Repeatedly putting an aircraft on an up-and-down parabolic trajectory angled at up to 50° creates brief periods of weightlessness. During the climb and pulling out of the descent, the occupants then endure almost twice normal gravity. Throughout the “Space Race” of the 1960s NASA used two Boeing KC-135 Stratotankers in this way to provide periods of “weightlessness” to train astronauts. Because of the radical flight maneuvers necessary to create this condition the aircraft were nicknamed “vomit comets”. One, a KC-135A known as NASA 930, is estimated to have flown over 58,000 parabolas. The KC-135s were used until December 2004 and have since been retired.
Recently, ESA, France’s space agency CNES and the German aerospace center DLR inaugurated an Airbus A310 dubbed “ZERO-G” and refitted for altered gravity by running 12 scientific experiments. Flying from Bordeaux, France, French company Novespace has been running parabolic flights for more than 25 years. Last year they acquired their new aircraft to replace their Airbus A300 – maintenance costs were growing due to its age. To turn it into a parabolic science aircraft most seats were removed to provide as much space as possible inside , while padded walls provide a soft landing for the passengers – the changes in ‘gravity’ can be hard to handle. Extra monitoring stations have been installed for a technician to oversee the aircraft’s systems while it is pushed to its limits.
During the altered gravity flight program first a person weighing 175lb. on Earth would feel as if they weighed 350lbs. for around 20 seconds. At the top of each curve, the forces on the passengers and objects inside then cancel each other out, causing everything to freefall in weightlessness.
This campaign’s experiments include understanding how humans sense objects under different gravity levels, investigating how the human heart and aorta cope, looking at how plants grow, testing new equipment for the International Space Station, trying out new techniques for launching nanosatellites, investigating whether pharmaceutical drugs will work without ‘gravity’, and understanding Solar System dust clouds and planet formation.
The aircraft offers more than just weightlessness, by changing the thrust and angle of attack, the team of pilots flying the plane can recreate other gravity levels such as those found on the Moon or Mars.