A bell rings and a strobe light flashes as a pilot quickly raises the nose of a DC-9 plane. Blood rushes from the researchers’ heads as they are pulled to the floor of the cabin by twice the force of normal gravity. Once the acceleration reaches the desired level, and the NASA plane climbs its arc, the flight test director announces, “We’re at the top!”
As the aircraft falls forward in free fall, the pressure decreases. For the next 20 to 25 seconds, everyone and everything that doesn’t close begins to float. The researchers quickly return to their experiments before the bell rings again as the pilot returns the aircraft to normal level flight and Earth’s gravity.
By flying up and down in a series of parabolas, the airplane can simulate weightlessness. Such flights in a DC-9 by NASA’s Lewis Research Center (now NASA Glenn) in the 1990s gave scientists a unique way to study the behavior of liquids, combustion, and materials in microgravity environments.
In the 1960s, NASA Lewis used North America’s AJ-2 to fly parabolas to study the behavior of liquid propellants in low-gravity conditions. The center later expanded its microgravity research to include combustion and materials testing.
So, when the introduction of the Space Shuttle in the early 1980s led to a surge in microgravity research, NASA Lewis was drafted to become a leader in the agency’s microgravity science efforts. To help scientists test experiments on Earth before long-duration flights on the shuttle, Lewis engineers modified a Largejet aircraft to fly microgravity test flights with a single strapped experiment and researcher.
In 1990, NASA officials decided that Lewis needed a larger aircraft to accommodate more experiments, including free-floating tests. Officials determined that the McDonnell Douglas DC-9 would be the most economical option and decided to assume responsibility for the DC-9 leased by the US Department of Energy.
In the fall of 1993, 50 potential aircraft users visited the center to discuss changes that would be necessary for their research. In October 1994, the DC-9 arrived at Lewis in its normal passenger configuration. Over the next three months, Lewis technicians removed almost all of the seats. reinforced floors and ceilings; and installed new power, communications, and guidance systems. A 6.5-by-11-foot cargo door was also installed to allow the transfer of larger items.
The DC-9 was the final element in making NASA Lewis the nation’s largest microgravity facility. The Center’s Space Experiment Division was recently expanded. 2.2-second drop tower And Zero gravity facility was upgraded, and the Space Experiments Laboratory was recently built to centralize microgravity activities.
Lewis researchers partnered with industry and universities to design and test experiments that could fly aboard the space shuttle or a future space station. The DC-9 can accommodate eight experiments and 20 research personnel on each flight.
Experiments included measurements of space acceleration, capillary pump loops, bubble behavior, thin-film liquid rupture, material flammability, and flame propagation. It was a highly interactive experiment, in which the researchers gained additional information through direct observation along with their tests. Researchers were often so focused on their work that they hardly noticed their bodies moving.
The DC-9 flew every other week to allow time for installation of experiments and maintenance of the aircraft. The flights, which were out of Cleveland Hopkins International Airport, were flown in restricted airspace over northern Michigan. The aircraft sometimes flew up to 40 parabolas in a single mission.
When the aircraft’s lease expired in the late 1990s, NASA returned the DC-9 to its owner. From May 18, 1995 to July 11, 1997, the Lewis Microgravity Flight Team used the DC-9 to fly more than 400 hours, perform more than 70 maneuvers, and conduct 73 research projects, allowing scientists to Helped to research microgravity. Testing and preparation of experiments designed to fly on Earth as well as in space. The aircraft served as a unique and important instrument, contributing to the body of knowledge of microgravity science as a whole and the center’s expertise in this research field.
NASA Glenn’s microgravity mission continues. The center has supported experiments on the International Space Station that could improve crew health, as well as spacecraft fire safety, propulsion and propellant. The Glen is also home to two microgravity drop towers, including the Zero Gravity Research Facility, NASA’s premier ground-based microgravity research lab.
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