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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
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist’s concept of an emergency response flyer from a team at Texas A&M University and Oklahoma State University, one of 14 university teams that received NASA-supported GoAERO awards in 2025.Texas A&M University and Oklahoma State University With support from NASA, the international GoAERO Prize competition recently announced funding for 14 U.S. university teams to build innovative new compact emergency response aircraft.
The teams will develop prototype versions of Emergency Response Flyers, aircraft intended to perform rescue and response missions after disasters and in crisis situations. The flyers must be designed to deliver a first responder, evacuate victims, provide emergency medical supplies, and aid in humanitarian efforts. Teams will bring their test aircraft to a fly-off expected in 2027.
These awards will provide students with an opportunity that might have otherwise been difficult – a chance to design and build potentially lifesaving aircraft.
koushik datta
NASA Project Manager
“These awards will provide students with an opportunity that might have otherwise been difficult – a chance to design and build potentially lifesaving aircraft,” said Koushik Datta, University Innovation Project manager in NASA’s Aeronautics Research Mission Directorate at NASA Headquarters in Washington. “At NASA, we’re looking forward to seeing how these young innovators can contribute to our mission to advance futuristic aviation technologies that can benefit first responders and the public.”
With support from NASA’s University Innovation Project, GoAERO named 14 awardee teams at the following universities:
Auburn University, in Leeds, Alabama California Polytechnic University, in Pomona Carnegie Mellon University, in Pittsburgh Embry-Riddle Aeronautical University, in Daytona Beach, Florida Georgia Institute of Technology, in Atlanta North Carolina Agricultural & Technical State University, in Greensboro North Carolina State University, in Raleigh The Ohio State University, in Columbus Penn State University, in State College Purdue University, in West Lafayette, Indiana Saint Louis University Texas A&M University, in College Station, and Oklahoma State University, in Stillwater University of Texas, Austin Virginia Tech, in Blacksburg Student teams can utilize the funds to purchase parts, materials, batteries, and other components for building their aircrafts.
When naming the university awardees, GoAERO – in partnership with Boeing, RTX, and Honeywell – also announced 11 winners of Stage 1 of its competition. These include teams from the private sector and universities. These awardees were selected to build full- or smaller-scale flyers for evaluation. Eight entries will be selected for the next round of Stage 2 awards. The GoAERO Prize is still accepting new teams. While prizes are awarded at Stage 1 and Stage 2, teams do not need to win prizes to continue on to the next stage or compete in the final fly-off.
In addition to the University Innovation Project support for the university teams, NASA has partnered with GoAERO through a non-funded Space Act Agreement to provide U.S. teams with mentorship, educational opportunities, and access to specialized software tools.
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Last Updated Feb 11, 2025 EditorLillian GipsonContactJim Bankejim.banke@nasa.gov Related Terms
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Equipped with state-of-the-art technology to test and evaluate communication, navigation, and surveillance systems NASA’s Pilatus PC-12 performs touch-and-go maneuvers over a runway at NASA’s Armstrong Flight Research Center in Edwards, California on Sept. 23, 2024. Researchers will use the data to understand Automatic Dependent Surveillance-Broadcast (ADS-B) signal loss scenarios for air taxi flights in urban areas. To prepare for ADS-B test flights pilots and crew from NASA Armstrong and NASA’s Glenn Research Center in Cleveland, ran a series of familiarization flights. These flights included several approach and landings, with an emphasis on avionics, medium altitude air-work with steep turns, slow flight and stall demonstrations.NASA/Steve Freeman As air taxis, drones, and other innovative aircraft enter U.S. airspace, systems that communicate an aircraft’s location will be critical to ensure air traffic safety.
The Federal Aviation Administration (FAA) requires aircraft to communicate their locations to other aircraft and air traffic control in real time using an Automatic Dependent Surveillance-Broadcast (ADS-B) system. NASA is currently evaluating an ADS-B system’s ability to prevent collisions in a simulated urban environment. Using NASA’s Pilatus PC-12 aircraft, researchers are investigating how these systems could handle the demands of air taxis flying at low altitudes through cities.
When operating in urban areas, one particular challenge for ADS-B systems is consistent signal coverage. Like losing cell-phone signal, air taxis flying through densely populated areas may have trouble maintaining ADS-B signals due to distance or interference. If that happens, those vehicles become less visible to air traffic control and other aircraft in the area, increasing the likelihood of collisions.
NASA pilot Kurt Blankenship maps out flight plans during a pre-flight brief. Pilots, crew, and researchers from NASA’s Armstrong Flight Research Center in Edwards, California and NASA’s Glenn Research Center in Cleveland are briefed on the flight plan to gather Automatic Dependent Surveillance-Broadcast signal data between the aircraft and ping-Stations on the ground at NASA Armstrong. These flights are the first cross-center research activity with the Pilatus-PC-12 at NASA Armstrong.NASA/Steve Freeman To simulate the conditions of an urban flight area and better understand signal loss patterns, NASA researchers established a test zone at NASA’s Armstrong Flight Research Center in Edwards, California, on Sept. 23 and 24, 2024.
Flying in the agency’s Pilatus PC-12 in a grid pattern over four ADS-B stations, researchers collected data on signal coverage from multiple ground locations and equipment configurations. Researchers were able to pinpoint where signal dropouts occurred from the strategically placed ground stations in connection to the plane’s altitude and distance from the stations. This data will inform future placement of additional ground stations to enhance signal boosting coverage.
“Like all antennas, those used for ADS-B signal reception do not have a constant pattern,” said Brad Snelling, vehicle test team chief engineer for NASA’s Air Mobility Pathfinders project. “There are certain areas where the terrain will block ADS-B signals and depending on the type of antenna and location characteristics, there are also flight elevation angles where reception can cause signal dropouts,” Snelling said. “This would mean we need to place additional ground stations at multiple locations to boost the signal for future test flights. We can use the test results to help us configure the equipment to reduce signal loss when we conduct future air taxi flight tests.”
Working in the Mobile Operations Facility at NASA’s Armstrong Flight Research Center in Edwards, California, NASA Advanced Air Mobility researcher Dennis Iannicca adjusts a control board to capture Automatic Dependent Surveillance-Broadcast (ADS-B) data during test flights. The data will be used to understand ADS-B signal loss scenarios for air taxi flights in urban areas.NASA/Steve Freeman The September flights at NASA Armstrong built upon earlier tests of ADS-B in different environments. In June, researchers at NASA’s Glenn Research Center in Cleveland flew the Pilatus PC-12 and found a consistent ADS-B signal between the aircraft and communications antennas mounted on the roof of the center’s Aerospace Communications Facility. Data from these flights helped researchers plan out the recent tests at NASA Armstrong. In December 2020, test flights performed under NASA’s Advanced Air Mobility National Campaign used an OH-58C Kiowa helicopter and ground-based ADS-B stations at NASA Armstrong to collect baseline signal information.
NASA’s research in ADS-B signals and other communication, navigation, and surveillance systems will help revolutionize U.S. air transportation. Air Mobility Pathfinders researchers will evaluate the data from the three separate flight tests to understand the different signal transmission conditions and equipment needed for air taxis and drones to safely operate in the National Air Space. NASA will use the results of this research to design infrastructure to support future air taxi communication, navigation, and surveillance research and to develop new ADS-B-like concepts for uncrewed aircraft systems.
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Last Updated Jan 23, 2025 EditorDede DiniusContactLaura Mitchelllaura.a.mitchell@nasa.govLocationArmstrong Flight Research Center Related Terms
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By NASA
2 Min Read Advanced Modeling Enhances Gateway’s Lunar Dust Defense
A sample holder in a vacuum chamber spins during a lunar dust adhesion test at NASA’s Johnson Space Center. Credits: NASA/Josh Litofsky NASA’s Artemis campaign aims to return humans to the Moon, develop a sustainable presence there, and lay the groundwork for the first crewed missions to Mars. As the agency prepares for longer stays on and around the Moon, engineers are working diligently to understand the complex behavior of lunar dust, the sharp, jagged particles that can cling to spacesuits and jam equipment.
Lunar dust has posed a problem since astronauts first encountered it during the Apollo missions. Ahead of more frequent and intense contact with dust, NASA is developing new strategies to protect equipment as astronauts travel between the Moon and spacecraft like Gateway, humanity’s first lunar space station.
Josh Litofsky, systems engineer at NASA’s Johnson Space Center, scoops material designed to behave like lunar dust to test how it adheres to Gateway materials. NASA/Bill Stafford Unlike Apollo-era spacecraft that faced lunar dust exposure just once, Gateway will encounter it each time a Human Landing System spacecraft returns to the space station from the lunar South Pole region. Dust could enter Gateway’s environment, risking damage to science instruments, solar arrays, robotic systems, and other important hardware.
Josh Litofsky is the principal investigator and project manager leading a Gateway lunar dust adhesion testing campaign at NASA’s Johnson Space Center in Houston. His team tracks how the dust interacts with materials used to build Gateway.
An artist’s rendering of the Gateway lunar space station in polar orbit around the Moon. NASA/Alberto Bertolin “The particles are jagged from millions of years of micrometeoroid impacts, sticky due to chemical and electrical forces, and extremely small,” Litofsky said. “Even small amounts of lunar dust can have a big impact on equipment and systems.”
Litofksy’s work seeks to validate the Gateway On-orbit Lunar Dust Modeling and Analysis Program (GOLDMAP), developed by Ronald Lee, also of Johnson Space Center. By considering factors such as the design and configuration of the space station, the materials used, and the unique conditions in lunar orbit, GOLDMAP helps predict how dust may move and settle on Gateway’s external surfaces.
Josh Litofsky, systems engineer at NASA’s Johnson Space Center, places a sample holder inside a vacuum chamber to test how lunar dust sticks to Gateway materials. NASA/Bill StaffordNASA/Bill Stafford Early GOLDMAP simulations have shown that lunar dust can form clouds around Gateway, with larger particles sticking to surfaces.
The data from these tests and simulations will help NASA safeguard Gateway, to ensure the space station’s longevity during the next era of lunar exploration.
The lessons learned managing lunar dust and other harsh conditions through Gateway and Artemis will prepare NASA and its international partners for missions deeper into the cosmos
Learn More About Gateway Facebook logo @NASAGateway @NASA_Gateway Instagram logo @nasaartemis Share
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Last Updated Jan 22, 2025 ContactLaura RochonLocationJohnson Space Center Related Terms
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
A Boeing 777-300ER aircraft is being inspected by one of Near Earth Autonomy’s drones Feb. 2, 2024, at an Emirates Airlines facility in Dubai, United Arab Emirates.Near Earth Autonomy A small business called Near Earth Autonomy developed a time-saving solution using drones for pre-flight checks of commercial airliners through a NASA Small Business Innovation Research (SBIR) program and a partnership with The Boeing Company.
Before commercial airliners are deemed safe to fly before each trip, a pre-flight inspection must be completed. This process can take up to four hours, and can involve workers climbing around the plane to check for any issues, which can sometimes result in safety mishaps as well as diagnosis errors.
With NASA and Boeing funding to bolster commercial readiness, Near Earth Autonomy developed a drone-enabled solution, under their business unit Proxim, that can fly around a commercial airliner and gather inspection data in less than 30 minutes. The drone can autonomously fly around an aircraft to complete the inspection by following a computer-programmed task card based on the Federal Aviation Administration’s rules for commercial aircraft inspection. The card shows the flight path the drone’s software needs to take, enabling aircraft workers with a new tool to increase safety and efficiency.
“NASA has worked with Near Earth Autonomy on autonomous inspection challenges in multiple domains,” says Danette Allen, NASA senior leader for autonomous systems.
“We are excited to see this technology spin out to industry to increase efficiencies, safety, and accuracy of the aircraft inspection process for overall public benefit.”
The photos collected from the drone are shared and analyzed remotely, which allows experts in the airline maintenance field to support repair decisions faster from any location. New images can be compared to old images to look for cracks, popped rivets, leaks, and other common issues.
The user can ask the system to create alerts if an area needs to be inspected again or fails an inspection. Near Earth Autonomy estimates that using drones for aircraft inspection can save the airline industry an average of $10,000 per hour of lost earnings during unplanned time on the ground.
Over the last six years, Near Earth Autonomy completed several rounds of test flights with their drone system on Boeing aircraft used by American Airlines and Emirates Airlines.
NASA’s Small Business Innovation Research / Small Business Technology Transfer program, managed by the agency’s Space Technology Mission Directorate, aims to bolster American ingenuity by supporting innovative ideas put forth by small businesses to fulfill NASA and industry needs. These research needs are described in annual SBIR solicitations and target technologies that have significant potential for successful commercialization.
Small business concerns with 500 or fewer employees, or small businesses partnering with a non-profit research institution such as a university or a research laboratory can apply to participate in the NASA SBIR/STTR program.
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Last Updated Jan 03, 2025 EditorDede DiniusContactTeresa Whitingteresa.whiting@nasa.govLocationArmstrong Flight Research Center Related Terms
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