NASA’s MMS (Magnetospheric Multiscale) mission consists of four identical spacecrafts orbiting Earth and studying a little-understood phenomenon called magnetic reconnection (believed to trigger the northern lights). Each observatory, weighing about 3,000 pounds fully fueled, is equipped with 25 sensors that can record magnetic interactions more than 100 times faster than any previous mission.

For the MMS mission’s project transporter, TRAX International was tasked with procuring two mobile environmental control units (ECUs) for NASA. These units would protect the equipment during the transfer from the Goddard Space Flight Center in Greenbelt, Maryland to Cape Canaveral, Florida.

The two ECUs would mean the difference between payloads safely arriving at the pre-launch — or taking damage from unregulated heat and humidity and causing costly delays to the launch.

Through TRAX, Air Rover worked with NASA’s engineers at the Goddard Space Flight Center. Together we designed the systems to reliably maintain environmental parameters, meet the high standards of a NASA mission and guarantee a safe and successful launch.

Tight environmental controls for pre-launch transfer

Whether the pre-launch transfer is a 30-minute trip or 30-hour journey, the spacecraft equipment is at risk of exposure to temperature, humidity and air quality fluctuations.

For example, sensitive batteries are a spacecrafts’ only source of energy during periods in which solar energy isn’t available (4-hour eclipses for the MMS satellites). If the batteries aren’t adequately protected from temperature and humidity swings, they risk failure and that power source is gone.

ECUs are essential to providing this protection, preventing millions of dollars in repairs and avoiding delays to the mission launch date.

Spacecraft project transporters typically call for a tandem ECU system for 100% redundancy, and the MMS project was no different. This project transporter in particular consisted of a ruggedized shipping container mounted atop a truck bed to travel the 880 miles to Cape Canaveral.


Together, our electrical and mechanical engineers, sheet metal designer and sales consultant worked with NASA engineers to design a precise and reliable solution for the mission-critical application.

Early design consultations overcome dimensional challenges

The application required two independent, generator-powered ECUs to be hard-mounted to various flatbed trailers. In addition to providing temperature and humidity control, the project required sufficient redundancy and air purification capabilities.

During the design review with the NASA engineers, our team noticed a challenge right away. The airflow (3,500 CFM) and static pressure requirements of the application exceeded those of our standard 5-ton system. And due to the size and weight of the high-static blower, the HEPA filters and molecular filters, they wouldn’t fit in the standard ECU cabinet either. Essentially, pure physical limitations meant we couldn’t meet the cooling capacity and the additional filtration and satisfy the specified dimensions — design negation and rethinking needed to be done.

To solve this problem, we came to an agreement with the NASA team to amend the initial dimensional and weight specifications. Additionally, we enlarged the standard size of our 5-ton cabinet to accommodate for the larger-than-usual evaporator blowers and filters. Our early involvement in the design process allowed us to quickly catch these problems, balance compromise with innovation and still achieve the desired cooling and filtration.

Finally, we included a customized system controller, which was loaded with custom programmed firmware and network accessible web user interface for remote control and monitoring capability. This gave NASA engineers greater insight into the payload’s conditions during the transfer.

Successful spacecraft transfer with two constant-run ECUs

NASA and the MMS project staff required thorough testing to meet the standards of a spacecraft transfer. After the design stage, we tested (with NASA’s witness) the thermal, air flow, static pressure and electrical performance to ensure the product was ready for the transfer. We verified network control and monitoring functionalities as well via web user interface and tested the HEPA and molecular filters efficiency through a particle count test.

Additionally, the MMS project and contamination department required submittals of the ECU components’ safety data sheets (SDS), drawings and technical manuals for review and approval prior to fabrication. Following these strict approval parameters also improved the way we approach similar projects with respect to the design review process, strict compliance with design and quality control standards. We’re always seeking ways to improve the process and product for our mission critical customers.

The project took approximately six months from start to finish, and resulted in two constant-run generators with remote control and monitoring capability (through TCP/IP protocol) to achieve redundancy in the event of mechanical failure. They were also equipped with HEPA and molecular filtration for the supply and makeup air. The ECUs provided 5 tons of constant-run cooling capacity, 15 kW of single-stage electric heat, electric reheat for humidity control and 3,500 CFM of supply airflow.

Our team leaned on our proven experience in the design of ruggedized, customized ECUs for mobile applications. With this high quality solution from a proven ECU provider, TRAX International and NASA achieved a safe arrival and launch for the MMS mission.

Reliable, precision-engineered solutions from an ECU partner

Military, defense and aerospace engineers partner with Air Rover to achieve reliable ECU solutions. With an experienced and flexible team, we’ll overcome design challenges and guarantee durability in the face of even the most demanding environments, ensuring a successful mission.

Take the next step towards your precision-engineered ECU and speak with an Air Rover engineer today.