FDMO Peer Review RFA Summary Manfred Bester 1
FDMO Peer Review RFA Summary Manfred Bester 1 23 -Mar-2004
FDMO Peer Review RFAs RFA Title Rationale Reviewer Response Status FDMO-1 Investigate monthly lunar Lunar perturbations can Richon perturbation effects to determine be used to reduce fuel optimal time during month to launch. required if judicious selection of launch date is made. However, lunar perturbations can also increase fuel required by decreasing orbit energy & negatively impacting orbit inclination. The THEMIS team has already CLOSED built tools which allowed investigation of lunar perturbations on orbits P 1, P 2 and P 3 as well as on the LV insertion orbit in order to minimize potential for re-entry on the science orbits, and to maximize the potential for re-entry within 10 years for the LV to adhere to orbital debris requirements. Lunar effects due to different launch dates on the P 3, P 4 and P 5 orbits were found to be very small. FDMO-2 Decide on one pre-injection nomenclature for each probe. Should not be names associated with integers 1 -5 since the probes will be numbered Probe 1, Probe 2, etc. post-launch according to their final orbit positions (similar to TDRSS). Richon The team agreed that the pre. CLOSED launch assignment of probe names shall be THEMIS A-E. These names are uniquely related to the CCSDS telemetry and command IDs for each probe bus. Probe constellation IDs P 1 -P 5 are assigned post-launch, once the probes and their instruments have been checked out and the probe placement decision has been made. FDMO-3 Resolve time tag issue. Harman The THEMIS attitude sensor read- CLOSED out timing and attitude determination system is modeled after the FAST system which has been operational for almost 8 years. Manfred Bester Currently probes are designated as “Themis 1, Themis-2, …”, “red, green…”, and “A, BC…”. Multiple names for same probe causes confusion & misidentification of specific probes. 2 23 -Mar-2004
FDMO Peer Review RFAs RFA Title Rationale Reviewer Response Status FDMO-4 Get initial 3 rd-stage separation states Needed for orbit Richon (attitude & orbit) for each probe from injection analysis. If Boeing. Delta PMA is being done, these states should be available soon. UCB received the nominal launch trajectory ephemeris from KSC. These data are used to perform subsequent studies such as communications coverage and probe re-contact analyses. FDMO-5 GMAN modeling issues: define each ‘maneuver mode’ including type of maneuver, which thrusters used, pulsed/continuous, etc. Then determine if GMAN can model maneuver correctly. Richon All anticipated orbit and attitude CLOSED maneuvers have been summarized analyzed. Bob De. Fazio verified that all maneuvers can be modeled with GMAN. FDMO-6 Determine ground station contact tracking requirements such as pass frequency & duration, number of stations, for maneuver planning & recovery versus regular OD, etc. Richon Mark Beckman performed an OD covariance analysis that shows what number of passes and arc lengths are required to meet THEMIS OD requirements. FDMO-7 Determine UCB station capabilities Mission depends heavily Richon including support for perigee passes. on UCB antenna for tracking. Need to know if orbit determination constraints can be met. Manfred Bester Several questions regarding whether GMAN can be used to model finite maneuvers in all maneuver configurations. 3 CLOSED Two-way Doppler tracking CLOSED capabilities of BGS demonstrated with equipment on loan from Wallops Flight Facility. Expected 1 sigma error of range rate measurements is expected to be 3. 5 mm/s in 10 -s integration time. Due to the low orbital inclination the maximum azimuth and elevation rates will be less than 0. 2 deg/s. 23 -Mar-2004
FDMO Peer Review RFAs RFA Title Rationale Reviewer Response Status FDMO-8 ITOS-to-MSASS interface code to be Harman used provided to UCB. successfully for other mission. Richon UCB will provide interface code to extract attitude sensor data from ITOS and reformat these to be compatible with MSASS/MTASS input. FDMO-9 Real-time attitude determination - is this a requirement? If so, which software? Possibly use MTASS with modifications. Harman Real-time attitude determination is CLOSED required for maneuver support. A ground-based real-time ADS will be implemented, based upon the quaternions that are derived from sun sensor and IRU data and are propagated on-board. FDMO-10 Multi-satellite critical operations: need to have at least two prime workstations supporting, plus at least one hot back-up for emergencies. FDMO-11 MSASS is not capable of performing magnetometer alignment. Determine if UCB needs to acquire MTASS in addition to MSASS for this function. Manfred Bester Normally one has one Richon prime and one back-up for any critical operation for a single-satellite mission. UCB will have to be able to support multiple satellites with critical operations. Harman 4 CLOSED The ground systems design CLOSED includes at least 10 ITOS workstations, including a designated prime and back-up for each probe. Furthermore, any of these workstations can be assigned to any probe. In addition, two ITOS workstations will be connected to the Closed IONet for communications via TDRSS. UCB will obtain ADS which CLOSED includes both MSASS and MTASS. A software usage agreement is in the process of being finalized. 23 -Mar-2004
FDMO Peer Review RFAs RFA Title FDMO-12 Include pre-launch operations (Simulation planning & support, launch preparations) in future FD&MO reviews. FDMO-13 Provide access to latest mission information to peer panel at least two weeks before review. FDMO-14 FDMO-15 Rationale Response Status Richon Pre-launch operations and CLOSED simulations including green card exercises were already included in the MPDR presentations. Richon The review team will receive most CLOSED recent mission documentation at least two weeks prior to future peer reviews. Maneuver calibration procedures need to be documented. Each orbit & attitude Richon maneuver should be analyzed post-maneuver for efficiency & accuracy. Results should be applied to future maneuver planning. Also needed for bookkeeping of fuel used. The UCB team has received CLOSED sample procedures from GSFC FDAB and from Swales for EO-1 maneuver planning and execution. Appropriate elements of these procedures will be incorporated into the THEMIS procedures. Document who is responsible for fuel -used bookkeeping (propulsion engineer or Flight Dynamics Engineer or other FOT member). One entity should have Richon responsibility for this function. It is particularly critical at the end of life when probes must perform a controlled reentry. A dedicated member of the THEMIS flight dynamics team, i. e. the propulsion engineer, will be responsible for bookkeeping the fuel usage. Manfred Bester Ensure resource requirements are identified & included in planning. Reviewer 5 CLOSED 23 -Mar-2004
FDMO Peer Review RFAs RFA Title Rationale Reviewer Response Status FDMO-16 Institute Command Authorization Meetings (CAMs) for all orbit & attitude maneuvers. Requires participation & ‘signoff’ from all relevant subsystems & systems (FOT, flight dynamics, thermal, power, C&DH, scientists, etc. ). Best practices. Reduces Richon risk. Command Authorization Meetings CLOSED (CAMs) will be held prior to any critical command operation, including execution of orbit and attitude maneuvers as well as critical instrument operations such as boom deployment or HV turn-on. Such meetings are common practice with all missions currently operated by UCB. FDMO-17 Provide MAP Anomalous Forces technical paper to UCB. Outgassing of Richon instruments & other hardware may introduce anomalous forces creating torques on probes). UCB received a copy of the MAP anomalous force paper. FDMO-18 Provide JON/WBS to Code 595 for THEMIS support. Code 595 flight Angelopoulos GNCD has received a JON for CLOSED dynamics engineers & Richon support of THEMIS flight dynamics cannot support THEMIS support. without charge number. Manfred Bester 6 CLOSED 23 -Mar-2004
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