The earth is always pulling us to its centre with its gravity, a force to which all bodies on the planet are subjected to. In the beginning of the space program of United States, reduced gravity was an important matter on the general body behavior, making this study as a key on space exploration and transportation, and a capability of testing the personnel and equipment.
For this option, it is necessary to simulate a zero gravity or well said a weightless environment. Here comes the role of Fritz Haber, an aeronautical engineer, and Heinz Haber, physicist who proposed the idea of a gravity free environment similar to space, simulating this by means of parabolic flight using an aircraft.
They were recruited after World War II in the operation paperclip, serving the American Space Program. The Haber brothers were researching the effects of space travel on humans and animals.
The parabolic flight allows the training of astronauts, and the studies of living organism in weightlessness, such as the experiments with cats’ orientation, and with pigeons in observing how their navigation capabilities are affected.
The training of astronauts helps the experiments, and floating activities inside the aircraft, this change the body behavior, could cause airsickness, dizziness, among others. The plane is commonly known as Vomit Comet, thanks to this effects. When starting these flights, the NASA in 1959 used a C-131 Samaritan aircraft for carrying out the astronauts training and contributing to Project Mercury.
Flying in a parabolic flight, the reduced-gravity aircraft, needs to perform a parabolic trajectory relative to center of earth. When this happens, the things within the aircraft experience a free fall, a sensation similar to orbiting the earth.
The aircraft is set on 45-degree climb (nose high) on full engine thrust, at this state the bodies within the plane are subjected to 1.8g because of the engine acceleration and the earth gravity. after the lapse of 20 seconds, the engines are set on almost null thrust. All forces other than gravity are cancelled out and the plane is in freefall. Then, the weightlessness begins within the first 25 seconds approximately. The plane goes to 45 below horizontal, so the engines are set on power again experience the 1.8g. in this way the parabolic flight are performed. Throughout the flight, all personnel are kept continuously informed of the flight status, i.e. indication of how many seconds to the next parabola, number of minutes of rest period, etc.
A relevant story, it is that this parabolic flight technique was used while filming the “Apollo 13” Movie, The scenes were shot aboard a KC-135 NASA, simulating the null gravity in the astronauts’ activities in the film.
Since 1984, the ESA used a NASA KC-135 in the beginning, and from 1996 flew an A300 Airbus “Zero-G” of Novespace, in 2014 the aircraft was replaced by an A310 equipped for parabolic flights, it was first used for scientific research in May 2015.
The Airbus Zero-G is now the world’s largest zero-gravity aircraft in terms of passenger capacity and experiment surface area, enabling scientists and the general public to access gravity-free conditions.Airzerog
The main characteristics and features of the Airbus A310 Zero-G aircraft are:
- The aircraft is a two-engine modified Airbus A310 “Zero-G” aircraft.
- It is based at the Aéroport International de Bordeaux–Mérignac.
- Aircraft maximum mass:157 tonnes.
- Overall length: 46.4 metres.
- Wingspan: 43.9 metres.
- Fuselage diameter: 5.6 metres.
- Total cabin volume: 300 m3.
Partial-gravity flights are rare and offer a unique opportunity to conduct research in conditions that have only been reproduced a handful of timesnotes ESA’s head of human research, Jennifer Ngo-Anh
As seen, all these activities related to weightlessness, are a relevant step in development and validation of experiments and equipment or space hardware, as well as the important astronaut`s training before carrying all of them to space, where the conditions and the space mission will be longer.
Researches have been hard working the different scenarios of the human space exploration, such as the moon and mars travel and settlement programs. One experiment is how will be walking on mars. They stated that the ideal walking speed turns out to be around half the speed on Earth.
Therefore, we can observe how the parabolic flights have change the aeronautics and space field, allowing the outstanding experiments only achieved by a peculiar flight path.