Deployable Structures and Advanced Loop Heat Pipes
Deployable structures combined with advanced loop heat pipes (LHPs) are transforming spacecraft thermal management by overcoming the limitations of small satellite radiator area and increasing heat rejection capability. LHPs provide passive, highly efficient heat transport through two-phase fluid dynamics, enabling uniform temperature control across deployable radiators. When paired with additive manufacturing, these systems become more cost-effective and scalable, supporting next-generation high-power, compact spacecraft designs.
KEY TAKEAWAYS
- Deployable radiators expand available surface area after launch, helping small satellites reject more heat without increasing launch size.
- Loop Heat Pipes (LHPs) provide passive, highly efficient heat transfer using phase-change, eliminating the need for mechanical pumps.
- Two-phase thermal systems like LHPs outperform traditional conduction methods by improving temperature uniformity and reducing thermal resistance.
- Additive manufacturing enables more complex, lightweight, and cost-effective thermal system designs.
- Combining deployable structures with LHPs supports higher power-density spacecraft and more advanced mission capabilities.
As space missions become more ambitious, spacecraft are being asked to do more with less mass and less volume, all while retaining the same level of reliability. Deployable structures, including antennas, solar arrays, booms, radiators, and instrument platforms, have become a necessary solution. The spacecraft is launched in a compact form factor (“stowed”) and relevant mechanisms deploy when in a stable flight condition, allowing larger surface areas and enhanced performance otherwise unavailable with given launch constraints.
While deployable structures unlock new mission capabilities, they can also impose significant thermal management challenges – there’s no free lunch, especially in space. Components mounted on deployable elements often generate heat far from the spacecraft bus and often can’t cohabit the structure with a dedicated radiator. Likewise, deployable radiator panels afford a system with significantly more heat rejection capability than fixed radiator panels mounted to the primary structure, but design engineers must determine a means of transporting this energy efficiently across rotating/dynamic joints required for these enhancement features. Both conditions put waste energy a far, and torturous, distance away from radiator panels needed to maintain critical thermal balance. Addressing this complicated challenge is where ACT’s advanced Loop Heat Pipe (LHP) technology enters as the current state-of-the-art.
The Thermal Challenge of Deployable Structures
Deployable structures operate in a dynamic environment. They experience:
- Large temperature swings between sunlit and shadowed conditions
- Mechanical movement and articulation during deployment
- Limited conduction paths due to hinges, joints, and lightweight (typically non-conductive) materials
- Strict mass and volume constraints
Traditional thermal solutions—such as thermal straps—can struggle in these applications. They can add significant mass for any reasonable waste heat, limit deployability/flexibility, or introduce reliability risks.
To ensure long-term performance, deployable structures require lightweight, flexible, and highly reliable heat transport solutions that can operate across varying orientations and thermal loads.
Thermal Systems, Structural Excellence.
Seamlessly combining advanced thermal management with structural excellence, our solutions are designed to perform reliably in the most demanding space missions. Download the brochure.
Loop Heat Pipes: Enabling Efficient Heat Transport
Loop Heat Pipes (LHPs) are passive, two-phase heat transport devices capable of moving large amounts of heat over long distances with minimal temperature drop. Unlike conventional heat pipes, LHPs are particularly well-suited for deployable systems because they:
- Operate effectively in 1-g and microgravity environments
- Contain all wick structure in the pump body (evaporator and compensation chamber, located at the side receiving the waste heat from the components to be cooled), allowing seamless tubing coils or flexible lines to be integrated in locations where deployment dynamics occur
- Provide high heat transport capacity with exceptional reliability and are able to receive heat fluxes well beyond those of traditional Aluminum Ammonia Constant Conductance Heat Pipes (CCHPs)
- Can effectively maintain an evaporator temperature, or shut down heat transport from evaporator to condenser, with minimal energy inputs – typically single-digit Watts
For deployable structures, LHPs can transport heat from distributed or articulated components directly to radiator panels, even when those radiators are mounted on separate deployable elements.
ACT’s Advantage- 3D Printed Loop Heat Pipes
Loop Heat Pipes have decades of heritage within ACT and in use in spaceflight environments, and traditionally manufactured LHPs continue to be a valuable technology to spacecraft thermal engineers. ACT has developed advanced 3D printed Loop Heat Pipes, purpose-built for demanding aerospace applications and a new tool in the proverbial toolbox for spacecraft thermal engineers.
Additive manufacturing offers unique advantages over traditionally-manufactured LHPs:
Design Freedom
3D printing allows for complex internal and external geometries, enabling optimized wick structures, integrated features, and compact evaporator designs that fit within tight structural envelopes not possible with traditional manufacturing approaches.
Mass and Volume Optimization
By tailoring each LHP to the specific mission and structure, ACT minimizes mass while maintaining high thermal performance – critical for deployable systems.
Reliability and Derisking
ACT’s 3D printed LHPs remove traditional knife-edge seals within the pump body, a prevalent risk item for traditional LHPs. The wick is also printed integrally to the solid metal envelope, eliminating complicated manufacturing processes previously required.
Structural Integration
ACT’s LHPs can be designed to integrate seamlessly with thermal/structural components, reducing interfaces and simplifying integration.
Proven Performance Through Testing
ACT conducts comprehensive thermal and mechanical testing to ensure LHP performance through launch, deployment, and on-orbit operations.
From Structure to Radiator- A Complete Thermal Path
In deployable spacecraft architectures, ACT’s 3D printed LHPs provide a reliable thermal bridge, transporting heat efficiently from:
- Electronics or instruments mounted on deployable booms or panels
- Mechanisms and actuators that require temperature control
- Distributed payloads that cannot rely on direct conduction
- Radiator panels optimized for heat rejection to space
This capability enables spacecraft designers to place components where they perform best—without being constrained by thermal limitations. By combining advanced additive manufacturing, deep thermal expertise, and rigorous testing, ACT delivers thermal solutions that deploy with confidence—mission after mission.
