[Sis-csi] Cislunar Section 8

[Krupiarz, Christopher]

Keith,

Thanks for the comments.  

You make a valid point about the complexity of the scenario and I
struggled with at what level to start.  One of the primary thoughts I
had on choosing a more complex architecture is that it gives an end-game
for why we want to introduce this in earlier missions.  One of the areas
of concern I have on trying to move to a network based architecture is
how can a convincing argument be made for why we need it.  I can
certainly understand why there would be reluctance to put in place this
technology at the outset.  As a mission manager, I wouldn't want to
introduce unnecessary risk and as someone in mission ops, I'd want a
really good reason to deviate from what I've already done successfully
on previous missions.  My thought was that if we could provide a
"medium" level complex architecture, the mission managers could see how
their spacecraft would fit into the evolved architecture, albeit either
near the end of the program's life or during an extended phase of the
mission.  If it's not sufficiently complex, I'm not sure it shows enough
about the architecture that we don't already do.

Regarding the lower link layers, that's what I get for putting in
something I haven't used before. ;)  I should have kept it to TC/TM.
However, the question of whether we should even include it is also valid
and it's something that could be left off the table if we have agreement
on that.  To be honest, I'm still having a bit of trouble breaking
through the mindset of anything beyond command/telemetry so any examples
of applications other than that would be appreciated.  I think these
would fit well as subsections showing example data flow.

Chris


-----Original Message-----
From: sis-csi-bounces at mailman.ccsds.org
[mailto:sis-csi-bounces at mailman.ccsds.org] On Behalf Of Keith Hogie
Sent: Tuesday, August 23, 2005 3:18 PM
To: Krupiarz, Christopher
Cc: sis-csi at mailman.ccsds.org
Subject: Re: [Sis-csi] Cislunar Section 8


Chris,

   A couple of thoughts on section 8.

1 - The general process of laying out the systems and describing an
application and details of the flow looks good.

2 - You started with a scenario with 3 lunar relay satellites, 3 science
satellites, 2 landers,
  and 2 rovers.  Should the
scenarios start with a more minimal set of components and then scale up
to more complex ones or should we focus more on all the possibilities if
you have a full complement of communication resources in place?

   Does anyone have any thoughts on what resources might be deployed in
some sequence?

3 - The protocol stack diagram is nice but I'm not sure about the AOS
boxes.  Normally AOS is used for data coming down from space. It also
has Reed-Solomon coding on it.  The diagram uses AOS in both directions.
Are we proposing the use of AOS and Reed-Solomon coding both ways.  This
would require R/S encoders at ground stations and decoders installed on
spacecraft?

   Do we want to get into the details of lower layer protocols to use
for two-way links or do we just worry about IP and above.  The visions
for the Cislunar environment are moving away from the normal mode of
sending commands to a spacecraft and receiving data from it. If this
group is not dealing with lower layers, should the diagrams just leave
them blank and start with the network layer?


----------------------------------------------------------------------
   Keith Hogie                   e-mail: Keith.Hogie at gsfc.nasa.gov
   Computer Sciences Corp.       office: 301-794-2999  fax: 301-794-9480
   7700 Hubble Dr.
   Lanham-Seabrook, MD 20706  USA        301-286-3203 @ NASA/Goddard
----------------------------------------------------------------------

_______________________________________________
Sis-CSI mailing list
Sis-CSI at mailman.ccsds.org
http://mailman.ccsds.org/cgi-bin/mailman/listinfo/sis-csi