Every now and then a part of the International Space Station falls back to Earth, but other than that you don’t hear much about it anymore. You wouldn’t dare say off the top of your head how many men (m/f) are on board now and what they are doing. Working on friendship between peoples, as was the intention? Recently a few had headaches, but that was due to the weightlessness.
The entire station will be thrown into the sea around 2030 and by then people will want to know what it was all worth. Has all that expensive research into and with weightlessness yielded enough? When this newspaper checked how the flag was hanging twelve years ago, it did not look good. Insofar as the work produced results, they hardly ended up in decent journals. The top magazines were done with osteoporosis and muscle loss. Or perfect crystal growth under ‘zero gravity’.
“The International Space Station is an orbital turkey. No important science has come out of it,” said Nobel Prize winner Steven Weinberg in 2007. The picture has since improved, as NASA, the main funder and user of the ISS, is also happy to say. The annual number of publications in ‘top 100 journals’ has risen tremendously and is becoming more regular Nature, Science and the PNAS fetched. Based on the favorable trend in peer-reviewed articles, political scientists at Indiana University expected in 2017 that science on the ISS would be fine. Science just takes time.
Strangely enough, it was NASA itself that once again cast doubt on the value of its work. At the end of 2020, in celebration of twenty years of research, the organization listed scientific breakthroughs that could be attributed to the ISS. That turns out to be a mess in which there is no real breakthrough, unless you want to consider the weightless cultivation of lettuce and radishes as such. Or observing natural disasters and identifying bacteria within the contaminated platform.
An old-fashioned cannonball
NASA must look for new platforms for research that anticipates trips to the moon and Mars. Fortunately, there are enough of those. Very inspiring platforms still come from aircraft that offer weightlessness by putting themselves in free fall and in the process travel a more or less parabolic trajectory like an old-fashioned cannonball. The idea emerged in the early 1950s and was first used for astronaut training in 1959.
It’s not complicated. You bring a horizontally flying plane up to maximum speed and then suddenly pull it back steeply. Then you reduce almost all engine power until only some power remains to overcome air resistance. The aircraft then follows the classic parabolic trajectory, which results in weightlessness for the occupants, even in the rising part of the parabola.
How long the period of weightlessness lasts depends on the initial speed and the steepness of the angle at which the climb was started. Usually it takes about 25 seconds, but that turns out to be enough for many types of research. Up to 30 to 60 parabolas can be described per flight at intervals of a few minutes. The European Space Agency ESA uses an Airbus A310 from Novespace in Bordeaux for its research. The French also provide ‘Zero G’ trips for private individuals for 7,000 euros. A strong stomach is appreciated.
Weightlessness is not for the small man with his small wallet, unless he is lucky enough to use an elevator in a high-rise apartment building that breaks free from its cables. Then he can feel weightless for up to three seconds. With a bit of luck, there will be a facility at the bottom of the elevator shaft that will catch him, but if you look at the horrific list of accidents that the elevator institute regularly publishes, the chance of that happening is not great.
Closed and streamlined box
This is better arranged in the drop towers that use the concept of ‘falling elevator’ to induce weightlessness for scientific research. There are about ten such towers. With a height of 122 meters, the Fallturm in Bremen is the largest, it can also be vacuumed.
The elevator cabins always have the shape of a closed, streamlined box in which a test setup can be placed, with space for cameras. Sometimes the temperature can also be controlled. At time zero the box is released at a great height and then, depending on the drop height, there is weightlessness for a few seconds. In Bremen the drop height is 110 meters and the fall takes 4.7 seconds. But it can be doubled by shooting the box up from the ground floor with a pneumatic catapult. Then it follows a kind of compressed vertical parabola.
The drop tower of Portland State University in Oregon, with its drop height of 31.1 meters, has a fall time of 2.1 seconds. When heavy scientific research is not being conducted, teacher William A. Dittrich uses the installation for small educational experiments. He puts a glass of water in which a spherical cork floats into the falling container and asks his students what they think will happen if the container falls. They are then shown a video of the experiment. There are about a dozen such videos: of streamers, piles of coins, a ball that can roll in a bowl and more. Fascinating! The question was what do those short, jerky videos remind us of? Suddenly the answer was: the first images of the Earth made from space: by a V2 rocket in 1946 and a Thor rocket in 1959. Let’s see.