Tech UPTechnologyEveryday phenomena that are rare in space

Everyday phenomena that are rare in space

We are so used to gravity that we don’t even realize it exists… except when something slips out of our hands. However, there are many processes where the subtle effect of the weakest and most ubiquitous force of nature is decisive . We have been able to verify this in space and the results are surprising.

The water boils in a big bubble

On Earth, when we put a pot full of water on a fire , a large number of tiny bubbles begin to form. In space, on the other hand, there is a single, enormous one.

Fluid dynamics is one of the most complicated disciplines in physics. That’s why before we did the experiment no one had any idea what happened when you boiled water in microgravity. And it was in 1992, aboard the space shuttle, that we found out. This way of boiling is due to the absence of two phenomena caused by gravity: convection (which causes the circulation of the liquid, rising the hotter and lowering the coldest) and hydraulic lift (which determines the buoyancy of the bubbles) .

The flames are spheres

On Earth the flames go up but in space they move in all directions. The reason is that the atmosphere gets thinner as we go higher, which leads to a gradual drop in pressure. In the case of the flame, that minimum pressure difference of a couple of centimeters, although very small, is enough for it to have its well-known appearance. As in the previous case, the small pressure difference is enough to cause convection: As the air around the flame heats up, it expands and therefore becomes less dense than the surrounding cold air. The hot molecules rise and their place is taken by the cold air molecules.

At the base of the flame there are more molecules of cold air pushing the hot ones than at the top, so here it encounters less resistance, and that is why it rises. In the absence of gravity, the hot air molecules experience the same resistance in all directions, they tend to move in the same way, which makes the flame acquire a spherical shape.

Bacteria grow faster and are more deadly

More than 30 years of experiments have shown that colonies of bacteria grow faster in space . Thus, E. coli does it twice as fast. Even some bacteria become more dangerous. In 2007, a controlled experiment with Salmonella was carried out on the shuttle Atlantis, and it was found that the space environment changed the expression of 167 genes. Post-flight studies proved that these mutations made this Salmonella colony more than 3 times more virulent in mice than control bacteria grown on land.

Why does this happen in the absence of gravity? It is not very clear but there are several hypotheses in play. On the one hand, in the absence of gravity, bacteria have more space : on Earth they huddle together at the bottom of Petri dishes. Changes in gene expression are thought to be the result of a stress response by the Hfq protein , which works by controlling gene expression. Microgravity imposes mechanical stress on bacteria by changing the way liquids move through them. The Hfq protein responds by entering a kind of “survival mode” that makes the cell more virulent.

You can’t burp in space

Since there is no gravity in space there is no buoyancy or hydraulic lift, so nothing pushes the bubbles up and out of carbonated drinks. This means that the carbon dioxide in the bubbles simply stagnates inside, even in the astronauts’ bellies. So without gravity, astronauts can’t burp, making beers, sodas, and champagnes pretty annoying drinks in space. Fortunately, the Australian company 4 Pine Brewing has created a weak carbonation beer, the Vostok 4 Pines Stout Space Beer. Checking if its consumption will be safe in future flights for space tourists is in the hands of the company Astronauts4Hire.

roses smell different

Flowers produce different aromas when they are in space. This is because the creation of volatile oils – which carry the fragrance – strongly depends on environmental conditions such as temperature, humidity and the age of the flower. So it’s not surprising that microgravity also affects their production inside the plant. Taking advantage of this, on the 1998 Discovery shuttle flight, the fragrance produced by a variety of dwarf rose called Overnight Scentsation was collected, which was analyzed and duplicated on land and incorporated into the Shiseido company’s Zen perfume.

Human beings sweat more

We already know that in microgravity there is no convection, which means that the heat produced by our body does not move away from our skin. The consequence is obvious: we do not stop sweating in a vain effort of our metabolism to cool our body. It’s even worse, because the absence of gravity means that sweat neither drips nor evaporates, staying there, soaking us.

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