Or why the inhabitants of other worlds can not fly into space.
Astronomers are paying close attention to the super — earth exoplanet, whose radius is about 2 times higher than the earth, because they could also become the cradle of life in space. The trouble is that gravity, which provides all the conditions for the development of alien life, is also a trap that prevents hypothetical aliens to go into outer space!
The study of exoplanets orbiting distant stars has shown that worlds like our Earth are rare. Much more common are rocky planets, the radius of which is approximately one and a half times bigger than earth — astronomers call them super-earths. However, they are of interest to science, and therefore researchers are studying hard every possibility that somewhere among the rocks may lurk alien life.
If life on such a planet not only emerged, but have evolved to a technological level of modern humanity, we could, for example, to detect signals from spacecraft or other xenos. But a new study presented at the International Journal of Astrobiology, makes clear one important fact: even a slight increase in gravity (compared to earth) could have a significant impact on any intelligent civilization.
Gravity: friend and enemy aliens.
"Many exoplanets, larger and heavier than Earth, abdallat also, the larger surface gravity", says in his work Michael Hippke (Michael Hippke), a scientist from the Observatory Sonneberg in Germany. "This circumstance makes space travel from such worlds much more complex, since the required fuel mass in this case will grow exponentially." For example, on planets with a radius twice as large as the earth's, the mass will be about 10 times more, and gravity is about 2 times stronger (in many ways it depends on the composition of the planet itself).
Such "heaviness" can contribute to the development of life, as it will facilitate the retention of atmospheric gases and thus form a dense enough atmosphere to protect the surface from the effects of cosmic radiation. But high gravity will also be a kind of trap that keeps intelligent life on the planet.
In order to launch into space only one ton of matter on the Kepler-20b (rocky exoplanet, the radius of which is greater than the earth's 1,87 times, and the mass — 9,7 times), the rocket should be about 3 times larger than the famous "Saturn-5". And to launch into orbit something more useful (for example, a new telescope named James Webb, which weighs 6.2 tons), it will take about 55,000 tons of fuel! In such circumstances, the launch of the spacecraft is seen as something unimaginable: in order for the device the size of Apollo 11 to overcome the attraction of the planet, it would need a fuel tank the size of a Great pyramid in Giza!
Space flights
Of course, if the aliens are actually highly developed creatures, sooner or later they will find a way to bypass the restrictions imposed by the gravity of the planet. The article describes one of such strategies: Hippke suggests that the construction of launch platforms of cosmodromes on the mountain tops will help to ease the situation. But even here there is one unfortunate circumstance: on the big planets the mountains are usually relatively small — otherwise they would simply collapse under their own weight with such high gravity.
Alternatively, the technology that scientists are developing on Earth, namely, the launching of rockets from the lower atmosphere, can help the inhabitants of super Earth. In addition, the exoplanet can be a world completely covered with water, and in this case, the underwater cosmodrome will be equipped with a kind of submarines with ballistic missiles that can "take" the spacecraft into space — another complication in an already not very simple process.
Conclusion
In conclusion, Michael notes that in the case of planets with a mass greater than 10 times the earth's mass, chemical-fuelled missiles completely disappear as a means for space travel. According to the researcher, the launch of one such missile will take a significant part of the resources of the whole planet — a very unreasonable waste of money.
The only way for a hypothetical brothers in mind can be space elevators, build only with materials on the Earth are not known with sufficient margin of safety. So, even if humanity finds a reasonable life among the stars - it (fortunately or unfortunately) does not mean that the aliens will come back with a return visit.