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Always Look Up: Earth’s Top 7 Asteroid Defenses


One day, we might scan the sky and see it coming: an asteroid heading straight for Earth.

One the day we can scan the sky and see it coming: an asteroid heading straight for Earth.

Our response will depend on how far away the asteroid is when we see it, how big it is, and where exactly it will land.

There are most likely four strategies, but many more are being explored to come up with we best chance to deflect a fast-moving traveler from space.

‘Hide in the basement’

Or, in formal terms, civil defense – response used for natural disasters like hurricanes or tornadoes when there is a short-term warning.

Everyone will evacuate the affected area if possible, then crouch and hide.

This would be the obvious choice for smaller objects, like those 1m across, that enter Earth’s atmosphere several times a year but don’t reach the ground intact.

It can also be a response to objects as large as 20 meters small planet exploded in the Siberian city of Chelyabinsk in 2013, injuring more than 1500 people.

People were found to be unnoticed and unshielded, so these injuries were largely caused by flying glass being smashed in the impact shock wave. Even a small amount of warning can keep everyone safe.

For a relatively small impact of this nature, the resources required to prepare the city would be far less than those needed to attempt to deflect the asteroid.

Because small planet less than 20m in diameter, Everyone may evacuate the affected area and then crouch and hide.

The impact of a larger asteroid would be catastrophic for an area, a continent, or the entire world depending on its size.

Even a smaller tourist like the one in Chelyabinsk would pose a bigger threat if it came to a large city – making evacuation more difficult and risking the loss of more homes and infrastructure – or will make landfall in the ocean and cause a tsunami.

In these cases, there may be pressure to contain the impact if possible.

Send in kernel

The most powerful tool humanity has for deflecting asteroids is also the most controversial.

Nuclear explosives are a common choice in movies, although the scenarios that use them in protecting the planet don’t involve unlucky astronauts laying charges and then escaping.

It is better to keep the asteroids intact and move them as a single track that is easier to track than to explode them into many small pieces – some of which may still be headed for Earth.

Instead of burying the device near the center of the threatening object, nuclear deflection situations involve vertical explosions: the blast energy vaporizes part of the asteroid and propels it. space kicking up a new and safer road, far enough The earth that radiation and fallout wouldn’t be a problem.

Final scenarios involving nuclear devices can also be considered, although the side effects of using them for mitigation at very close to Earth could be as bad as the aftermath of a collision .

And there is no way to test them against a real threat: nuclear devices have been tested on Earth for nearly 80 years, but testing them in space is a violation of international law.

A nuclear explosion vaporizes part of the asteroid and propels the space rock into a safe orbit, far enough away from Earth that radiation and fallout won’t matter.

Ram it by spaceship

Kinetics (KI) techniques may offer a third option – and it can be (and is being) tested.

The KI technique is simple: crash the spacecraft into the asteroid of interest and use the spacecraft’s momentum to change the asteroid’s momentum (and trajectory).

The Double Asteroid Redirection Test (DART), to be launched in November 2021, will test the technique. DART will target Dimorphos, depth 160 meters moon of the asteroid Didymos is 780 meters high, and aims to change Dimorphos’s orbit around Didymos by the end of September 2022.

The change will be small, but measurable from Earth. KI missions will provide a non-nuclear option to deflect objects up to several hundred meters across, especially if a series of KIs are sent and each provides the asteroid with a nozzle small to form a larger bucket together.

A kinetic impact on the asteroid is of interest to change the momentum (and trajectory) of the asteroid.

Let gravity do the work

The gravity tractor is an elegant concept that uses the laws of physics: even small masses can have a strong attraction if they are very close.

This technique would involve operating a very large spacecraft very close to the asteroid of interest, and using the mass of the spacecraft to attract the asteroid. Because the spacecraft’s position can be controlled, it can pull the asteroid in any direction and change its orbit so that it slips away from Earth.

Unlike nuclear devices or kinematics, which make change all at once, gravity tractors are a slow-moving method that can take decades to do the job. It is best suited for smaller objects and – of course – objects detected for a very long time before they are capable of reaching Earth.

Gravity traction also allows for much more accurate results than other approaches.

Gravity tractors alter the asteroid’s path simply by pushing in a consistent direction relative to the asteroid’s path.

Planetary defenders have offered other options for deflecting asteroids, but they need more research to see how realistic they are.

A passive alternative involves altering part or all of the luminosity of the threatened asteroid and allowing a non-gravity force (known as the Yarkovsky effect) to alter the asteroid’s orbit.

This will be a very long job. Another option is to place a spacecraft with a powerful laser near the asteroid and vaporize it face below, this would reduce the asteroid’s mass and act as a small rocket to change its orbit.

But this really requires a very powerful laser and a suitable large power source and/or a set of solar panels. Another approach is to attach a tether many kilometers long to the asteroid, which would effectively change its center of mass and lead to a change in orbit.

Asteroid impacts are the only disaster scenario because they can be completely prevented if we have enough warning.

Thousands upon thousands of asteroids orbit the Earth, and scientists are constantly cataloging them to try to make sure anything on the way to impact is found as soon as possible.

Should a real threat emerge, the approach we take will also depend on the response from the specific country (or countries) affected, and how well the international community can cooperate. how through committees at United Nation.

In the meantime, scientists will continue to observe the skies and work on techniques to send space travelers on their way before they land on Earth’s doorstep.

(360info.org)



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