Mars is a bad place for equipment to spring a leak.
It can get as cold as -161 °F (-107 °C); planet-wide dust storms scour the surface; the atmosphere is much thinner than Earth's; and, of course, it's 139 million miles (234 million kilometers) away from the nearest mechanic or replacement part.
Faced with these extremes, Eaton engineers knew the seals they made for a helium system on NASA's Curiosity rover — which landed successfully on Mars in early August 2012 — had to be leak tight. Specifically, they had to be so tight that they would leak helium at a rate no faster than it would take to empty a 12-ounce soda can in 11,508 years.
"The issue for (NASA) is even a single part leaking would limit their ability to use this particular module on this mission," said Matthew Roach, Eaton senior product design engineer.
Eaton's seals are in the SAM (Surface Analysis at Mars), a microwave-sized collection of instruments that Curiosity rolls along the Red Planet in search of signs of past or present life. Helium powers some of SAM's equipment and experiments, so a leak would imperil the rover's mission.
"If that helium is lost during the course of the long journey, you're going to lose your ability to function when you get to the actual time of need. So the sealing integrity is really critical," said Jeff Swensen, manager of the Eaton plant in Beltsville, Maryland, where the seals were designed and manufactured.
Over the course of several years, NASA and Eaton engineers collaborated in turning an off-the-shelf C-seal into something that would hold up to the rigors of space travel and up to two years of experiments on the surface of Mars.
"It came down to looking at our process specifications and understanding how we could improve the specifications for these particular parts to meet NASA's requirements," Roach said. "The truth is that, for most of our customers, the off-the-shelf version of these seals would work fine. For NASA, in particular, they needed a higher level of sealing integrity with these parts."
Eaton has a long history of rising to the challenges posed by space travel. It first worked with NASA on the Apollo program in 1961 and has designed and manufactured products that have been used in civilian, military and commercial space programs, including space shuttles, space launch vehicles, long-range military missiles and the International Space Station.
With seals needed in 38 critical locations on SAM, Eaton engineers performed a series of experiments to determine how different factors, such as the thickness of gold plating used on some of the seals, affected the seals' performance and made adjustments until they were optimized.
Knowing the seals were destined for a mission to Mars made the project special, Roach said.
"It's something that not everyone gets an opportunity to touch throughout their engineering careers. So even though I know I played just a small piece in the engineering of this part, it's really cool to think about and something I can always look back on fondly," he said. "And, hopefully, if something comes about from the mission and we learn a number of new things we didn't know before about life on Mars or space in general, that would be great to hear."