Astronauts for a day, affordable for everyone, possible? The trick (which is not trick) is called parabolic flight, an aircraft that simulates, albeit in 30-second "sessions" which are however repeated numerous times, exactly what astronauts find themselves experiencing with zero atmosphere. To do science experiments or spin in the air, we did it: here's how it went.
The gravity
Gravity is one of the four fundamental interactions of physics, and it is a phenomenon to which everyone in the Universe is subject: from birth to death we spend our entire lives subject to a force, in some ways still mysterious, which makes us fall objects out of hand, allows us to lay in bed without flying off, and allows our Earth to orbit the sun.
Until the 60s no human had experienced theweightlessness, then with the first space travel and subsequently with the first laboratories in space, it was possible to bring men and equipment into an environment where gravity is canceled or almost canceled, opening new frontiers to science.
The study of the effects of weightlessness on the human body, for example, is essential to understand if and how man can live for prolonged periods in space and therefore, theoretically, colonize new planets after long journeys in weightlessness. Over the years it has become clear that the effects of weightlessness on the human body are remarkable, muscles and bones no longer stressed by the weight of the body tend to lose mass and density even after only 30 days in space, and this is why on the international space station the astronauts must follow a heavy regimen of physical exercises where they simulate the conditions of the Earth to keep muscles and bones in shape.
In the laboratories of the space station they are also tested Medicines, materials and physical phenomena which can only be experienced in the presence of microgravity; naturally the very high cost of space missions allows only a few experiments to be brought to the ISS, but the requests are many and therefore a way has been sought to create conditions on earth similar or equal to those of space, in order to be able to carry out experiments on things and people without having to undertake a space journey.
But none exist on Earth anti-gravity machine, therefore, to experience the conditions that they will find in orbit, astronauts and materials have few possibilities: astronauts can train in huge pools to recreate effects similar to those of the spatial microgravity, but for experiments and objects it is more complicated.
They can be housed in catapults that launch an object as high as possible or dropped into high towers: during the fallout phase the object (or the person) is in the same conditions as the space, but this effect lasts a very few seconds and c 'is still the problem of sudden deceleration.
The parabolic flight
The most practical method currently used is that of parabolic flights with special planes, where, during the fall phase, everything inside it floats exactly as if you were in space. Just as jumping from a high cliff into the sea one experiences a sensation of weightlessness for a few moments, so during a plane dive, people and things inside are virtually in weightlessness. In reality, during these special flights, the aircraft never falls into a vertical dive, but performs a specific parabola where, following a very strong acceleration uphill, it is possible to float in zero gravity for about 30 seconds, from the peak of the parabola to its final end, before the plane resumes level flight, re-establishing gravity. During the parabolic flight scientific experiments can be carried out and given that numerous parabolas (thirty) are performed for each flight, in the end many minutes of weightlessness can be collected, invaluable for carrying out scientific tests.
The Airbus used by ESA
ESA uses a modified Airbus of the company Ninespace for this type of flight, and we were able to participate in the 71st parabolic flight campaign by witnessing the experiments being made and floating in weightlessness like the astronauts. The Airbus used, formerly state aircraft of Chancellor Merkel, in reality it has been modified only internally, removing most of the seats and adapting part of the fuselage to a windowless cargo area: the exterior and the avionics have not been changed and this means that, theoretically, any airliner can perform parabolic flight maneuvers.
These maneuvers are quite extreme even if perfectly safe. The plane rears up very fast and almost vertically in the sky, with an inclination of about 50 degrees causing a strong internal acceleration of up to 1,8G, which means almost twice the force perceived on the ground and slightly less than the maximum acceleration experienced during the launch of the space shuttle, equal to 3G. Arrived just before the climax of the parable begins the phase zero G (although it is more correct to say "microgravity" as there is still a small residual acceleration), which lasts throughout the descent of the aircraft, until it takes off in level flight. After about a minute and a half, a new parabola begins and the cycle repeats itself from the beginning: during all the phases, the captain announces the inclination degrees and the residual time at zero G through the loudspeaker.
It is important to note how the physical phenomena experienced in about 30 seconds are exactly the same as experienced on the ISS, including the behavior of fluids and even flames: a match lit at zero G in fact behaves differently, the flame it is smaller and almost spherical, with temperatures lower than on land. In fact, even the ISS is in free fall e it is incorrect to speak of lack of gravity: in fact this is canceled by the circular motion of the station around the earth, a motion which prevents it from crashing on the Earth. In its parabolic flights, ESA is also able to recreate conditions of particular gravity, such as that found on the Moon or Mars, to perform specific tests for those missions.
Flying in a zero-G aircraft
But does flying at zero G cause discomfort? In fact the first aircraft of this type were called "Vomit Comet" for obvious reasons, but today it's harder to feel bad, both for the medicines that can be taken (similar to those against seasickness) and for the specific training on the best position to hold during the parables. In fact, if you adapt almost immediately to the phase of absence of gravity, the previous phase of strong acceleration is more annoying, in which you feel the whole body, and the skin, pull violently downwards.
In this phase it is recommended for the first parables of lie down on the ground, but already after a while you can safely stand, the important thing is to stare and not move your head, otherwise the sense of balance could be affected with consequent malaise. However, the adaptation is quite rapid and in any case everything, from the initial acceleration to the end of the parabola, takes only 1,15 minutes; also for this reason parabolic flights are now mainly used for scientific experiments and they are almost no longer the prerogative of astronauts, who only make acclimatization flights, preferring the swimming pool where they can have long sessions similar to stressful space walks. The aircraft is being flown by three pilots simultaneously, each of which is concerned with maintaining one of the fundamental parameters (climb, dive, etc.) perfectly aligned to avoid problems in the cabin. A curiosity: the total time spent at zero G inside the ESA plane is in any case greater than what will be experienced once the suborbital flights currently being tested by some companies, such as Virgin Galactic, are open to space tourists. For those who want to immediately experience the thrill of flying without gravity Ninespace organizes flights open to all, costing approx 6.000€ per person: part of the proceeds is donated to scientific research activities.
Experimenting with zero G
The possible scientific research on the Novespace plane can concern practically any field of science: generally they are university e research institutes who devise a scientific project to be submitted to theThat. If this is approved the experimenters and their equipment will be hosted on the plane to put their theories into practice, and some of these experiments may even later be hosted on the ISS.
Carrying out experiments in such extreme conditions requires careful planning of the equipment, also due to the limited time available for the experiment: everything must be firmly secured to the aircraft or contained in special racks, which in turn are covered with shockproof material and foam rubber, to avoid damage or injury when things and people stop floating to quickly return to normal gravity.
The experimenters are generally anchored with tapes to the floor or to the walls during the zero G phase, in order to be able to carry out the measurements necessary to collect the data, equipment and PCs must in any case be calibrated to withstand the great acceleration of the initial phase of the parabola : for example there could be problems with the heads of the hard disks, which could get damaged or put themselves in the rest position automatically, causing the loss of data, for this reason they are almost always used solid-state hard drives with no moving parts. During the 71st campaign many very different experiments have been performed, ranging from biology to chemistry to physics. For example, the University of Lucerne has carried out tests to see how cartilage behaves in zero gravity, while the University of Zurich has devised an experiment to evaluate the effects of weightlessness on spinal stiffness: a volunteer, anchored on the ground with a bare torso and with a device attached to his back, where to carry out tests in the zero G phases. Another particularly complex experiment in terms of logistics was the one tested by Research Center for Neurosciences of Lyon who wanted to test the influence of gravity on distance perception between objects and the observer, setting up a sort of sled to try approaching an object with a blindfolded experimenter in microgravity conditions.
Italy in zero gravity
Italy was represented byUniversity of Pisa in collaboration with MIT where the team led by Professor Paolo Di Marco experimented with the "wettability" of surfaces, i.e. the way in which a liquid wets a surface: for example, the way in which a drop remains on a steel or on butter, and this simple example has huge industrial applications, because the way a surface is wettable has implications for heat transfers, for example in nuclear reactor cooling systems.
Apart from the work, however, there is an area in the plane called "free floating area”, a sort of cage surrounded by nets where you can simply have fun floating in the air without the danger of accidents: obviously none of the experimenters resists the temptation to try it at least once when he is free from scientific tests, and it is possible for the more daring experience the walk on the walls, or just whirling in the air col just for fun.
La total duration of a flight campaign, from take-off from the Bordeaux base in France to its return, is approx three hours and for pilots, experimenters or anyone on board, it is a term to keep in mind for a specific reason: there are no traditional toilets on board for, let's say, reasons of gravity, there are only "emergency devices" for situations truly undelayable. The physiological needs they don't even look in the face of gravity.
