An Asteroid Field Would Actually Be Quite Safe to Fly Through

Today I found out it is actually quite safe to fly through an asteroid field.

The reality is that the asteroids in asteroid fields are incredibly far apart and most of the objects in these fields are very tiny. There are generally hundreds of thousands of miles between these objects and most of them are no bigger than a tennis ball (called meteoroids, with the cutoff for being called an asteroid at around 164 feet or 50 meters on a side).

In fact, if you added up the mass of all the asteroids in our solar system’s asteroid belt, it’s a mere 4% of the mass of our moon with about 1/3 of that total mass coming from one asteroid, Ceres, and about 1/2 of the total mass from just four asteroids, Ceres, Vesta, Pallas, and Hygiea.

So that’s our asteroid belt. What about others? Could there be an asteroid belt out there that would be dangerous to fly through? It’s a big universe, so it’s entirely possible that there exists such fields at any given moment in time somewhere in the universe, but it would be very unlikely that you’d encounter it, even if you could travel anywhere you wanted in the universe. The reason being that even if the asteroid belt is initially packed with debris that are colliding everywhere and basically is like what is depicted by Hollywood, this would quickly (on a galactic time scale) sort itself out with most of the mass being ejected from the belt, due to these collisions. Eventually, the system would stabilize itself to something like what our asteroid belt is. So you’d need to find a system that was just forming and even then you’d likely see vast distances between the objects in the fields in such a system.

It’s estimated that our asteroid belt once contained about 1000 times the mass it currently contains. However, within about one million years of its formation, it was down to somewhere in the vicinity of the stabilized amount we see today. Once this system was stabilized with almost no collisions, the asteroids simply travel in their respective orbits with the field itself neither increasing nor decreasing in mass significantly since that initial stabilization period.

So how many collisions actually occur in our solar system’s asteroid belt? Of the asteroids above about 6 miles wide, it’s expected they’ll encounter about one collision of some sort every 10 million years. While that’s certainly a lot of collisions on a galactic time scale, it would have made Han Solo’s daring flight through the Hoth system’s asteroid field a bit less dramatic if depicted accurately…

In case you’re wondering, the odds of successfully navigating an asteroid field isn’t “approximately 3,720 to 1!” The actual odds would entirely depend on what asteroid field you were talking about and a variety of other factors. But for reference, NASA estimates the odds of one of their probes traveling through our asteroid field actually hitting an asteroid to be about one in a billion.

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Bonus Facts:

  • To date, 12 probes have traveled through the asteroid field in our solar system: Pioneer 10; Pioneer 11; Voyagers 1 and 2; Ulysses; Galileo; NEAR, Hayabusa, Cassini; Stardust; New Horizons; and Roesseta. None has encountered a problem due to asteroids or debris and several of them didn’t spot any asteroids whatsoever while they passed through. It should also be noted that of some of those that did spot asteroids did so because they were specifically aimed such as part of their mission.
  • NASA recently launched a new probe aimed at being the first to encounter two asteroids in our asteroid field. This Dawn spacecraft is set to look at Vesta and Ceres and study them in detail. If it happens to still be functional afterward, they plan on pointing it at other asteroids to study them as well.
  • The largest known asteroid in our solar system’s asteroid field is Ceres, which is around 650 miles in diameter and is now sometimes classified as a dwarf planet. The runner up is Pallas, which is about 360 miles in diameter.
  • Ceres was discovered by Giuseppe Piazzi in 1801. Once it was realized that it was neither a comet nor a planet, Sir William Herschel named it an asteroid, a word he made up. The word itself means “star-rock” or “star-planet” (aster-oid). Sir William Herschel was also the astronomer who discovered Uranus.
  • To date about 280,000+ asteroids have been found in our solar system with that number continuing to rise rapidly. Of those 280,000 only about 200 are bigger than about 60 miles in diameter (about 100km). It’s estimated that there are around 1-2 million asteroids in our solar system.
  • The vast majority of asteroids seem to be made of mostly carbon (3/4, called C-type); the vast majority of the rest seem to be made of iron and nickel (M-type) with some are composed of silicates (S-type).
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16 comments

  • That’s something new that I’ve learned. I myself haven’t seen it in person, I only see the asteroid belt on movies. Though they look closer, it’s surprising to know that they are thousand miles away from each other. So it’s safe to fly between these asteroids then.

  • How would the mass of all these meteoroids and asteroids be measured to arrive at the 4% of our moon. There must be thousands in the belt which are many miles from earth. How do they arrive at such an exact number?

  • Hehe this is interesting. All this time watching Battlestar Galactica, Starwars and Star Trek I was under the impression that it is only the ace pilots who could navigate through an asteroid belt.

    P.S Could you put autofill/suggestion during filling up the comment name, email and website. It would be good for us.

  • Francis, the real belts don’t look ANYTHING like they do in the movies. The one’s in the movies look that close because they are. That’s what makes them so dangerous. But in the real asteroid belt, you’d be lucky to see more than on asteroid at a time.

  • Actually, the Hoth asteroid field was caused by the collision of two planets some time in the past.

    http://starwars.wikia.com/wiki/Hoth_asteroid_field

  • One thing I’ve never understood is why don’t these spaceships on TV ever just blow the asteroids or meteoroids out of the way? It’s like having a snow plough in front of you but not using it to clear the way and in stead way threw the deep snow.

  • What this article doesn’t mention is the fact that, in an star system (assuming it’s a star system) in an unknown galaxy in an unknown part of the universe, why is it so implausible that there is a densely-packed asteroid belt? Sure, our asteroid belt may not be that dense, but then again, our solar system is pretty old. Most estimates place the number of asteroids now at about 1% of what they were ~4 billion years ago. Because of that, how can we say with any degree of certainty that the scene in Star Wars is such an unlikely occurrence? If we base it only on our own star system, then yes, it’s not accurate. But we’re talking about a fictional asteroid belt in a fictional universe – how do we know it’s not like that? Because we plug our ears and cover our eyes to possibilities that we’re unfamiliar with? How scientific is that?

    • Scott, I think he covered that pretty well in the article… Here’s the quote. “It’s a big universe, so it’s entirely possible that there exists such fields at any given moment in time somewhere in the universe, but it would be very unlikely that you’d encounter it, even if you could travel anywhere you wanted in the universe. The reason being that even if the asteroid belt is initially packed with debris that are colliding everywhere and basically is like what is depicted by Hollywood, this would quickly (on a galactic time scale) sort itself out with most of the mass being ejected from the belt, due to these collisions” wham bam thank you ma’am

  • I only recently stumbled across this article, so I hope my comment isn’t completely uncalled for — but one question immediately comes to mind.

    How fast do these asteroids whirl through their orbit?

    I mean, it’s one thing to point out that our asteroid belt isn’t as dense as the asteroid belts we commonly see depicted in science fiction. That’s fine. But a small family of even tennis-ball sized meteoroids could present a serious danger if they were fast enough.

  • In our asteroid field, they aren’t quick at all… okay, at least in relation to everything else (the solar system is hurtling through space at fantastic speed, but we’re all going that speed, so we aren’t aware of it). They might be hard to see due to their size, depending on the ship’s sensors, but if they knew they were there, your speed is more problematic than the asteroid’s.

    My bugaboo has always been phasers and lasers shot by Hollywood ships. Seems those that don’t hit the ship being shot at, could do damage to whatever planet is behind them (how fast do such lasers attenuate?). It’s like all those idiots on TV firing their guns in the air. That bullet has to come down somewhere. (Happened in Florida a few years ago. Some New Year’s idiot shot his gun in the sky and the bullet hit a little girl).

    Love this site, by the way.