# How fast would a bullet reach Mars (if shot from the ISS)?
**URL:** https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873
**Category:** Factual Questions
**Created:** [February 10, 2011, 8:57am UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873 "2011-02-10T08:57:05Z")
**Posts on this page:** 11
**Page:** 2
### Author:  [@Spoke](https://boards.straightdope.com/u/Spoke)
#### Post date: [February 10, 2011, 5:58pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/21 "2011-02-10T17:58:22Z")
> [@'\[Undecided](#):
>
> Adrian;13450522’]1220 m/s is not fast enough to escape Earth’s gravity starting from a Low Earth Orbit.
IANAPhysicist…
Could you use the forward velocity of the space station to add to the velocity of the bullet? In other words, fire forward, in the same direction the space station is traveling? (Of course, I have no idea how fast the space station is moving…)
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### Author:  [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)
#### Post date: [February 10, 2011, 6:03pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/22 "2011-02-10T18:03:21Z")
> [@Spoke](#):
>
> IANAPhysicist…
>
> Could you use the forward velocity of the space station to add to the velocity of the bullet? In other words, fire forward, in the same direction the space station is traveling? (Of course, I have no idea how fast the space station is moving…)
Still not fast enough. ISS moves about 17,500 MPH. Put the bullet’s 2700 MPH on top of that, you get 20,200 MPH. Escape velocity from the earth is about 25,000 MPH, so you’ve still got about 5000 MPH to go.
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### Author:  [@Jake](https://boards.straightdope.com/u/Jake)
#### Post date: [February 10, 2011, 7:03pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/23 "2011-02-10T19:03:22Z")
If the bullet \*was \*lucky enough to reach Mars, would it melt in Mars’ thin atmosphere?
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### Author:  [@Projammer](https://boards.straightdope.com/u/Projammer)
#### Post date: [February 10, 2011, 7:21pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/24 "2011-02-10T19:21:00Z")
What about using the Earth or moon to set up a gravitational slingshot?
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### Author:  [@Scuba\_Ben](https://boards.straightdope.com/u/Scuba_Ben)
#### Post date: [February 10, 2011, 7:23pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/25 "2011-02-10T19:23:24Z")
> [@komolono](#):
>
> Hijack with a gun. What is the jurisdiction of this on the Moon - felony?😕
Selenic Law, of course.
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### Author:  [@Washoe](https://boards.straightdope.com/u/Washoe)
#### Post date: [February 10, 2011, 8:09pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/26 "2011-02-10T20:09:32Z")
> [@komolono](#):
>
> Hijack with a gun. What is the jurisdiction of this on the Moon - felony?😕
Yes, the penalty for doing so is a lengthy incarceration in a lunatic asylum.
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### Author:  [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)
#### Post date: [February 10, 2011, 8:30pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/27 "2011-02-10T20:30:36Z")
> [@Washoe](#):
>
> Could you stand on top of the highest mountain on the Moon and shoot yourself in the back of the head with it?
I can stand in my bedroom and shoot myself in the back of the head.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [February 10, 2011, 8:51pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/28 "2011-02-10T20:51:56Z")
> [@](#):
>
> What about using the Earth or moon to set up a gravitational slingshot?
You need at least two bodies (other than your projectile itself) to do a gravitational slingshot, which means you’d need to have enough initial thrust to reach the vicinity of the Moon. Which is a little bit less than the amount needed to escape outright, but not by all that much.
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### Author:  [@komolono](https://boards.straightdope.com/u/komolono)
#### Post date: [February 11, 2011, 9:40am UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/29 "2011-02-11T09:40:13Z")
> [@MikeS](#):
>
> No, you’d need a muzzle velocity of about 1680 m/s to do that.
Maybe **Washoe** should build a railgun - somehow W reminds me of Moe in the Simpsons.
> **[Moe Szyslak](https://en.wikipedia.org/wiki/Moe_Szyslak)**
>
> Moe Szyslak (/ˈsɪzlæk/ SIZ-lak) is a recurring character from the animated television series The Simpsons. He is voiced by Hank Azaria and first appeared in the series premiere episode "Simpsons Roasting on an Open Fire". Moe is the proprietor and bartender of Moe's Tavern, a Springfield bar frequented by Homer Simpson, Barney Gumble, Lenny Leonard, Carl Carlson, Sam, Larry, and others.
> Grouchy, lonely, miserable, and prone to violent outbursts, Moe is constantly down on his luck and has attem...
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### Author:  [@Kevbo](https://boards.straightdope.com/u/Kevbo)
#### Post date: [February 11, 2011, 6:12pm UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/30 "2011-02-11T18:12:42Z")
> [@Gray\_Ghost](#):
>
> T Is it the combustion rate of the propellant that sets the top end of velocity? Is it that modern chambers can’t handle higher chamber pressures? Is it that you’d need a 4 foot barrel to go faster? Just wondering, as modern saboted projectiles can go a lot faster.
It is the heat and pressure that the steel of the barrel can tolerate. Even though there is other fuel, the oxidizer in the powder is also working like a cutting torch on the steel of the barrel. The barrel life is fairly short at the top end of velocity spectrum. They erode at the throat, just ahead of the chamber where the heat and pressure is the highest. The steel is very thick there, so not a safety issue, but it kills accuracy.
If you don’t care about barrel life, then the combustion rate of the powder becomes the limit. This is where gas guns come in. They use pressurized gas, usually hydrogen to save mass, instead of powder. One of those puppie would probably get you to escape velocity.
The sabot helps, because the pressure gets to work on a light bullet with a large piston area.
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### Author:  [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)
#### Post date: [February 13, 2011, 1:21am UTC](https://boards.straightdope.com/t/how-fast-would-a-bullet-reach-mars-if-shot-from-the-iss/570873/31 "2011-02-13T01:21:02Z")
😕😕
> [@Contrapuntal](#):
>
> I can stand in my bedroom and shoot myself in the back of the head.
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