Is it possible to shift the orbit of the Earth? And most importantly, why do it?

In the new Chinese sci-Fi film “Wandering the Earth” recently released by Netflix, the humanity, using huge engines that are installed throughout the world, attempts to change the orbit of the Earth to avoid its destruction under the influence of the dying and expanding Sun, as well as to prevent collision with Jupiter. This scenario of cosmic Apocalypse may one day actually happen. In about 5 billion years our Sun will run out of fuel for thermonuclear reactions, it will expand and probably engulf our planet. Of course, before we all die from global temperature increase, but change the orbit of the Earth could indeed be the right solution to avoid disaster, at least in theory.

But how will humanity be able to cope with such a daunting engineering challenge? Engineer space systems Matteo Ceriotti from the University of Glasgow shared the pages of the portal, the Conversetion several variants of possible scenarios.

Suppose that our task is to move the orbit of the Earth, it is distant from the Sun about half the distance from its current location, about where Mars is now. The leading space agencies around the world is looking on and even working on the idea of displacement of small celestial bodies (asteroids) from their orbits, which in the future will allow us to protect the Earth from external attacks. Some options offer extremely destructive solution: a nuclear explosion near the asteroid or on its surface; the use of “kinetic impactor“, which, for example, can play spacecraft, sent on a collision course with an object at high speed to change its trajectory. But, as for the Earth, these options of course will not work because of its destructive nature.

In the frames of other approaches proposed to divert the asteroid from a dangerous trajectory using the spacecraft, which will act as tugs or larger spaceships, which due to its gravity will take away a dangerous object from the Ground. With the Earth, again, that doesn’t work, since the mass of the objects will be absolutely incomparable.

Electric motors

You’ll probably see, but we have been shifting the Earth from its orbit. Every time when our planet leaves another probe to explore the other worlds of the Solar system, carrying its booster creates tiny (on a global scale of course) momentum and impacts them on the Ground, pushing it in the opposite movement direction. As example, the shot from the weapon and created the result it returns. Fortunately for us (but unfortunately for our “plan to shift the orbit of the Earth”) this effect for the planet is almost imperceptible.

Currently, most high-performance missile in the world is the American Falcon Heavy from SpaceX. But we will need about 300 quintillion launches of these carriers with a full load to use the above described method to push the Earth’s orbit to Mars. The mass of the materials necessary to build all these missiles will be equivalent to 85 percent of the mass of the planet itself.

The use of electric motors, in particular ion, producing a stream of charged particles, whereby there is an acceleration, is a more effective way of imparting acceleration to the mass. And if you install several of these engines on one side of our planet, our old Earth can really explore the Solar system.

However, in this case, you need an engine truly gigantic proportions. They will need to be installed at a height of 1000 miles above sea level, outside the earth’s atmosphere, but securely attach to the surface of the planet to be able to give her the pushing force. Besides, even with the ion beam, thrusting with a speed of 40 kilometers per second in the right direction, we still need to throw away the equivalent of 13 percent of the mass of the Earth in the form of ion particles to move the remaining 87 percent of the mass of the planet.

Light sail

Since light carries momentum, but not mass, we can also use to offset the planet’s very powerful and a long focused beam of light, e.g., laser. In this case, you will use the energy of the Sun itself, not in any way using the mass of the Earth itself. But even with an incredibly powerful 100-gigawatt laser facility, which is planned to involve in the project Breakthrough Starshot, in which by means of a laser beam, the scientists want to send a small space probe to our nearest star system, we need three trillion years long laser pulse in order to achieve our goal to change the orbit.

Sunlight can be reflected directly from the giant solar sail, which will be located in space, but attached to the Land. In the framework of past studies, scientists have found that this requires a reflective disk the size at 19 times the diameter of our planet. But in this case, to achieve a result will have to wait about one billion years.

Interplanetary Billiards

Another possibility of withdrawal of the Earth from its current orbit could become a well-known method of exchange pulses between two rotating bodies to change their acceleration. This method is also known as gravity assist. This method is quite often applied in the interplanetary exploratory missions. For example, the spacecraft “Rosetta”visiting comet 67P in 2014-2016 in the framework of its ten-year journey to the object of the study used a gravity-assist maneuver around the Earth twice, in 2005 and 2007.

As a result, Earth’s gravitational field each time gave increased acceleration “Rosetta” that would be impossible using only one of the motors of the device. The land within these gravitational maneuvers also received opposite and equal momentum acceleration, but, of course, it had no measurable effect due to the mass of the planet itself.

What if we use the same principle, but with something more massive than the spacecraft? For example, the same asteroids can certainly change their trajectory under the influence of Earth’s gravity. Yes, a one-time retroactive impact on the Earth’s orbit would be negligible, but this action can be repeated many times to eventually change the position of the orbit of our planet.
Some areas of our Solar system quite tightly “staffed” by numerous small celestial bodies such as asteroids and comets whose mass is sufficiently small in order to draw them closer to our planet with the help of appropriate and realistic in terms of technology development.

With a very careful calculation of the trajectory it is possible to use a method called “Delta-v-offset”, when a small body can be shifted from its orbit by a strong approach that will provide much greater impetus to our planet. All this, of course, sounds very cool, but previous studies that have found that in this case we need a million such close flybys of asteroids, each of them must occur in the interval of several thousand years, otherwise we’ll be late by the time when the Sun will expand so much that life on Earth has become impossible.

Insights

Of all the above options today use many of the asteroids for a gravity assist 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 heavy-duty laser systems. In any case, these technologies will also be useful for our future space exploration.

And yet, despite the theoretical possibility and probability of feasibility in the future for us may be the most suitable option of save will be the relocation to another planet such as Mars that can survive the death of our Sun. In the end, humanity has long been stare at him as a potential second home for our civilization. And if we consider how difficult it will be to implement the idea of the displacement of the Earth’s orbit, the colonization of Mars and terraforming to make the planet more habitable appearance may not look so challenging.

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