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RELEASE NO. 02-033
NASA Helps Preserve Our Nation’s History
A team of NASA scientists working at the request of the National
Archives has determined why the United States’ most important
historical documents may be sealed in an atmosphere unhealthy to
their future preservation.
Scientists from NASA’s Langley Research Center in Hampton,
Va., presented their final report in Gaithersburg, Md., at the
National Institute of Standards and Technology, the organization
contracted to provide encasements to the National Archives. They
announced their findings on the composition of the atmosphere in
the encasements of the Declaration of Independence, the U.S.
Constitution and the Bill of Rights.
"The problem of deterioration has to do with the amount of water
vapor or humidity in the encasements," said Joel Levine, the NASA
Langley scientist who managed the project and gave the
presentation. "There is nearly twice as much water vapor in the
atmosphere around the documents as there should be. Too much water
vapor in a closed system like an encasement can cause the glass to
chemically decompose, which will lead to the deterioration of the
documents."
Some humidity is necessary to keep the sheepskin documents from
becoming brittle, but too much moisture could cause them to
deteriorate.
In the early 1950s, the documents, collectively known as the
Charters of Freedom, were sealed in specially prepared containers.
The cases were filled with humidified helium to protect the
documents. Many experts of document preservation suspected the
helium had leaked and allowed air to enter the encasements, causing
the documents to deteriorate. But the NASA Langley team proved that
the cases remained safely sealed in the original atmosphere.
"We also discovered a very large amount of carbon dioxide in the
encasements that is nearly ten times higher than what is found in
Earth’s atmosphere, and that is a very surprising result,"
said Levine.
Over the next few months, the National Archives will replace the
containers preserving the Charters of Freedom. Before doing so, the
agency wanted to understand why the documents were deteriorating
and contacted Dr. Levine for assistance.
His research group consisted of three independent teams that
included NASA Langley researchers Patricia Davis, Jeffrey Jordan,
Glen Sachse, Glenn Diskin, James West and Cecil Burkett. Two teams
used non-invasive measurements techniques to study the atmosphere
through the glass encasement. The third team used NASA Langley
instruments to determine the chemical composition of extracted
samples from each case. The teams, unaware of the others’
findings and applying different methods, produced very consistent
results.
"These documents form the basis of U.S. democracy, and it is
important to preserve them," said Levine. "We’re happy we were
able to apply technology, originally developed at Langley for
atmospheric science, remote sensing, laser spectroscopy and wind
tunnel measurements, to ensure the future stability of the Charters
of Freedom."
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