Reusability in ESOC mission control systems developments The SMART1 mission case

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Reusability in ESOC mission control systems
developmentsThe SMART-1 mission case

• Max Pignède, Kevin Davies
• European Space Agency (ESA) / European Space
  Operations Centre (ESOC)
• Darmstadt, Germany eMail max.pignede_at_esa.int
  
• Terma GmbH - Weiterstadt, Germany
  eMail ked_at_terma.com
• Presented by Michael Jones (ESA/ESOC)

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Summary Slide

• Presentation outline
• Background
• Assets in the ESOC infrastructure and potential
• SMART-1 control system high level overview
• Main features of the SCOS-2000 infrastructure
• Approach to software development for reuse
  feasibility
• Actually measurable results in the SMART-1
  development
• Lessons learnt for beneficial reuse strategies

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Background

• Reusability is an essential and often compulsory
  strategy, especially for low cost space missions
• Development of reusable infrastructure is part of
  ESOC strategy
• For SMART-1 there was no choice left to ESOC for
  meeting the project requirements on time within
  the available budget
• Existence of a number of mission control software
  components, availability of experience staff,
  commonalities with other systems in development,
  adherence to Standards

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Assets in the ESOC infrastructure and potential

• Existing elements for building up control systems
• The Spacecraft Control and Operations System
  (SCOS-2000)
• SCOS-2000 is ESOCs 3rd generation of mission
  control systems infrastructure
• The Network Control and TM/TC Router System
  (NCTRS) infrastructure
• Other systems based on the same infrastructure
  (ROSETTA, INTEGRAL, MSG, Mars Express)
• Common software development methodologies
• Software requirements production tools and
  generic test support tools
• Broad base of industrial support for ESOCs
  infrastructure

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SMART-1 control system high level overview (1)

• SMART-1 is the first ESA 'Small Missions for
  Advanced Research in Technology
• Flight test Solar Electric Primary Propulsion as
  the key technology for future ESA deep-space
  missions
• Objective selected for the SMART-1 mission is for
  Europe to send for the first time a spacecraft to
  the Moon using electric propulsion
• Low budget, tight schedule
• Spacecraft reference database tool (MS-Access)
  shared with Prime (Swedish Space Corporation)
• Stable external interfaces (e.g. ground systems)

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SMART-1 control system high level overview (2)

• Telemetry monitoring subsystem
• Frame reception from two virtual channels,
  telemetry parameter extraction, time correlation,
  on-board events monitoring, handling of telemetry
  dumped from on-board stores, time correlation
• Telecommanding subsystem
• Pre-transmission command safety checks, Manual
  commanding, maintenance of on-board command
  queue, interface to external command sources,
  post-transmission command verification checks,
  command history display
• On-board software maintenance
• Uplink of memory images, management of memory
  dumps

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Main features of the SCOS-2000 infrastructure

• Flexible and maintainable generic kernel
  constituent of spacecraft control and monitoring
  software system
• Main features include
• Distributed client/server system architecture
• Easily scalable
• In-built redundancy (Prime/Backup)
• Core applications directly available in full
• For example telemetry processing,
  telecommanding, data archiving, data remote
  access and distribution, on-board software
  maintenance
• Object oriented design
• Designed for configurability and software
  reusability
• Supports ESA packet standards (PUS)

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Approach to software development for reuse
feasibility

• Direct reuse of infrastructure software (such as
  SCOS-2000 and NCTRS) and of major parts of other
  mission specific software (such as MSG, INTEGRAL,
  ROSETTA)
• Definition of the contents of successive software
  deliveries driven by the availability of
  components planned to be reused
• Synchronisation with dependent projects
  schedules
• Risk monitoring if projects original schedules
  change
• The SMART-1 project could not impose its schedule
  requirements on the other projects but the main
  contributor project (ROSETTA) schedule could not
  be delayed
• Enforce clear baseline definition for the reused
  software
• But also reuse of concepts and work methodology
• Synchronisation of the prime and backup central
  servers
• Production of test plans and management of
  problem reports

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Development schedule synchronisation
Development timelines
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Actually measurable results in the SMART-1
development

• In addition to the integration of the SCOS-2000
  kernel, complete reuse of the ROSETTA commanding
  system, of the INTEGRAL file transfer system
• In terms of total source code metrics
• Refer to Software Reuse Metrics showing that 6
  only of the source code modules are new in the
  overall S1MCS source code
• In terms of cost saving achievements
• Smart-1 has an equivalent functional scope than
  other missions yet its software development
  final cost is 4 to 5 times cheaper than for these
  (which were its prime source of reuse)

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Software Reuse Metrics
Table shows number of modules (files) from each
project contributing to the SMART-1 mission
control system
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Example snapshots - Manual Stack
SCOS-2000

• Smart-1
• 2 telemetry virtual channels (VC0, VC7) for
  execution verification
• Automatic command blocking of commands into CLTUs

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Lessons learnt for beneficial reuse strategies

• Compliance to Standards without this, reuse
  cannot be applied
• Thorough analysis of project dependencies is
  mandatory
• Do not rely on a project for reuse by another if
  there is a risk that the re-used software may not
  be available in time
• Define (and stick to) baselines
• Adequate understanding is needed of the software
  to be reused and to ensure matching to the system
  requirements
• Use of object oriented architecture and
  development helps reuse
• Do not reduce testing
• Adequate regression testing of reused software is
  still needed
• Even with little money a big system can be made
  to work by applying reuse..!!..