The Air Force Research Laboratory, or AFRL, launched the Space Power InfraRed Regulation and Analysis of Lifetime, or SPIRRAL, experiment, November 4, 2024. SPIRRAL, flown by AFRL through the DOD Space Test Program, will characterize the performance of Variable Emissivity Materials, or VEMs, an approach toward solving thermal challenges for space vehicles while on-orbit.
VEMs are surface finishes that act like color-changing paints, however, the changes in coloration are only in the infrared light spectrum and are not visible to the human eye. VEMs can either reject or retain heat depending on the temperature being experienced. When the VEMs are hot, the material’s optical properties change to reject heat; when they are cold, they retain heat, effectively reducing temperature extremes.
“Similar to the many electronics we use in our daily lives such as cell phones and computers, maintaining optimal temperature ranges are crucial for a device’s efficiency and life expectancy,” said Bryce Hart, SPIRRAL Program Manager. “Due to the irreversible damage extreme temperatures can cause, managing temperature is vital for electronics to thrive in the space environment.”
SPIRRAL will host a variety of VEMs onboard an Aegis Aerospace Materials International Space Station Experiment or MISSE carrier. The carrier will be secured to an external face of the International Space Station (ISS), exposing the VEM samples to the space environment. While the VEMs undergo the temperature extremes of space, performance data is then captured. The data collected will be compared to their expected performance based on models formulated by terrestrial characterization.
The SPIRRAL Principal Investigator, Isaac Foster, highlighted the importance of this technology.
“Thermal management in space is incredibly challenging. VEMs enable more efficient and reliable spacecraft in ways that current thermal management solutions do not. Demonstrating these VEMs on-orbit is imperative to understanding how to implement this technology going forward to ultimately bolster spacecraft resiliency,” Foster said.
This type of perpetual modernization is key to ensuring that U.S. forces are equipped with the necessary tools to enhance space asset resiliency, autonomy, and flexibility.
SPIRRAL is a critical component of AFRL’s Space Solar Power Incremental Demonstrations and Research or SSPIDR Project, which is focused on developing and demonstrating technologies for a space-based solar power collection and transmission system capable of providing uninterrupted, assured, and logistically agile power to expeditionary forces.
A system of this magnitude would consist of large arrays with minimal thermal mass; making the system’s electronics highly susceptible to damage due to extreme temperature changes on-orbit – a challenge that can be overcome by VEMs as they offer a passive, low-mass solution, dethroning the current active thermal control systems used today.
James Winter, SSPIDR Program Manager, said, “VEMs not only provide solutions toward making a space-based solar power system a reality, but they will also usher in a new paradigm for spacecraft thermal designers, revolutionizing the way space-based thermal systems are designed and implemented.”
Dr. Andrew Williams, Deputy Technology Executive Officer for Space at AFRL, underscored this point by projecting that the impact of SPIRRAL will extend far beyond benefits to SSPIDR, completely changing spacecraft thermal control for all satellites. He said, “This technology is the holy grail for spacecraft thermal control and will revolutionize the cost and time for thermal design.”
“We are committed to win the future in Space. The advancements we are making in space-based solar power systems are game changers for space vehicle resiliency,” said Brig. Gen. Jason Bartolomei, AFRL Commander and Department of the Air Force Technology Executive Officer.
About AFRL
The Air Force Research Laboratory, or AFRL, is the primary scientific research and development center for the Department of the Air Force. AFRL plays an integral role in leading the discovery, development and integration of affordable warfighting technologies for our air, space and cyberspace force. With a workforce of more than 12,500 across nine technology areas and 40 other operations across the globe, AFRL provides a diverse portfolio of science and technology ranging from fundamental to advanced research and technology development.
