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By NASA
Advancing Single-Photon Sensing Image Sensors to Enable the Search for Life Beyond Earth
A NASA-sponsored team is advancing single-photon sensing Complementary Metal-Oxide-Semiconductor (CMOS) detector technology that will enable future NASA astrophysics space missions to search for life on other planets. As part of their detector maturation program, the team is characterizing sensors before, during, and after high-energy radiation exposure; developing novel readout modes to mitigate radiation-induced damage; and simulating a near-infrared CMOS pixel prototype capable of detecting individual photons.
Single-photon sensing and photon-number resolving CMOS image sensors: a 9.4 Mpixel sensor (left) and a 16.7 Mpixel sensor (right). Credit: CfD, RIT Are we alone in the universe? This age-old question has inspired scientific exploration for centuries. If life on other planets evolves similarly to life on Earth, it can imprint its presence in atmospheric spectral features known asbiosignatures. They include absorption and emission lines in the spectrum produced by oxygen, carbon dioxide, methane, and other molecules that could indicate conditions which can support life. A future NASA astrophysics mission, the Habitable Worlds Observatory (HWO), will seek to find biosignatures in the ultraviolet, optical, and near-infrared (NIR) spectra of exoplanet atmospheres to look for evidence that life may exist elsewhere in the universe.
HWO will need highly sensitive detector technology to detect these faint biosignatures on distant exoplanets. The Single-Photon Sensing Complementary Metal-Oxide-Semiconductor (SPSCMOS) image sensor is a promising technology for this application. These silicon-based sensors can detect and resolve individual optical-wavelength photons using a low-capacitance, high-gain floating diffusion sense node. They operate effectively over a broad temperature range, including at room temperature. They have near-zero read noise, are tolerant to radiation, and generate very little unwanted signal—such as dark current. When cooled to 250 K, the dark current drops to just one electron every half-hour. If either the read noise or dark current is too high, the sensor will fail to detect the faint signals that biosignatures produce.
A research team at the Rochester Institute of Technology (RIT) Center for Detectors (CfD) is accelerating the readiness of these SPSCMOS sensors for use in space missions through detector technology maturation programs funded by NASA’s Strategic Astrophysics Technology and Early Stage Innovations solicitations. These development programs include several key goals:
Characterize critical detector performance metrics like dark current, quantum efficiency, and read noise before, during, and after exposure to high-energy radiation Develop new readout modes for these sensors to mitigate effects from short-term and long-term radiation damage Design a new NIR version of the sensor using Technology Computer-Aided Design (TCAD) software SPSCMOS sensors operate similarly to traditional CMOS image sensors but are optimized to detect individual photons—an essential capability for ultra-sensitive space-based observations, such as measuring the gases in the atmospheres of exoplanets. Incoming photons enter the sensor and generate free charges (electrons) in the sensor material. These charges collect in a pixel’s storage well and eventually transfer to a low-capacitance component called the floating diffusion (FD) sense node where each free charge causes a large and resolved voltage shift. This voltage shift is then digitized to read the signal.
Experiments that measure sensor performance in a space relevant environment use a vacuum Dewar and a thermally-controlled mount to allow precise tuning of the sensors temperature. The Dewar enables testing at conditions that match the expected thermal environment of the HWO instrument, and can even cool the sensor and its on-chip circuits to temperatures colder than any prior testing reported for this detector family. These tests are critical for revealing performance limitations with respect to detector metrics like dark current, quantum efficiency, and read noise. As temperatures change, the electrical properties of on-chip circuits can also change, which affects the read out of charge in a pixel.
The two figures show results for SPSCMOS devices. The figure on the left shows a photon counting histogram with peaks that correspond to photon number. The figure on the right shows the dark current for a SPSCMOS device before and after exposure to 50 krad of 60 MeV protons. Credit: CfD, RIT The radiation-rich environment for HWO will cause temporary and permanent effects in the sensor. These effects can corrupt the signal measured in a pixel, interrupt sensor clocking and digital logic, and can cause cumulative damage that gradually degrades sensor performance. To mitigate the loss of detector sensitivity throughout a mission lifetime, the RIT team is developing new readout modes that are not available in commercial CMOS sensors. These custom modes sample the signal over time (a “ramp” acquisition) to enable the detection and removal of cosmic ray artifacts. In one mode, when the system identifies an artifact, it segments the signal ramp and selectively averages the segments to reconstruct the original signal—preserving scientific data that would otherwise be lost. In addition, a real-time data acquisition system monitors the detector’s power consumption, which may change from the accumulation of damage throughout a mission. The acquisition system records these shifts and communicates with the detector electronics to adjust voltages and maintain nominal operation. These radiation damage mitigation strategies will be evaluated during a number of test programs at ground-based radiation facilities. The tests will help identify unique failure mechanisms that impact SPSCMOS technology when it is exposed to radiation equivalent to the dose expected for HWO.
Custom acquisition electronics (left) that will control the sensors during radiation tests, and an image captured using this system (right). Credit: CfD, RIT While existing SPSCMOS sensors are limited to detecting visible light due to their silicon-based design, the RIT team is developing the world’s first NIR single-photon photodiode based on the architecture used in the optical sensors. The photodiode design starts as a simulation in TCAD software to model the optical and electrical properties of the low-capacitance CMOS architecture. The model simulates light-sensitive circuits using both silicon and Mercury Cadmium Telluride (HgCdTe or MCT) material to determine how well the pixel would measure photo-generated charge if a semiconductor foundry physically fabricated it. It has 2D and 3D device structures that convert light into electrical charge, and circuits to control charge transfer and signal readout with virtual probes that can measure current flow and electric potential. These simulations help to evaluate the key mechanisms like the conversion of light into electrons, storing and transferring the electrons, and the output voltage of the photodiode sampling circuit.
In addition to laboratory testing, the project includes performance evaluations at a ground-based telescope. These tests allow the sensor to observe astronomical targets that cannot be fully replicated in lab. Star fields and diffuse nebulae challenge the detector’s full signal chain under real sky backgrounds with faint flux levels, field-dependent aberrations, and varying seeing conditions. These observations help identify performance limitations that may not be apparent in controlled laboratory measurements.
In January 2025, a team of researchers led by PhD student Edwin Alexani used an SPSCMOS-based camera at the C.E.K. Mees Observatory in Ontario County, New York. They observed star cluster M36 to evaluate the sensor’s photometric precision, and the Bubble Nebula in a narrow-band H-alpha filter. The measured dark current and read noise were consistent with laboratory results.
The team observed photometric reference stars to estimate the quantum efficiency (QE) or the ability for the detector to convert photons into signal. The calculated QE agreed with laboratory measurements, despite differences in calibration methods.
The team also observed the satellite STARLINK-32727 as it passed through the telescope’s field of view and measured negligible persistent charge—residual signal that can remain in detector pixels after exposure to a bright source. Although the satellite briefly produced a bright streak across several pixels due to reflected sunlight, the average latent charge in affected pixels was only 0.03 e–/pix – well below both the sky-background and sensor’s read noise.
Images captured at the C.E.K. Mees Observatory. Left: The color image shows M36 in the Johnson color filters B (blue), V (green), and R (red) bands (left). Right: Edwin Alexani and the SPSCMOS camera (right). Credit: : CfD, RIT As NASA advances and matures the HWO mission, SPSCMOS technology promises to be a game-changer for exoplanet and general astrophysics research. These sensors will enhance our ability to detect and analyze distant worlds, bringing us one step closer to answering one of humanity’s most profound questions: are we alone?
For additional details, see the entry for this project on NASA TechPort.
Project Lead(s): Dr. Donald F. Figer, Future Photon Initiative and Center for Detectors, Rochester Institute of Technology (RIT), supported by engineer Justin Gallagher and a team of students.
Sponsoring Organization(s): NASA Astrophysics Division, Strategic Astrophysics Technology (SAT) Program and NASA Space Technology Mission Directorate (STMD), Early Stage Innovations (ESI) Program
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Last Updated Sep 02, 2025 Related Terms
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By NASA
Astronaut Victor Glover interacts with an Orion spacecraft simulator during NASA’s “All-Star Shoot for the Stars” event at The Children’s Museum of Indianapolis on Saturday, July 18, 2025. Credit: NASA/Zach Lucas From astronauts to athletes, researchers to referees, and communicators to coaches, NASA is much like basketball – we all train to reach the top of our game. Staff from NASA’s Glenn Research Center in Cleveland drove home this point during the “All-Star Shoot for the Stars” event at The Children’s Museum of Indianapolis, July 17-19. As part of WNBA All-Star Game activities, this event highlighted NASA technology while illuminating the intersection of sports and STEM.
The event offered a captivating look into space exploration, thanks to the combined efforts of NASA and museum staff. Highlights included a detailed Orion exhibit, a new spacesuit display featuring five full-scale spacesuits, and virtual reality demonstrations. Visitors also had the chance to enjoy an interactive spacesuit app and a unique cosmic selfie station.
On Friday, July 18, 2025, visitors at NASA’s “All-Star Shoot for the Stars” event at The Children’s Museum of Indianapolis look at a new spacesuit display featuring five full-scale spacesuits. Credit: NASA/Christopher Richards The event was made even more memorable by Artemis II astronaut Victor Glover, who connected with visitors and posed for photos. WNBA legend Tamika Catchings also made a special appearance, inspiring attendees with a message to “aim high!”
“All Star Weekend presented an excellent opportunity to share NASA’s mission with the Indianapolis community and people across the Midwest who were in town for the game,” said Jan Wittry, Glenn’s news chief. “I saw children’s faces light up as they interacted with the exhibits and talked to NASA experts, sparking a curiosity among our potential future STEM workforce.”
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Ocean currents swirl around North America (center left) and Greenland (upper right) in this data visualization created using NASA’s ECCO model. Advanced computing is helping oceanographers decipher hot spots of phytoplankton growth.NASA’s Scientific Visualization Studio As Greenland’s ice retreats, it’s fueling tiny ocean organisms. To test why, scientists turned to a computer model out of JPL and MIT that’s been called a laboratory in itself.
Runoff from Greenland’s ice sheet is kicking nutrients up from the ocean depths and boosting phytoplankton growth, a new NASA-supported study has found. Reporting in Nature Communications: Earth & Environment, the scientists used state-of-the art-computing to simulate marine life and physics colliding in one turbulent fjord. Oceanographers are keen to understand what drives the tiny plantlike organisms, which take up carbon dioxide and power the world’s fisheries.
Greenland’s mile-thick ice sheet is shedding some 293 billion tons (266 billion metric tons) of ice per year. During peak summer melt, more than 300,000 gallons (1,200 cubic meters) of fresh water drain into the sea every second from beneath Jakobshavn Glacier, also known as Sermeq Kujalleq,the most active glacier on the ice sheet. The waters meet and tumble hundreds of feet below the surface.
Teal-colored phytoplankton bloom off the Greenland coast in this satellite image captured in June 2024 by NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) mission.NASA The meltwater plume is fresh and more buoyant than the surrounding saltwater. As it rises, scientists have hypothesized, it may be delivering nutrients like iron and nitrate — a key ingredient in fertilizer — to phytoplankton floating at the surface.
Researchers track these microscopic organisms because, though smaller by far than a pinhead, they’re titans of the ocean food web. Inhabiting every ocean from the tropics to the polar regions, they nourish krill and other grazers that, in turn, support larger animals, including fish and whales.
Previous work using NASA satellite data found that the rate of phytoplankton growth in Arctic waters surged 57% between 1998 and 2018 alone. An infusion of nitrate from the depths would be especially pivotal to Greenland’s phytoplankton in summer, after most nutrients been consumed by prior spring blooms. But the hypothesis has been hard to test along the coast, where the remote terrain and icebergs as big as city blocks complicate long-term observations.
“We were faced with this classic problem of trying to understand a system that is so remote and buried beneath ice,” said Dustin Carroll, an oceanographer at San José State University who is also affiliated with NASA’s Jet Propulsion Laboratory in Southern California. “We needed a gem of a computer model to help.”
Sea of Data
To re-create what was happening in the waters around Greenland’s most active glacier, the team harnessed a model of the ocean developed at JPL and the Massachusetts Institute of Technology in Cambridge. The model ingests nearly all available ocean measurements collected by sea- and satellite-based instruments over the past three decades. That amounts to billions of data points, from water temperature and salinity to pressure at the seafloor. The model is called Estimating the Circulation and Climate of the Ocean-Darwin (ECCO-Darwin for short).
Simulating “biology, chemistry, and physics coming together” in even one pocket along Greenland’s 27,000 miles (43,000 kilometers) of coastline is a massive math problem, noted lead author Michael Wood, a computational oceanographer at San José State University. To break it down, he said the team built a “model within a model within a model” to zoom in on the details of the fjord at the foot of the glacier.
Using supercomputers at NASA’s Ames Research Center in Silicon Valley, they calculated that deepwater nutrients buoyed upward by glacial runoff would be sufficient to boost summertime phytoplankton growth by 15 to 40% in the study area.
More Changes in Store
Could increased phytoplankton be a boon for Greenland’s marine animals and fisheries? Carroll said that untangling impacts to the ecosystem will take time. Melt on the Greenland ice sheet is projected to accelerate in coming decades, affecting everything from sea level and land vegetation to the saltiness of coastal waters.
“We reconstructed what’s happening in one key system, but there’s more than 250 such glaciers around Greenland,” Carroll said. He noted that the team plans to extend their simulations to the whole Greenland coast and beyond.
Some changes appear to be impacting the carbon cycle both positively and negatively: The team calculated how runoff from the glacier alters the temperature and chemistry of seawater in the fjord, making it less able to dissolve carbon dioxide. That loss is canceled out, however, by the bigger blooms of phytoplankton taking up more carbon dioxide from the air as they photosynthesize.
Wood added: “We didn’t build these tools for one specific application. Our approach is applicable to any region, from the Texas Gulf to Alaska. Like a Swiss Army knife, we can apply it to lots of different scenarios.”
News Media Contacts
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 / 818-354-0307
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
Written by Sally Younger
2025-101
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Last Updated Aug 06, 2025 Related Terms
Earth Carbon Cycle Earth Science Ice & Glaciers Jet Propulsion Laboratory Oceans PACE (Plankton, Aerosol, Cloud, Ocean Ecosystem) Water on Earth Explore More
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By NASA
The NASA Ames Science Directorate recognizes the outstanding contributions of (pictured left to right) Sigrid Reinsch, Lori Munar, Kevin Sims, and Matthew Fladeland. Their commitment to the NASA mission represents the entrepreneurial spirit, technical expertise, and collaborative disposition needed to explore this world and beyond.
Space Biosciences Star: Sigrid Reinsch
As Director of the SHINE (Space Health Impacts for the NASA Experience) program and Project Scientist for NBISC (NASA Biological Institutional Scientific Collection), Sigrid Reinsch is a high-performing scientist and outstanding mentor in the Space Biosciences Research Branch. Her dedication to student training and her efforts to streamline processes have significantly improved the experience of welcoming summer interns at NASA Ames.
Space Science and Astrobiology Star: Lori Munar
Lori Munar serves as the assistant Branch Chief of the Exobiology Branch. In the past few months, she has gone above and beyond to organize a facility and laboratory surplus event that involved multiple divisions over multiple days. The event resulted in considerable savings across the groups involved and improved the safety of N239 staff and the appearance of offices and labs.
Space Science and Astrobiology Star: Kevin Sims
Kevin Sims is a NASA Technical Project Manager serving the Astrophysics Branch as a member of the Flight Systems Implementation Branch in the Space Biosciences Division. Kevin is recognized for outstanding project management for exoplanet imaging instrumentation development in support of the Habitable Worlds Observatory. Kevin has streamlined, organized, and improved the efficiency of the Ames Photonics Testbed being developed as part the AstroPIC Early Career Initiative project.
Earth Science Star: Matthew Fladeland
Matthew Fladeland is a research scientist in the Earth Science Division managing NASA SMD’s Program Office for the Airborne Science Program, located at Ames. He is recognized for exemplary leadership and teamwork leading to new reimbursable agreements with the Department of Defense, for accelerating science technology solutions through the SBIR program, and for advancing partnerships with the US Forest Service on wildland ecology and fire science.
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