Aggreko Chillers Assist NASA Tests on Mars SLS Rocket


Mars is that much closer. The journey toward new human exploration missions beyond Earth’s orbit took a major step forward on June 28 with the successful completion of the second and final qualification test of a five-segment rocket motor for NASA’s heavy-lift Space Launch System (SLS). The motor manufacturer, Orbital ATK, based in Dulles, Va., recently confirmed the QM-2 motor performed as designed.

 

Low-Temperature Performance Is Key Test Objective

NASA’s SLS is dubbed as the biggest, most capable rocket ever built for human exploration. It’s getting a lot of attention given its ambitious, deep space, human exploration goals and the estimated $10 billion investment in rocket technology alone. As with every rocket program, the heavy lifting starts on the ground, where development and qualification motors are thoroughly tested before first flight. SLS development followed a five-test protocol that began in 2009 and culminated with the final, successful qualification test of the QM-2 in June. This final test included 82 qualification objectives. Among the most important of these was the evaluation of solid rocket motor performance at its low-temperature range, 40 °F, +/- 2 °F.

Cooling a 12 foot diameter, five segment rocket requires equal parts performance, diligence and patience. Orbital ATK relied on Aggreko, based in Glasgow, U.K., to provide the cold conditioning system to reduce propellant mean bulk temperature (PMBT) from its initial 73 °F down to a test-ready PMBT of 40 °F.

 

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NASA’s SLS is dubbed as the biggest, most capable rocket ever built for human exploration.

 

The 154-foot long, five-segment solid rocket motor was housed in Orbital ATK’s T-97 test facility in Promontory, Utah. This free-standing, moveable enclosure was built on an electrically driven rail system. Keys to successful cold conditioning the rocket and propellant inside this facility included:

  • Controlling humidity
  • Maintaining positive pressure within the enclosure
  • Minimizing foreign object debris
  • Providing a portable system
  • 48-hour resolution of any necessary repairs or replacements of system components

 

Mobile Temperature Control System Hits Target

To meet testing requirements, Aggreko helped Orbital ATK design a temporary, portable solution for temperature control and power generation. At the heart of the system were two, 200-ton, low-temperature mechanical chillers and two pumps used to deliver a 50 percent propylene glycol solution to the air handling units (AHU). Three sets of two, 120-ton AHUs circulated cold air to the enclosure. The tandem arrangement allowed one AHU to deliver chilled air while the other operated in defrost mode. An additional AHU dehumidified and cooled outside air to maintain positive pressure in the enclosure.

 

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Aggreko temperature control and power gen equipment onsite at Orbital ATK’s T-97 test facility.

 

Behind it all was a temporary power system designed for two purposes. The first was to power the distribution panel for the chillers and pumps. The second was to provide backup power for three, three-phase, 480-VAC power stanchions for the AHUs. Aggreko provided two, containerized 500 kW generators and cabling to meet these requirements.

Finally, a senior technical support team provided continuous on-site oversight and support for the duration of the conditioning protocol, including on-demand control of the cool-down rate based on customer instructions.

Once the systems and personnel were in place, the conditioning started at T minus 80 days to test. The required PMBT was achieved in approximately 64 days. Ultimately, the motor and propellant were successfully delivered for the test at 40 °F, within the specified, acceptable temperature range.

“The scale of NASA’s investment and the historic significance of SLS testing, especially the final qualification test before flight, are things you can’t help but get excited about,” stated Steven Bukoski, on-site program manager for Aggreko. “When the rocket fires, all the work that went into making sure we had the propellant at the right temperature is easily forgotten. Our team is good with that. Being part of something this important is very worthwhile and fulfilling.”

While it’s easy to get caught up in the dramatic 126 seconds of ground testing, the importance of cold conditioning can’t be overlooked,” stated Curtis Wise, Test Motor Program Manager, for Orbital ATK. “Reducing and maintaining the propellant temperature to the exact test specifications requires well-engineered, reliable systems, as well as a full staff of support personnel around the clock. Aggreko met all of our requirements.”

 

Ready to Take Flight

QM-2 was the final ground test before Exploration Mission 1—the first planned flight of the SLS scheduled for late 2018. According to Orbital ATK, the test provided critical data that demonstrated nozzle, ballistics and other design performance parameters met requirements at the design temperature of 40 °F. The previous qualification test, QM-1, validated motor performance at its high-temperature range of 90 °F. The QM-1 test, as well as the Design Motor tests, DM-1, DM-2 and DM-3, also employed Aggreko temperature and power generation systems.

Supplying temporary, mobile cold conditioning systems can easily go unnoticed. Relatively speaking, it’s not rocket science. But it is essential that these systems and the people who support them perform reliably—especially when they’re at the heart of establishing a critical test objective for the most advanced rocket development program in NASA’s history.

See a YouTube Video of the Test Firing https://youtu.be/7yT8Sc-ifZw?list=PLBEXDPatoWBmX3yrpEObbUoNF5rbbNcgX.

For more information visit us.aggreko.com.