[ARCHIVED THREAD] - How Do You Navigate In Space? (Page 1 of 2)
Posted: 5/20/2012 7:01:31 PM EDT
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For the simple minded who ate the lead paint chips off of their crib as a baby.... How would you navigate in space? Say a mission to mars, I imagine you could use satellite and radar while you are near Earth, but after so far out then what? How do you know you are headed, distance traveled, speed? When I was watching the super moon awhile back, it struck me just how awesome it was to be able to put men on the moon. I just can't even grasp the engineering feats that had to be done, it is just unreal. |
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Celestial navigation. Nearest stars are several light years away. Inertial navigation measures accelerations so once your velocity is known by celestial navigation, magnitudes of acceleration can be measured and integrated over time to determine position. It isn't too precise so multiple corrections enroute are needed. |
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If you really are interested in this, I recommend CARRYING THE FIRE by Michael Collins, Command Module Pilot, Apollo 11.
He devotes a considerable amount of time to discussing the technical aspects of navigation in space, but there is also enough interesting "human drama" stuff so that the techincal stuff doesn't become too dry. It was one of the most enjoyable books I've read in the last ten years. |
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Inside Sol's system, it's pretty simple; don't into the bright light.
Outside that, a whole pile of calculations are needed, especially since we don't take the direct route but coast most of the distance out and back, plus the corrections mentioned against the position of the stars. For a simple method for calculating how to get from here, to there, google up "Hohman Transfer". |
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Dirt simple and fiendishly complicated is how my astrophysicist buddy called it.
Point in the right direction, burn a certain amount of time at a known thrust and you're on your way! Point in near the opposite direction for about the same amount of time at that thrust and you're there! The trick is pointing the right direction. As shooters we know you have to lead a moving target, so you have to aim at where Mars will be when you get there rather than where you can see Mars now, which isn't where it actually is because light takes a noticeable amount of time to get here. Easy! Now get out your math books and figure out your aiming points. Don't forget that your ships mass changes constantly throughout the burn, giving you more acceleration for a given impulse. Remember that the ship is lighter by that amount of fuel when you start your braking burn. It's simpler if you can thrust constantly the whole way and make a turnover at the mid-point, but that's a lot more reaction mass. There are some decent layman's guides to helping with this out there. I learned my limited understanding from a table-top roleplaying game suppliment; GURPS: Space and two of my players being astrophysicists. Running a hard science-fiction game where you have real hard-scientists is a challenge! Heh heh heh, I said hard scientist. |
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Quoted: If you really are interested in this, I recommend CARRYING THE FIRE by Michael Collins, Command Module Pilot, Apollo 11. He devotes a considerable amount of time to discussing the technical aspects of navigation in space, but there is also enough interesting "human drama" stuff so that the techincal stuff doesn't become too dry. It was one of the most enjoyable books I've read in the last ten years. Thanks. I need a new book to read and this sounds good.  |
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Quoted:
Quoted:
If you really are interested in this, I recommend CARRYING THE FIRE by Michael Collins, Command Module Pilot, Apollo 11. He devotes a considerable amount of time to discussing the technical aspects of navigation in space, but there is also enough interesting "human drama" stuff so that the techincal stuff doesn't become too dry. It was one of the most enjoyable books I've read in the last ten years. Thanks. I need a new book to read and this sounds good.
You'll be quite amused when he starts talking about "whifferdills." (Has to do with docking the CMP and the LEM in lunar orbit). |
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Quoted: Celestial navigation. Nearest stars are several light years away. Inertial navigation measures accelerations so once your velocity is known by celestial navigation, magnitudes of acceleration can be measured and integrated over time to determine position. It isn't too precise so multiple corrections enroute are needed. So celestial navigation would be similar to how the sailors navigated? You could plot the stars to reference your position from Earth, and by calculating the amount of thrust used to date, you get your speed? I really should have stopped eating lead paint chips and huffing model glue as a child...  |
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OK, honestly I don't know because as far as I know we've never done it.
Yes, we went to the Moon. That was a spectacular set of a series of mathematical calculations, the same calculations that get us to the ISS and back. To the best of my knowledge (which is small) these calculations are based upon known physics pertaining to ballistics, gravity, acceleration, deceleration, etc. all within an enclosed system (even though this enclosed system is to the Moon and back). I'm totally unaware of any free space navigation that man has ever done other than the free trajectory return of Apollo 13 and several others. |
But tzatziki sauce is very messy in zero gravity.|
Quoted: OK, honestly I don't know because as far as I know we've never done it. Yes, we went to the Moon. That was a spectacular set of a series of mathematical calculations, the same calculations that get us to the ISS and back. To the best of my knowledge (which is small) these calculations are based upon known physics pertaining to ballistics, gravity, acceleration, deceleration, etc. all within an enclosed system (even though this enclosed system is to the Moon and back). I'm totally unaware of any free space navigation that man has ever done other than the free trajectory return of Apollo 13 and several others. That is what got me to thinking about the so-called Mission to Mars. Earth to moon travel there would be comms and such from NASA, going to Mars your ass would be floating out there alone for something like 30 years? |
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Quoted:
OK, honestly I don't know because as far as I know we've never done it. Yes, we went to the Moon. That was a spectacular set of a series of mathematical calculations, the same calculations that get us to the ISS and back. To the best of my knowledge (which is small) these calculations are based upon known physics pertaining to ballistics, gravity, acceleration, deceleration, etc. all within an enclosed system (even though this enclosed system is to the Moon and back). I'm totally unaware of any free space navigation that man has ever done other than the free trajectory return of Apollo 13 and several others. Mars rovers? |
I see you are a man of science.|
Quoted:
Quoted:
OK, honestly I don't know because as far as I know we've never done it. Yes, we went to the Moon. That was a spectacular set of a series of mathematical calculations, the same calculations that get us to the ISS and back. To the best of my knowledge (which is small) these calculations are based upon known physics pertaining to ballistics, gravity, acceleration, deceleration, etc. all within an enclosed system (even though this enclosed system is to the Moon and back). I'm totally unaware of any free space navigation that man has ever done other than the free trajectory return of Apollo 13 and several others. That is what got me to thinking about the so-called Mission to Mars. Earth to moon travel there would be comms and such from NASA, going to Mars your ass would be floating out there alone for something like 30 years? Well, actually that's not true. We have sent many missions to Mars and the other planets using the same ballistic and gravitational acceleration calculations. I'm thinking you are talking about free space navigation where we haven't been yet. By that, I mean - whoops, we missed our turn at Alpha Centari lets recalculate and head for Sirius.... |
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OK, honestly I don't know because as far as I know we've never done it. Yes, we went to the Moon. That was a spectacular set of a series of mathematical calculations, the same calculations that get us to the ISS and back. To the best of my knowledge (which is small) these calculations are based upon known physics pertaining to ballistics, gravity, acceleration, deceleration, etc. all within an enclosed system (even though this enclosed system is to the Moon and back). I'm totally unaware of any free space navigation that man has ever done other than the free trajectory return of Apollo 13 and several others. 
Voyager AKA V'Ger. |
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Quoted:
Quoted:
OK, honestly I don't know because as far as I know we've never done it. Yes, we went to the Moon. That was a spectacular set of a series of mathematical calculations, the same calculations that get us to the ISS and back. To the best of my knowledge (which is small) these calculations are based upon known physics pertaining to ballistics, gravity, acceleration, deceleration, etc. all within an enclosed system (even though this enclosed system is to the Moon and back). I'm totally unaware of any free space navigation that man has ever done other than the free trajectory return of Apollo 13 and several others. http://voyager.jpl.nasa.gov/images/inner/inlineImg310x230_voyager.jpg Voyager AKA V'Ger. Again, not free space navigation. That flight plan was not made up on the fly. It was programmed from the beginning using planetary sling to get that thing where it is now, granted with minor in flight trajectory corrections based on telemetry from the ground - not from navigation in space. |
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Quoted: Quoted: Celestial navigation. Nearest stars are several light years away. Inertial navigation measures accelerations so once your velocity is known by celestial navigation, magnitudes of acceleration can be measured and integrated over time to determine position. It isn't too precise so multiple corrections enroute are needed. So celestial navigation would be similar to how the sailors navigated? You could plot the stars to reference your position from Earth, and by calculating the amount of thrust used to date, you get your speed? I really should have stopped eating lead paint chips and huffing model glue as a child... Celestial navigation here on the surface is made more complex by the rotation of the Earth. It wasn't until accurate clocks which could work on the rolling deck of a ship were made that celestial navigation was most practical. Ordinary pendulum clocks won't work on a ship, the rotary oscillator was the solution (and it works in zero G too, a pendulum won't work in zero g at all). CN is much better in space. |
