Dextre tests a new tool to detect leaks

Dextre is putting a new NASA tool through its paces that will help pinpoint potentially dangerous ammonia leaks on the International Space Station (ISS). If the tests prove successful, the ISS Robotic External Leak Locator (IRELL) will help detect leaks more effectively so that they can be fixed quickly, and confirm that repairs are successful. IRELL was designed to be sensitive enough to sniff out traces of ammonia from a football field away.

Dextre tests NASA's International Space Station Robotic External Leak Locator (IRELL)

While riding on the end of Canadarm2, Dextre will move to various locations on the ISS's exterior, using the IRELL tool to scan the cooling system to detect traces of ammonia. (Credit: Canadian Space Agency)

Why use ammonia on the ISS if it is dangerous?

We tend to think of space as a vast, cold void, so it is a bit surprising to learn that the ISS has a special system just to manage the extra heat generated by its solar panels.

The ISS's cooling system works by pumping ammonia through a series of pipes alongside the solar panels, which prevents them from overheating. Ammonia is an efficient substance for dissipating heat, but it can be dangerous to the ISS itself if it leaks, especially if it affects the Station's environmental control and life support systems. Leaks can even jeopardize a spacecraft's stability.

If a leak is sufficiently large, the ammonia looks like snowflakes on the Station's exterior. However, small leaks are not as easy to spot. Pinpointing their exact origin can be difficult and time-consuming, and typically requires a spacewalk to identify and repair the problem. This is where Dextre steps in. By using IRELL, Dextre can save the crew valuable time and resources—not to mention the inherent risks of a spacewalk. Dextre is entirely operated by mission controllers at either NASA's Johnson Space Center in Houston, Texas, or at the Canadian Space Agency's headquarters in Saint-Hubert, Quebec. This way, the astronauts aboard the ISS can continue to conduct science and other important tasks. In fact, most of Dextre's work takes place while the crew is asleep. If the leak locator tests prove successful, IRELL could be used not only to find leaks but also to verify that repairs have fixed the problem.

The International Space Station Robotic External Leak Locator (IRELL)

Dextre is testing IRELL to determine its efficiency in sniffing out potentially hazardous ammonia leaks on the ISS's exterior. (Credit: NASA/Chris Gunn)

An unplanned spacewalk

During Chris Hadfield's expedition to the ISS, two of his crewmates conducted an unplanned spacewalk to perform urgent repairs on the cooling system. Expedition 35 flight engineers Tom Marshburn (left) and Chris Cassidy (right) completed a 5.5-hour spacewalk to replace a pump controller box that was leaking ammonia coolant. (Credit: NASA)