One-Million-Liter Test Sphere

Jun 18, 2021 1 comments

Tucked away at a corner of Fort Detrick in Frederick, Maryland, dwarfed by buildings on three, sides stands a relic of Cold War—a humongous steel sphere 40 feet across with volume of 1 million liters. For most of its existence, the sphere remained hidden enclosed under a large wood and metal cube. But the timber has now disintegrated away revealing this extraordinary contraption with a sinister past.

Fort Detrick was the center of the US biological weapons program from 1943 to 1969. Much of the tests involving aerosols of infectious agents was conducted inside this steel sphere, lovingly referred to as the Eight Ball.

One-Million-Liter Test Sphere in Google Maps

The One-Million-Liter Test Sphere was like a cloud chamber used to test how aerosolized biological agents highly pathogenic to man and animals would suspend in the air and infiltrate the lungs in a controlled environment. Access ports along the perimeter of the sphere, fitted with biological safety cabinets allowed small tethered animals such as monkeys to be introduced into the chamber for live testing. Human volunteers could also breath in metered aerosols of infectious organisms through these ports. Such test allowed scientists to determine the lethal doses of biological agents. Scientists also tested the most effective method of dissemination of deadly agents, from bombs to sprays.

Containment of the infectious aerosol was insured by pre-testing for gas-tight integrity using a test gas of high detection sensitivity. Protection against system failures and human errors was provided by means of backup systems that were energized, either automatically or instantly by manual means upon-functioning of warning alarms. In addition to the gas-tight feature of the system, the entire complex was routinely rated on a slight negative pressure so that any leakage that should develop would only permit clean air to enter the system; contaminated air could not escape. The air process system used for achieving and maintaining controlled environments was displayed schematically, giving the operations supervisor continual surveillance over the status of the equipment.

In testimony to the integrity of the Test Sphere facility with respect to agent containment, it is worthwhile noting that in 19 years of almost daily operations, its biological safety record was perfect. Not only was there never an escape of any of the lethally dangerous biologicals worked with in the Sphere, there were also no instances of occupational illness among operating personnel. These personnel worked in the area surrounding the sphere without benefit of or need for respiratory protection.

United States Department of Interior, National Park Service


The Eight Ball wasn’t always used for offensive purposes. The sphere was also used in the development of vaccines against other nations’ biological weapons. The Test Sphere’s best known use was during Operation Whitecoat, a program intended to test the effects of biological agents on humans through exposure.

More than 2,300 Army volunteers, often drawn from the ranks of conscientious objectors, inhaled lung full of air into which biological agents had been released, and researchers then monitored their reactions. Some subjects were given investigational vaccines for Q fever and tularemia, as well as for yellow fever, Rift Valley fever, hepatitis A, Yersinia pestis (plague), and Venezuelan equine encephalitis and other diseases, before being exposed to the agent to test the vaccines’ effectiveness.

Workers standing outside the 1-million-liter sphere, circa 1968. Photo: Wikimedia Commons

Photo: Wikimedia Commons

The test sphere has not been used since 1969, when the U.S. biological weapons program was discontinued. Five years later, a fire razed the structure that enclosed the sphere, but the sphere itself remained unhurt, although the fire did damage the control panels and exposure chambers at the base of the test sphere.

Because of its historical scientific significance, the Test Sphere is now on the National Register of Historic Places.

# USArmy Whitecoat
# National Register of Historic Places Nomination Form
# Beth Perretta, Historic 1-Million-Liter Structure Stands as Reminder of Biological Warfare, Capital News Service
# Wikipedia


  1. Check out the Horton Sphere at Kesselring Atomic Power Labratory


Post a Comment

More on Amusing Planet


{{posts[0].date}} {{posts[0].commentsNum}} {{messages_comments}}


{{posts[1].date}} {{posts[1].commentsNum}} {{messages_comments}}


{{posts[2].date}} {{posts[2].commentsNum}} {{messages_comments}}


{{posts[3].date}} {{posts[3].commentsNum}} {{messages_comments}}