[Smwg] PIF question -- off earth aperture coordinates

[Colin.Haddow at esa.int]

Hi Erik,
               In principle I have no problem adding altitude, but perhaps 
as an optional parameter as altitude may not make sense in all cases, e.g. 
smaller celestial bodies ?

Cheers for now,

Colin


---------------------------------------------------------------------------------------------------------
Dr. Colin R. Haddow,
HSO-GI, European Space Agency,
European Space Operations Centre,
Robert-Bosch-Str 5,
64293 Darmstadt,
Germany.

Phone; +49 6151 90 2896
Fax;      +49 6151 90 3010
E-Mail;  colin.haddow at esa.int
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From:   "Barkley, Erik J (3970)" <Erik.J.Barkley at jpl.nasa.gov>
To:     "Colin.Haddow at esa.int" <Colin.Haddow at esa.int>, "Anthony Crowson 
(anthony.crowson at telespazio-vega.de)" <anthony.crowson at telespazio-vega.de>
Cc:     "Bui, Tung (397G)" <Tung.Bui at jpl.nasa.gov>, CCSDS Service Mgmt WG 
<smwg at mailman.ccsds.org>
Date:   06/10/2018 03:27
Subject:        PIF question -- off earth aperture coordinates



Colin, Anthony,
 
 
As you may recall, the PIF has an accommodation for specifying the 
coordinates for apertures on celestial bodies other than earth.  You may 
also recall that we (NASA/JPL) are supporting one of the prototypes for 
the PIF exchange. In working through this, we have found out that indeed 
the Mars relative Lat/Long coordinates are used for determining the 
communication geometry for the overflight orbiters.  But the PIF appears 
to be a tad bit deficient in that it only specifies Lat/Long whereas the 
current local implementation used in coordinating all of this also 
supplies altitude as part of the coordinate information. Given that Mars 
definitely has variations in local terrain altitude, I think this is in 
fact important to include in the PIF. In fact in poking around with the 
internal services I made a query that returned location information 
indicating over 3,300 m in elevation -- I suspect that if we are to be 
accurate etc. this has some bearing on the communication geometry in terms 
of properly reporting range and/or light time. However, somewhat 
interesting to me is that the altitude is from the center of the planet. 
It seems a bit odd but it also makes sense in that there really is no 
definition of ?sea level? for Mars.  So my suggestion is to add an 
altitude parameter as indicated below.  Perhaps we can further discuss 
this at the Berlin meetings.
 
Best regards,
-Erik 
 
 



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