• The ISS has ammonia pumps to keep it cool
  • Robotic External Leak Locators (RELL) were sent to the ISS to detect possible ammonia leaks
  • A "robot hotel" RiTS was just sent to the ISS to house two RELLs 
  • With RiTS, the two RELLs can work more efficiently

In order to keep the International Space Station (ISS) cool, it is fitted with ammonia pumps, much like a very advanced house air conditioning system. However, just like with a regular house, the system can break down and accumulate leaks over time, often due to micrometeoroids or tiny high-speed objects flying through space.

Although it is not a major safety hazard, having leaks to the system can directly impact its efficiency.

For this matter, the first Robotic External Leak Locators (RELL) was sent to the ISS in 2015. Equipped with mass spectrometers, RELL is able to detect leaks from the station by “ sniffing ” out signs of gasses such as ammonia. Because the first unit was a major success, a second unit was sent to the ISS as a back up earlier this year.

However, as important as the RELLs are, having to keep two of them inside the space station takes up space that could be used for other important tools, especially since RELL actually works outside the space station where they can be remotely controlled.

What's more, it takes quite a lot of precious time before RELL can be used because once the robots are brought out of the station, they still need about 12 hours before they can be used. This is because RELL's hypersensitive gas analyzers still need to clear waver vapor and other gases from inside the ISS.

Because of this lengthy process, it could take weeks to even months before a suspected leak is finally detected.

This is where Robotic Tool Stowage (RiTS) comes in. At the recent commercial resupply mission to the ISS, SpaceX brought a “robot hotel” that will sit outsite the ISS and protect the two very critical robots currently on the station.

Once installed by ISS astronauts, RiTS will provide its robotic tenants with heat and physical protection from micrometeoroids and from radiation, and provide the ideal temperature that will keep the robots’ instruments working properly. With RiTS, the robots are also at a much easier reach for the ISS's robotic arm, Dextre.

“This hardware will significantly reduce time and cost for the station crew to deploy leak detection capabilities using Dextre,” NASA Senior Systems Integration Lead Chris Craw said. “With RiTS, we'll have easier and faster access to RELL, which can help ensure our astronauts’ safety in space.”

Such technologies, although they seem as though their purposes are not major, could prove critical to future space missions. For instance, on missions to moon, Mars, or perhaps in deeper space, the RELL-RiTS collaboration could be used to detect possible leaks from human habitats.

Rell and RiTS
Photographed is a RELL Engineering Development Unit on the left beside the RiTS "robot hotel." NASA