273 billion tonnes of ice per year since the year 2000 – but hidden within this average there has been an alarming increase over the last 10 years.
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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
For more than a decade, Tristan McKnight has been a driving force behind some of NASA’s most iconic events, orchestrating the behind-the-scenes magic that brings each historic moment to life while sharing the agency’s advancements with the public.
As a multimedia producer on the audiovisual team at Johnson Space Center in Houston, McKnight produces and directs live broadcasts and manages event planning, coordination, and execution. From overseeing resources, mitigating risks, and communicating with stakeholders, he ensures every detail aligns seamlessly.
Official portrait of Tristan McKnight.NASA/Josh Valcarcel McKnight has played an integral role in the audiovisual team’s coverage of major events including the Artemis II crew announcement, where NASA revealed the astronauts who will venture around the Moon and back, to Johnson’s 2023 Open House, which celebrated the agency’s 65th anniversary and the 25th anniversary of the International Space Station’s operations. These achievements highlight key milestones in human space exploration.
A standout achievement was contributing to the Dorothy Vaughan Center in Honor of the Women of Apollo naming ceremony, held on the eve of the 55th anniversary of the Apollo 11 Moon landing. The event honored the unsung heroes who made humanity’s first steps on the Moon possible.
The team’s dedication and passion are a testament to their commitment to sharing NASA’s legacy with the world.
“Not only have these events been impactful to Johnson, but they have also resonated across the entire agency,” McKnight said. “That is what I’m most proud of!”
Tristan McKnight at the 45th Annual Original Martin Luther King Jr. Day Parade in downtown Houston.NASA/James Blair One of McKnight’s most memorable events was the 2023 “Back in the Saddle,” an annual tradition designed to refocus Johnson’s workforce at the start of a new year and renew the center’s commitment to safety and mission excellence. McKnight recalled how the speaker transformed Johnson’s Teague Auditorium into a venue filled with drum kits, inspiring messages, and lighting displays. Each audience member, drumsticks in hand, participated in a lesson on teamwork and synchronization to create a metaphor for working in harmony toward a shared goal.
Like many high-achieving professionals. McKnight has faced moments of self-doubt. Then he realized that he is exactly where he is supposed to be. “As I settled into my role, I recognized that my contributions matter and simply being true to who I am adds value to the Johnson community,” he said.
Tristan McKnight (right) receives a Group Special Act Award from Johnson Space Center Director Vanessa Wyche for his contributions to the Dorothy Vaughn in Honor of the Women of Apollo naming ceremony.NASA Each day brings its own set of challenges, ranging from minor issues like communication gaps and scheduling conflicts to major obstacles like technology failures. One of McKnight’s most valuable lessons is recognizing that there is no one-size-fits-all solution, and each situation requires a thoughtful analysis.
McKnight understands the importance of the “check-and double-check,” a philosophy he considers crucial when working with technology. “Taking the extra time to do your due diligence, or even having someone else take a look, can make all the difference,” he said.
“The challenges I’ve faced helped me grow as a problem solver and taught me valuable lessons on resilience and adaptability in the workplace,” he said. McKnight approaches obstacles with a level head, focusing on effective solutions rather than dwelling on the problem.
Tristan McKnight (left) with his daughter Lydia McKnight and Johnson’s External Relations Director Arturo Sanchez at the 2024 Bring Your Youth To Work Day. NASA/Helen Arase Vargas As humanity looks to the stars, McKnight is energized about the future of exploration, particularly advancements in spacesuit and rocket technology that will enable us to travel farther, faster, and safer than ever before. His work, though grounded on Earth, helps create the inspiration that fuels these bold endeavors.
“My hope for the next generation is that they dive deeper into their curiosity—exploring not only the world around them but also the Moon, planets, and beyond,” he said. “I also hope they carry forward the spirit of resilience and a commitment to making the world a better place for all.”
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By NASA
Artistic rendering of Intuitive Machines’ Nova-C lander on the surface of the Moon.Credit: Intuitive Machines NASA’s Polar Resources Ice Mining Experiment-1 (PRIME-1) is preparing to explore the Moon’s subsurface and analyze where lunar resources may reside. The experiment’s two key instruments will demonstrate our ability to extract and analyze lunar soil to better understand the lunar environment and subsurface resources, paving the way for sustainable human exploration under the agency’s Artemis campaign for the benefit of all.
Its two instruments will work in tandem: The Regolith and Ice Drill for Exploring New Terrains (TRIDENT) will drill into the Moon’s surface to collect samples, while the Mass Spectrometer Observing Lunar Operations (MSOLO) will analyze these samples to determine the gas composition released across the sampling depth. The PRIME-1 technology will provide valuable data to help us better understand the Moon’s surface and how to work with and on it.
“The ability to drill and analyze samples at the same time allows us to gather insights that will shape the future of lunar resource utilization,” said Jackie Quinn, PRIME-1 project manager at NASA’s Kennedy Space Center in Florida. “Human exploration of the Moon and deep space will depend on making good use of local resources to produce life-sustaining supplies necessary to live and work on another planetary body.”
The PRIME-1 experiment is one of the NASA payloads aboard the next lunar delivery through NASA’s CLPS (Commercial Lunar Payload Services) initiative, set to launch from the agency’s Kennedy Space Center no earlier than Wednesday, Feb. 26, on Intuitive Machines’ Athena lunar lander and explore the lunar soil in Mons Mouton, a lunar plateau near the Moon’s South Pole.
Developed by Honeybee Robotics, a Blue Origin Company, TRIDENT is a rotary percussive drill designed to excavate lunar regolith and subsurface material up to 3.3 feet (1 meter) deep. The drill will extract samples, each about 4 inches (10 cm) in length, allowing scientists to analyze how trapped and frozen gases are distributed at different depths below the surface.
The TRIDENT drill is equipped with carbide cutting teeth to penetrate even the toughest lunar materials. Unlike previous lunar drills used by astronauts during the Apollo missions, TRIDENT will be controlled from Earth. The drill may provide key information about subsurface soil temperatures as well as gain key insight into the mechanical properties of the lunar South Pole soil. Learning more about regolith temperatures and properties will greatly improve our understanding of the environments where lunar resources may be stable, revealing what resources may be available for future Moon missions.
A commercial off-the-shelf mass spectrometer, MSOLO, developed by INFICON and made suitable for spaceflight at Kennedy, will analyze any gas released from the TRIDENT drilled samples, looking for the potential presence of water ice and other gases trapped beneath the surface. These measurements will help scientists understand the Moon’s potential for resource utilization.
Under the CLPS model, NASA is investing in commercial delivery services to the Moon to enable industry growth and support long-term lunar exploration. As a primary customer for CLPS deliveries, NASA is one of many customers on future flights. PRIME-1 was funded by NASA’s Space Technology Mission Directorate Game Changing Development program.
Learn more about CLPS and Artemis at:
https://www.nasa.gov/clps
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By European Space Agency
The European Space Agency (ESA) Planetary Defence Office is closely monitoring the recently discovered asteroid 2024 YR4, which has a very small chance of impacting Earth in 2032.
This page was last updated on 29 January 2025.
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