[Sea-sa] Next telecon planning

Roger Thompson roger.rocketbrain at btinternet.com
Wed Jun 7 13:28:39 UTC 2017

Which is one reason for avoiding mentioning PUS at all.


You are correct that the MOIMS interactions have traditionally been internal to the ground segment, but that as spacecraft become more complex and autonomous, the MOIMS functions are migrating to spacecraft.  Having a set of standardised interactions between those functions that can be deployed across any type of link:  Ground-Ground, Space-Ground, Space-Space (or at least internal to a Spacecraft) is the raison d’être of MO.  You are correct that within Europe, PUS has been used to support this migration in terms of standardised services to support on-board scheduling, etc., but it has limitations (very basic services, mixed layering, dependency on Packets as the only transfer protocol) and it is not globally accepted.  Within CCSDS, it is the MO path that enables this in a way that is not restricted to the Space-Ground link.


From: Ramon Krosley [mailto:r.krosley at andropogon.org] 
Sent: 07 June 2017 13:36
To: peter.m.shames at jpl.nasa.gov
Cc: roger.rocketbrain at btinternet.com; sea-sa at mailman.ccsds.org
Subject: Re: [Sea-sa] Next telecon planning


PUS is taking more of this conversation that I had in mind.  I was hoping to represent two modes of spacecraft operation, which are opposite ends of a spectrum extending from ground control to autonomy, the latter applying more to future missions.  The idea is that MOIMS SM&C may be a more suitable platform for autonomous operations than the older technologies, perhaps due to the "same level" architecture that Roger mentioned.  If we could discuss the requirements driving the architectural choices, that might provide some material for the green book to gain more support from people who currently design around older technologies. 

On June 6, 2017 17:14 MDT, "Shames, Peter M (312B)" <peter.m.shames at jpl.nasa.gov> wrote:




The older PUS spec was rejected by NASA when I was offered up a few years ago, for a number of technical reasons.  The new PUS is a 600 page behemouth.  And, from a NASA point of view we would have to ask, why not also DEM, and GMSEC, and …


Let's not stray into that territory unless we really need to.


Thanks, Peter



From: Ramon Krosley <r.krosley at andropogon.org>
Date: Tuesday, June 6, 2017 at 12:25 PM
To: Roger Thompson <roger.rocketbrain at btinternet.com>, Peter Shames <peter.m.shames at jpl.nasa.gov>, SEA-SA <sea-sa at mailman.ccsds.org>
Subject: RE: [Sea-sa] Next telecon planning


Thanks, Roger, I’m glad to learn of the “next generation” view; that sounds contemporaneous with increasing autonomy.  The reason for mentioning PUS was that it often comes up in SOIS discussions in the context of remote operation of a vehicle, rather than in facilitating some degree of autonomous operation.  There is a willingness in the SOIS app working group to support PUS, in addition to supporting MOIMS.  I think those goals are probably compatible; they are treated in SOIS as externalities.  I’m eager to hear your thoughts, both on the autonomy issue and on the mutual support idea.



From: Roger Thompson [mailto:roger.rocketbrain at btinternet.com]
Sent: Tuesday, June 6, 2017 1:12 PM
To: 'Ramon Krosley' <r.krosley at andropogon.org>; 'Shames, Peter M (312B)' <peter.m.shames at jpl.nasa.gov>; 'SEA-SA' <sea-sa at mailman.ccsds.org>
Subject: RE: [Sea-sa] Next telecon planning


Hi Ray,


I will consider more fully and respond during our telecon.  However, a key point to note is that the PUS is not a CCSDS standard – it is a current ECSS standard and widely used within Europe by ESA and EUMETSAT.  It has never been adopted by NASA.  The standardisation space occupied by PUS overlaps with the MO Services, but unlike MO it is explicitly cast in terms of CCSDS Packets and so is really only applicable to a space link.  Like MO, it has standardised services, although it is worth noting that these are not all at the same level, and as a result end-to-end interactions may actually require the use of multiple PUS services.  You could view MO as the “next generation” PUS.  As MO does not require PUS, it would seem an unnecessary complication to include it in our reference model.






From: SEA-SA [mailto:sea-sa-bounces at mailman.ccsds.org] On Behalf Of Ramon Krosley
Sent: 06 June 2017 18:38
To: 'Shames, Peter M (312B)'; 'SEA-SA'
Subject: Re: [Sea-sa] Next telecon planning


I was working on writing some of the material for the SAA green book, and came to the conclusion that there is an aspect of the material that we have not yet discussed.  We have seen the architecture of MOIMS, and we have pursued the architecture of SOIS.  We have even gotten a hint of parallel functions in Richard’s review of MO and EDS.  There still remains a gap in the overall interoperation between MOIMS and SOIS.

Roger mentioned recently that, if he could see the SOIS application support services, then he could talk about how MOIMS could use them.  I have some results from the Spring meeting that address this issue, which I’ll put into the meeting materials on CWE.  I think there is more to the interaction between these domains than the service interfaces, and that addition is the subject of this message.

If it seems reasonable to the group, here is a start on this gap, a potential topic in tomorrow’s teleconference.  The following is draft text for Section 1.1 in the SAA green book, for discussion.  I am probably doing an injustice by mentioning packet utilization standard, but Roger can set me straight on how that school of thought is represented in MOIMS.  The new topic introduced here is reuse of components on different platforms.  There may be other topics in the interaction of MOIMS and SOIS that I have missed.  This deviates slightly from Peter’s initial <<summary>>, so I want to test that possibility.


The purpose of this document is to harmonize the standards for mission operations with the standards for onboard interface services.  This harmonization must occur in two modes of operation.

·         Historically, onboard interface services have been a simple conduit at the space end of telecommands and telemetry, while mission operations has occupied the Earth end of those communications.

·         As missions move farther from Earth, mission operations inevitably will place applications onboard space vehicles, due to the increasing need for timely autonomous behavior in distant flight.

The packet utilization standard (PUS) has emerged as an organizing principle affecting data onboard a vehicle to serve the needs of Earth-based mission operations.  Within CCSDS, the MOIMS standards are developing to support increasing autonomy in flight.  SOIS must provide useful services in both modes of operation.

Another trend in space technology is an increasing need for economy in the infrastructure.  One manifestation of this trend is that reuse is replacing recurring engineering.  SOIS provides techniques for reusing hardware and software among projects and among agencies.  As the common denominator in the two modes of operation, the techniques provided by SOIS can increase the reusability of MOIMS applications.

This document reviews the architectures of MOIMS and SOIS in order to recognize how to harmonize communications and how to improve reusability.  As the first step in that review, the separate goals of MOIMS and SOIS appear below.  Recommendations for future collaboration appear at the end of this document.

1.1.1     Purpose of MOIMS

…to be written…

1.1.2     Purpose of SOIS

The fundamental purpose of SOIS is to provide communication between applications onboard a vehicle and the following categories of communication endpoints.

·         Devices onboard the vehicle

·         Other applications onboard the vehicle

·         Applications external to the vehicle

For communications with endpoints external to the vehicle, SOIS organizes onboard protocols as necessary to supplement external protocols provided by communication devices onboard the vehicle.

In addition to facilitating communication, SOIS provides an electronic data sheet (EDS) standard that enables reuse of devices and software functions among projects and among agencies.  In this role, SOIS can assure compatibility of data interfaces of reused applications in new assemblies.


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