From fiery space reentries to cutting-edge hypersonic weapons, heat shields quietly do one of the hardest jobs in engineering: they keep vehicles from burning up. Every time a spacecraft returns to Earth or a hypersonic vehicle tears through the atmosphere at extreme speed, its survival depends on a thermal protection system working exactly as expected.
History has shown what happens when this protection fails. The 2003 space shuttle Columbia disaster, caused by damage to its heat shield, remains a painful reminder of how unforgiving reentry physics can be. Since then, heat-shield technology has improved greatly, enabling routine returns of spacecraft and the rapid growth of commercial spaceflight.
Now, engineers at Sandia National Laboratories have taken a major step forward. They have developed a new, faster way to evaluate heat-shield materials—one that combines advanced computer modeling, laboratory experiments, and real flight tests. This method can predict how heat shields behave under extreme conditions much more quickly than before, saving time, money, and potentially lives.
Why Heat Shields Matter More Than Ever
Heat shields, formally called thermal protection systems, are designed to protect vehicles from the enormous heat and friction generated when moving through Earth’s atmosphere at high speeds. During atmospheric reentry, temperatures can rise to several thousand degrees Celsius—hot enough to melt steel.
This challenge becomes even greater for hypersonic vehicles, which travel at speeds of Mach 5 or higher—more than five times the speed of sound, or over 3,800 miles per hour. At these speeds, air behaves more like a plasma than a gas, creating extreme heat, pressure, and chemical reactions on the vehicle’s surface.
While ballistic missiles can reach hypersonic speeds, hypersonic glide vehicles are different. They are highly maneuverable and unpredictable, making them difficult to intercept. Because of this, the United States is investing heavily in hypersonic systems for national defense.
Unlike reusable spacecraft, however, the heat shields on U.S. hypersonic missiles are designed for a single use. They must perform perfectly the first and only time they fly. This makes accurate and rapid testing absolutely critical.
The Problem with Traditional Testing
Traditionally, qualifying a new heat-shield material is a slow and expensive process. Engineers rely on:
Ground-based laboratory tests, which can simulate parts of flight conditions but never the full environment at once
Complex computer models, which are accurate but can take days to run on supercomputers
Flight tests, which are the most realistic but extremely costly and limited in number
Each new material or design change often requires repeating much of this process. For defense applications, where timelines are tight and designs evolve quickly, this slow pace is a serious limitation.
That is the problem Sandia’s research team set out to solve.
A Conversation That Sparked a Breakthrough
The project began with a simple conversation.
Justin Wagner, an aerospace engineer at Sandia and the project’s lead researcher, recalls talking with Jon Murray, another Sandia engineer who works closely with Department of Defense customers.
Murray needed a way to predict how heat shields would respond much faster than existing tools allowed.
“Can we find a way to use the science tools that are being developed here,” Wagner recalls Murray asking, “and combine that with our systems integration know-how?”
That question became the foundation of a three-year research project focused on one goal: understanding what will happen to heat-shield materials in flight—more quickly and more reliably than ever before.
Testing Materials from Simple to Exotic
To build a better evaluation method, the team first needed high-quality data. That meant testing a wide range of materials under extreme conditions.
The materials tested ranged from ordinary graphite—the same form of carbon found in No. 2 pencils—to advanced carbon-based and ceramic composites designed specifically for extreme environments.
Hundreds of samples were produced by Sandia’s materials science team, led by researcher Bernadette Hernandez-Sanchez, with contributions from Oak Ridge National Laboratory. Each sample represented a possible future heat-shield material.
The goal was not just to see whether these materials survived, but to understand how they failed, changed, or protected the vehicle under intense heat.
Simulating Hell on Earth: Laboratory Experiments
Reentry and hypersonic flight create conditions that are nearly impossible to fully reproduce on the ground. The temperatures, pressures, vibrations, and chemical reactions all happen at once and at extreme levels.
Still, researchers can recreate pieces of that environment.
Plasma Torch Experiments
One key tool was an inductively coupled plasma torch, used to study how materials burn away, or ablate, under extreme heat.
In these experiments, small samples of heat-shield material were blasted with plasma hotter than the surface of the sun. These tests allowed scientists to observe chemical and physical changes in real time as the materials eroded.
Much of this work was conducted at the University of Texas at Austin, and the results were published in the Journal of Thermophysics and Heat Transfer.
Solar Furnace Testing
To test larger samples, the team used Sandia’s National Solar Thermal Test Facility. This unique facility uses thousands of mirrors to concentrate sunlight onto a single point, generating incredibly high temperatures without combustion.
This allowed the team to study how larger slabs of heat-shield material responded to sustained heating—closer to real flight conditions.
Hypersonic Shock Tunnel
To simulate the aerodynamics of hypersonic flight, the researchers turned to a hypersonic shock tunnel capable of producing Mach 10 gas flows.
These tests generate both extreme temperatures and high-speed airflow, but only for a fraction of a second. Even so, they provide invaluable data on how materials respond to the sudden shock of hypersonic conditions.
Turning Data into Understanding
Data from these experiments alone is not enough. To be useful, it must feed into accurate models.
The team compared their laboratory results with advanced ablation models developed by collaborators at the University of Minnesota Twin Cities. Additional materials data came from researchers at:
University of Colorado Boulder
University of Illinois Urbana–Champaign
Kratos Inc.
This collaborative effort ensured that the data reflected real material behavior as closely as possible.
Building the Full-Physics Model
With experimental data in hand, the next step was modeling.
A team led by Scott Roberts, a chemical engineer at Sandia, developed a full-physics computer model. This model captured:
Heat-shield material properties
Aerodynamics of hypersonic flight
Heat-transfer physics
Chemical reactions during ablation
The result was an extremely detailed and accurate simulation of how a heat shield behaves in flight.
The downside? Running this model could take days on a supercomputer.
While highly accurate, it was too slow for rapid design changes or quick decision-making.
From Bitmap to JPEG: Faster Models with Smart Simplification
To solve this problem, aerospace engineer Jon Murray led a second modeling effort: creating a reduced-order model.
Murray explains the idea with a simple analogy.
If the full-physics model is like a bitmap image, containing data for every single pixel, then the reduced-order model is like a JPEG. It keeps the most important features while compressing the rest.
The challenge was deciding what information mattered most.
Using results from the full-physics model, Murray’s team applied machine learning techniques to identify the key features that control heat-shield behavior. They then trained the reduced-order model on multiple simulation sets.
The outcome was impressive.
The reduced-order model achieved about 90% accuracy compared to the full-physics model for similar missions and vehicle designs.
Even more importantly, it ran thousands of times faster.
What once took days now takes seconds on a desktop computer.
Why Speed Changes Everything
This dramatic speed increase transforms how engineers work.
With the reduced-order model, researchers can:
Rapidly explore new vehicle designs
Quickly test how changes in material properties affect performance
Evaluate whether an existing design will work for a new mission
Reduce the number of materials that need full qualification
The team is now working to make the process even smoother—so that any change made in the full-physics model can automatically retrain the reduced-order model with minimal human effort.
The goal is a seamless pipeline from deep physics to fast decision-making.
Proving It in the Real World: Flight Tests
No matter how good a model looks, it must be validated in flight.
“Flight tests are really important,” says Katya Casper, the aerospace engineer who coordinated the testing. “They provide the actual environment you’re trying to qualify these materials for.”
Ground tests can mimic pieces of flight, but only flight delivers everything at once.
Suborbital Rocket Flights
So far, the team has flown heat-shield samples on two suborbital rocket launches through the Multi-Service Advanced Capability Hypersonics Test Bed program.
Each launch is expensive and carries experiments from 10 to 20 research teams, making careful planning essential.
The samples ranged from quarter-sized pieces to 4-inch-long wedges, each equipped with temperature sensors to record heating during flight.
Watching Chemistry in Real Time
In addition to temperature, the team wanted to observe chemical changes during flight.
The first flight included an optical emission spectrometer, while the second used a laser absorption spectroscopy system developed with Purdue University and PSE Technology.
These instruments helped validate whether the chemical reactions predicted in laboratory and computer models actually occurred in real hypersonic conditions.
The Next Big Test: Bringing Materials Back Home
The most exciting test is still ahead.
In summer 2026, the team plans to fly a new heat-shield tile on the nose of a reentry capsule through the Prometheus program, sponsored by the Air Force Research Laboratory.
This tile will contain multiple material samples and temperature sensors, and—if all goes well—it will be recovered after flight.
Getting the materials back allows researchers to:
Measure exactly how much material ablated
Study the chemistry of what remains
Compare real damage with model predictions
This level of validation will further strengthen confidence in both the full-physics and reduced-order models.
Why This Research Matters
This new approach does more than save time.
It helps ensure that future hypersonic vehicles and spacecraft are safer, more reliable, and better understood before they ever fly.
By reducing the number of materials that need extensive testing and speeding up design decisions, the method also saves money and accelerates innovation.
In a field where failure can be catastrophic, the ability to predict performance quickly and accurately is invaluable.
From Tragedy to Trust
More than two decades after the Columbia disaster, the lessons of the past continue to shape the future.
Heat shields remain one of the most critical—and challenging—components of aerospace engineering. Thanks to the work of Sandia’s engineers and their collaborators, scientists now have a powerful new way to understand and trust these materials.
It truly is rocket science—but now, it’s faster, smarter, and safer than ever before.
Reference: Dan Fries et al, Coherent Raman Measurements of Temperature and CO/N2 Concentration During Plasma Torch Graphite Ablation, Journal of Thermophysics and Heat Transfer (2025). DOI: 10.2514/1.t7080
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