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

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

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.%20Systems/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

Sample Requirements CINEMA 2009-10-19 -23

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

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

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

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

Electrical Block Diagram CINEMA 2009-10-19 -23

Mechanical Configuration CINEMA 2009-10-19 -23

Ground System CINEMA 2009-10-19 -23

Operations Launched powered-off Power up into Safe mode Contact Ground power-up on deployment from P-Pod Power up into Safe mode Instrument and ACS Off Transceiver powered on, listening Contact Ground Set-up time-tagged contact windows so transceiver can be powered off between passes, freeing up power for ACS MAG Boom Deploy Determines major axis for stable spin Deploys magnetometer for ACS MAG Cal Use torque rods to determine MAG orientation ACS Acquisition Mode Detumble, Spin up, Sun-normal spinning Precession Mode Reorient to Ecliptic Normal Spin (requires ground interaction) Science Mode Power off ACS, Power up instruments Return to ACS Mode 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

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

Mass CINEMA 2009-10-19 -23

Power Generation CINEMA 2009-10-19 -23

Battery CINEMA 2009-10-19 -23

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

Telecom Assumes 1 pass/day for command / housekeeping via MHX2400 transceiver Remaining passes for Science recorder download with S-band transmitter CINEMA 2009-10-19 -23

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