[CESG] LunaNet Interoperability Specification

Thu Jun 8 22:38:18 UTC 2023

Dear Klaus-Juergen and the rest of the CESG team,

During last week’s CMC meeting several of the topics relating to the “NASA / ESA LunaNet Interoperability Specification” were explored.  The CESG discussed it again on Tuesday, with specific emphasis on the LunaNet Position, Navigation, and Timing spec (or lack of info on this).  A set of PPT materials were presented to the CMC last week and these will be made available.

I believe that it is the case that the strongest motivation for digging into this specification is that there are at least three separate missions, from three separate agencies, that are intending to (or have) asserted compliance with this spec.  These are:

  *   NASA’s Lunar Communications Relay and Navigation Systems (LCRNS)
  *   ESA’s Moonlight
  *   JAXA’s “LNSS” mission (I missed the name, anyone???)

The LNIS spec is out in the public domain.  It can be found here (https://esc.gsfc.nasa.gov/static-files/LunaNet%20Interoperability%20Specification.pdf), and at several other locations as well.  If you know what to look for it is there.  Just search for “LunaNet Interoperability  Specification”.   When you do that you will find several versions of the spec, related articles and papers, etc.   There are also links, if you dig for them, to the ESA Moonlight project (https://www.esa.int/Applications/Connectivity_and_Secure_Communications/Moonlight) and to the JAXA LNSS plans (https://www.unoosa.org/documents/pdf/icg/2022/ICG16/WG-B/ICG16_WG-B_03.pdf).

There is an open question as to just how closely these separate agency Lunar comm and nav missions are coordinating, and if the LNIS is truly the coordinated comm and nav architecture for all three.  The LNIS document itself is a little confusing in this regard, in that it is a GSFC Code 453 document stated to be developed by the NASA LCRNS Project, and signed by the LCRNS Project Manager.  It mentions “This current version of the document was written and reviewed by NASA and the European Space Agency (ESA).”, but there is no ESA signature nor named contributor.  And there is no mention of JAXA.  The LNIS document, after a brief scan for my favorite DTN interoperability topics, was found to be vague on some key features, like the distinctly different DTN and IP semantics and the need for some sort of protocol matching “bridge”, which is entirely missing.

There are many diagrams that appear to have been lifted from the IOAG comm and nav architecture specs, and the IOAG SISG and Lunar Comm Architecture documents are listed as References.  There are many tables that appear to be borrowed from the IOAG Lunar Comm doc that list many different CCSDS standards, including RFM, Coding, Link, DTN, and some SLE.  These are all essential to the comm architecture, but are given short shrift, and casually listed as “Other relevant documents”, when they should be listed as Requirements.

And there is a list of new “Applicable Documents”, which all appear to be, as of yet, TBD.   These Applicable Documents include:

[AD1] LunaNet and User Signal Structure Definition Document (LNIS4-TBD-AD0001)
[AD2] LunaNet Measurement Schema and Parameters Document (LNIS4-TBD-AD0002)
[AD3] LunaNet Detailed Message Definition Document (LNIS4-TBD-AD0003)
[AD4] LunaNet Location Services for Users Document (LNIS4-TBD-AD0004)
[AD5] Lunar Reference Frame Standard (LNIS4-TBD-AD0005)
[AD6] Lunar Time System Standard (LNIS4-TBD-AD0006)
[AD7] LunaNet LunaSAR Definition Document (LNIS4-TBD-AD0007)
[AD8] LunaNet Interoperability Security Specifications (LNIS4-TBD-AD0008)

The “mysteries” about how Lunar CPNT are intended to actually operate would appear to be hidden somewhere in these TBD docs.  My attempt to get any info about this from Cheryl Gramling, the NASA lead LNSS person, has yet to turn up anything useful.  Perhaps someone else, or in another agency like ESA, can provide some useful details of what the current thinking is?

At the CMC meeting we discussed the possibility of creating a new Lunar PNT WG in CCSDS to help support and structure this work and to give it a home in an international standards organization.  It is not yet clear whether this would be welcomed by the existing team or rejected because it might be seen as a constraint.   We do already have the MOIMS Nav WG, which provides many nav data interchange standards.  And we have in process the newly re-chartered SEA Time Management WG which is to include a time code, time exchange, and time distribution standard.  Plus there are some different SLS link and modulation layer standards that may be relevant, and even the possibility of using D-DOR for positioning info.

It seems to be an open question as to just how to tackle this, either in separate, but coordinated, WGs or in some new (or re-chartered) existing WG.

Regards, Peter

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