Space and Tech
I’ve fired one of America’s most powerful lasers – here’s what a shot day looks like
A lead scientist takes you inside the Texas Petawatt at UT Austin, where hours of careful alignment and safety checks build to a single, breath-holding laser shot that briefly creates star-like conditions in a vacuum chamber.
Ahmed Helal, The University of Texas at Austin
If you walk across the open yard in front of the Physics, Math and Astronomy building at the University of Texas at Austin, you’ll see a 17-story tower and a huge L-shaped building. What you won’t see is what’s underneath you. Two floors below ground, behind heavy double doors stamped with a logo that most students have never noticed, sits one of the most powerful lasers in the United States.
I was the lead laser scientist on the Texas Petawatt, or TPW as we called it, from 2020 to 2024. Texas Petawatt, which is currently closed due to funding cuts, was a government-funded research center where scientists from across the country applied for time to use specialized equipment. It was part of LaserNetUS, a Department of Energy network of high-power laser labs.
This type of laser takes a tiny pulse of light, stretches it out so it doesn’t blast optics to pieces, and amplifies it until, for a brief instant, it carries more power than the entire U.S. electrical grid. Then it compresses the pulse back to a trillionth of a second to create a star in a vacuum chamber.
On a typical shot day, the target might be a piece of metal foil thinner than a human hair, a jet of gas or a tiny plastic pellet – each designed to answer a different scientific question.
Scientists from across the country applied for time on TPW to study everything from the physics of stellar interiors and fusion energy to new approaches for cancer treatment.
Most people hear about petawatt lasers and picture something out of a movie. A “shot day” is actually hours of quiet, repetitive work followed by about 10 seconds where nobody breathes.
I now work as a research scientist at the University of Texas-Austin, studying the interaction of lasers with different materials, but a typical shot day during my time running TPW would look like this:
7 a.m.
I arrive two hours before the first scheduled shot. I put on my gown, boots and hairnet and step into the cold clean room. The laser doesn’t just turn on. You coax it awake.
I start with the oscillator, a small box that generates the first seed of light. I write down the parameters that define how the laser will behave during the shot: energy, center frequency, vacuum pressure in the tubes, cooling water level and flow. At this stage, they are fixed regardless of the experiment. The laser must perform the same way every time before the science can begin. Then I fire up the pump laser that will amplify this tiny pulse from nanojoules to about half a joule.
The system needs at least 30 minutes to stabilize. During that time, I check alignment through every pinhole and every camera along the beam path. A slight misalignment at this stage isn’t just a problem; it can be catastrophic – a mispointed beam at full power can burn through optics that take months to source and replace, setting the entire laser back.
Building the beam
Once the system is warmed up, I send the beam into the first amplifier: a glass rod surrounded by bright flash lamps that pump light into the glass – like charging a battery. With each pass, the beam absorbs energy from the glass and grows stronger. Then the beam travels into a larger rod, where it makes four passes, picking up more energy each time until it reaches about 12 joules, roughly the energy of a ball thrown hard across a room.
This process alone takes the better part of an hour, most of it spent checking and confirming alignment and energy at each stage.
I expand the beam and send it through the final stage: the disk amplifiers. Two amplifiers, each consisting of two massive 30-centimeter glass disks, are pumped by a huge bank of flash lamps powered by capacitor banks – essentially giant batteries that store electrical energy and release it in a sudden burst. They are so large that they have their own room on a separate floor. Fast optical shutters between each stage act as gates, controlling exactly when and where the beam travels.
The shot
When the experimental team confirms that the target is in position, it asks me to prepare for a system shot. I run through the long checklist. We test the shutters and switch to system shot mode. Every monitor in the facility changes to display the same message – “System Shot Mode” – and flashes red.
I lean into the microphone at the control desk, a vintage piece that looks like it belongs in a World War II radio room, and announce that we’re going into a system shot. Then I open the compressor beam dump: a heavy glass plate that normally blocks the beam from reaching the target. It takes about two minutes to move.
“Sweeping, sweeping for a system shot.”
The announcement goes out over speakers across the facility. I grab a small interlock key, put on my laser safety goggles and head downstairs. I walk a specific pattern through every room, checking that nobody is still inside. As I go, I lock each door with the key. If anyone opens one of those doors after I’ve locked them, the entire shot sequence aborts.
Back in the control room, I sit down and start charging the capacitor banks. At this point, there’s no going back except for an emergency shutdown, and that means losing the shot and waiting for everything to cool down.
“Charging.”
The room goes silent. Everyone’s eyes are on the monitors. Nobody talks.
I typically will share a glance with the researcher whose project the shot is for – today it’s Joe, a visiting scientist from Los Alamos National Lab, who designed the target we’re about to vaporize. He’s gripping his coffee cup like it owes him money. I turn back to the console.
“Charge complete. Firing system shot in three, two, one. Fire.”
I press the button. A loud thud rolls through the building as all that stored energy dumps into the beam. The monitors freeze, capturing everything at the moment of the shot: beam profiles, spectra, diagnostics – these metrics provide a full picture of exactly how the laser performed and whether the shot was clean. Downstairs, in the vacuum chamber, a spot smaller than a human hair just reached temperatures measured in millions of degrees.
I lean back in my chair and start recording laser parameters as everyone exhales. A radiation safety officer heads down first to check readings around the target chamber before anyone else can enter. The experimental team follows to collect data.
Sometimes it all works perfectly. Sometimes a shutter fails to open and you lose the shot.
For example, one afternoon in 2023, we’d spent three hours preparing for a high-priority shot. Target aligned. Capacitors charged. I pressed the button and heard nothing. A shutter had failed somewhere in the chain. The monitors stayed frozen, showing black. Nobody said anything. I wrote SHOT FAILED in the logbook and started the hourlong cooldown sequence. That’s the part they don’t show in movies: sitting in silence, waiting to try again. We got the shot four hours later.
This anticipation is all part of the job: hours of patience for 10 seconds you never quite get used to. Everything happens underneath a campus where thousands of people walk above, unaware that for a fraction of a second, a tiny point of matter hotter than the surface of the Sun just existed below their feet.
Ahmed Helal, Research Scientist, The University of Texas at Austin
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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From Hand Signals to Smart Crosswalks: The Evolution of the Modern Pedestrian Signal
Discover the history of the modern pedestrian signal, from Garrett A. Morgan’s groundbreaking traffic signal to today’s smart, accessible crosswalks.
Last Updated on July 12, 2026 by Daily News Staff
Every day, millions of people rely on pedestrian signals to cross busy street safely. A glowing white walking figure, an orange-red hand, and a countdown timer have become familiar sights around the world. While these signals may seem like simple pieces of infrastructure, they are the result of more than a century of innovation, engineering, and public safety improvements.
The modern pedestrian signal did not appear overnight. Instead, it evolved through the contributions of inventors, engineers, city planners, and transportation officials who continually refined traffic control systems as cities grew and automobiles became more common.
The Early Days of Traffic Control
Before electric traffic signals, intersections were controlled by police officers, railway-style semaphores, or even hand signals. As horse-drawn wagons gave way to automobiles in the early 1900s, traffic congestion and accidents increased dramatically, creating an urgent need for better traffic management.
One of the earliest electric traffic lights was installed in Cleveland, Ohio, in 1914. It used red and green lights and was manually operated. While it improved vehicle movement, pedestrians still had to judge for themselves when it was safe to cross.
Garrett A. Morgan’s Breakthrough
One of the most important milestones came in 1923 when inventor and entrepreneur Garrett Augustus Morgan received U.S. Patent No. 1,475,024 for an improved traffic signal.
Morgan’s design introduced a third position in addition to “Stop” and “Go.” This intermediate phase temporarily stopped traffic in every direction before allowing vehicles to proceed. The brief pause reduced confusion at intersections and provided additional time for pedestrians to cross safely.
Morgan reportedly developed his design after witnessing a serious traffic accident. His invention demonstrated how thoughtful engineering could improve public safety while making increasingly busy streets more efficient.
Although Morgan did not invent the illuminated “WALK” and “DON’T WALK” pedestrian signal used today, his three-position signal became a foundational step in the evolution of modern traffic control.
The Birth of Dedicated Pedestrian Signals
As cities expanded after World War II, pedestrian safety became an even greater concern. More people were walking in increasingly crowded downtown districts, and separating pedestrian movements from vehicle traffic became a priority.
During the early 1950s, several American cities began experimenting with dedicated pedestrian signals. New York City became one of the first major municipalities to install illuminated “WALK” and “DON’T WALK” signs at busy intersections.
These early systems gave pedestrians their own designated crossing phase, reducing conflicts with turning vehicles and improving safety at some of the nation’s busiest intersections.
Standardization Across America
By the 1960s and 1970s, traffic engineers recognized the importance of creating consistent traffic control devices nationwide.
The Manual on Uniform Traffic Control Devices (MUTCD) established national standards for traffic signs, pavement markings, and pedestrian signals. Standardized designs helped ensure that pedestrians could understand crossing signals regardless of where they traveled in the United States.
Eventually, words gave way to internationally recognized symbols—a walking person to indicate it was safe to cross and an upraised hand to indicate pedestrians should wait. These symbols transcended language barriers and improved accessibility for visitors and non-English speakers.
The Countdown Era
One of the most significant modern improvements arrived with pedestrian countdown timers.
Rather than simply flashing a warning, countdown displays show exactly how many seconds remain before the crossing phase ends. Research has shown that countdown timers help pedestrians make better crossing decisions and improve compliance with traffic signals.
Today, countdown timers have become standard equipment at intersections across much of the United States.
Accessibility Takes Center Stage
Modern pedestrian signals are designed to serve everyone.
Accessible Pedestrian Signals (APS) now provide audible tones, spoken messages, vibrating push buttons, and locator sounds that assist pedestrians who are blind or have low vision. These features allow more people to navigate intersections independently and safely.
The continued development of accessible technology reflects a broader commitment to making transportation systems inclusive for all users.
The Future of Pedestrian Safety
Pedestrian signals continue to evolve.
Many cities now use smart traffic systems that detect pedestrians waiting to cross, automatically adjust signal timing based on traffic conditions, and prioritize people walking during busy periods.
Researchers are exploring artificial intelligence, connected vehicle technology, and sensor-based systems capable of communicating directly with autonomous vehicles. Future pedestrian crossings may adapt in real time to weather conditions, crowd sizes, emergency vehicles, and even the needs of older adults or individuals with disabilities.
A Legacy Built by Many Innovators
The pedestrian signal we know today is the product of more than a century of collaboration and innovation.
Early traffic engineers created the first electric traffic lights. Garrett A. Morgan improved intersection safety with his groundbreaking three-position traffic signal. Transportation agencies standardized traffic control devices, while engineers continued refining pedestrian technology through countdown timers, accessible features, and intelligent traffic systems.
Every safe crossing today reflects the work of countless inventors, planners, researchers, and public officials dedicated to protecting lives.
As cities continue to grow and transportation technology advances, the humble pedestrian signal remains one of the most effective—and often overlooked—public safety innovations ever developed.
At STM Daily News, we celebrate the inventors, engineers, and visionaries whose everyday innovations quietly improve life for millions of people. Sometimes the most important inventions aren’t the ones that grab headlines—they’re the ones we depend on every single day without giving them a second thought.
Related Reading
- Federal Highway Administration – Manual on Uniform Traffic Control Devices (MUTCD)
- National Museum of African American History and Culture – Garrett Augustus Morgan
- United States Patent and Trademark Office
- Federal Highway Administration – Accessible Pedestrian Signals
- National Highway Traffic Safety Administration (NHTSA)
🧠 Discover the remarkable innovators, inventors, and trailblazers who helped shape our world but rarely receive the recognition they deserve. Share your thoughts in the comments and subscribe to the STM Daily News newsletter to catch every new Forgotten Genius Friday feature and more inspiring stories delivered to your inbox.
Last Updated on June 12, 2026 by Rod Washington
Valerie Thomas is a true pioneer in the world of science and technology. A NASA engineer and physicist, she is best known for inventing the illusion transmitter, a groundbreaking device that creates 3D images using concave mirrors. This invention laid the foundation for modern 3D imaging and virtual reality technologies.
Beyond her inventions, Thomas broke barriers as an African American woman in STEM, mentoring countless young scientists and advocating for diversity in science and engineering. Her work at NASA’s Goddard Space Flight Center helped advance satellite technology and data visualization, making her contributions both innovative and enduring.
In our latest short video, we highlight Valerie Thomas’ remarkable journey—from her early passion for science to her groundbreaking work at NASA. Watch and be inspired by a true STEM pioneer whose legacy continues to shape the future of space and technology.
🎥 Watch the video here: https://youtu.be/P5XTgpcAoHw
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A Short-Form Series from The Knowledge by STM Daily News
Every Friday, STM Daily News shines a light on brilliant minds history overlooked.
Forgotten Genius Fridays is a weekly collection of short videos and articles dedicated to inventors, innovators, scientists, and creators whose impact changed the world—but whose names were often left out of the textbooks.
From life-saving inventions and cultural breakthroughs to game-changing ideas buried by bias, our series digs up the truth behind the minds that mattered.
Each episode of The Knowledge runs 30–90 seconds, designed for curious minds on the go—perfect for YouTube Shorts, TikTok, Reels, and quick reads.
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Artemis II crew brought a human eye and storytelling vision to the photos they took on their mission
Artemis II crew: Artemis II’s astronaut photos show how human perspective and storytelling make space imagery feel authentic—especially in an era of AI-generated visuals.
Christye Sisson, Rochester Institute of Technology
In early April 2026, the Artemis II mission captivated me and millions of people watching from across the world. The crew’s courage, skill and infectious wonder served as tangible proof of human persistence and technological achievement, all against the mysterious backdrop of space.
People back on Earth got to witness the mission through remarkable photos of space captured by astronauts. Images created and shared by astronauts underscore how photography builds a powerful, authentic connection that goes beyond what technology alone can capture.
As a photographer and the director of the Rochester Institute of Technology’s School of Photographic Arts and Sciences, I am especially drawn to how these photographs have been at the center of the public’s collective experience of this mission.
In an era when image authenticity is often questioned and with the capabilities of autonomous, AI-driven imaging, NASA’s choice to train astronauts in photography has placed meaning over convenience and prioritized their human perspectives and creativity.
Capturing space from the crew’s perspective
Photography was not originally placed as a high priority in NASA’s Apollo era. The astronauts only took photographs if they had the chance and all their other tasks were complete.
Thanks largely in part to public response to those images from Apollo, including “Earthrise” and the “Blue Marble” being widely credited for helping catalyze the modern environmental movement, NASA shifted its approach to utilize photography to help capture the public’s imagination by training their astronauts in photographic practices.
The Artemis II mission’s photographs have helped cut through the increasing volume of artificially generated images circulating on social media. NASA’s social media releases of the crew’s photographs have garnered thousands of shares and comments.
This excitement could be explained by the novelty of photos from space, but these images also distinguish themselves as products of astronauts experiencing these sights and interpreting them through their photographs. These differences require an important distinction around where technology ends and humanity begins.
Human perspective versus AI tools
Photography has long integrated AI-powered software and data-driven tools in a variety of ways: to process raw images, fill in missing color information, drive precise focus and guide image editing, among others. These modern technological assists help human photographers realize their vision.
Artificial intelligence is also increasingly capable of operating machinery competently and autonomously, from cars to drones and cameras.
And AI can generate convincing, realistic images and videos from nothing more than a text prompt, using readily available tools.
Researchers train AI to mimic patterns informed by millions of sample images, and the algorithm can then either take or create a photograph based on what it predicts would be the most likely version of a successful, believable image.
Human-created photos are rooted in direct observation, intent and lived experience, while AI images – or choices made by AI-driven tools – are not. While both can produce compelling and believable visuals, the human photographs carry emotional power because the photographer is drawing from their experiences and perspective in that moment to tell an authentic story.
Artemis II photographs resonate, not only because they are historic, but because they reflect the deliberate choices and intent of a human being in that specific moment and context. The exposure, camera setting, lens choice and composition are all dictated by the astronaut’s vision, skill, perspective and experience. Each image is unique in comparison with the others. These choices give the images narrative power, anchoring them in human perspective.
Images to tell a story
Photographers choose what to include in the final version of their image to tell a story. In the Artemis II images, this human perspective comes out. In the “Earthset” photo, you see a striking juxtaposition of the Moon’s monochromatic, textured surface in the foreground against a slivered, bright Earth.
The choice to include both in the frame contrasts these objects literally and figuratively, inviting comparison. It creates a narrative where Earth is contrasted against the Moon – life is contrasted against the absence of it.
Another photo shows the nightside of the whole Earth, featuring the Sun’s halo, auroras and city lights. The choice to include the subtle framing of the window of the capsule in the lower left corner reminds the viewer where and how this image was captured: by a human, inside a capsule, hurtling through space. That detail grounds the photograph in the human perspective.
Both photos are reminiscent of Earthrise and the Blue Marble. These past images hold a place in the global collective consciousness, shaped by a shared historical moment.
The Artemis II photographs are anchored in this collective moment of lived human experience, yet also shaped by each astronaut’s viewpoint. The crew’s unique perspectives exemplify photography’s transformative power by inviting viewers to engage emotionally and intellectually with their journey. These photographs share the astronauts’ awe and wonder and affirm the value of human creativity and its ability to connect us in a captured moment.
Christye Sisson, Professor of Photographic Sciences, Rochester Institute of Technology
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
