NASA’s PACE Mission is set to launch on Feb 8th with Boyd’s loop heat pipes on board. This mission is the latest highlight in Boyd’s extensive, decades long, aerospace heritage. Boyd is proud to collaborate with NASA engineers to assist in the latest space missions to help us learn more about the world we live in.

More About the PACE Mission

PACE stands for Plankton, Aerosol, Cloud, ocean Ecosystem, which are all key indicators to the health and status of Earth’s oceans and climate. PACE will be launched on February 8, 2024 on board SpaceX’s Falcon 9 payload fairings. PACE’s mission is to assess and measure the distribution of phytoplankton, tiny plants and algae that sustain the marine food web. It will also continue systematic records of key atmospheric variables associated with air quality and Earth’s climate.

Learn more about the NASA PACE Mission (NASA.gov)

More About Loop Heat Pipes (LHPs)

Loop heat pipes are a specialized thermal management component uniquely suited to both launch and microgravity environments. LHPs are a method of passive heat transport that can span over 20 meters and can resist up to 9g acceleration forces. Loop heat pipes are also flexible up to millions of cycles, meaning it can withstand any vibrational flexing or actuations over the lifespan of the LHPs application.

Learn more about our heat pipe assemblies.

In our previous blogs, we’ve gone over What Are Thermosiphons? and the various Thermosiphon Configurations and Applications. Here we’ll be answering one of the most commonly asked questions regarding Two-Phase Cooling: what is the difference between a Thermosiphon and a Heat Pipe?

The Main Distinction

While both are passive cooling systems that are based on evaporation and condensation of a working fluid, the distinction between a Heat Pipe and a Thermosiphon is the existence of a wicking structure within Heat Pipes that is absent from Thermosiphons. This wicking structure, usually a sintered powder, axially grooved, wire mesh, or screen wick, creates a capillary pressure that allows working fluid to return to the condenser, in any orientation including against gravity. For a Thermosiphon, the working fluid returns via gravity, meaning the heat source and evaporator need to be located below the condenser unit.

What Are Other Benefits and Drawbacks?

Qmax:

The maximum heat transfer capacity (Qmax) for a Thermosiphon is typically going to be greater than that of a Heat Pipe of an equal diameter and length. The wick structure restricts the amount of vapor space and the potential speed of liquid returning to the evaporator through the wick capillaries. In a Thermosiphon, fluid and heat can move more efficiently since it gravity removes the need for a wick.

Distance from Heat Source

Because Thermosiphons do not rely on a wicking structure to transfer fluid, the length that a Thermosiphon can transfer heat is much longer than that of a Heat Pipe. At Boyd, Thermosiphons have been created upwards of several meters in length. If the gravity is favorable, Thermosiphon length can be virtually unlimited.

Temperature Control:

Thermosiphons tend to allow for much tighter temperature control over multiple heat sources when compared to Heat Pipes. Since a Thermosiphon doesn’t rely on multiple individual tubes, the vapor pressure stays the same throughout the assembly. This means the temperature is going to be similar across the entire Thermosiphon assembly as heat is pulled from the heat sources.

Fewer Tubes and Lower Profile:

When using a Thermosiphon construction with a remote condenser unit, due to the higher heat transfer capacity, the number of tubes needed between the evaporator and condenser is much smaller than the number used for a similar Heat Pipe Assembly. Thermosiphon tubes also have a lower profile than Heat Pipes for similar heat transferability, meaning that they can potentially block less airflow through the system, leading to more efficient cooling.

Design and Complexity:

Thermosiphons are always custom designed for each specific application, based on a variety of factors. This can result in complex and involved design, planning, and development to bring a concept into a manufactured product. Heat Pipe Assemblies are also customized, but individual Heat Pipes have more off-the-shelf constructions readily available for integrating into an assembly.

Boyd has decades of experience creating both Heat Pipe and Thermosiphon assemblies for a wide variety of applications and industries. To learn more about our Two-Phase Cooling capabilities, visit our website or reach out to our experts.

Cooling Solution for the Critical SuperCam Assembly of the Perseverance Mars Rover

The SuperCam Module of the Perseverance Mars Rover

NASA’s Perseverance Rover mission is to search for signs of previously or currently habitable conditions on Mars and for signs of past microbial life. The SuperCam utilizes remote-sensing techniques to conduct minerology analysis of both the environment and samples within the robotic-arm workspace. The SuperCam is a technological improvement over Curiosity’s ChemCam, as it adds two new techniques for determining mineralogy a color imager, and an acoustic system to remotely determine physical properties of targets.long tradition The SuperCam includes a broad range of spectroscopy instruments, some of which utilize Thermal Electric Coolers (TECs) that use the Peltier effect to pump heat away from electronics and maintain tight temperature control. The TECs need to reject heat to help protect the electronics vital to minerology observations.

Custom Cryogenic Heat Pipes to Withstand Martian Environments

Heat pipes are a common component in many electronic assemblies used to either spread or transport heat. Many applications use heat pipes to prevent heat build-up and potential damage to sensitive and expensive equipment by quickly moving heat away to cooler regions. While most heat pipes are robust and straightforward; customizations and material selections enable these straightforward solutions to solve more complex challenges, applications and operating environments.

For the Perseverance Rover, maintaining a safe operating temperature of data collection equipment is paramount to the success of the rover. There is no way to do maintenance and repair to the Rover once it’s launched, so thermal management solutions must reliably perform in extreme temperatures common on Mars over the entire lifetime of the rover. Failure is not an option. Boyd’s heat pipes are an ideal solution for space applications like these as they’ve been proven to operate consistently over decades of operation with no active moving parts.

Mars is much colder than Earth but there is less atmosphere, so natural convection air cooling is much slower making electronics at risk of overheating despite the colder environment. This colder environment makes common copper-water heat pipes unsuitable for the Mars Rovers. To solve the performance and environment challenge, Boyd uses our Material Engineering expertise to feature methanol as an alternative working fluid for passive two-phase cooling, which doesn’t freeze at Rover temperatures.

Boyd has previous experience fabricating solutions for Mars missions, making us a solid partner in developing reliable thermal management solutions that meet the demands of reliably performing on Mars. We leveraged our understanding of Martian environment design challenges to create a new heat pipe solution in partnership with Los Alamos National Labs for the SuperCam module. The SuperCam module enables critical imaging, mineral, and chemical analysis, a central portion of the Perseverance Rover mission.

Los Alamos National Labs approached Boyd to help transport a total 6W of heat away from the charge-coupled devices (CCDs, optical detectors) within the SuperCam Module to be transferred to thermoelectric coolers (TECs). As a team, LANL and Boyd developed three heat pipe assembliesto cool 2W each, constructed with two 5mm diameter plated copper-methanol heat pipes. This enables a stable ~20°C of cooling below the temperature of the Rover Accessory Mounting Plate (RAMP).*

One Company, Many Solutions for Space Exploration

Thermal Management is only one of Boyd’s strengths when it comes to supporting space exploration and aerospace applications. From our flame-resistant SOLIMIDE® Insulating Foams to EMI/RFI Management, Boyd can help protect your equipment and cargo in the demanding environments of space with thin atmospheric conditions. Other Engineered Material solutions like Optically Clear Adhesives and High Performance Gaskets protect camera and sensor lenses, sealing and protecting against harsh external environments.

Boyd strives to provide quality, reliable solutions to all industries, but it is a privilege to support the Perseverance Rover and be a part of NASA’s mission to explore Mars. Our long tradition of providing highly engineered thermal management solutions for space exploration will enable the Perseverance Rover to endure for years to come.

Preparing for Launch

As NASA is making final preparations for the launch, Boyd Corporation continues to develop and fabricate solutions for upcoming Martian projects. We’re looking forward to a successful launch on July 22nd (or August 11th at the latest) and the eventual deployment of the Perseverance Rover on Mars in February 2021. Good Luck NASA and thank you Los Alamos National Laboratory for the opportunity to be a part of history!

Are you working on a project that has demanding thermal management requirements or must survive harsh environments? for your challenging applications!