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By NASA
Research Astrophysicist and Roman’s Deputy Wide Field Instrument Scientist – Goddard Space Flight Center
From a young age, Ami Choi — now a research astrophysicist at NASA — was drawn to the vast and mysterious. By the fifth grade, she had narrowed her sights to two career paths: marine biology or astrophysics.
“I’ve always been interested in exploring big unknown realms, and things that aren’t quite tangible,” Choi said. That curiosity has served her all throughout her career.
In addition to conducting research, Ami Choi shares science with the public at various outreach events, including tours at NASA’s Goddard Space Flight Center in Greenbelt, Md. This photo captures one tour stop, outside the largest clean room at Goddard.Credit: NASA/Travis Wohlrab As a student at University Laboratory High School in Urbana, Illinois, Choi gravitated toward astrophysics and was fascinated by things like black holes. She studied physics as an undergraduate at the University of Chicago, though she says math and physics didn’t necessarily come easily to her.
“I wasn’t very good at it initially, but I really liked the challenge so I stuck with it,” Choi said.
Early opportunities to do research played a pivotal role in guiding her career. As an undergraduate, Choi worked on everything from interacting galaxies to the stuff in between stars in our galaxy, called the interstellar medium. She learned how to code, interpret data, and do spectroscopy, which involves splitting light from cosmic objects into a rainbow of colors to learn about things like their composition.
After college, Choi read an article about physicist Janet Conrad’s neutrino work at Fermilab and was so inspired by Conrad’s enthusiasm and inclusivity that she cold-emailed her to see if there were any positions available in her group.
On October 14, 2023, Ami took a break from a thermal vacuum shift to snap a selfie with a partial eclipse. She was visiting BAE, Inc. in Boulder, Co., where the primary instrument for NASA’s Nancy Grace Roman Space Telescope was undergoing testing. Credit: Courtesy of Ami Choi “That one email led to a year at Fermilab working on neutrino physics,” Choi said.
She went on to earn a doctorate at the University of California, Davis, where she studied weak gravitational lensing — the subtle warping of light by gravity — and used it to explore dark matter, dark energy, and the large-scale structure of the universe.
Her postdoctoral work took Choi first to the University of Edinburgh in Scotland, where she contributed to the Kilo-Degree Survey, and later to The Ohio State University, where she became deeply involved in DES (the Dark Energy Survey) and helped lay the groundwork for the Nancy Grace Roman Space Telescope — NASA’s next flagship astrophysics mission.
“One of my proudest moments came in 2021, when the DES released its third-year cosmology results,” Choi said. “It was a massive team effort conducted during a global pandemic, and I had helped lead as a co-convener of the weak lensing team.”
Choi regularly presents information about NASA’s Nancy Grace Roman Space Telescope to fellow scientists and the public. Here, she gives a Hyperwall talk at an AAS (American Astronomical Society) meeting.Credit: Courtesy of Ami Choi After a one-year stint at the California Institute of Technology in Pasadena, where Choi worked on SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer)—an observatory that’s surveying stars and galaxies—she became a research astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. She also serves as the deputy Wide Field Instrument scientist for Roman. Choi operates at the intersection of engineering, calibration, and cosmology, helping translate ground-based testing into flight-ready components that will help Roman reveal large swaths of the universe in high resolution.
“I’m very excited for Roman’s commissioning phase — the first 90 days when the spacecraft will begin transmitting data from orbit,” Choi said.
Choi, photographed here in Death Valley, finds joy in the natural world outside of work. She cycles, hikes, and tends a small vegetable garden with a friend from grad school. Credit: Insook Choi (used with permission) She’s especially drawn to so-called systematics, which are effects that can alter the signals scientists are trying to measure. “People sometimes think of systematics as nuisances, but they’re often telling us something deeply interesting about either the physics of something like a detector or the universe itself,” Choi said. “There’s always something more going on under the surface.”
While she’s eager to learn more about things like dark energy, Choi is also looking forward to seeing all the other ways our understanding of the universe grows. “It’s more than just an end goal,” she said. “It’s about everything we learn along the way. Every challenge we overcome, every detail we uncover, is an important discovery too.”
For those who hope to follow a similar path, Choi encourages staying curious, being persistent, and taking opportunities to get involved in research. And don’t let the tricky subjects scare you away! “You don’t have to be perfect at math or physics right away,” she said. “What matters most is a deep curiosity and the tenacity to keep pushing through.”
By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Sep 09, 2025 EditorAshley BalzerLocationGoddard Space Flight Center Related Terms
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By NASA
NASA’s James Webb Space Telescope recently imaged the Sombrero Galaxy with its NIRCam (Near-Infrared Camera), which shows dust from the galaxy’s outer ring blocking stellar light from stars within the galaxy. In the central region of the galaxy, the roughly 2,000 globular clusters, or collections of hundreds of thousands of old stars held together by gravity, glow in the near-infrared. The Sombrero Galaxy is around 30 million light-years from Earth in the constellation Virgo. From Earth, we see this galaxy nearly “edge-on,” or from the side.NASA, ESA, CSA, STScI After capturing an image of the iconic Sombrero galaxy at mid-infrared wavelengths in late 2024, NASA’s James Webb Space Telescope has now followed up with an observation in the near-infrared. In the newest image, released on June 3, 2025, the Sombrero galaxy’s tightly packed group of stars at the galaxy’s center is illuminated while the dust in the outer edges of the disk blocks some stellar light. Studying galaxies like the Sombrero at different wavelengths, including the near-infrared and mid-infrared with Webb, as well as the visible with NASA’s Hubble Space Telescope, helps astronomers understand how this complex system of stars, dust, and gas formed and evolved, along with the interplay of that material.
Learn more about the Sombrero galaxy and what this new view can tell us.
Image credit: NASA, ESA, CSA, STScI
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By NASA
Explore This Section Science Science Activation Take a Tour of the Cosmos with… Overview Learning Resources Science Activation Teams SME Map Opportunities More Science Activation Stories Citizen Science 4 min read
Take a Tour of the Cosmos with New Interactives from NASA’s Universe of Learning
Ready for a tour of the cosmos? NASA’s Universe of Learning has released a new, dynamic way for lifelong learners to explore NASA’s breathtaking images of the universe—ViewSpace interactive Image Tours. ViewSpace has an established track record of providing museums, science centers, libraries, and other informal learning environments with free, web-based videos and digital interactives—like its interactive Image Sliders. These new Image Tours are another unique experience from NASA’s Universe of Learning, created through a collaboration between scientists that operate NASA telescopes and experts well-versed in the most modern methods of learning. Hands-on, self-directed learning resources like these have long been valued by informal learning sites as effective means for engaging and intriguing users with the latest discoveries from NASA’s space telescope missions—while encouraging lifelong learners to continue their passionate exploration of the stars, galaxies, and distant worlds.
With these new ViewSpace Image Tours, visitors can take breathtaking journeys through space images that contain many exciting stories. The “Center of the Milky Way Galaxy” Tour, for example, uses breathtaking images from NASA’s Hubble, Spitzer, and Chandra X-ray telescopes and includes eleven Tour Stops, where users can interact with areas like “the Brick”—a dense, dark cloud of hydrogen molecules imaged by Spitzer. Another Tour Stop zooms toward the supermassive black hole, Sagittarius A*, offering a dramatic visual journey to the galaxy’s core.
In other tours, like the “Herbig-Haro 46/47” Tour, learners can navigate through points of interest in an observation from a single telescope mission. In this case, NASA’s James Webb Space Telescope provides the backdrop where lifelong learners can explore superheated jets of gas and dust being ejected at tremendous speeds from a pair of young, forming stars. The power of Webb turns up unexpected details in the background, like a noteworthy distant galaxy famous for its uncanny resemblance to a question mark. Each Interactive Image Tour allows people to examine unique features through videos, images, or graphical overlays to identify how those features have formed in ways that static images alone can’t convey.
These tours, which include detailed visual descriptions for each Tour Stop, illuminate the science behind the beauty, allowing learners of all ages to develop a greater understanding of and excitement for space science, deepening their engagement with astronomy, regardless of their prior experience. Check out the About the Interactives page on the ViewSpace website for a detailed overview of how to use the Image Tours.
ViewSpace currently offers three Image Tours, and the collection will continue growing:
Center of the Milky Way Galaxy:
Peer through cosmic dust and uncover areas of intense activity near the Milky Way’s core, featuring imagery from the Hubble Space Telescope, Spitzer Space Telescope, and the Chandra X-ray Observatory.
Herbig-Haro 46/47:
Witness how a tightly bound pair of young stars shapes their nebula through ejections of gas and dust in an image from the James Webb Space Telescope.
The Whirlpool Galaxy:
Explore the iconic swirling arms and glowing core of a stunning spiral galaxy, with insights into star formation, galaxy structure, and more in a Hubble Space Telescope image.
“The Image Tours are beautiful, dramatic, informational, and easy to use,” explained Sari Custer, Chief of Science and Curiosity at Arizona Science Center. “I’m excited to implement them in my museum not only because of the incredible images and user-friendly features, but also for the opportunity to excite and ignite the public’s curiosity about space.”
NASA’s Universe of Learning is supported by NASA under cooperative agreement award number NNX16AC65A and is part of NASA’s Science Activation Portfolio. Learn more about how Science Activation connects NASA science experts, real content, and experiences with community leaders to do science in ways that activate minds and promote deeper understanding of our world and beyond: https://science.nasa.gov/learn/about-science-activation/
Select views from various Image Tours. Clockwise from top left: The Whirlpool Galaxy, Center of the Milky Way Galaxy, Herbig-Haro 46/47, detail view in the Center of the Milky Way Galaxy. Share
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Last Updated May 13, 2025 Editor NASA Science Editorial Team Related Terms
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
This picture of Mars is a composite of several images captured by Europa Clipper’s thermal imager on March 1. Bright regions are relatively warm, with temperatures of about 32 degrees Fahrenheit (0 degrees Celsius). Darker areas are colder. The darkest region at the top is the northern polar cap and is about minus 190 F (minus 125 C).NASA/JPL-Caltech/ASU Headed for Jupiter’s moon Europa, the spacecraft did some sightseeing, using a flyby of Mars to calibrate its infrared imaging instrument.
On its recent swing by Mars, NASA’s Europa Clipper took the opportunity to capture infrared images of the Red Planet. The data will help mission scientists calibrate the spacecraft’s thermal imaging instrument so they can be sure it’s operating correctly when Europa Clipper arrives at the Jupiter system in 2030.
The mission’s sights are set on Jupiter’s moon Europa and the global ocean hidden under its icy surface. A year after slipping into orbit around Jupiter, Europa Clipper will begin a series of 49 close flybys of the moon to investigate whether it holds conditions suitable for life.
A key element of that investigation will be thermal imaging — global scans of Europa that map temperatures to shed light on how active the surface is. Infrared imaging will reveal how much heat is being emitted from the moon; warmer areas of the ice give off more energy and indicate recent activity.
The imaging also will tell scientists where the ocean is closest to the surface. Europa is crisscrossed by dramatic ridges and fractures, which scientists believe are caused by ocean convection pulling apart the icy crust and water rising up to fill the gaps.
This picture of Mars is a colorized composite of several images captured by Europa Clipper’s thermal imager. Warm colors represent relatively warm temperatures; red areas are about 32 degrees Fahrenheit (0 degrees Celsius), and purple regions are about minus 190 F (minus 125 C).NASA/JPL-Caltech/ASU “We want to measure the temperature of those features,” said Arizona State University’s Phil Christensen, principal investigator of Europa Clipper’s infrared camera, called the Europa Thermal Imaging System (E-THEMIS). “If Europa is a really active place, those fractures will be warmer than the surrounding ice where the ocean comes close to the surface. Or if water erupted onto the surface hundreds to thousands of years ago, then those surfaces could still be relatively warm.”
Why Mars
On March 1, Europa Clipper flew just 550 miles (884 kilometers) above the surface of Mars in order to use the planet’s gravitational pull to reshape the spacecraft’s trajectory. Ultimately, the assist will get the mission to Jupiter faster than if it made a beeline for the gas giant, but the flyby also offered a critical opportunity for Europa Clipper to test E-THEMIS.
For about 18 minutes on March 1, the instrument captured one image per second, yielding more than a thousand grayscale pictures that were transmitted to Earth starting on May 5. After compiling these images into a global snapshot of Mars, scientists applied color, using hues with familiar associations: Warm areas are depicted in red, while colder areas are shown as blue.
By comparing E-THEMIS images with those made from established Mars data, scientists can judge how well the instrument is working.
“We wanted no surprises in these new images,” Christensen said. “The goal was to capture imagery of a planetary body we know extraordinarily well and make sure the dataset looks exactly the way it should, based on 20 years of instruments documenting Mars.”
NASA’s Mars Odyssey orbiter, launched in 2001, carries a sister instrument named THEMIS that has been capturing its own thermal images of the Red Planet for decades. To be extra thorough, the Odyssey team collected thermal images of Mars before, during, and after Europa Clipper’s flyby so that Europa scientists can compare the visuals as an additional gauge of how well E-THEMIS is calibrated.
Europa Clipper also took advantage of the close proximity to Mars to test all the components of its radar instrument in unison for the first time. The radar antennas and the wavelengths they produce are so long that it wasn’t possible for engineers to can do that in a clean room before launch. The radar data will be returned and analyzed in the coming weeks and months, but preliminary assessments of the real-time telemetry indicate that the test went well.
To leverage the flyby even further, the science team took the opportunity to ensure that the spacecraft’s telecommunication equipment will be able to conduct gravity experiments at Europa. By transmitting signals to Earth while passing through Mars’ gravity field, they were able to confirm that a similar operation is expected to work at Europa.
Europa Clipper launched from NASA’s Kennedy Space Center in Florida on Oct. 14, 2024, via a SpaceX Falcon Heavy, embarking on a 1.8 billion-mile (2.9 billion-kilometer) journey to Jupiter, which is five times farther from the Sun than Earth is. Now that the probe has harnessed the gravity of Mars, its next gravity assist will be from Earth in 2026.
More About Europa Clipper
Europa Clipper’s three main science objectives are to determine the thickness of the moon’s icy shell and its interactions with the ocean below, to investigate its composition, and to characterize its geology. The mission’s detailed exploration of Europa will help scientists better understand the astrobiological potential for habitable worlds beyond our planet.
Managed by Caltech in Pasadena, California, NASA’s Jet Propulsion Laboratory in Southern California leads the development of the Europa Clipper mission in partnership with the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, for NASA’s Science Mission Directorate in Washington. APL designed the main spacecraft body in collaboration with JPL and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, NASA’s Marshall Space Flight Center in Huntsville, Alabama, and Langley Research Center in Hampton, Virginia. The Planetary Missions Program Office at NASA Marshall executes program management of the Europa Clipper mission. NASA’s Launch Services Program, based at NASA Kennedy, managed the launch service for the Europa Clipper spacecraft.
Find more information about Europa Clipper here:
News Media Contacts
Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
818-287-4115
gretchen.p.mccartney@jpl.nasa.gov
Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
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Last Updated May 12, 2025 Related Terms
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