[time-nuts] Fundamental limits on performance

bg at lysator.liu.se bg at lysator.liu.se
Sat Sep 19 17:05:39 UTC 2009

Hi Jim,

"Leapfrog" navigation has been discussed for mars navigation.




>> Just realized that the gravity potential detuning needs to be adapted to
>> the mars orbit and gravity field. Which also makes an interesting
>> side-project to develop gravity maps for mars.
>> Is there an established coordinate system of suitable precission for
>> mars? Essentially the equalent of WGS 84.
> I would assume so.  I seem to recall a definition of a Mars sphereoid,
> etc.,
> in Bulletin 74 from USGS.
> Gravity maps in general are important for spacecraft navigators, so
> there's
> probably also good knowledge of that.
>> Assuming a decent IMU, receiver aiding can be used. But the IMU aspect
>> should not be very new to you guys. :)
> Most spacecraft have very small accelerations/jerk.  We use IMUs for
> things
> like entry descent and landing of rovers, but for spacecraft nav, it's all
> about things like star trackers and measuring range and range rate.

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