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Re: RE: mars express orbit



Yuri,

Yes, this helps quite a bit. Thank you for the references. My search 
(worst case) needs to be expanded a bit - I am off by about +-20kHz.

Best Regards.

Joe
k6sat

On Apr 12, 2004, at 5:05 PM, Yuri Kagari wrote:

> Hello Joe,
>
> The current Mars ephemeris gives +13.9 km/s for
> the gross motion of Mars, which provides -390kHz
> Doppler for Mars Express' 8420.4321MHz signal.
> This will change a lot in a couple of months
> and need correction.
>> http://sunearth.gsfc.nasa.gov/eclipse/TYPE/mars2.html
>
> The Earth's diurnal motion is about 0.5 km/s on
> the equator and provides +/-13kHz.
>
> The orbit of the Mars Express seems highly eccentric
> (e=0.4).
>> http://sci.esa.int/science-e/www/area/index.cfm?fareaid=9
> The max velocity is 3.3 km/s at pericentre, which
> provides +/-93kHz Doppler.
>
> Those numbers are the worst case. The actual Doppler
> should be much smaller.
>
> Hope this helps,
>
> Yuri
>

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