In the new Chinese science fiction film“Wandering Earth”, recently released by Netflix, mankind, using huge engines installed all over the planet, is trying to change the Earth's orbit to avoid its destruction under the influence of the dying and expanding Sun, and also to prevent a collision with Jupiter. Such a cosmic apocalypse scenario may one day actually happen. After about 5 billion years, our Sun will run out of fuel for a thermonuclear reaction, it will expand and most likely absorb our planet. Of course, even earlier we will all die from a global rise in temperature, but a change in the Earth’s orbit may indeed be a necessary solution to avoid a catastrophe, at least in theory.
But how can humanity cope with suchsuper challenging engineering challenge? Space Systems Engineer Matteo Cheriotti from the University of Glasgow shared several scenarios on the pages of The Conversetion portal.
Suppose our task is tomove the Earth's orbit away from the Sun about half the distance from its current location, about where Mars is now. Leading space agencies around the world have long been considering and even are working out ideas for the displacement of small celestial bodies (asteroids) from their orbits, which in the long term will help protect the Earth from external impacts. Some options offer a very destructive solution: a nuclear explosion near the asteroid or on its surface; the use of a “kinetic impactor”, the role of which, for example, can be played by a spacecraft aimed at colliding with an object at high speed to change its trajectory. But, as for the Earth, these options, of course, will not work because of their destructive nature.
In the framework of other approaches, it is proposed to divertasteroids with a dangerous trajectory using spacecraft that will perform the role of tugs, or using larger spacecraft, which due to their gravity will divert the dangerous object from the Earth. With the Earth, again, this is not a ride, because the mass of objects will be completely incomparable.
You will probably see each other, but we’ve been moving for a long time.Earth from its orbit. Every time when our planet leaves another probe to explore other worlds of the Solar System, its carrier rocket creates a tiny (on the planet's scale of course) impulse and acts on Earth, pushing it in the opposite direction of its movement. An example is a shot from a weapon and the recoil created as a result of it. Fortunately for us (but unfortunately for our “plan for shifting the Earth's orbit”), this effect for the planet is almost imperceptible.
Currently the most high-performingrocket in the world is the American Falcon Heavy from the company SpaceX. But we will need about 300 quintillion launches of these carriers with a full load in order to move the Earth’s orbit to Mars using the method described above. In this case, the mass of materials needed to create all of these rockets will be equivalent to 85 percent of the mass of the planet itself.
The use of electric motors, inIn particular, ionic, releasing a stream of charged particles, due to which acceleration occurs, there will be a more efficient way to impart acceleration to the mass. And if you install several such engines on one side of our planet, our old Earth can really go on a journey through the solar system.
However, in this case engines will be required.truly gigantic sizes. They will need to be installed at an altitude of about 1000 kilometers above sea level, outside the earth’s atmosphere, but at the same time securely fastened to the surface of the planet so that it can transmit a pushing force to it. In addition, even with an ion beam emitted from a speed of 40 kilometers per second in the right direction, we still need to throw out the equivalent of 13 percent of the mass of the Earth in the form of ionic particles to shift the remaining 87 percent of the mass of the planet.
Since light carries momentum, but has no mass, weIt can also use a very powerful, long-lasting and focused beam of light, such as a laser, to displace the planet. In this case, it will be possible to use the energy of the Sun itself, in no way using the mass of the Earth itself. But even with an incredibly powerful 100-gigawatt laser system, which is planned to be used in the Breakthrough Starshot project, in which scientists use a laser beam to send a small space probe to the star closest to our system, we will need three quintillion years of continuous laser pulse for in order to achieve our goal of changing the orbit.
Sunlight can be reflected directly fromgiant solar sail, which will be in space, but fixed on Earth. As part of past research, scientists have found that this would require a reflecting disk 19 times larger than the diameter of our planet. But even in this case, in order to achieve the result, we will have to wait on the order of one billion years.
Another possible option to remove the Earth from itsThe current orbit can be a well-known method of exchanging pulses between two rotating bodies to change their acceleration. This method is also known as gravity maneuver. This method is quite often used in interplanetary research missions. For example, the Rosetta spacecraft, which visited comet 67P in 2014–2016 as part of its ten-year journey to the object of study, used the gravitational maneuver around the Earth twice, in 2005 and in 2007.
As a result, the gravitational field of the Earth eachjust gave increased acceleration "Rosette", which would be impossible to achieve using only the engines of the device itself. The Earth, within the framework of these gravitational maneuvers, also received an opposite and equal impulse of acceleration, however, of course, this had no measurable effect due to the mass of the planet itself.
And what if you use the same principle, butwith something more massive than a spacecraft? For example, the same asteroids can certainly change their trajectories under the influence of the gravity of the Earth. Yes, a one-time mutual influence on the Earth’s orbit will be insignificant, but this action can be repeated many times to eventually change the position of the orbit of our planet.
Some areas of our solar systemrather densely “staffed” with many small celestial bodies, such as asteroids and comets, whose mass is small enough to pull them closer to our planet using appropriate and quite realistic in terms of technology development.
With a very careful calculation of the trajectory is quiteIt is possible to use the so-called “delta-v-displacement” method, when a small body can be displaced from its orbit as a result of a close approach to the Earth, which will provide a much greater impetus to our planet. All this, of course, sounds very cool, but earlier studies were carried out, which established that in this case we would need a million of such close asteroids, and each of them should occur in the span of several thousand years, otherwise we will be late by that moment. when the Sun expands so much that life on Earth will become impossible.
Of all the options described today usesets of asteroids for gravity maneuver seems the most realistic. However, in the future, the use of light may be a more suitable alternative, of course, if we learn to create giant space structures or super-power laser systems. In any case, these technologies can also be useful for our future space research.
And yet, despite the theoretical possibility andthe likelihood of practical realizability in the future, for us, perhaps, the most appropriate option for salvation will be a relocation to another planet, for example, the same Mars, which can survive the death of our Sun. In the end, humanity has long been seen at it as a potential second home for our civilization. And if you also consider how difficult it will be to realize the idea of displacing the Earth's orbit, the colonization of Mars and the possibility of its terraforming to give the planet a more habitable appearance may not look so difficult.
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