Why don't astronauts sublimate in space? (Advanced)

I'm a High Schooler who is very interested in science, especially physics. After taking several science classes last year I've spent much of the summer wondering and pondering certain topics which were covered in class. I can't wait any longer to find a teacher who can answer my questions so I thought you might be able to help.

The question is why do astronauts and the space shuttle not boil away (or sublimate) as they travel out of the earth's atmosphere?

Here are the facts(or false information) that have me stumped concerning this seemingly foolish question.

Boiling point is defined as the temperature at which the vapor pressure equals the atmospheric pressure. The atmospheric pressure in space would have to be zero.

It would seem that as the space shuttle traveled through the steadily decreasing atmospheric pressure it would reach the point at which the metal of the ship would sublimate, and then the astronauts would also sublimate. A phase diagram would help me in explaining my confusion but you'll have to imagine that one.

I can't figure out where the error in my logic is. Please help.

I can see where the confusion comes from and it certainly seems reasonable enough to make this conclusion! It is certainly true that there are no liquids in space and that if the liquid form of the metal that the Shuttle is made from went into Space it would boil very quickly. The difference is that the Shuttle and the Astronauts are solid objects. In order for them to sublimate, then there needs to be enough energy incident on them to break the strong bonds making the solid. This can be true for some solids in some conditions (for example it happens to comets as they near the Sun) but not in the case of the shuttle or the Astronauts' space suits. 

Page last updated on June 25, 2015.

About the Author

Karen Masters

Karen Masters

Karen was a graduate student at Cornell from 2000-2005. She went on to work as a researcher in galaxy redshift surveys at Harvard University, and is now on the Faculty at the University of Portsmouth back in her home country of the UK. Her research lately has focused on using the morphology of galaxies to give clues to their formation and evolution. She is the Project Scientist for the Galaxy Zoo project.

Twitter:  @KarenLMasters
Website:  http://icg.port.ac.uk/~mastersk/

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