l14_structures

l14_structures - Structures in Space Systems Structures in...

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Unformatted text preview: Structures in Space Systems Structures in Space Systems Roles Shielding Thermal, radiation, glint Maintaining System Geometry Carrying Loads Applications Power and thermal management Aperture forming Spacecraft backbone Issues Light-weighting Structural dynamics Thermal distortion Technologies Multifunctional Structures Deployment and geometry maintenance Deployable booms Mesh antennas Membrane structures Inflatables Tethers Formation Flight (virtual structure) Deployment and Geometry Maintenance Deployment and Geometry Maintenance Deployable Membranes Used for solar arrays, sunshields, decoys Being researched for apertures starting at RF and eventually going to optical Inflatables First US satellite was inflated (ECHO I) Enables a very large deployment ratio = deployed over stowed dimension Membranes stretched across an inflated torus Outgassing and need for gas replenishment has led to ultra-violet cured inflatables that rigidize after being exposed to the UV from the Sun. Deployment and Geometry Maintenance Deployment and Geometry Maintenance Truss Structures High strength to weight ratio due to large cross-sectional area moment of inertia Deployable Booms (ABLE Engineering) A bearing ring at the mouth of the deployment canister deploys pre-folded bays in sequence EX: SRTM mission on Shuttle Moment = EI 2 w x 2 Handout gives key relationships between l, EI and: truss diameter total system mass canister mass fraction Deployment for Aperture Maintenance Deployment for Aperture Maintenance Aperture physics requires: large dimensions for improved angular resolution Large area for good sensitivity (SNR) Options include: Filled Apertures Deployed membranes Deployed panels Sparse Apertures Deployed booms Formation flown satellites r = 1.22 D = B (Courtesy of the European Space Agency. Used with permission.) Origins Telescope Dynamics and Controls Origins Telescope Dynamics and Controls Integrated Model Integrated Model #1 #2 #3 #4 Example Transfer Function Example Transfer Function RWA RWA Tx Tx to Internal OPD #1 : Reduced to Internal OPD #1 : Reduced 10-6 10-4 10-2 10 10 2 10 4 Magnitude [nm /Nm] Transfer Function of RWATx to Int. Met. Opd #1 Original JPL Reduced MIT (536 states) 10-1 10 10 1 10 2 10 3 10-4 10-2 10 10 2 TF Normalized to JPL Original Frequency [Hz] SIM Dynamics and Control Block Diagram...
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This note was uploaded on 11/08/2011 for the course AERO 16.851 taught by Professor Ldavidmiller during the Fall '03 term at MIT.

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l14_structures - Structures in Space Systems Structures in...

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