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You have a completely wrong idea of the laws of orbital dynamics. If satellites don't want to keep burning tons of fuel, they will orbit the center of the earth

by qart 5y ago

You have a completely wrong idea of the laws of orbital dynamics. If satellites don't want to keep burning tons of fuel, they will orbit the center of the earth, not its axis. The only situation where your comment could apply is if the satellite is orbiting only above the equator. All of this, completely disregarding the economics of satellite mapping, their operational limits, etc.

azernik 5y ago
Note I said "at a similar latitude". A satellite at a given inclination will trace out a ground path oscillating back and forth between D degrees north and D degrees south, where D is its inclination, with latitude varying sinusoidally with time. So it will spend different amounts of time at different latitudes, hence choice of inclination depending heavily on observation/communication target. However, for any given latitude it will spend an equal amount of time at each longitude (east-west location) as the Earth rotates under its orbit. See e.g. https://en.wikipedia.org/wiki/Ground_track https://en.wikipedia.org/wiki/Ground_track So for example, any satellite that images Georgia (the US state) or Taiwan will spend an approximately equal amount of time over Lebanon and Israel.
- qart 5y ago
  There are so many incorrect and vague things here, but rather than listing them out, I point back to my counter examples. Zooming in on Kumasi, Ghana should show you why you're wrong. Look at the mosaic lines. There are both N/S lines of disparity as well as E/W lines of disparity of resolution. Use your own example, if you wish. Zoom in on Taiwan, and look at the cars. Next, zoom in on King Abdullah Economic City, Saudi Arabia at the same latitude. Look for cars there. Verify if your explanation fits the data.
areoform 5y ago
I believe you have an incorrect mental model of orbital mechanics. I would recommend playing with KSP to more intuitively understand the concepts, and then reading resources like, http://www.braeunig.us/space/orbmech.htm http://www.braeunig.us/space/orbmech.htm For now, here's a video that might help you get a clearer idea, https://www.youtube.com/watch?v=y_jM_BxQGvE https://www.youtube.com/watch?v=y_jM_BxQGvE - as you can see there's no fuel required. It's all about the inclination of the orbit (i.e. the angle it makes with Earth's equator). At a 85˚ to 98˚ inclination, the satellite will pass over every to almost every point on the Earth (save for some bits on the poles depending on where you are on that spectrum. There is no fuel required to make passes over Gaza. The satellite does that naturally, as a matter of course.
- qart 5y ago
  The video shows a polar orbit. How does this address azernik's point that "if the data exists for one place at a similar latitude, then it exists for every other place at a similar latitude"? With a polar or near-polar orbit, you'd get the densest (fewest stitches) and freshest data near the poles. > as you can see there's no fuel required. Like I wrote before, no fuel is required if you're orbiting the center of the earth. No one orbits the axis of the earth (other than orbiting above the equator). I was only responding to what azernik wrote. Here's what I am saying: 1. the resolution of the images on Google Maps varies a lot from place to place. Not just Gaza, but other places too. I mentioned specific places too. Please verify that for yourself. 2. Orbital mechanics is the wrong explanation to reach for to account for the disparities.

by qart 5y ago

azernik 5y ago

Note I said "at a similar latitude". A satellite at a given inclination will trace out a ground path oscillating back and forth between D degrees north and D degrees south, where D is its inclination, with latitude varying sinusoidally with time. So it will spend different amounts of time at different latitudes, hence choice of inclination depending heavily on observation/communication target. However, for any given latitude it will spend an equal amount of time at each longitude (east-west location) as the Earth rotates under its orbit. See e.g. https://en.wikipedia.org/wiki/Ground_track https://en.wikipedia.org/wiki/Ground_track So for example, any satellite that images Georgia (the US state) or Taiwan will spend an approximately equal amount of time over Lebanon and Israel.

qart 5y ago
There are so many incorrect and vague things here, but rather than listing them out, I point back to my counter examples. Zooming in on Kumasi, Ghana should show you why you're wrong. Look at the mosaic lines. There are both N/S lines of disparity as well as E/W lines of disparity of resolution. Use your own example, if you wish. Zoom in on Taiwan, and look at the cars. Next, zoom in on King Abdullah Economic City, Saudi Arabia at the same latitude. Look for cars there. Verify if your explanation fits the data.

areoform 5y ago

I believe you have an incorrect mental model of orbital mechanics. I would recommend playing with KSP to more intuitively understand the concepts, and then reading resources like, http://www.braeunig.us/space/orbmech.htm http://www.braeunig.us/space/orbmech.htm For now, here's a video that might help you get a clearer idea, https://www.youtube.com/watch?v=y_jM_BxQGvE https://www.youtube.com/watch?v=y_jM_BxQGvE - as you can see there's no fuel required. It's all about the inclination of the orbit (i.e. the angle it makes with Earth's equator). At a 85˚ to 98˚ inclination, the satellite will pass over every to almost every point on the Earth (save for some bits on the poles depending on where you are on that spectrum. There is no fuel required to make passes over Gaza. The satellite does that naturally, as a matter of course.

qart 5y ago
The video shows a polar orbit. How does this address azernik's point that "if the data exists for one place at a similar latitude, then it exists for every other place at a similar latitude"? With a polar or near-polar orbit, you'd get the densest (fewest stitches) and freshest data near the poles. > as you can see there's no fuel required. Like I wrote before, no fuel is required if you're orbiting the center of the earth. No one orbits the axis of the earth (other than orbiting above the equator). I was only responding to what azernik wrote. Here's what I am saying: 1. the resolution of the images on Google Maps varies a lot from place to place. Not just Gaza, but other places too. I mentioned specific places too. Please verify that for yourself. 2. Orbital mechanics is the wrong explanation to reach for to account for the disparities.