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Got Mercury?Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/cu m in the total spacecraft atmosphere for exposures lasting 30 days or less or 0.01 mg/cu m mercury vapor for exposures lasting more than 30 days. We also encourage the use of alternative devices that do not contain mercury.
Document ID
Acquisition Source
Johnson Space Center
Document Type
Meyers, Valerie E.
(NASA Johnson Space Center Houston, TX, United States)
McCoy, J. Torin
(NASA Johnson Space Center Houston, TX, United States)
Garcia, Hector D.
(NASA Johnson Space Center Houston, TX, United States)
James, John T.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
September 8, 2013
Publication Date
January 1, 2009
Subject Category
Space Transportation And Safety
Report/Patent Number
Meeting Information
Meeting: Fourth Annual Meeting of the International Association for the Advancement of Space Safety
Location: Huntsville, AL
Country: United States
Start Date: May 19, 2010
End Date: May 21, 2010
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