weapons on the surface of mars?...calling all physics people

[ddrew13]

hi everyone,<br />I am trying to finish a short science fiction story set on the surface of Mars, I just need help with some technical details.<br /><br />1. Lets say the standard earth pistol is brought to Mars. Would it work? Would it be more effective/less?(like out on the surface and not indoors.)<br />2. Would said pistol be able to pierce metal or rock more easily due to less density or something?<br />3. I sort of imagined a glorified CO2 BB gun only with a larger bolt instead of a BB. The CO2 would come from the atmosphere and be constantly recharged. Is this a bad idea or good? Maybe instead of CO2 it can be O2 feed of the breathing tank. Would this type of weapon even be practical, with the ability to penetrate armor/spacesuit/skin <img src="/images/icons/smile.gif" />? If anyone can improve on the design somehow, or think up something cool that would be awesome too.<br />4. Ok last one is kind of fun. What happens when human blood is driped onto the Martian surface?<br /><br />Alrighty, I know that reads sort of like an insane physics test, but all help would truly be appreciated. Thanks in advance.<br />Drew

 

[ddrew13]

oh and just to clarify for question 3, please suggest like homemade type weapons that can easily be manufactured on Mars without any infrastructure, and with today's technology. Thanks again

 

[pyoko]

A normal Earth pistol would work anywhere, including vaccuum or the thin atmosphete of Mars. The gunpowder inside the cartrige contains an oxidiser, so it provides its' own oxygen. As for gravity, I expect the range would be much higher, as the 'spiral spin' effect that comes from air friction on earth would be much less on Mars, and the gravity would pull the bullet down less, also. <br /><br />At a short range, the power of the gun blast on Mars would not be more powerful than on Earth, however. At long range, however, on Mars it would have more power.<br /><br />Dan Brown, in his book Deception Point, had a gun that fired ice pellets. You pack snow into the gun, and it compresses it into ice and shoots the projectile out. The ice pelles can kill, and later melt, leaving no trace of a bullet. Maybe you can have something like that, but with CO2. There just isn't that much atmosphere on Mars, though (something like 3% of Earths). You would have to use CO2 cylinders. But since it's science fiction, you could have the cylinder constantly 'trickle charge'. So if you leave it overnight, the cylinder auto-charges.<br /><br />Lastly, the blood spilt will do two things: it will freeze faster since Mars is cold. It will also probably dry up faster, since Mars is very dry. But it will probably just freeze before it can dry. <div class="Discussion_UserSignature"> <p> </p><p> </p><p><span style="color:#ff9900" class="Apple-style-span">-pyoko</span> <span style="color:#333333" class="Apple-style-span">the</span> <span style="color:#339966" class="Apple-style-span">duck </span></p><p><span style="color:#339966" class="Apple-style-span"><span style="color:#808080;font-style:italic" class="Apple-style-span">It is by will alone I set my mind in motion.</span></span></p> </div>

 

[docm]

The "spiral spin" has little to do with the atmosphere and everything to do with the gun barrels rifling; spiral grooves cut into its interior. These give the bullet spin stabilization, a gyroscopic effect just like that you see applied to a shuttle launched satellite but at higher RPM's. <br /><br />In both cases it works as well in a vacuum as in an atmosphere, if not better because in a vacuum there is no drag to slow down the bullets RPM's at long range.<br /><br />On Mars the effect would be enhanced accuracy at long range because of the additional retained bullet RPM's, higher retained velocity due to less atmospheric drag and flatter trajectory due to less gravity <i>and</i> drag. <br /><br />Crosswinds would be faster, but with the low atmospheric density the sideways displacement effect on the bullet per km/h of wind velocity (windage) would be reduced.<br /><br />In short Mars would be a snipers dream.<br /><br />Frozen water bullets only work with reduced powder charges. Otherwise the higher pressures cause it to fragment soon after leaving the barrel. Frozen meat works marginally better. Trust me <img src="/images/icons/wink.gif" /><br /><br />That said additives might help. <br /><br />OTOH frozen mercury bullets of a small caliber (.17 Remington etc.) would work nicely, melting in the victim quickly due to their low mass and leaving no ballistic evidence. <br /><br />A hollow point or soft point form factor is a good plan; you don't want it to go through and stick somewhere intact where it could be recovered, which it could do on a cool Martian day (melting point = -38.83°C, -37.89°F). A chilled bullet case might be a good idea, but one keeping their tips in dry ice would suffice (-78.5°C,-109.3ºF).<br /><br />Another option would be a frozen sabot around a conventional bullet, but here the disadvantage is that you need an environment warmer than its melting point. <br /><br />Then there's the problem of the bullet being relatively intact; no rifling for ballistics, <div class="Discussion_UserSignature"> </div>

 

[pyoko]

The spiral spin I was refering to is not the one you think. I know that the bullet spins because of the grooves in the barrel, giving the bullet a straighter trajectory. The 'spiral spin' I meant is the one that every bullet gradually gets as it travels further and further. In fact, 1 km after leaving the barrel, it is not uncommon for a bullet to be travelling forwards in a spiraling motion of up/ down/ left/right of 1 meter or more, greatly reducing the accuracy. <br /><br />If you like, I could have used the word 'wobble' instead of 'spiral spin'. But in no way was I refering to the stabilising spin put on the bullet by the barrel. <div class="Discussion_UserSignature"> <p> </p><p> </p><p><span style="color:#ff9900" class="Apple-style-span">-pyoko</span> <span style="color:#333333" class="Apple-style-span">the</span> <span style="color:#339966" class="Apple-style-span">duck </span></p><p><span style="color:#339966" class="Apple-style-span"><span style="color:#808080;font-style:italic" class="Apple-style-span">It is by will alone I set my mind in motion.</span></span></p> </div>

 

[docm]

<font color="yellow">The 'spiral spin' I meant is the one that every bullet gradually gets as it travels further and further. In fact, 1 km after leaving the barrel, it is not uncommon for a bullet to be travelling forwards in a spiraling motion of up/ down/ left/right of 1 meter or more, greatly reducing the accuracy.</font><br /><br />You're talking about the Magnus effect, AKA "spin drift", which is the same force responsible for curve balls in baseball and dipsy-doodling ping-pong balls. <br /><br />Since its caused by a boundary layer interaction between the spinning bullet and the atmosphere, if any, atmospheric density is critical to its degree. On Mars there is very little atmosphere and therefore minimal if any spin drift. In a vacuum there is none. <br /><br />Like I said: a snipers dream.<br /><br />Also; there are recent improvements to accuracy you might be interested in. One example is the CheyTac M200 Intervention .408 sniper rifle that groups just 16.625 inches (42.23 cm) at 2,321 yards (<b>1.32 miles or 2.12 km</b>), a record that may have already been broken already if I know my armorers <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

 

[vandivx]

<font color="orange">Dan Brown, in his book Deception Point, had a gun that fired ice pellets</font><br /><br />S. Gould had one of his villains shooting ice pellets in Dick Tracy comic and that was probably way before this guy was even born<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[keermalec]

I think that blood, like water, would dry up faster than it would freeze. Even if it froze first, I beleive it would sublimate very quickly because of the extreme dryness. <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>

 

[Boris_Badenov]

docm, congrats on your new star status <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[docm]

Thanks, but I must admit it caught me by suprise <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[heyscottie]

I used to be a star ... before the meltdown ... *sigh*.<br /><br />I coulda been a star, I tell ya!