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Sierra Space has successfully completed thermal vacuum chamber (TVAC) testing on a deployable radiator panel prototype at NASA’s Johnson Space Center, marking a milestone in advancing the company’s spacecraft thermal control capabilities. The test evaluated the radiator’s performance under the extreme thermal and vacuum conditions of space and represented another successful collaboration under CCSC-2 (Collaborations for Commercial Space Capabilities 2), Sierra Space’s unfunded Space Act Agreement (uSAA) with NASA.

Through this ongoing collaboration, Sierra Space continues to mature in-space technologies that will support future commercial, government, and exploration missions. All spacecraft generate heat from electronics, life support, and propulsion systems. Without a way to remove that heat, onboard equipment can fail and crew can overheat. Radiator systems provide critical heat rejection capability. They allow excess heat generated within the vehicle to be radiated into space.

Large spacecraft often use pumped fluid loops that collect waste heat within the vehicle and transport it to the radiator panels. This ensures efficient, continuous thermal regulation — a requirement for both crewed and uncrewed missions in low Earth orbit and beyond. Thermal Vacuum (TVAC) testing replicates the harsh environmental extremes of space, combining near-vacuum pressure with cycles of high and low temperatures. This process validates a system’s performance, durability, and ability to maintain functionality under repeated exposure to these conditions.

The prototype performed as expected under simulated orbital conditions, confirming the radiator’s design and functionality while reducing potential risks for future deployment. This work was conducted as part of CCSC-2 (Collaborations for Commercial Space Capabilities 2), Sierra Space’s unfunded Space Act Agreement (uSAA) with NASA, executed in June 2023. Following successful TVAC testing, Sierra Space engineers are using the data to refine radiator design, improve manufacturing processes, and continue advancing thermal control systems toward flight readiness.