Concept Vehicle Configuration

Hubble Space Telescope Program -- Robotic Servicing Mission Concept Review

1051304_MW_HSTRoboticConcept.ppt

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Goddard Space Flight Center Concept Vehicle Configuration

Deorbit Module (DM)

Ejection Module (EM)

Hubble RoboticVehicle

Robotic Module

V1

V2

V3



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Goddard Space Flight Center Conduit Deploy

Deploy Conduit and Latch onto the HST Handrails/Structure

– Conduit provides 1553 Bus connection from RSUs attached to WFC3 to 486 Computer located in Bay 1 and electrical connections between HST SA3 Diode Boxes and new batteries



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Goddard Space Flight Center

Arm Characteristics:– Grapple Arm end effector captures HST Grapple

Fixture (GF)– 7 joints, 8” diameter to null differential rates upon

capture– Closed loop vision system to track GF target

without an operator in event of LOS– Open loop positioning error less than 1.5” and 2

degrees for berthing to HRV

Grapple Arm Task 1: HST Capture/Berthing

Large end effector capture envelope and high arm tip speed permits:– Relaxed requirement on HRV tracking errors with

respect to HST at rendezvous– High confidence of capture even if HST is rolling

since arm can track HST



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Goddard Space Flight Center

1. HRV approaches HST and holds at 7m range

2. Arm assumes ‘Ready to Capture’ pose

3. HRV positions HST GF in ‘Capture Box’, arm acquires GF target

4. When position/orientation meets “Ready to Capture” conditions, HRV triggers arm to Capture and turns off thrusters

5. Arm tracks GF target with EE camera and closed loop vision processing/servo’ing

6. EE captures HST GF and brings HST to near rest, brakes applied

7. HRV thrusters enabled and combined vehicle stabilized

Approach vector and standoff distance may be selected from a variety of options

HST Capture Sequence



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Goddard Space Flight Center EM Equipment Breakdown

Propulsion system

– ‘TDRSS’ program Hydrazine tanks (4)

• Used for HRV pursuit & docking, and during EM deorbit

– Pressurant (‘blow-down’) tanks (2)

– Valves, filters, plumbing, regulators, heaters, etc. (not shown)

(Note that EM bulkhead at tank mounting flange level blocks view of lower half of tanks)



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GN&C system, cont:

– IMU’s (2)

– Magnetometers (2)

– Torquer bars (3)

• Mounted along X,Y,& Z axes

– Momentum wheels (4)

• Mounted in pyramid pattern

Mag Torquer bars

Several of the listed items are not shown in these views. There is radiator panel mounting space to accommodate all the items listed.



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GN&C system:

– Horizon sensors (2)

– Star trackers / celestial nav (2)

– Coarse Sun Sensors (8)

• 1 each on fwd & aft ends, 6 distributed around DM-end, on L-brackets facing radially out.

– (GPS antennae – also on next slide)



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Goddard Space Flight Center Simulated Performance Results



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Goddard Space Flight Center Capture Approach Candidates1. Baseline Approach

• Point relative navigation sensors at one of the HST grapple fixtures

• Most conceptually straightforward approach for a grapple capture

• Mismatch in HST/HRV inertia properties result in torque and momentum storage requirements which exceed reaction wheel capabilities

2. “Sideways” Approach• Make minor HRV axis nominally parallel with

HST minor axis• Torque and momentum storage requirements

reduced to within reaction wheel capabilities• Requires repackaging of relative navigation

sensor suite 3. Aft End Approach

• Applicable to both grapple and direct docking capture methods

• Matches HST/HRV minor axes• Avoids potential sources of interference (i.e.

HST”s high gain antenna and solar arrays)• Control analysis pending

Documents

Concept Vehicle Configuration