Dodging Asteroids

[Jim Leff]

Do Mars missions skillfully navigate around asteroids or do they simply blast through and hope for the best?

[neufer]

Do Mars missions skillfully navigate around asteroids or do they simply blast through and hope for the best?

There aren't very many asteroids that are not in the asteroid belt which lies outside of Mars's orbit.

<<The first spacecraft to traverse the asteroid belt was Pioneer 10, which entered the region on July 16, 1972. At the time there was some concern that the debris in the belt would pose a hazard to the spacecraft, but it has since been safely traversed by 9 Earth-based craft without incident. Pioneer 11, Voyagers 1 and 2 and Ulysses passed through the belt without imaging any asteroids. Galileo imaged the asteroid 951 Gaspra in 1991 and 243 Ida in 1993, NEAR imaged 253 Mathilde in 1997, Cassini imaged 2685 Masursky in 2000, Stardust imaged 5535 Annefrank in 2002, New Horizons imaged 132524 APL in 2006, and Rosetta imaged 2867 Šteins in 2008. Due to the low density of materials within the belt, the odds of a probe running into an asteroid are now estimated at less than one in a billion.>>

[Chris Peterson]

Do Mars missions skillfully navigate around asteroids or do they simply blast through and hope for the best?

Even in the asteroid belt (which is outside Mars's orbit), you could cruise around for thousands of years and never get close enough to see one. Space is really, really empty.

[neufer]

Do Mars missions skillfully navigate around asteroids or do they simply blast through and hope for the best?

Even in the asteroid belt (which is outside Mars's orbit), you could cruise around for thousands of years and never get close enough to see one. Space is really, really empty.

Click to play embedded YouTube video.

• Conquest of Space (1955)

General Samuel T. Merritt: Merritt speaking. Here's the report. Lost course for several days due to near-collision with asteroid, but we can still reach destination as planned... which may be Mars, or Hell. This voyage is a cursed abomination! If it were possible I'd come back now, return the ship to Earth and blow it up--

Captain Barney Merritt: General, please!

General Samuel T. Merritt: --together with all plans in existence for building another! We're committing Man's greatest sacrilege, and we can't stop.
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* Revealing mistake:

When the engines are turned on during the asteroid scene,
strings can be seen holding up the ship.

[Beyond]

Hey neufer, are the strings those little short white lines that extend from the two wings ?? Thats all i could pick up.

[Jim Leff]

Ok, sorry. Make it Jupiter and the rest, then.

We don't sweat it 'cuz (as air traffic controllers, somewhat scarily, say) "it's a big sky"?

[dougettinger]

Do Mars missions skillfully navigate around asteroids or do they simply blast through and hope for the best?

Even in the asteroid belt (which is outside Mars's orbit), you could cruise around for thousands of years and never get close enough to see one. Space is really, really empty.

However, due to the gravitational field close to Earth, meteors and sizable dust particles may be encountered with a much higher probability than in interplanetary space by man-made satellites and space startions. I believe that some collisions with natural space debris have been recorded ?

Doug Ettinger
Pittsburgh, PA
01/26/2011

[Chris Peterson]

However, due to the gravitational field close to Earth, meteors and sizable dust particles may be encountered with a much higher probability than in interplanetary space by man-made satellites and space startions. I believe that some collisions with natural space debris have been recorded ?

Earth's gravitational field has very little to do with this. The meteoroid environment around Earth isn't significantly different that it is out between the planets.

There are two things to consider here. First is the size of particles in interplanetary space. They follow a power law, meaning that as the size gets smaller the number of particles gets rapidly larger. There are only a few objects of planet size in the Solar System, but there are countless trillions of particles the size of sand grains. So even in the Asteroid belt, you will encounter far more sand-sized grains than you will asteroids.

Second, you need to consider the source of debris that hits satellites in Earth orbit. It isn't material from the natural background, but material associated with passing through cometary debris trails- the same thing that produces meteor showers. These are regions where the debris is substantially above the background level, in rings orbiting the Sun. They exist throughout the Solar System, in the orbit of every comet that gets close enough to the Sun to shed material.

[dougettinger]

I believe I am correct is stating the collisions between debris from comets and our man-made satellites and space stations are known and recorded ?

Doug Ettinger
Pittsburgh, PA

[Chris Peterson]

I believe I am correct is stating the collisions between debris from comets and our man-made satellites and space stations are known and recorded ?

There have been a couple of satellites that ceased to operate, where meteoroid collisions are suspected. Since the satellites can't be examined, it is impossible to know for sure, but detailed failure analysis combined with timing during major showers is highly suggestive.

Other than that, all objects in Earth orbit undergo steady collisional damage from small particles. Many space-based experiments have been performed to analyze micrometeorite impacts, notably, the Long Duration Exposure Facility experiment, which was in orbit for over five years.