[Smwg] PIF question -- off earth aperture coordinates

Barkley, Erik J (3970) Erik.J.Barkley at jpl.nasa.gov
Tue Oct 9 19:17:31 UTC 2018


Okay, but even 162173 Ryugu (Hyabusa 2's recent encounter) has a radius of ~400 meters.  On the other hand, for something really small, maybe even the lat/long does not really make the most sense.  So it could be argued that in fact it might be just some point in space...but now I suspect we are on to some other coordinate system.  Ultimately I have no problem making altitude optional.  Let's go with that for now, as it will enable prototyping to offer "complete" coverage.

Best regards,

From: Colin.Haddow at esa.int <Colin.Haddow at esa.int>
Sent: Tuesday, October 9, 2018 02:19
To: Barkley, Erik J (3970) <Erik.J.Barkley at jpl.nasa.gov>
Cc: Anthony Crowson (anthony.crowson at telespazio-vega.de) <anthony.crowson at telespazio-vega.de>; Bui, Tung (397G) <Tung.Bui at jpl.nasa.gov>; CCSDS Service Mgmt WG <smwg at mailman.ccsds.org>
Subject: Re: PIF question -- off earth aperture coordinates

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,


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

Phone; +49 6151 90 2896
Fax;      +49 6151 90 3010
E-Mail;  colin.haddow at esa.int<mailto:colin.haddow at esa.int>

From:        "Barkley, Erik J (3970)" <Erik.J.Barkley at jpl.nasa.gov<mailto:Erik.J.Barkley at jpl.nasa.gov>>
To:        "Colin.Haddow at esa.int<mailto:Colin.Haddow at esa.int>" <Colin.Haddow at esa.int<mailto:Colin.Haddow at esa.int>>, "Anthony Crowson (anthony.crowson at telespazio-vega.de<mailto:anthony.crowson at telespazio-vega.de>)" <anthony.crowson at telespazio-vega.de<mailto:anthony.crowson at telespazio-vega.de>>
Cc:        "Bui, Tung (397G)" <Tung.Bui at jpl.nasa.gov<mailto:Tung.Bui at jpl.nasa.gov>>, CCSDS Service Mgmt WG <smwg at mailman.ccsds.org<mailto: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,


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