tytower

If we get to seriously attempt space travel to the nearest star system I would imagine that the craft we use travelling at such high speeds as are necessary would need frontal protection.

A large mass up fromt which would survive a chunk of debris, say the mass of a tank, hitting it head on . Thinking about it the entrance to such a craft would beon the other end ,as would the means of propelling the craft.

Looking at the Martian moon Phobos it certainly seems like a possible candidate . Possibly hit by something a bit too big to continue on and abandoned in orbit around Mars ? APOD: 2008 April 10 - Stickney Crater

nomeat

Have you ever been hit by a meteor?
I believe there is a record of only one person who has ever been hit on this planet by a meteor or was it space junk?
And we are constantly travelling through space at great speed!

The only real threat is getting past all the junk in our own geo-physical orbit.
Compared to that the likely hood of accidently crashing into something in space is practically nil.

I know plenty is burned up before it reaches earth, but it is our planet's gravity field that attracts meteors. A space craft has no practical gravity field.

trash

I do believe DEVO wrote a song about it. Her name was Sally, well, according to the song it was

I think tytower might be thinking about micrometeors as they're often refered to. It also depends on where we're thinking of sending tytower if we want to keep him alive on his long journey.
If he's just going to the moon, well there isn't a lot of concern. as nomeat said, there may be a lot of junk or stuff floating out there, but there is a whole lot more of nothing.

Interplanetary space has even less stuff and more nothing and interstellar space more and less again. But when it comes to hitting something bigger than dust at 50-100kps. Not forgetting all the other more important problems about space travel.

Accellerating a large dead mass is one thing, and it also has to be decellerated at the other end.

tytower

In my books the decelleration starts at the mid point. I was thinking of say going to Alpha Centauri at 50% of light speed . There would be a lot of dust in the way

trash

Dust is a bit of a broad description. Just simplify it a little and say that this dust isn't fine particles as we know it here on Earth. Consider it to be nothing more than molecules, or more particularly atoms or ions of those atoms.

Now consider one such example of such dust here on Earth that we can study, Alpha particles (Helium Nuclei) traveling at much slower speeds.
At higher speeds, protons and other larger high energy particles are often grouped as cosmic radiation. So by traveling at a high velicity through space we not only are exposed to background cosmic radiation, but we create our own but just moving through ... err.. the dust. Anything bigger is going to be seriously destructive.
Time for those Star Trek deflectors !

nomeat

I don't know about 50% light speed but if I were to believe in special relativity, I would conclude that a ship travelling close to light speed would cause a time dilation that could be so large that a slower object would not have enough time to deform it.

It's relativistic mass could be many times higher than a planet if travelling fast enough, so a ship could even fly right through the planet without noticing serious deceleration.
However we don't have proof that special relativity is really applicable at such speeds. It is mainly mathematics, I don't think we have actually seen heavy massive objects moving at such speeds to prove it.

trash

Theoretically possible, just not practical (in the present).