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Author Topic: Would my GPS device work on the moon?  (Read 32993 times)

Offline Jolly- Joliver

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Would my GPS device work on the moon?
« Reply #75 on: 03/04/2011 19:49:38 »
Where is Cilla Black when you need her?

I think I'll go with no. 2. Price is no object is it.
It's WAAS.

 
 

Offline Jolly- Joliver

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Would my GPS device work on the moon?
« Reply #76 on: 03/04/2011 22:38:23 »
Where is Cilla Black when you need her?

I think I'll go with no. 2. Price is no object is it.
It's WAAS.


So are there any objections to going with the WAAS? no 2? It's WAAS so it'll be better than the older GPS hand held devices.
 

Offline Jolly- Joliver

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Would my GPS device work on the moon?
« Reply #77 on: 11/04/2011 22:22:41 »
Have we still not decided on a GPS device? Money being no object and all I think for the sake of a far test we go with number one.

Ouu and I found these on youtube:

GPS 30 satalites 6 orbits of 4 per orbit, at a given time between 4 to 9 satalites can see a GPS reciever, on earth.

It shows a signal footprints at different sizes but I'm not sure how close they are.
feature=related
 

Offline JP

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Would my GPS device work on the moon?
« Reply #78 on: 12/04/2011 02:21:37 »
Have we still not decided on a GPS device? Money being no object and all I think for the sake of a far test we go with number one.

Since it's your question, why not pick one from your list and ask how good a signal it can get from the moon?
 

Offline Jolly- Joliver

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Would my GPS device work on the moon?
« Reply #79 on: 12/04/2011 12:57:12 »
Have we still not decided on a GPS device? Money being no object and all I think for the sake of a far test we go with number one.

Since it's your question, why not pick one from your list and ask how good a signal it can get from the moon?

Already have number one, it's the middle price one.

Although though I am quiet sure even if it was adapted to deal with space and had the needed software, it's reception still wouldn't be good enought to pick up a signal, All three are W.A.S.S tho. So next generation and probably better than the orginal devices.
 

Offline Bored chemist

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Would my GPS device work on the moon?
« Reply #80 on: 12/04/2011 20:49:20 »
So, knowing that none of them will work, you have chosen one.
Fair enough.
 

Offline Jolly- Joliver

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Would my GPS device work on the moon?
« Reply #81 on: 12/04/2011 21:28:41 »
So, knowing that none of them will work, you have chosen one.
Fair enough.

Hey some were suggesting it could, I suggested choosing a device first to then know the reception specs. I even ungraded to W.A.S.S.

I still think it's a no, but then I'm not an expert.

You suggested some signal would reach the moon, so how much? I still debate that but... That's the point
 

Offline Kirkaiya

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Re: Would my GPS device work on the moon?
« Reply #82 on: 12/03/2013 23:13:37 »
So, knowing that none of them will work, you have chosen one.
Fair enough.

Hey some were suggesting it could, I suggested choosing a device first to then know the reception specs. I even ungraded to W.A.S.S.

I still think it's a no, but then I'm not an expert.

You suggested some signal would reach the moon, so how much? I still debate that but... That's the point

I know this is an old topic, but after reading the thread, it's clear that some of you were "talking past each other" (or, in fact, talking about different things).

There are two basic questions:
  • Will an off-the-shelf, commercially available GPS receiver "work" on the moon (eg, tell me my position in any way)?
  • Is it possible to construct a GPS receiver which can (a) detect the transmitted signals of GPS satellites on the moon, and (b) use them to calculate a position on the moon?

The answer to #1 is (fairly obviously) no. Hand-held or even boat or commercial aircraft GPS receivers don't have sufficiently large antennae, and in any case use chip-sets that are hard-coded for calculating positions inside a fixed range of possible locations.

The answer to #2, as Bored Chemist and others pointed out, is "probably yes".  Given that on the moon, one could construct an receiving antenna of arbitrary size, capable of receiving signals from GPS satellites; even with directional antennas, the strength of the signal heading away from the Earth would be far stronger a mere 260,000 miles away on the lunar surface than the strength of transmissions from Voyager and Pioneer probes were at Earth when the probes were transmitting from past Jupiter).   Since GPS satellites are not (all) in-plane with the moon, there would always be a triangle of them (at least) visible from the side of the moon facing Earth.  Caveats are that you'd need a large antenna, and you'd probably need a custom chip-set (or at least, custom software) to convert the time-pulses into useful coordinates, but since the original question said to ignore that, then yes, it's almost certainly possible to get some position (how accurate it might be is another question altogether).
 

Offline Pmb

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Re: Would my GPS device work on the moon?
« Reply #83 on: 12/03/2013 23:43:43 »
The answer to number two is still now. The GPS system wasn't designed for that. It is a system that is calibrated to earth orbits relating to earh bound recievers. The signals are meaningless to a receiver on the moon. For example: Suppose we constructed artificical moons around the earth each with different zeros if lat and long. How would the recievers be able to tell which one it was on? Remeber that it can't receive a signal if its on the opposite side of the earth either. Nope. The GPS system is for Earth based receivers only.
 

Offline evan_au

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Re: Would my GPS device work on the moon?
« Reply #84 on: 13/03/2013 09:34:23 »
Quote
if you were to put the GPS in a position beyond the orbits of the satellites, I think it would try to report a position within the orbits

With line-of-sight to 4 satellites and a strong signal, you can solve 4 equations in 4 unknowns, producing: X, Y, Z and Time (or Latitude, Longitude, Altitude & Time).

This will allow you to work out your correct position, whether it is inside or outside the satellite's orbit.
  • To get a strong signal on the Moon, you would need a big antenna - and the strongest signal would not come from the nearest satellites (which are broadcasting away from you), but from GPS satellites which are on the far side of the Earth, so they are transmitting towards you.
  • GPS is designed to compensate for passage through the Earth's atmosphere - but on the Moon, the GPS signal would pass through no atmosphere, or an extra-long grazing path through the Earth's atmosphere.
  • Another constraint on solving 4 equations in 4 unknowns is that the set of equations is "well-conditioned". This is best achieved if the satellites are widely spread across the sky. However, from a viewpoint on the Moon, all the GPS satellites are in the smallish patch of sky that includes the Earth. This means that the equations will not produce results which are as accurate as you would get on Earth.
...so when you set up your Moon base, don't plan on saving a bit of money by taking the GPS receiver from your car on Earth.
 
 

Offline Lmnre

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Re: Would my GPS device work on the moon?
« Reply #85 on: 13/03/2013 14:39:59 »
If you could receive a decent signal and bypass the govt restriction about use in space, the receiver would triangulate a position in Earth coordinates say, somewhere over the tropical Pacific Ocean, but at an altitude of about 1,250,000,000 feet. 
 

Offline syhprum

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Re: Would my GPS device work on the moon?
« Reply #86 on: 13/03/2013 18:03:46 »
Apart from the geometric and time of flight problems there is the problem of the received signal strength at 800 Km where the satellites operate the received signal strength is pretty marginal imagine how weak it would be at 400,000 Km
 

Offline Bored chemist

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Re: Would my GPS device work on the moon?
« Reply #87 on: 13/03/2013 22:18:47 »
The answer to number two is still now. The GPS system wasn't designed for that. It is a system that is calibrated to earth orbits relating to earh bound recievers. The signals are meaningless to a receiver on the moon. For example: Suppose we constructed artificical moons around the earth each with different zeros if lat and long. How would the recievers be able to tell which one it was on? Remeber that it can't receive a signal if its on the opposite side of the earth either. Nope. The GPS system is for Earth based receivers only.

Did you not read the earlier posts?
I pointed out that, while people were "designed" to work on earth they worked OK on the moon.

In principle the system would still tell you latitude (relative to Earth's equator) , longitude (Relative to Greenwich) and altitude (relative to the earth's surface).
That identifies a unique position in the universe so it tells you where you are.
It would, for example, be able to show you the way home.

In practice there would be problems, but the idea that it wouldn't work in space because it was designed to work on earth is absurd.
 

Offline Don_1

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Re: Would my GPS device work on the moon?
« Reply #88 on: 14/03/2013 11:23:51 »
"At the next meteor, enter roundabout and take the third exit."



It would, for example, be able to show you the way home.


C'mon everybody, let's all sing........ ♫ I'm garmin home baby now.♫
 

Offline Bored chemist

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Re: Would my GPS device work on the moon?
« Reply #89 on: 14/03/2013 19:47:03 »
Would sound better with percussion: bongo drums or something.
 

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Re: Would my GPS device work on the moon?
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