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Keeping Astronauts Cool and Coffee Hot with Reflective Surfaces and Vacuums

The Eagle landing module on the surface of the moon.  July 20, 2009, marks the 40th anniversary of the Apollo 11 lunar mission.

"Houston, Tranquility Base here.  The Eagle has landed."  On July 20, 1969, the Eagle landing module became the first manned spacecraft to land on the moon.  The crew of Neil Armstrong and Edwin "Buzz" Aldrin soon became the first humans to explore the dusty, gray surface.

The success of NASA's Apollo 11 lunar mission depended on many unique technologies, one of which is the metallic silver and gold material covering the Eagle landing module.  This light-weight, metallized plastic film was used to insulate the Eagle's crew and instrumentation from radiative heat transfer from the sun.¹  Interestingly, insulation against other forms of heat transfer did not require NASA engineering; in fact, it was provided by the near-vacuum conditions in space where the absence of molecules limits conductive and convective heat transfer.

Long before the Apollo 11 lunar mission, chemist James Dewar combined the same principles of insulation, a reflective surface and a vacuum, to construct a specialized glass flask for his research on the liquefaction of hydrogen and helium.²  (Coincidentally, his work led to the liquid hydrogen rocket fuel technology that propelled the Apollo mission's Saturn V rocket into space.)  In his 1898 publication in the Journal of the Chemical Society, Transactions, Dewar noted how super-cooled liquid hydrogen could be collected and stored "in a vacuum vessel doubly silvered and of special construction".³

The vacuum vessel, or "Dewar flask" as it was later named, was essentially a flask within a flask, with the air between the two layers evacuated to form a partial vacuum.  Like the Eagle landing module, the flasks were coated with silver to prevent radiative heat transfer.  Along with the vacuum, the reflective coating effectively blocked heat transfer in and out of the vessel, keeping cold contents cold and hot contents hot for extended periods of time.  In 1906 and 1907, Reinhold Burger and the American Thermos Bottle Company filed U.S. patent applications^4,5 for improvements to Dewar's vacuum flask:

• "My invention relates to a new and useful article of manufacture comprising inner and outer glass vessels inclosing rarefied space between them.  Such vessels are used for hot and cold drinks, eatables, etc. and are made in various forms and sizes."⁵

While reflective surfaces and vacuums continue to be used to prevent heat transfer in modern Dewar flasks and NASA spacecraft, a more familiar application of these principles of insulation is in the thermos bottles designed to keep your morning coffee hot well into the afternoon. 

Contributed by
Peter S. Carlton, Ph.D.
CAS Communications

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Additional Resources

You can use SciFinder or STN to search the CAS databases for additional information about the Apollo 11 lunar mission and the research of James Dewar.  If your organization is enabled to use the web version of SciFinder, you can click the links in this article to directly access details of the references.

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References

1. NASA Scientific and Technical Information (STI). http://www.sti.nasa.gov/ (accessed July 8, 2009).
2. Sella, A. Classic Kit: Dewar's Flask. Chemistry World [Online] 2008, 5, http://www.rsc.org/chemistryworld/Issues/2008/August/DewarsFlask.asp (accessed July 8, 2009).
3. Dewar, J. Note on the Liquefaction of Hydrogen and Helium. J. Chem. Soc., Trans. 1898, 73, 528.
4. Burger, R. Double Walled Vessel with a Space for a Vacuum Between the Walls. U.S. Patent 872,795, Dec 3, 1907.
5. Burger, R. Double Walled Vessel or the Like. U.S. Patent 888,783, May 26, 1908.

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