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Micro-Arcsecond Imaging Mission, Pathfinder (MAXIM-PF). Thermal. Wes Ousley Dan Nguyen May 13-17, 2002. Summary. Concept meets scientific instrument requirements Maintain mirror modules at 20+/- 0.1 o C, mirror structures at 20+/- 1 o C Accommodate detector CCDs at –100 o C
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Micro-Arcsecond Imaging Mission, Pathfinder (MAXIM-PF) Thermal Wes Ousley Dan Nguyen May 13-17, 2002
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
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
Optics Spacecraft Sun Hub radiator used when separated Radiator with Louver MLI on other exposed sides Heat pipe coupler used when together MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
Detector Craft Sunshield MLI blankets Spacecraft radiators MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
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
Backup Slides MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
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
1 km Science Phase #2 High Resolution Science Phase #1 Low Resolution 200 km 20,000 km Mission Sequence Launch Transfer Stage MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
Component LayoutHub Core & Petal Hub Core Hub Petal (6) Detector S/C Payload Adapter Fitting Optical Module (9) Optical Module (11) Comm Antenna (S/C to S/C 0.3 m) LOS Laser MAXIM-PF, May 13-17, 2002Goddard Space Flight Center
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 Electronics CCD Camera MAXIM-PF, May 13-17, 2002Goddard Space Flight Center