CINEMA System Engineering Dave Curtis CINEMA 2009 10

CINEMA System Engineering Dave Curtis CINEMA 2009 -10 -19 -23 1

System Engineering Tasks • Requirements Flowdown – Identify top-level science and programmatic requirements – Flow those requirements down to subsystems • Involves some system-level design – Verify by analysis and/or test that each requirement is met • Interface Control, Specifications – Document and track interfaces between subsystems • System Design – Top-level design of how the subsystems work together • Resource Allocation and Tracking – Mass, Power, Link Margin, Pointing, etc. – Money, schedule, manpower resources typically tracked by Project Manager • Technical Coordination and Evaluation – Coordinate the various technical disciplines and subsystem leads to ensure that requirements are being met – Perform technical reviews with independent reviewers to identify any issues • Reliability Engineering and Risk Management – Identify potential technical risks and failure modes and mitigate where possible • System Integration and Test Coordination – Ensure adequate testing to verify all requirements CINEMA 2009 -10 -19 -23 2

Requirements • • Top level science and programmatic requirements identified in the CINEMA NSF AO and Proposal Requirements have been extracted into a document and flowed down to the subsystem – ftp: //apollo. ssl. berkeley. edu/pub/cinema/2. %20 Systems/CINEMA_Requirements. xls – Flowdown depends on system design, which has evolved a bit since the proposal based on design trade studies – Subsystem allocations still in work • Some requirements cannot be nailed down until we have a launch selected – Orbit, Launch loads, etc. ; nominal values assumed for now • Requirements organized as follows: – Level 1 Science, Programmatic, and Mission Assurance – Level 2 Subsystems (STEIN, MAGIC, ACS, Telecom, etc) – Level 3 Components (MAGIC Boom, Torque Coils, etc) • • Documented requirements provides an agreed upon baseline for the system and subsystem engineers to design and test to, along with a rationale to remind us what we are losing if we cannot meet the requirements The System Engineer controls the requirements document. CINEMA 2009 -10 -19 -23 3

Sample Requirements CINEMA 2009 -10 -19 -23 4

Verification • Each requirement must be verified during system testing • Verify early at subsystem/component level where possible • Verify again at the full system level • Verify environmental requirements – Survive launch loads – Operate in vacuum and over temperature • Some requirement verified by analysis, but test is preferred • Ready to launch when all requirement verified – System Engineer tracks verification of requirements CINEMA 2009 -10 -19 -23 5

Interface Control Documents • An Interface Control Document (ICD) describes how one subsystem or component interacts with another or with the system as a whole – It augments the requirements document with detailed information about how the interaction between subsystems takes place such that an engineer can design his subsystem. – It includes things like mass and power, interface voltages, currents, signals, timing diagrams, pinouts, etc. • The System Engineer, together with the subsystem engineer, develops the ICD for the subsystem • MAGIC ICD first draft provided by IC. Others to follow as needed CINEMA 2009 -10 -19 -23 6

Specifications • Specifications describe the implementation of a component or subsystem – Includes details of how the item works, User information, handling details, etc. – May take the place of an ICD in some cases – Commercial equipment typically includes a specification or users manual • Specifications provide a way of documenting the design as it progresses – Important due to the transient nature of the students who are doing much of the CINEMA development – Specifications are not formally controlled documents; they are expected to evolve with the design and include by reference the schematics, listings, and other low level design information • All controlled documentation available on the CINEMA Web page – ftp: //apollo. ssl. berkeley. edu/pub/cinema • All working documentation on the CINEMA Wiki page – http: //wiki-new. ssl. berkeley. edu/index. php/Cinema – Password controlled. CINEMA 2009 -10 -19 -23 7

System Design • Current top-level design shown in following slides • Design continues to evolve • Design to meet requirements – Science, Technical, and Programmatic • Details of subsystem designs in later talks CINEMA 2009 -10 -19 -23 8

Electrical Block Diagram CINEMA 2009 -10 -19 -23 9

Mechanical Configuration CINEMA 2009 -10 -19 -23 10

Ground System CINEMA 2009 -10 -19 -23 11

Operations • Launched powered-off – • Power up into Safe mode – – • Power off ACS, Power up instruments Return to ACS Mode – • Reorient to Ecliptic Normal Spin (requires ground interaction) Science Mode – • Detumble, Spin up, Sun-normal spinning Precession Mode – • Use torque rods to determine MAG orientation ACS Acquisition Mode – • Determines major axis for stable spin Deploys magnetometer for ACS MAG Cal – • Set-up time-tagged contact windows so transceiver can be powered off between passes, freeing up power for ACS MAG Boom Deploy – – • Instrument and ACS Off Transceiver powered on, listening Contact Ground – • power-up on deployment from P-Pod Periodic drift correction Return to Safe Mode – – In the event of problems (low power, no ground contact, system reset) Power up transceiver, wait to be contacted. CINEMA 2009 -10 -19 -23 12

Resource Budgets • The following budgets are based on the proposal configuration • Design trades continue to refine the configuration CINEMA 2009 -10 -19 -23 13

Mass CINEMA 2009 -10 -19 -23 14

Power Generation CINEMA 2009 -10 -19 -23 15

Battery CINEMA 2009 -10 -19 -23 16

Power Usage Telecom Power CINEMA 2009 -10 -19 -23 17

Telecom • Assumes 1 pass/day for command / housekeeping via MHX 2400 transceiver • Remaining passes for Science recorder download with S-band transmitter CINEMA 2009 -10 -19 -23 18

Reliability • Good design practices, workmanship standards, and high quality parts are key to reliable systems – But are limited by the reality of limited cost and schedule • On such a severely cost constrained mission as CINEMA, reliability is obtained by primarily through testing – – Identifies design flaws, poor quality parts, bad workmanship Test early, test often Include margin testing (voltage, temperature, frequency, etc) Include ‘test-as-you-fly’ CINEMA 2009 -10 -19 -23 19