Author Topic: A Mars Rover post that only a Rifleman could appreciate...  (Read 905 times)

Offline Foppish Dandy

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A Mars Rover post that only a Rifleman could appreciate...
« on: August 06, 2012, 08:31:17 PM »
A friend of mine (who previously attended an Appleseed) posted this on my Facebook profile today... Thought this group would appreciate it. Anyone want to double-check my math?



FD

Offline Edheler

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #1 on: August 06, 2012, 09:01:54 PM »
Here is what I get: 102,393 miles is 1 MOA (arc minute) at 352 million miles.

100 yards is approximately 33.3 microarc seconds at 352 million miles.

arc minute (MOA)
arc second (1/60th of an arc minute)
milliarc second (1/1000 of an arc second)
microarc second (1/1000 of a milliarc second)
"While the people have property, arms in their hands, and only a spark of noble spirit, the most corrupt Congress must be mad to form any project of tyranny." Rev. Nicholas Collin (1745-1831) Fayetteville Gazette (N.C.), October 12, 1789

Offline 92trk

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #2 on: August 06, 2012, 09:28:12 PM »
So much math it makes my head hurt. The analogy here is this, with much determination and effort NASA hit the mark. Anyone who applies themself to becoming a Rifleman can do the same.

hinermad

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #3 on: August 06, 2012, 09:31:58 PM »
I also get about 98k miles = 1 MOA at 352 million miles.

Not to diminish NASA's and JPL's accomplishment, but they did get a few chances to do mid-course corrections on that shot. On the other hand, the come-ups in multiple gravity fields are positively freaky!

Dave

Offline Foppish Dandy

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #4 on: August 06, 2012, 09:36:25 PM »
Here is what I get: 102,393 miles is 1 MOA (arc minute) at 352 million miles.

100 yards is approximately 33.3 microarc seconds at 352 million miles.

arc minute (MOA)
arc second (1/60th of an arc minute)
milliarc second (1/1000 of an arc second)
microarc second (1/1000 of a milliarc second)

Where'd you get 102,393 miles? This is how I did the math:

352,000,000 miles = 619,520,000,000 yards
1 MOA = 1" per 100 yards
1 MOA = 61,95,200,000 inches at 619,520,000,000 yards
619,520,000,000 yds = 97777.8 mi

Offline Edheler

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #5 on: August 06, 2012, 09:40:19 PM »
I also get about 98k miles = 1 MOA at 352 million miles.

You're getting that result because you're using 1" is 1 MOA per 100 yards. We round it down because it doesn't matter for 4 MOA accuracy out to 500 yards. An approximation with 4 significant digits is: 1.047" is 1 MOA per 100 yards.
"While the people have property, arms in their hands, and only a spark of noble spirit, the most corrupt Congress must be mad to form any project of tyranny." Rev. Nicholas Collin (1745-1831) Fayetteville Gazette (N.C.), October 12, 1789

Offline Edheler

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #6 on: August 06, 2012, 09:45:39 PM »
To eight significant digits: 1.0471976" is 1 MOA per 100 yards
To twelve significant digits: 1.04719755858" is 1 MOA per 100 yards.

Rounding really bites at 352 million miles. ;)
« Last Edit: August 06, 2012, 09:49:44 PM by Edheler »
"While the people have property, arms in their hands, and only a spark of noble spirit, the most corrupt Congress must be mad to form any project of tyranny." Rev. Nicholas Collin (1745-1831) Fayetteville Gazette (N.C.), October 12, 1789

Offline Foppish Dandy

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #7 on: August 06, 2012, 09:51:13 PM »
Makes sense then... I still want to see a grouping of at least two more shots before I make any determination as to whether or not they're shooting to standard.  ;D

Offline Edheler

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #8 on: August 06, 2012, 09:57:12 PM »
Makes sense then... I still want to see a grouping of at least two more shots before I make any determination as to whether or not they're shooting to standard.  ;D

Knowing NASA they would be more concerned with hitting their existing very expensive SUV on Mars if they sent more. ;D
"While the people have property, arms in their hands, and only a spark of noble spirit, the most corrupt Congress must be mad to form any project of tyranny." Rev. Nicholas Collin (1745-1831) Fayetteville Gazette (N.C.), October 12, 1789

hinermad

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #9 on: August 06, 2012, 10:07:00 PM »
You're getting that result because you're using 1" is 1 MOA per 100 yards. We round it down because it doesn't matter for 4 MOA accuracy out to 500 yards. An approximation with 4 significant digits is: 1.047" is 1 MOA per 100 yards.

Guilty as charged.

tan(1/60) x 3.52E8 = 102,392.652 miles.

Dave

Offline gonejohnny

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #10 on: August 07, 2012, 11:08:43 AM »
 :pop:

Makes sense then... I still want to see a grouping of at least two more shots before I make any determination as to whether or not they're shooting to standard.  ;D

Offline Barbie

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #11 on: August 07, 2012, 11:35:23 AM »
:pop:

Makes sense then... I still want to see a grouping of at least two more shots before I make any determination as to whether or not they're shooting to standard.  ;D

Well who knew our AS folks were so proficient in their math skills  ;)

I'm with GJ, im just gonna sit back and watch ya'll do the math!  I ran out of fingers and toes a long time ago!   :pop:
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Offline LittleMo

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Re: A Mars Rover post that only a Rifleman could appreciate...
« Reply #12 on: August 07, 2012, 06:46:46 PM »
Makes sense then... I still want to see a grouping of at least two more shots before I make any determination as to whether or not they're shooting to standard.  ;D

First shot (in the target) may be luck, second shot may be cooincidence, third is skill.
But gotta give them credit for limiting their shots, after all look at the cost per round!
It isn't about 5 cents per shot like a .22LR! ;D

Thanks, EDheler, for posting the info.  :)

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