What Is a Keyhole in Space?

Question

I heard that an asteroid will just miss earth in 2029. But if it goes to a keyhole, it will hit earth. To what is this refering.

Anyone know what causes such keyholes?

Answer 1

The "keyhole" is a small area in space through which the asteroid must pass at a certain time in order for it to be on a collision course with Earth. This keyhole area is not a physical structure, made of matter, but is instead a conceptual location, calculated by knowing the location and velocity of both the Earth and the asteroid. You cannot see the keyhole by looking for it with a telescope; there is nothing material to see.

Saying that the asteroid must pass through the keyhole to collide with Earth is kind of like saying you must be at the train station at the right time to catch the train, else you will miss it.

Each asteroid will have a different keyhole, depending on its orbit and on the orbit of the Earth.

Answer 2

Fundamentally, we don’t know the exact orbits of most asteroids. It takes repeated, precise observations to devise an accurate orbit for an object in the solar system, and many near-earth objects (or “NEOs”) are only now being cataloged.

The term “keyhole” (or “resonance keyhole”) refers to a region of space that, if an object passes through it at a certain time, specifies the object’s orbit to be on a future collision course.

In the case of Apophis, which will pass near Earth in 2029, we know its orbit well enough to know that it could pass through a tiny keyhole (about 600 meters wide) that would most likely cause it to collide with Earth in 2036. As astronomers make more observations of the asteroid, they may find that it’s less likely to pass through that keyhole, but it will take repeated observations to get an accurate orbit. Some scientists are suggesting that we intercept Apophis and place a transponder on its surface, so we could get more specific data about its location and come up with an even better orbit. We’d want to do this before 2014, so we’d have enough time to do something about changing the asteroid’s trajectory if indeed it were found to be heading toward the keyhole.

The B612 Foundation is a good source of information about asteroid tracking and about the possibilities of asteroid deflection.


Ryan Wyatt
Rose Center for Earth & Space
New York, New York

Answer 3

To answer this the best I can: A keyhole is a small area where the gravitational fields differs from that around it.. What you are referring to here is approximately a 6 meter area that if the asteroid went through, it would alter the path of it, making it orbit 5 times or so and splat.. Hope this answerer's your question..

Answer 4

I am not sure what are you talking about. But The mechanics of their orbit depends upon 2 things. The velocity of the object and the angle at which it enters the earth's gravity. Then depending upon these factors It may orbit the earth, or leave the earth with a higher speed ( sling action) or hit earth. May be that small window they are mentioning.

Answer 5

the point where it will be pulled in by gravity