Advanced Scanning; How To Find A Good Orbit
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Advanced Scanning
🔝 Orbital Overlays
After confirming that your scanning instruments are functioning correctly and within their limits you can move on to figuring out a good orbit for scanning any given celestial body.
SCANsat provides only one primary form of feedback for quickly determining how good your orbit is.
The big map orbit overlay has two functions.
- The primary, and obvious, function is to show the previous and current orbital trajectory for your current vessel, in orange and blue, respectively
- The position of the orbital prediction over the surface of the planet reflects where the vessel will be, when the vessel is at that location, as opposed to the orbital lines in map mode
- The upper and lower extents of scanning can be seen by looking at how high/low the orbit extends (in the rectangular or Kavrayskiy VII map projections), indicating orbital inclination
- The secondary function is the equatorial crossing lines
- They display where your vessel will cross the equator over the next 100 orbits
- The direction of the lines indicates whether the vessel is crossing the equator from north to south (blue), or south to north (orange)
- These little lines drawn above and below the equator are invaluable for getting into a good scanning orbit
🔝 Examples
A few examples of different orbits and how to setup a good scanning orbit will help to understand this feature.
🔝 Bad Orbit
This example displays a very problematic orbit for scanning. The equatorial crossing lines are very closely grouped together, which means that the vessel will continuously pass over the equator at the same place, this will lead to gaps where regions of the planet never get scanned, while others get scanned repeatedly. The reasons for why this occurs can get a little complicated, but basically your orbits becomes synchronized with the planet's rotation. In the example above the high-resolution scanner, which has a relatively narrow scanning width, will never completely cover the surface.
🔝 Good Orbit
This example shows a good scanning orbit. The equatorial crossing lines are evenly spaced and span the width of the planet. This means that within 100 or so orbits a complete map of the surface should be obtained.
On slowly rotating planets (ie Moho, Bop, ect...) it can require much more than 100 orbits to scan the entire surface. In this case you should still try to get the equatorial crossing as evenly spaced as possible, there will just be large gaps separating each grouping of crossings.
🔝 From Bad to Good Orbit
The difference between bad and good orbit can be very small. A very short burn (usually 1-5 m/s of dV) can turn a poor orbit into a near ideal orbit. Usually just burning pro- or retro-grade (make sure to stay within scanner altitude limits) a small amount will be enough to change the orbit as shown above.
There are more advanced methods for determining the absolute best scanning orbit. These involved finding the best orbital altitude for each type of scanner given their scanning characteristics. But using the orbital feedback provided by SCANsat is usually enough to get into a reasonably good orbit.