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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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By NASA
5 Min Read Webb Maps Full Picture of How Phoenix Galaxy Cluster Forms Stars
Spectroscopic data collected from NASA’s James Webb Space Telescope is overlayed on an image of the Phoenix cluster that combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope. Credits:
NASA, CXC, NRAO, ESA, M. McDonald (MIT), M. Reefe (MIT), J. Olmsted (STScI) Discovery proves decades-old theory of galaxy feeding cycle.
Researchers using NASA’s James Webb Space Telescope have finally solved the mystery of how a massive galaxy cluster is forming stars at such a high rate. The confirmation from Webb builds on more than a decade of studies using NASA’s Chandra X-ray Observatory and Hubble Space Telescope, as well as several ground-based observatories.
The Phoenix cluster, a grouping of galaxies bound together by gravity 5.8 billion light-years from Earth, has been a target of interest for astronomers due to a few unique properties. In particular, ones that are surprising: a suspected extreme cooling of gas and a furious star formation rate despite a roughly 10 billion solar mass supermassive black hole at its core. In other observed galaxy clusters, the central supermassive black hole powers energetic particles and radiation that prevents gas from cooling enough to form stars. Researchers have been studying gas flows within this cluster to try to understand how it is driving such extreme star formation.
Image A: Phoenix Cluster (Hubble, Chandra, VLA Annotated)
Spectroscopic data collected from NASA’s James Webb Space Telescope is overlayed on an image of the Phoenix cluster that combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope. Webb’s powerful sensitivity in the mid-infrared detected the cooling gas that leads to a furious rate of star formation in this massive galaxy cluster. Credit: NASA, CXC, NRAO, ESA, M. McDonald (MIT), M. Reefe (MIT), J. Olmsted (STScI) “We can compare our previous studies of the Phoenix cluster, which found differing cooling rates at different temperatures, to a ski slope,” said Michael McDonald of the Massachusetts Institute of Technology in Cambridge, principal investigator of the program. “The Phoenix cluster has the largest reservoir of hot, cooling gas of any galaxy cluster — analogous to having the busiest chair lift, bringing the most skiers to the top of the mountain. However, not all of those skiers were making it down the mountain, meaning not all the gas was cooling to low temperatures. If you had a ski slope where there were significantly more people getting off the ski lift at the top than were arriving at the bottom, that would be a problem!”
To date, in the Phoenix cluster, the numbers weren’t adding up, and researchers were missing a piece of the process. Webb has now found those proverbial skiers at the middle of the mountain, in that it has tracked and mapped the missing cooling gas that will ultimately feed star formation. Most importantly, this intermediary warm gas was found within cavities tracing the very hot gas, a searing 18 million degrees Fahrenheit, and the already cooled gas around 18,000 degrees Fahrenheit.
The team studied the cluster’s core in more detail than ever before with the Medium-Resolution Spectrometer on Webb’s Mid-Infrared Instrument (MIRI). This tool allows researchers to take two-dimenstional spectroscopic data from a region of the sky, during one set of observations.
“Previous studies only measured gas at the extreme cold and hot ends of the temperature distribution throughout the center of the cluster,” added McDonald. “We were limited — it was not possible to detect the ‘warm’ gas that we were looking for. With Webb, we could do this for the first time.”
Image B: Phoenix Cluster (Hubble, Chandra, VLA)
This image of the Phoenix cluster combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory, and the Very Large Array radio telescope. X-rays from Chandra depict extremely hot gas in purple. Optical light data from Hubble show galaxies in yellow, and filaments of cooler gas where stars are forming in light blue. Outburst generated jets, represented in red, are seen in radio waves by the VLA radio telescope. NASA, CXC, NRAO, ESA, M. McDonald (MIT). A Quirk of Nature
Webb’s capability to detect this specific temperature of cooling gas, around 540,000 degrees Fahrenheit, is in part due to its instrumental capabilities. However, the researchers are getting a little help from nature, as well.
This oddity involves two very different ionized atoms, neon and oxygen, created in similar environments. At these temperatures, the emission from oxygen is 100 times brighter but is only visible in ultraviolet. Even though the neon is much fainter, it glows in the infrared, which allowed the researchers to take advantage of Webb’s advanced instruments.
“In the mid-infrared wavelengths detected by Webb, the neon VI signature was absolutely booming,” explained Michael Reefe, also of the Massachusetts Institute of Technology, lead author on the paper published in Nature. “Even though this emission is usually more difficult to detect, Webb’s sensitivity in the mid-infrared cuts through all of the noise.”
The team now hopes to employ this technique to study more typical galaxy clusters. While the Phoenix cluster is unique in many ways, this proof of concept is an important step towards learning about how other galaxy clusters form stars.The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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Laura Betz – laura.e.betz@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Hannah Braun hbraun@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
Christine Pulliam – cpulliam@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
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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 NASA
X-ray: NASA/CXC/Penn State Univ./L. Townsley et al.; Infrared: NASA/JPL-CalTech/SST; Optical: NASA/STScI/HST; Radio: ESO/NAOJ/NRAO/ALMA; Image Processing: NASA/CXC/SAO/J. Schmidt, N. Wolk, K. Arcand A bouquet of thousands of stars in bloom has arrived. This composite image contains the deepest X-ray image ever made of the spectacular star forming region called 30 Doradus.
By combining X-ray data from NASA’s Chandra X-ray Observatory (blue and green) with optical data from NASA’s Hubble Space Telescope (yellow) and radio data from the Atacama Large Millimeter/submillimeter Array (orange), this stellar arrangement comes alive.
X-ray: NASA/CXC/Penn State Univ./L. Townsley et al.; Infrared: NASA/JPL-CalTech/SST; Optical: NASA/STScI/HST; Radio: ESO/NAOJ/NRAO/ALMA; Image Processing: NASA/CXC/SAO/J. Schmidt, N. Wolk, K. Arcand Otherwise known as the Tarantula Nebula, 30 Dor is located about 160,000 light-years away in a small neighboring galaxy to the Milky Way known as the Large Magellanic Cloud (LMC). Because it one of the brightest and populated star-forming regions to Earth, 30 Dor is a frequent target for scientists trying to learn more about how stars are born.
With enough fuel to have powered the manufacturing of stars for at least 25 million years, 30 Dor is the most powerful stellar nursery in the local group of galaxies that includes the Milky Way, the LMC, and the Andromeda galaxy.
The massive young stars in 30 Dor send cosmically strong winds out into space. Along with the matter and energy ejected by stars that have previously exploded, these winds have carved out an eye-catching display of arcs, pillars, and bubbles.
A dense cluster in the center of 30 Dor contains the most massive stars astronomers have ever found, each only about one to two million years old. (Our Sun is over a thousand times older with an age of about 5 billion years.)
This new image includes the data from a large Chandra program that involved about 23 days of observing time, greatly exceeding the 1.3 days of observing that Chandra previously conducted on 30 Dor. The 3,615 X-ray sources detected by Chandra include a mixture of massive stars, double-star systems, bright stars that are still in the process of forming, and much smaller clusters of young stars.
There is a large quantity of diffuse, hot gas seen in X-rays, arising from different sources including the winds of massive stars and from the gas expelled by supernova explosions. This data set will be the best available for the foreseeable future for studying diffuse X-ray emission in star-forming regions.
The long observing time devoted to this cluster allows astronomers the ability to search for changes in the 30 Dor’s massive stars. Several of these stars are members of double star systems and their movements can be traced by the changes in X-ray brightness.
A paper describing these results appears in the July 2024 issue of The Astrophysical Journal Supplement Series. NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory.
Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features a highly detailed composite image of a star-forming region of space known as 30 Doradus, shaped like a bouquet, or a maple leaf.
30 Doradus is a powerful stellar nursery. In 23 days of observation, the Chandra X-ray telescope revealed thousands of distinct star systems. Chandra data also revealed a diffuse X-ray glow from winds blowing off giant stars, and X-ray gas expelled by exploding stars, or supernovas.
In this image, the X-ray wind and gas takes the shape of a massive purple and pink bouquet with an extended central flower, or perhaps a leaf from a maple tree. The hazy, mottled shape occupies much of the image, positioned just to our left of center, tilted slightly to our left. Inside the purple and pink gas and wind cloud are red and orange veins, and pockets of bright white light. The pockets of white light represent clusters of young stars. One cluster at the heart of 30 Doradus houses the most massive stars astronomers have ever found.
The hazy purple and pink bouquet is surrounded by glowing dots of green, white, orange, and red. A second mottled purple cloud shape, which resembles a ring of smoke, sits in our lower righthand corner.
News Media Contact
Megan Watzke
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Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
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By NASA
“People are excited and happy about working at Goddard,” said optics engineer Margaret Dominguez. “Most people are willing to put in the extra effort if needed. It makes work stimulating and exciting. Management really cares and the employees feel that too.”Credits: Courtesy of Margaret Dominguez Name: Margaret Dominguez
Formal Job Classification: Optical engineer
Organization: Code 551, Optics Branch, Instrument Systems and Technology Division, Engineering Directorate
What do you do and what is most interesting about your role here at Goddard? How do you help support Goddard’s mission?
I build space telescopes. I am currently working on building one of the components for the Wide Field Instrument for the Roman Space Telescope. The component is called “Grism.” A grism is a combination of a grating and a prism.
What is unique about your childhood?
I went to high school in Tecamachalco in Puebla, Mexico, which is inland and south of Mexico City. My father raised pigs, chickens, rabbits, and cows. I am the oldest of four girls and two still live on the farm.
Why did you become a physicist?
I was always curious and had a lot of questions and thought that physics helped me answer some of these questions. I was good at math and loved it. When I told my dad I wanted to study physics, he said that I would be able to answer any question in the universe. He thought it was very cool.
What is your educational background? How an internship help you come to Goddard?
I went to the Universidad de las Americas Puebla college in Puebla and got an undergraduate degree in physics. I was very active in extracurricular activities and helped organize a physics conference. We invited Dr. Johnathan Gardner, a Goddard astronomer, who came to speak at the conference. Afterwards I spoke with him and he asked me if I was interested in doing an internship at NASA. I said I had not considered it and would be interested in applying. I applied that same spring of 2008 and got a summer internship in the Optics Branch, where I am still working today.
My branch head at Goddard was a University of Arizona alumnus. He suggested that I apply to the University of Arizona for their excellent optics program. I did, and the university gave me a full fellowship for a master’s and a Ph.D. in optical sciences.
In 2014, I began working full time at Goddard while completing my Ph.D. I graduated in May 2019.
What makes Goddard special?
Goddard has a university campus feel. It’s a place where you can work and also just hang out and socialize. Goddard has many clubs, a gym, cafeterias, and a health clinic.
People are really nice here. They are often excited and happy about working at Goddard. Most people are willing to put in the extra effort if needed. It makes work stimulating and exciting. Management really cares and the employees feel that too.
What are some of the major projects you have worked on?
Early on, I did a little bit of work on Hubble and later on, NASA’s James Webb Space Telescope. Since 2014, I have exclusively been working on Roman. We are building the grism, a slitless spectrograph, which will measure galaxy redshifts to study dark energy.
Presently we are building different grism prototypes. We work with outside vendors to build these prototypes. When we make a prototype, we test it for months. After, we use the results to build an improved prototype. We just finished making the third prototype. We are going to build a flight instrument of which the grism is a component.
What is it like to work in the clean room?
It’s exciting – it likely means I am working on flight hardware. However, because clean rooms must be kept at about 68 degrees Fahrenheit, it can feel chilly in there!
Who are your mentors? What are the most important lessons they have taught you?
Ray Ohl, the head of the Optics Branch, is a mentor to me. He is always encouraging me to get outside my comfort zone. He presents other opportunities to me so that I can grow and listens to my feedback.
Cathy Marx, one of the Roman optical leads, is also a mentor to me. She created a support network for me and is a sounding board for troubleshooting any kind of work-related issues.
What is your role a member of the Hispanic Advisory Committee (HACE)?
I joined HACE in 2010 while I was an intern. It’s a great opportunity to network with other Hispanics and gives us a platform to celebrate specific events like Hispanic Heritage Month. I really enjoy participating in HACE’s events.
What outreach do you do? Why is doing outreach so important to you?
I do educational outreach to teach people about optics. I mainly collaborate with elementary and middle schools.
I think we need more future engineers and scientists. I want to help recruit them. I specifically focus on recruiting minorities and Hispanics. I can make a special connection with women and Hispanics.
Who is your science hero?
It would probably be Marie Curie. She’s the first woman to win a Nobel Prize, and she is the only woman to win two Nobel Prizes and she had to overcome a lot of challenges to achieve that.
What is your “six-word memoir”? A six-word memoir describes something in just six words.
Disciplined. Organized. Diligent. Passionate. Curious. Family-oriented.
Is there something surprising about your hobbies outside of work that people do not generally know?
I am a certified Jazzercise instructor – I normally teach two to three times a week. I can even teach virtually if need be. It is an hour-long exercise class combining strength training and cardio through choreographed dancing. We also use weights and mats.
I also enjoy going for walks with my husband, James Corsetti, who is also an engineer in the Optics Branch.
By Elizabeth M. Jarrell
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Conversations With Goddard is a collection of Q&A profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage.
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