Comments on: NASA to Develop GPS-Like System for the Moon http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/ Space and astronomy news Sat, 21 Nov 2009 21:17:24 -0600 http://wordpress.org/?v=2.8.6 hourly 1 By: Aodhhan http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/comment-page-1/#comment-26798 Aodhhan Wed, 23 Jul 2008 15:46:05 +0000 http://www.universetoday.com/?p=15714#comment-26798 Chances of getting hit by an asteroid on the moon are less than getting struck by lightning on earth. I would compare it more to how many satellites we have lost in earth's orbit due to an asteroid conjunction. The moon has no atmosphere, so asteroids don't burn up before reaching the surface. The astronauts left various scientific instruments (mirrors, geological, etc) on the moon, and to my knowledge none of them have been destroyed by an asteroid... yet. GPS satellite antennas are directed towards earth. While replacement satellites could be designed to transmit towards the moon only one satellite at a time would be useful. To properly triangulate a stationary location, you need to have at least 3 points separated by a certain amount of space; dependent upon how many points you actually use. Even though it is likely the moon could see 6-7 gps satellites at one time, they probably aren't spread out enough from the moons perspective to give an accurate reading. Omega navigation (now I'm showing my age) isn't exactly the most accurate system available, and wouldn't be practicle for personal astronaut use, since VLF antennas need to be rather robust due to the large wavelengths. LORAN's different variations used different frequencies; and realistically was the basis for GPS. However, the transmitters are rather large! Not sure if they've gotten any smaller. Technically, any of the systems can work. The major feat is to get transmitters in locations to triangulate positions. Without an atmosphere line of sight will have to be attained. Chances of getting hit by an asteroid on the moon are less than getting struck by lightning on earth. I would compare it more to how many satellites we have lost in earth's orbit due to an asteroid conjunction. The moon has no atmosphere, so asteroids don't burn up before reaching the surface.
The astronauts left various scientific instruments (mirrors, geological, etc) on the moon, and to my knowledge none of them have been destroyed by an asteroid… yet.

GPS satellite antennas are directed towards earth. While replacement satellites could be designed to transmit towards the moon only one satellite at a time would be useful. To properly triangulate a stationary location, you need to have at least 3 points separated by a certain amount of space; dependent upon how many points you actually use. Even though it is likely the moon could see 6-7 gps satellites at one time, they probably aren't spread out enough from the moons perspective to give an accurate reading.

Omega navigation (now I'm showing my age) isn't exactly the most accurate system available, and wouldn't be practicle for personal astronaut use, since VLF antennas need to be rather robust due to the large wavelengths. LORAN's different variations used different frequencies; and realistically was the basis for GPS. However, the transmitters are rather large! Not sure if they've gotten any smaller.

Technically, any of the systems can work. The major feat is to get transmitters in locations to triangulate positions. Without an atmosphere line of sight will have to be attained.

]]> By: Chuck Lam http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/comment-page-1/#comment-26782 Chuck Lam Wed, 23 Jul 2008 13:06:48 +0000 http://www.universetoday.com/?p=15714#comment-26782 Why can't the "top side" of the existing earth orbiting GPS satellite system be used to navigate on the moon. There are more than enough satellites visible from the moon at any given moment to do the job. The RF easily and coherently reaches the moon for decoding. Of course it will be necessary to develop new hyper-sensitive GPS receivers and software that will interpret lunar surface position correctly. I suspect this approach will be dozens of times more economical than placing billions of dollars of satellite equipment in moon orbit. Why can't the "top side" of the existing earth orbiting GPS satellite system be used to navigate on the moon. There are more than enough satellites visible from the moon at any given moment to do the job. The RF easily and coherently reaches the moon for decoding. Of course it will be necessary to develop new hyper-sensitive GPS receivers and software that will interpret lunar surface position correctly. I suspect this approach will be dozens of times more economical than placing billions of dollars of satellite equipment in moon orbit.

]]> By: Maugrim http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/comment-page-1/#comment-26658 Maugrim Tue, 22 Jul 2008 08:10:53 +0000 http://www.universetoday.com/?p=15714#comment-26658 James, vanishingly small. How often do we get asteroids hitting earth? Micrometeorites are the significant problem, I would guess, and there are ways of dealing with those (e.g. don't build flimsy inflatable structures on the surface). James, vanishingly small. How often do we get asteroids hitting earth?

Micrometeorites are the significant problem, I would guess, and there are ways of dealing with those (e.g. don't build flimsy inflatable structures on the surface).

]]> By: James http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/comment-page-1/#comment-26648 James Tue, 22 Jul 2008 06:43:50 +0000 http://www.universetoday.com/?p=15714#comment-26648 What are the chances of a single spot on the moon to get struck by an asteroid in, say, a 5-year period? Isn't it a bad idea to build stuff on the moon? What are the chances of a single spot on the moon to get struck by an asteroid in, say, a 5-year period?
Isn't it a bad idea to build stuff on the moon?

]]> By: Kevin F. http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/comment-page-1/#comment-26618 Kevin F. Tue, 22 Jul 2008 01:09:53 +0000 http://www.universetoday.com/?p=15714#comment-26618 It would be cheaper to give each astronaut a deck of cards. When they get lost they can start playing solitaire on the ground and eventually another astronaut or n alien will come up behind them and tell them to put the 3 of clubs on the four of diamonds. For a more high tech approach, Tetris on Gameboy has the same effect. It would be cheaper to give each astronaut a deck of cards. When they get lost they can start playing solitaire on the ground and eventually another astronaut or n alien will come up behind them and tell them to put the 3 of clubs on the four of diamonds.

For a more high tech approach, Tetris on Gameboy has the same effect.

]]> By: Nephish777 http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/comment-page-1/#comment-26614 Nephish777 Tue, 22 Jul 2008 00:25:33 +0000 http://www.universetoday.com/?p=15714#comment-26614 Since the moon has no atmosphere, all radio would be line of sight. On earth the atmosphere bends low frequency radio or it bounces from the ionosphere. I was thinking about GPS satelellights, but Frank is no doubt right in that the mass distribution would complicate precise position measurements. At some point, perhaps very tall radio towers could be built so that two or three would be in sight for triangulation of position. Since the moon has no atmosphere, all radio would be line of sight. On earth the atmosphere bends low frequency radio or it bounces from the ionosphere. I was thinking about GPS satelellights, but Frank is no doubt right in that the mass distribution would complicate precise position measurements.

At some point, perhaps very tall radio towers could be built so that two or three would be in sight for triangulation of position.

]]> By: Frank Glover http://www.universetoday.com/2008/07/21/nasa-to-develop-gps-like-system-for-the-moon/comment-page-1/#comment-26607 Frank Glover Mon, 21 Jul 2008 21:58:23 +0000 http://www.universetoday.com/?p=15714#comment-26607 I always thought this or something like it * would ultimately be a good idea for the Moon and other worlds, when there's a signifigant human presence...but wouldn't the Lunar mascons constantly mess up the satellites' orbits? It only has to be a little bit, where navigation satellites are concerned, to degrade their accuracy. * Perhaps low-frequency radio, like Loran or the old Omega system, if the dry lunar surface could propogate VLF signals halfway decently. I always thought this or something like it * would ultimately be a good idea for the Moon and other worlds, when there's a signifigant human presence…but wouldn't the Lunar mascons constantly mess up the satellites' orbits?

It only has to be a little bit, where navigation satellites are concerned, to degrade their accuracy.

* Perhaps low-frequency radio, like Loran or the old Omega system, if the dry lunar surface could propogate VLF signals halfway decently.

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