Vomit Comet

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Vomit Comet is a nickname for any airplane that briefly provides a nearly weightless environment in which to train astronauts, conduct research, and film motion pictures. Versions of such airplanes have in the past been operated by NASA's Reduced Gravity Research Program since 1973, where the nickname originated. NASA prefers the nickname Weightless Wonder for public relations reasons.

Contents 1 Operating principles 2 History 3 Commercial flights 4 Airsickness 5 See also 6 Notes 7 References 8 External links

[edit] Operating principles

Main article: Weightlessness

The airplane simulates weightlessness by matching its acceleration (in terms of both magnitude and direction) to gravity. The resulting trajectory is elliptical with one focus at the center of the earth.^{[citation needed]}

The trajectory is often quoted as being parabolic. For the relatively short distances that the aircraft simulate weightlessness, a parabola matches the trajectory so closely, that it generally is also correct. Parabolas are so often quoted perhaps as a result of a common task assigned to beginning physics students: to calculate the trajectory of objects exclusively under the influence of a constant gravitational field. The mathematics is straightforward and results in a parabola. However, if one to take into account that gravity is described by the inverse square law, the mathematics becomes more complicated and results in an ellipse.

In general this aircraft is used to train astronauts in zero-g maneuvers, giving them about 25 seconds of weightlessness out of 65 seconds of flight. This often produces nausea due to airsickness, especially in novices, giving the plane its nickname. Astronauts training for the Moon missions practiced walking with 1/6 of their weight to simulate the level of gravity on the Moon.

[edit] History

Twin KC-135 Stratotankers were used until December 2004 and have since been retired. One, a KC-135A known as NASA 930 was also used by Universal Pictures and Imagine Entertainment for filming scenes involving weightlessness in the movie Apollo 13; that airplane was retired in 2000 and is now on display at Ellington Field, near the Johnson Space Center. It's estimated to have flown over 58,000 parabolas. The other made its final flight on October 29, 2004, and is permanently stored in the AMARC storage facility in Arizona.

In 2005, NASA replaced the airplane with a McDonnell Douglas C-9B Skytrain II that was formerly owned by KLM Airlines and the United States Navy [1]. The same year, the Zero-Gravity Corporation, a commercial parabolic flight operator which offers parabolic flight to both researchers and adventure tourists, began flying parabolic flights for NASA with Boeing 727 jets.

Since 1984, the ESA and the CNES have flown similar reduced-gravity missions in a variety of airplanes, including NASA's KC-135, a Caravelle, an Ilyushin IL-76 MDK, and, most recently, an Airbus A300 known as the Zero-G, which is flown out of the Bordeaux-Mérignac airport in France.^[1]

[edit] Commercial flights

In late 2004, Zero Gravity Corporation became the first and only company in the United States to offer parabolic weightlessness flights to the general public. Each flight consists of around 15 parabolas, including simulations of the gravity levels of the Moon and Mars, as well as complete weightlessness.^[2]

[edit] Airsickness

According to Reduced Gravity Research Program director John Yaniec, anxiety contributes most to passenger's airsickness. Yaniec gives a rough estimate that of passengers, "one third [become] violently ill, the next third moderately ill, and the final third not at all."

Commercial operator ZeroG Corp claims their tourist rides with up to 15 parabolas are much less traumatic compared to the typical research flight with from 40 up to 80 parabolas.^[3]

[edit] See also

• Microgravity
• Space tourism

[edit] Notes

[edit] References

• Haber, Fritz and Haber, Heinz: Possible Methods of Producing the Gravity-Free State for Medical Research, Journal of Aviation Medecine XXI (1950)
• Easton, Pam (Oct. 30, 2004). NASA's weightless aircraft is retired. Associated Press.
• Glen Golightly (May. 15, 2000). Vomit Comet finds a home. Space.com Houston Bureau.
• Dennis Overbye (March 1, 2007), Stephen Hawking plans prelude to the ride of his life, New York Times

[edit] External links

• "Bird's Eye View" of Planes
• Reduced Gravity Research Program
• Interview with John Yaniec
• About the NASA Reduced Gravity Research Program
• "ATLAS aerospace" is a Russian company that offers reduced gravity flights in an "IL-76 MDK" wide-body airplane.
• Virtual tour of the Airbus A-300 Zero-G
• C-135 Variants Part 6 - includes scale drawing of NASA 930
• Reduced Gravity Experiment in a Nasa´s KC-135A