Aerospace

PhD alum spent 45 days isolated in space. Well, kind of

Alexander James Servantez — Wed, 02 Apr 2025 20:35:17 +0000

PhD alum spent 45 days isolated in space. Well, kind of Alexander Jame… Wed, 04/02/2025 - 14:35

Robert Wilson (PhDMechEngr'20) spent 45 days locked inside NASA’s HERA facility, a high-tech simulation designed to test the limits of human endurance in deep space. His mission could help shape the future of space exploration—and life back on Earth.

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Aircrafts of the future: Boosting aerodynamic performance by engineered surface vibrations

Jeff Zehnder — Mon, 24 Mar 2025 16:34:49 +0000

Aircrafts of the future: Boosting aerodynamic performance by engineered surface vibrations Jeff Zehnder Mon, 03/24/2025 - 10:34

Jeff Zehnder

“This is probably the most radical conceptual advancement for airplanes since the replacement of propellers with jets.” – M.I. Hussein

Mahmoud Hussein is not pulling punches about the potential impact of a major aerospace materials research project.

As the principal investigator of a $7.5 million, five-year Department of Defense Office of Naval Research (ONR) Multidisciplinary University Research Initiative (MURI), Hussein is leading an effort to reshape the fundamental character of fluid-structure interactions to reduce drag on high-speed aerospace vehicles—the focus of the project.

“Since the dawn of aviation, aircraft design has been based on the premise of shaping the surface of the vehicle to create lift and minimize drag. Our team is pursuing a new paradigm where the phononic properties, or intrinsic vibrations, of a surface or subsurface provide an additional pathway to interact with the airflow, to enhance the vehicle performance in an unprecedented manner,” said Hussein, the Alvah and Harriet Hovlid Professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the �鶹ӰԺ.

Hussein also has a courtesy appointment in the Department of Physics and an affiliation with the Materials Science and Engineering Program.

MURI Partners

�鶹ӰԺ

Mahmoud I. Hussein
Professor & Principal Investigator
Armin Kianfar
Post-Doctoral Associate
Adam Harris
PhD Student

University of Maryland

Christoph Brehm
Associate Professor

Johns Hopkins University

Kevin Hemker
Professor

Purdue University

Joseph Jewell
Associate Professor

Applied Physics Laboratory

Keith Caruso
Principal Staff Engineer
Ken Kane
Researcher

University of Kentucky

Alexandre Martin
Professor

Case Western Reserve University

Bryan Schmidt
Assistant Professor

Office of Naval Research (Program Directors)

Eric Marineau
Eric Wuchina

Phononic Subsurfaces

Turbulent airflow is detrimental to the fuel economy and the surface temperature of aircrafts as they soar through the atmosphere. This research aims to mitigate the transition to turbulence using phononic subsurfaces (PSubs) – synthetic designed materials affixed beneath the surface of a wing or vehicle body that passively manipulate small-amplitude vibrations, and by extension flow fluctuations, point-by-point along the surface.

Turbulence and Fuel Economy

Passenger planes consume over 10,000 gallons of jet fuel on a single cross-country trip, so improvements in fuel economy could lead to big savings for airlines. The potential in hypersonic crafts is even more dramatic.

Hypersonic vehicles travel at velocities at least five times the speed of sound. The turbulence that results from such speeds causes the surface of the vehicles to heat up to thousands of degrees, requiring they be constructed of exotic, expensive materials.

“By introducing a phononic subsurface to precisely shape the vibrations along the surface, we can alter the way the air interacts with the vehicle such that we ultimately don’t need to come up with exceedingly high-temperature-resistant materials,” Hussein said. “We’re passively manipulating instabilities in air flow in a manner that is favorable in the boundary layer where the vehicle meets the surrounding air.”

2015 to Today

The concept of PSubs was discovered by Hussein. The work began from a collaboration over 15 years ago between Hussein and then CU �鶹ӰԺ Professor Sedat Biringen, who died in 2020. As leaders in the newly-born research area of phononics and the longstanding field of fluid dynamics, respectively, they worked together to theoretically demonstrate–for the first time–a way to manipulate phonons to improve the efficiency of flight, with tremendous potential for the aerospace industry and prospects for application to water vessels as well.

Recently Hussein gathered a team of experts from across the country to take the concept of PSubs to the next level with this hypersonics MURI grant. Over the duration of the project, the group will develop high-fidelity models and fabricate functional prototypes to effectively characterize and demonstrate the technology in high-speed wind tunnels.

“We’re most confident about this endeavor, because the idea is rooted in fundamental science marrying–in quite a sophisticated fashion–fluid dynamics with condensed matter physics as well as with the emerging field of elastic metamaterials,” Hussein said.

“This is probably the most radical conceptual advancement for airplanes since the replacement of propellers with jets.” – Mahmoud Hussein is not pulling punches about the potential impact of a major aerospace materials research project.

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Four with ties to CU elected to 2025 class of National Academy of Engineering

Emily Adams — Tue, 25 Feb 2025 20:06:09 +0000

Four with ties to CU elected to 2025 class of National Academy of Engineering Emily Adams Tue, 02/25/2025 - 13:06

Two CU �鶹ӰԺ faculty members, a former faculty member and a distinguished alumnus are among 128 new members elected to the National Academy of Engineering for 2025.

According to NAE, "election to the National Academy of Engineering is among the highest professional distinctions accorded to an engineer. Academy membership honors those who have made outstanding contributions in at least one of the following categories: 'engineering practice, research, or education,' 'pioneering of new and developing fields of technology, major advancements in traditional fields of engineering, or development/implementation of innovative approaches to engineering education' or 'engineering leadership of one or more major endeavors.'"

The four will be formally inducted during the NAE's Annual Meeting in October.

Scott Diddams

For contributions to optical frequency combs and their applications

Electrical engineer and physicist Scott Diddams holds the Robert H. Davis Endowed Chair. He carries out experimental research in the fields of precision spectroscopy and quantum metrology, nonlinear optics, microwave photonics and ultrafast lasers. Diddams earned his PhD degree from the University of New Mexico and previously served as a research physicist, group leader and fellow the National Institute of Standards and Technology. In 2022, he joined the CU �鶹ӰԺ faculty, where he is also the faculty director of the Quantum Engineering Initiative in the College of Engineering and Applied Science. As a postdoc, Diddams built the first optical frequency combs in the lab of Nobel Prize laureate John Hall, and throughout his career, he has pioneered the use of these powerful tools for optical clocks, tests of fundamental physics, novel spectroscopy and astronomy.

Related reading:

Hanspeter Schaub

For contributions to the control of satellite formations and relative orientations utilizing natural forces, including the use of electrostatics

A distinguished professor and chair of the Ann and H.J. Smead Department of Aerospace Engineering Sciences at CU �鶹ӰԺ, Hanspeter Schaub has made pioneering research advances in spacecraft formation flying, space debris mitigation, attitude dynamics, autonomous spacecraft tasking and charged astrodynamics. His work has been instrumental in high-profile space projects, including the development of key components for the UAE Hope mission to Mars and the creation of the widely used Basilisk software for spacecraft mission simulation. He has been recognized multiple times for excellence in research and education, including the 2024 American Astronautical Society Dirk Brouwer Award for transformational research. He is a Fellow of both AIAA and AAS. Schaub has been a member of the CU �鶹ӰԺ aerospace faculty since 2007 and holds a bachelor's, master's and PhD in aerospace engineering, all from Texas A&M University.

Related reading:

Dan Frangopol

For contributions to life-cycle civil engineering and leadership in its global development and adoption

Dan Frangopol is a distinguished CU �鶹ӰԺ professor emeritus with a significant career in the university’s Department of Civil, Environmental and Architectural Engineering. He joined CU �鶹ӰԺ’s faculty as an associate professor in March 1983. He was promoted to full professor in 1988 and became an emeritus professor in 2006. Renowned as an expert in structural reliability, optimization and life-cycle engineering, Frangopol earned the title "Father of Life-Cycle Analysis" from the American Society of Civil Engineers (ASCE). In November 2023, the ASCE board of directors established the Dan M. Frangopol Medal for Life-Cycle Engineering of Civil Structures in honor of Frangopol. Frangopol, currently a professor at Lehigh University, holds Lehigh’s inaugural Fazlur R. Khan Endowed Chair of Structural Engineering and Architecture. Frangopol received his diploma in engineering from the Institute of Civil Engineering, Bucharest, Romania, in 1969 and his doctorate of applied sciences from the University of Liège, Belgium, in 1976.

Related reading:

Civil engineering society establishes medal to honor Frangopol

Charles W. Hull (EngrPhys’61) and President Biden

Charles W. Hull

For the invention of 3D printing and the subsequent development of the additive manufacturing industry

After Chuck Hull (EngPhys'61) completed his degree, he worked with a DuPont subsidiary before going on to invent the solid imaging process known as stereolithography. This became the basis of the first commercial 3D printing technology, which spurred the dawning of a dynamic industry in the United States. Upon securing a stereolithography patent in 1986, Hull then founded 3D Systems Corp. Hull initiated the 3D printing industry and remains involved in the corporation’s day-to-day operations through a range of innovative applications, including state-of-the art production of 3D printers to the first home-certified 3D printer, the award-winning Cube. A member of the National Inventors Hall of Fame, Hull is credited as the inventor on more than 90 U.S. patents in the field of ion optics and 3D printing. As a strong advocate for education and training of youth in all aspects of this rapidly growing technology, Hull received an honorary degree from the University of Colorado Board of Regents in 2016.

Related reading:

CU �鶹ӰԺ alum’s invention of 3D printing recognized by President Biden

Two CU �鶹ӰԺ faculty members, a former faculty member and a distinguished alumnus will be among 128 new members inducted into the academy in October.

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Life in space from a CU �鶹ӰԺ alumna who has been there

Jeff Zehnder — Tue, 12 Nov 2024 18:53:33 +0000

Life in space from a CU �鶹ӰԺ alumna who has been there Jeff Zehnder Tue, 11/12/2024 - 11:53

Jeff Zehnder

Sarah Gillis (AeroEngr’17) is a lead space operations engineer and astronaut trainer at SpaceX with literal out-of-this-world experience.

The �鶹ӰԺ alumna recently returned from a five-day orbital mission aboard Polaris Dawn, which took astronauts further from Earth than any have traveled since the end of the Apollo program in 1972.

On Nov. 11, she spoke to students and community members in a special event at Fiske Planetarium.

A �鶹ӰԺ native, Gillis shared what life was like in space for the four-member crew and details of the science and engineering that brought them to orbit and safely home.

What it is like experiencing launch for the first time.

Intellectually, I had studied all the physical changes you go through going to space, but actually going through them is fascinating. For this one moment, you’re defying gravity as the rocket lifts off the pad and you start accelerating and accelerating. You get pushed into your seat. The Gs get to about 4.5. When you get to second engine cutoff and you’re just floating, you no longer have pressure pushing you into the seat — you have fluid in your face. You suddenly feel like when you’re a kid and you’re laying upside down off the bed.

There’s an adjustment period once you are in orbit.

Every crew member goes through this time on board where you’re adapting. The first two days are pretty hard in space. You’re figuring it out. You’re going through all the physiological changes. You have this brain fog; you have elevated fluid. You can have space motion sickness.

You’re probably not feeling your best, in all honesty. How you set up a timeline for crew members in space should account for that. You could not possibly have talked our crew into doing any less on our mission, but hindsight is definitely helpful, and it’s just a reality that it takes a bit of time for crew members to adapt.

Keep an eye on space while following your passions.

I always knew how unlikely it was to ever become an astronaut. The statistics are not in your favor right now at our point in human history. I do think that’s going to change in the very near future if SpaceX is successful in bringing Starship online. You go from having four people in a spacecraft to 100 people in a spacecraft. As you change those numbers, cost of access to space will go down, so the opportunities that will exist will look much different in next 10-15 years.

For me, knowing how unlikely it was, it was super important to find things I was genuinely interested in. That way, no matter what happening in life, I couldn’t be disappointed because I was doing things that were interesting and engaging and things I wanted to be pursuing. Follow your curiosity, and it will take you to extraordinary places.

The incredible complexity of designing a space suit from scratch.

It was about a 2.5-year development program where one day we would show up and we’d have the left shoulder rebuilt in a certain way. The next Monday we’d show up and they’d have a whole new elbow for us to try. Then we’d go and get in the simulator and understand what worked and what didn’t and really fed that into the design process of these suits. It was a pretty extraordinary development effort.

There were times that we were learning stuff that went against industry knowledge. One of the things we discovered pretty late was the risk of electrostatic discharge in the suits. That led to an entire deep dive into understanding material testing.

One of the last tests we did still on Earth was once the suit had gone through all sorts of iterations, we actually took them to a vacuum chamber at Johnson Space Center and we wore them in the vacuum chamber and ran through the entire depress and repress sequence. It was just an extraordinary test of competence into the suit, understanding what the pressure changes and temperature changes would feel like.

Moving in space without gravity to weigh you down creates challenges.

What’s so cool about moving in a pressurized suit is it’s really almost physical problem solving. You can only rotate your shoulder so many degrees, or you can only extend your arm so far in the suit. What that means is you have to make sure that a person of a certain stature can perform everything they need to in that pressurized environment. It was a really cool development process with SpaceX to figure out what new mobility aids we needed in the spacecraft. What additional handholds and footholds would be required to make sure we could accomplish all the tasks we needed to.

On flight day two we got pressurized in the suits and did a dry run (of the spacewalk). It was really fun to actually see how things worked, and what were the things we hadn’t accounted for. As soon as I went to the controls and interfaced with them, based on where my center of mass was, my feet would suddenly start rotating up, and so I had to find a whole new strategy for how to secure myself when I was at the displays and how to transition out from the displays.

Train for the worst day so you can experience the best day.

In training we had really prepared for every possible scenario we could come up with for the EVA (extravehicular activity). Really as much as we could use the imagination to prepare bad day scenarios, we had trained for them, and it was so smooth. You train for the worst day so you can actually experience the best day. The spacewalk went exactly as we had hoped.

There is so much we do not know about life in space.

We partnered with 31 institutions on 36 research experiments, a lot of which came from CU, which I was really excited about. Some of my former professors actually contributed experiments to the mission.

Overall, the research was really focused on experiments that needed human involvement, things that could benefit future life as we try and look toward Mars. There’s a lot of health issues that astronauts encounter over long duration, and this includes space motion sickness, and spaceflight associated neuro-ocular syndrome.

Many astronauts do have degraded vision over time, and we don’t actually understand the mechanism at this point. It’s often associated with the fluid shift that happens where you suddenly have more fluid in your brain, but if we’re going to actually mitigate that and fix it in the future, we need to get to the heart of the cause, so we did a whole slew of experiments looking at different eye pressure and vision change data.

Re-entry is awesome.

It’s so, so cool to reenter Earth’s atmosphere. We start seeing a glow around the spacecraft at around 100 km. Then as you start to get lower you start to see these neon colors, pinks and oranges, and you actually see some of the sparks flying past the window. As you get lower in the atmosphere you start encountering turbulence with the different layers of the atmosphere. The thrusters are firing all around and it really feels like Dragon is clawing its way back into the atmosphere.

The mission does not end at splashdown.

We were picked up by the recovery vessel, and about 30 minutes later we climbed out of the spacecraft. We were checked out by the doctors before being flown by helicopter back to Kennedy Space Center, where we met our families. From there the mission wasn’t over, we had about a week of science and research and data collection post flight. We traveled to Houston pretty immediately for some high-density bone scans.

Trusting others with your life — teamwork is critical.

Human spaceflight is the ultimate team sport. It’s not only you have to have an extreme working relationship with the people on that mission — you are absolutely trusting them with your life to keep you safe. That extends to the people on the ground team as well, you have this entire team supporting you, and even more people behind the scenes beyond that.

As a trainer, I knew the technical side of Dragon and what you need to do to live and work in space, and what I found most interesting was in one of our early sims, the four of us go in the spacecraft, and we did terribly. We completely messed up the scenario. We were all going in different directions, chasing rabbit holes and ultimately just failed the simulation in so many ways. You have to learn how to work as a team.

It doesn’t matter what you bring to the team, you have to learn when to lead, when to follow, how you bring what you can contribute through a different lens because ultimately the success of the crew is what’s most important versus your own knowledge.

Seeing Earth from space changes you.

Seeing the Earth from that perspective cannot not change someone. All of our time here on Earth is so precious, your life is only so many hours overall. I have this immense appreciation for maximizing what we are here to do in this world. I think you certainly take calculated risks when you put yourself on a rocket and launch to space, or reenter the atmosphere. Those are all things that you have to believe that the risk is worth it for the benefit. It’s shifted my perspective a little bit on how cherished our time is with our family and our friends and what we’re here to do on this Earth. I’m still reflecting on it. I think it will continue to change me.

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