Friday, February 13, 2015

KARI Lunar Orbiter Cont'd (3)

I think that the smoothed velocities are correct (i.e., the unsmoothed velocities with gaps are wrong).

Here is a plot comparing the smoothed and unsmoothed velocities of the spacecraft at launch time:

For both, the velocity profiles can be broken down into 3 main parts:

  1. Launch: Steep increase in velocity
  2. LEO orbit: Constant velocity (circular orbit)
  3. Trans-lunar Injection (TLI): Delta-v increase to push spacecraft towards the Moon

For the unsmoothed profile, the velocity evens out at only ~5.5 km/s, and the delta-v of TLI is only about +2 km/s.
These numbers are too small, especially considering that a typical orbital velocity of a circular LEO should be ~8 km/s.

By comparison, the smoothed profile flattens out at ~7.8 km/s, which is a reasonable velocity for LEO. Also, TLI delta-v is roughly +3 km/s, which is also in the ballpark for typical TLI delta-v's. :D

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