Navigating an Asteroid Field

In "The Empire Strikes Back" Han Solo navigates his Millennium Falcon through an asteroid field to escape star destroyers.  Since then, a number of other TV shows and movies have depicted similar crossings through asteroid fields where a space ship weaves through to avoid collisions.  How likely is a scenario such as this?

We do not have first hand knowledge of any actual asteroid fields similar to the one from Star Wars.  In our solar system, we have an asteroid belt between the orbits of Mars and Jupiter, but it is far more sparsely populated than the one depicted in Star Wars.  The average distance between asteroids is about 1 million miles.  All of our space probes have passed through it without incident and with no course corrections needed.  The probability of encountering even a single asteroid is remote, unless we explicitly set out to do so.

The asteroid belt was denser in the early solar system, but still nothing like the asteroid field from Star Wars.  Structures like that would be unstable.  Collisions would tend to knock asteroids further apart until they were far enough apart to make collisions a much more rare occurrence.  There are stable points of gravitational equilibrium called Lagrange points where debris could accumulate forming something as dense as that depicted in Star Wars, but these would not extend over a large area and would be very easy to avoid altogether.  Lagrange points are in known locations relative to large celestial bodies.

Perhaps it is possible for a dense asteroid field to exist for a short time before repeated collisions drive the asteroids further apart.  If so, it would always be much simpler to navigate around it rather than through it.  If it was uncharted and you came upon it suddenly, the speed differential between you and the asteroids would likely be so great that there would be no time to react before your spaceship was obliterated.  Bodies in space travel at extremely high velocities relative to each other unless they are in the same orbit around a planet or star.

The only way to produce the scene from Star Wars is to nearly match the speed of the asteroids with your spaceship before attempting to navigate through.  However, it would not look anything like that depicted on Star Wars.  The Star Wars spaceships fly more like airplanes than spaceships, which real spaceships cannot do because there is no air to push against (see blog post Spaceships That Fly Like Spaceships).  It would be more like navigating the spaceship in the old arcade game, Asteroids, but more complex because you would be dealing with three dimensions rather than two, and without the option of shooting the asteroids.

Remember also that if you have to flee from an enemy in space, you have many more possibilities than you do on the surface of the earth because you can fly in three dimensions.  It is difficult to get our minds wrapped around the possibility of traveling freely in three dimensions because we are too accustomed to traveling gravity-bound on the surface of the earth.  It is true that we can go short distances in the third dimension, but our travel on earth is predominantly in only two.  In space you could travel forever in a third dimension.

If you just need to get from point A to point B, it should be no problem to simply plan your course around the asteroid field.  Because of the way these type of structures might form, they are likely to lie in the same plane, meaning that you could just adjust your plane of travel by a small amount to get around it.

So even though the scene from Star Wars would likely never need to occur, no matter how advanced our technology, it still makes for an exciting action sequence.