USU tank to help mimic outer space

Liquid nitrogen contents will aid instrument tests
By Joe Bauman
Deseret News
July 1, 2002

Outer space is coming to Logan.

About 50 spectators at Utah State University's Space Dynamics Laboratory could see it begin to happen Friday morning. Two cranes hoisted a monster tank from a flatbed truck, and one of them lowered it into a tall housing in the lab's new Calibration and Optical Research Center.

This 32-foot-long, 11-foot-wide tank will be housed at the Calibration and Optical Research Center at USU's Space Dynamics Laboratory.

This 32-foot-long, 11-foot-wide tank will be housed at the Calibration and Optical Research Center at USU's Space Dynamics Laboratory.
Photo courtesy Brian Atkinson

The 32-foot-long, 11-foot-wide tank doesn't enclose a chunk of deep space. But by the first of October it is slated to hold tons of liquid nitrogen, which will be used to cool down a test chamber in order to mimic the harsh environment far beyond Earth.

Inside the chamber, a vacuum will be combined with the unbelievable cold of space so that instruments can be calibrated and tested in conditions like those they will encounter in orbit.

The 11,000-gallon tank weighs 23.5 tons empty; filled, it will tip the scales at around 60 tons. The liquid nitrogen will be able to drop the temperature in the "V2 radiometric test chamber" to a stunning minus 321 degrees Fahrenheit, according to USU.

"It was really neat," said Forrest Fackrell, the laboratory's business manager, who watched the great tank hoist. "It weighs about 23 tons, so it came in on a big flatbed trailer."

Workers connected the tank to two cranes, which then lifted the tank from the flatbed.

"The trailer pulled out, and then the large-capacity crane pulled the tank vertical to where it was upright," Fackrell said.

"They unhooked the small crane, and then the big crane just took it on up."

Fackrell watched as the crane lifted the tank 70 feet in the air, then swung it into place above the special housing. The tank had to be lowered in to stand upright on three massive legs.

"The concrete footing that it sits on is 30 inches thick, heavily rebar-reinforced," he said. The lift went smoothly, without the tank bumping walls or causing damage.

Liquid nitrogen will be trucked in by tanker truck, delivered from suppliers. The tank is insulated to protect the nitrogen and keep it from boiling away.

When finished, the new lab will cost about $8 million. But the V2 vacuum chamber is a donation from aerospace giant Boeing.

Company officials decided to move away from research and development of infrared sensors and focus more on production, so they made a gift of the test chamber, says USU. That allowed Boeing to take some tax benefits.

The vacuum chamber is 12 feet long and eight feet across. It will house a rock-stable optical test bench and specialized equipment.

"It definitely will increase our capability and allow us to do a little bit bigger things here in our facility," said Fackrell.

The tank will hold tons of liquid nitrogen, used to cool a test chamber.
Photo courtesy Brian Atkinson

Many of the space instruments that USU will calibrate and test for NASA and the military record infrared data. That's light of a wavelength beyond red, invisible to the human eye but providing a great deal of information to nonhuman sensors. Infrared light is released by heat.

"As things get hotter, you get more infrared energy from them," said Alan Thurgood, associate director of the lab. The instruments to be tested are extremely ensitive, so they will be able to pick up minute amounts of infrared energy.

A camera being calibrated may be required to see the feeble infrared gleam of a star thousands of light-years away. To make it work right, "you need to simulate the . . . same brightness of sources as you're going to be measuring," he said.

Think of a visible light equivalent, Thurgood suggested. If you want to calibrate a sensitive camera using a dim light, you don't want that tiny bulb competing with a roomful of bright light. Instead, you'd switch off the other lights and then you would see the little glow.

To calibrate a camera that detects infrared radiation, you need to "turn down" heat sources by bringing the room's temperature close to absolutely zero.

Meanwhile, the chamber will be nearly as airless as the moon.

"You have to have a vacuum inside of the chamber before you start cooling it," Thurgood said. Otherwise, cold that intense would freeze the water out of the air.

"All that moisture . . . will freeze out, form frost on everything," he said. When the calibration or test is over, the frost would melt, "and you've got water all over your stuff."

A vacuum is essential not only to insulate the chamber but to create realistic test conditions for gear that will go into space.

The Space Dynamics Laboratory has long been a leader in the development and testing of infrared sensors for satellites. It already has relatively small chambers, but for testing the larger instruments now on the drawing boards, it needed a bigger vacuum facility.

Once the 43,000-square-foot center is complete, it will provide office space for more than 60 researchers, managers and technicians, plus meeting areas and special labs.

Meanwhile, watching the nitrogen tank go in was a treat for lab experts.

The 32-foot tank had to get over a 33- or 34-foot wall, said Stephen Dansie, an engineer associated with the laboratory. "It's an impressive sight to see that crane lift that thing over the wall."