
The dark orange external tank is the largest component of the space shuttle stack. It holds 535,000 gallons of liquid hydrogen and liquid oxygen for the shuttle's three main engines.
There was an interesting article this week on GAWDAwiki about NASA, cryogenic gas and Facebook. In short, NASA fielded questions from its followers on Facebook, many of which were about the use of cryogenic propellants. There were a number things about this story that piqued my interest.
First, I think it’s great that so many people have an interest in gases. I definitely learned a lot about their use of liquid hydrogen and oxygen. NASA explains:
“The tank holds about 535,000 gallons of liquid hydrogen and liquid oxygen. Both propellants are cryogenic, which means they are super-cold. The oxygen is chilled and pressurized to minus 297 degrees F in its liquid form and the liquid hydrogen buries the temperature needle to minus 423 degrees F.”
Ever wonder about the filling? Wonder no more:
“The liquid oxygen and liquid hydrogen tanking process begin simultaneously. The process begins by chilling the transfer lines and main engines. Both commodities begin with slow fill to avoid thermal shocking of the aft domes. We then transition to fast fill up to about 98 percent capacity. We slow back down at this point to avoid overfilling. Once filled, we move into a stable replenish flow rate to maintain proper propellant levels and conditioning.
“Regarding the liquid hydrogen tank, we use helium to pressurize the tank for flight. The preburn you mention is actually for the liquid oxygen exhaust at the main engines.”

A look inside the external tank shows the junction of the liquid oxygen tank on top and the liquid hydrogen tank on the bottom. The intertank joins the two tanks together to make a complete external tank. Photos via NASA
Now you have a good reason to watch the next shuttle launch! (Check out the launch schedule here.) What questions would you ask NASA about their use of gases?
The second reason this story interested me is because it’s a great use of social media to connect with people and share knowledge. Education is a great way to establish yourself as a trustworthy authority.
In terms of a gases and welding distributor, how are you reaching out to your customers through social media? I’d love to hear any interesting stories you may have involving social media in your business.
Out of curiosity, anybody know who provides those 535,000 gallons of cryogenic gas? I’d love to hear if a GAWDA member is involved.