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Final Version
Wes OusleyDan Nguyen
May 13-17, 2002
Micro-Arcsecond Imaging Mission, Pathfinder (MAXIM-PF)
Thermal
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 2
Final Version
Summary
Concept meets scientific instrument requirements Maintain mirror modules at 20+/- 0.1oC, mirror structures at 20+/- 1oC Accommodate detector CCDs at –100oC Accommodate cryo-coolers to cool “Super Star Tracker” to 7oK Maintain other instrument support equipments between –10oC and 40oC
Spacecraft Bus requirements met Maintain Optic Hub, Free-Flyer and Detector spacecraft within
operational temperatures over Phase 1 and Phase 2 observations
Thermal system resource requirements TCS mass is about 50% MLI blankets and 40% heat pipe systems
Hub: 15kg, 80W heaters (Phase 1 total), $650K hardware, $1M manpower
Detector craft: 27kg, 10W, $1.1M hardware, $2.5M manpower Average FF: 13kg, 10W, $500K hardware, $400K manpower
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 3
Final Version
Design Features
Optics Spacecraft Maintain mirror module temperatures with MLI and heaters Mini sun shield for each mirror module minimizes impact of sun angle Radiator on a no-sun side of each spacecraft
Phase 1 Optics Hub All FF radiators blocked, except the one directly anti-sun Louver on the exposed radiator minimizes heater power Bottom-facing radiator not sufficient to keep Hub spacecraft cool Heat pipe coupling transports some heat from Hub to exposed radiator
via releasable junction
Detector Spacecraft Sunshield required to keep instruments cool Extreme thermal isolation required for SST and CCD detector system CCD temperature controlled with radiator and heaters Cryocooler radiator on spacecraft Locate all radiators on the anti-sun sides Heat pipes transport heat from spacecraft components to radiator
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 4
Final Version
Optics Spacecraft
MLI on other exposed sides
Sun
Radiatorwith
Louver
Hub radiatorused whenseparated
Heat pipe couplerused when together
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 5
Final Version
Detector Craft
Spacecraft radiators
MLI blankets
Sunshield
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 6
Final Version
Trades and Studies
Thermally couple hub and free flyers in Phase 1 Reduces heater power (now 80W) Mass and hardware costs would increase; very difficult to test
Distribute radiators on free flyer sides, so heat pipes not needed Reduces system mass and cost by about 18kg, $1M Phase 1 heater power increases by over 300W
Large sunshield for each free flyer and hub Slightly increases thermal stability Increases mass and complexity
Distribute radiators on detector craft, so fewer heat pipes needed Reduces system mass and cost by about 12kg, $500K Component location becomes critical, and heater power increases
Critical thermal system parameters Thermal isolation of mirrors, SST/cryocooler system, cold CCD and radiator Heat pipe systems design and testability
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 7
Final Version
Backup Slides
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 8
Final Version
Instrument Accommodations
Mirror Modules Radiate heat to space passively through MLI. Require 1.5W of heater power to maintain each module at 20o+/-0.1C Utilize sunshields to minimize temperature fluctuations Thermally isolate mirror modules from spacecraft deck
CCD Camera Cool detectors to –100oC using dedicated radiator on the anti-sun side Detector electronic heat dissipation combine with spacecraft dissipation
Super Star Tracker Utilize ACTDP cryo-cooler to maintain tracker at 7oK Radiate cryo-cooler rejected heat at the spacecraft radiator sized to
maintain at 10oC
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 9
Final Version
Mission Sequence
Launch
Transfer Stage
Science Phase #1
Low Resolution
200 km
Science Phase #2
High Resolution
1 km
20,000 km
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 10
Final Version
Component LayoutHub Core & Petal
Hub Core Hub Petal (6)
LOS Laser
Detector S/C
Payload Adapter Fitting
Optical Module (9)Optical Module (11)
Comm Antenna
(S/C to S/C 0.3 m)
MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
ThermalPage 11
Final Version
Component LayoutDetector
Solar Array (4.5 m2)
Comm Antenna
(Ground/SpaceCraft 0.5 m)
Comm Antenna
(S/C to S/C 0.3 m)
Comm Antenna
(Ground/SpaceCraft 0.5 m)
LOS laser receiver
CCD Camera
CCD Electronics