CREAM Systems Engineering Status April 2004 MSR Simon

CREAM Systems Engineering: Status April 2004 MSR Simon Dawson

Systems Engineering: Summary • Tasking over last month • Budgets – Mass & power • Issues – Open items 2

Systems Engineering Status • System Budgets – Power, Weight, Thermal • Document Review – Spec docs; test procedures; requirement docs; ADP reviews • Power system Verification Testing • CDM TVAC Planning • EU conversion support • Fuse & relay sizing support • PER • Document generation – Derived Requirements – Verification Test Matrices • PFR assessment • CCB • I&T Support • OTH Video Lead 3

Systems Engineering Budgets 4

Systems Engineering Fever Chart Technical Systems Engineering Instrument Operations I&T Engineering Mechanical Y Thermal Electrical / Power C&DH Telecom ACS Environmental Test Legend: Good Shape Y Minor Problem R Major Problem 5

Fever Chart Issues: Instrument • • Power Usage – Improved situation (again) – Latest measurements upped maturity with margined number retreating from 393 W to 385 W vs. last month – Instrument contingency back to 15 W out of 400 W • Requirement was < 385 W ; we maintained 400 W allocation internally Mitigation: – Maintain instrument reporting Result: – Instrument has moved back to green Mass Usage – Need update – CG and mass measurement to be made immediately prior to TVAC at Greenbelt 6

Fever Chart Issues: Mechanical • Balloon Termination Loads: – Peer Review report on stress analysis shows low margins of safety in places – Mech team presented to project list of failing and “<20% margin” components from FEA • This list has been culled by hand calculations showing whether problem is real or modeling artifact – Mechanical team working on fixes to failing components • Solar array and support hardware now does not fail • Battery is open issue for TVAC right now • HGA may be an issue • Mitigation – Suggestion: Impose minimum margin of safety of, say, 20 -25% • Result: – Mech subsystem remains at yellow until we have components that analytically work with TBD positive margin 7

Fever Chart Issues: Power • Thermal Poly. Fuses – In re-sizing fuses to support science it was discovered that potentially some fuses were sized with little or negative margin at operating temperatures • Under-sized fuses were swapped out and re-inspected after solder work; project waived thermal workmanship testing – Potential problem: • Calculations of the fuse temperature after they ‘open’ suggested that they will be ~250 C in vacuum – Testing showed that model was (happily) incorrect with peak temperature in vacuum ~117 C or below part limits • Mitigation: – Move power system back to green 8

Documentation Update 9

Documentation for TVAC, Sci Arrival & MRR: Post Delta-CDR “Triage” 10