N A S A G O D D A R D S P A C E F L I G H T C E N T E R

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Earth Atmosphere Solar-Occultation Imager

(EASI)Electro-Mechanical

Jason Budinoff

2 August 2002

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p22 August 2002 EASI

Mechanism Design Drivers

•Design operating environment 40-50+ K•50mm beam diameter•System-level alignment rate of > 1 Hz requires fast response, high duty cycle mechanisms– Dynamic balancing probably required to reduce

mechanism-induced jitter•System level 0.1 arcsec co-alignment requirement •All actuators will have dual windings (coils) for redundancy

•Some mechanisms dynamically balanced for minimal jitter input

•All mechanism drive electronics will have partial/on-board redundancy

•Costing assumes prototype, single ETU, flight units, ~50% flight spares

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p32 August 2002 EASI

EASI Mechanisms

• At each telescope (5x)– Tip/Tilt entire telescope– Tip/Tilt/Piston/Decenter secondary– Shutter

• At each delay line (5x)– Tip/Tilt single flat element– Piston dihedral element

• Combiner Telescope (1x)– Tip/Tilt/Piston/Decenter secondary– Shutter

• Spectrometer– Lens flip mechanism

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p42 August 2002 EASI

Delay Lines (per line)

• Delay Line Tip/Tilt Mechanism – 2-axis fast steering

mirror•Extensive heritage,

GLAS, TOP HAT, Left Hand Design, Ball Aerospace…

•Dynamically balanced•+/- 1 degree range•0.1 microradian (0.02

arcsec) resolution•200 mW avg

dissipation, >50% duty cycle

•2.5 kg

• Delay Line Piston Mechanism– CIRS-type linear

scanner– +/- 10 mm range– 0.05 micron resolution– Launch lock required– Dynamically balanced– 200 mW avg

dissipation, >50% duty cycle

– 7 kg w/ dihedral– New Technology =

Development Risk

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p52 August 2002 EASI

Collector Telescopes

• Secondary 5(6) DOF mechanism– Provides tip, tilt, focus,

decenter• +/- 2 degrees range

tip/tilt• 0.01 arcsec resolution• +/- 5 mm range focus,

decenter • 0.1 micron resolution

– Hexapod pointer w/ jitter attenuation

– 6 stepper-motor driven struts, power off hold

– Piezo- or voice coil attenuators

• Infrequent use, seasonal duty cycle for steppers, >50% for attenuators

• Mass ~3.1 kg

• Telescope tip/tilt mechanism– +/- 3 degree range– 0.1 arcsec resolution

• Power-off hold• Flexure-based• 2 Geared stepper

motor /cam drives• Mass ~ 4 kg• ~5W dissipation

(transient)• Infrequent use,

seasonal duty cycle• Shutter Mechanism

– Magnetic scissors shutter– DIRBE, CIRS heritage

• < 0.5 mW dissipation when closed

• Power-off open• Dynamically balanced• ~1.5 kg TBD

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p62 August 2002 EASI

Combiner Telescope

• Secondary 5(6) DOF mechanism– Provides tip, tilt, focus,

decenter• +/- 2 degrees range tip/tilt

– 0.01 arcsec resolution• +/- 5 mm range focus,

decenter – 0.1 micron resolution

– Hexapod pointer w/ jitter attenuation• 6 stepper-motor driven

struts, power off hold• Piezo- or voice coil

attenuators• Infrequent use, seasonal

duty cycle for steppers, >50% for attenuators

• Mass ~3.1 kg TBD• DCATT, LANL/Honeywell VISS• New Technology =

Development Risk

• Shutter Mechanism– Magnetic scissors shutter– DIRBE, CIRS heritage

•< 0.5 mW dissipation when closed

•Power-off open•Dynamically balanced

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p72 August 2002 EASI

Spectrometer

• 1-2 micron Coarse/Fine Piston Adjustment Mechanism– Rotates 50mm lens into/out of beam in 1-2 channel– Repeatability to +/-.5 degree, +/-2 mm

• Fairly insensitive to repeatability error– Stepper motor– Power-off position hold– HST heritage– Infrequent use, seasonal duty cycle– Mass 2 kg

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p82 August 2002 EASI

Mechanisms Electronics

• Separate electronics box in “warm” area of s/c• Baseline 6 boards w/partial (on-board)

redundancy• 6 board box will weigh ~4 kg

– Delay Line Piston Board– Delay Line Tip/Tilt Board– Secondary Mechanism Board– Shutter Board– Telescope Tilt Board– Secondary Power (+/-5V, +/-28V)

Conditioning Board• Total average power 66 Watts (GLAS MECH

board)

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p92 August 2002 EASI

Mechanisms Summary

•23 total– 6 telescope secondary 5(6) DOF pointers– 5 delay line tip/tilts– 5 delay line pistons– 5 telescope shutters – 1 focal plane shutter – 1 lens flip– 6 boards

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p102 August 2002 EASI

Mechanisms Cost Estimate

Mechanisms NRE, $K EA, $K QTY TOTAL, $K

EA x QTY

NET TOTAL, $K

TOTAL + NRE

5(6) DOF Secondary Mechanism

3000 400 9(6) 3600 6600

Delay Line Tip/Tilt Mechanism

1000 180 8(5) 1440 2440

Delay Line Piston Mechanism

3000 400 8(5) 3200 6200

Telescope Shutter 300 100 8(5) 800 1100

Focal Plane Shutter 300 100 2(1) 200 500

Lens Flip Mechanism 300 100 2(1) 200 500

Electronics Box, Harness

1000 200 1(1) 200 1200

Totals 8900 9640 18,540

-NRE includes manpower, breadboard, 1 engineering unit & supporting electronics & qualification environmental testing.-unit price (EA) includes manpower, 1 flight unit & acceptance environmental testing.-qty is shown as purchased(needed for flight); eg 8(5) means purchasing 8 and flying 5. This reflects ~50% flight spares

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p112 August 2002 EASI

Future Work 1

• Development of new technology mechanisms– Some EASI mechanisms require 1-2 orders of magnitude

increase in state-of-the-art performance (range/resolution/stability) in cryogenic environment.•Secondary 5(6) DOF mechanism

– Very high dynamic range, minimum power dissipation– Integrated vibration attenuation– Dynamic balancing– Tight packaging

•Delay line piston mechanism– Very high dynamic range, minimum power dissipation– Integrated vibration attenuation– Dynamic balancing

• Supporting facilities for 0.01 arcsecond-level stable measurements & alignments

– Verification of individual mechanism performance will require STABLE interferometric, cryogenic facility setup.

Electro-Mechanical

I n s t r u m e n t S y n t h e s i s a n d A n a l y s i s L a b o r a t o r y

Jason Budinoff p122 August 2002 EASI

Future Work 2

•Complexity of delay line control algorithm– Delay line controller will require multiple, recursive,

nested loops– Observatory delay lines will operate at high rates

>10 Hz?– This causes a flow-down to the individual

mechanisms•Each delay line correction will require many iterations in mechanism positions– Mechanisms will require very tight controllers,

with settle times in the low millisecond range to 0.01 (+/-0.005” !!) arcsecond, operating in concert with vibration attenuation controller.