v

Phase II

Design Definition of the

l"MSC-HSV TR F320789-1

Laser Atmospheric Wind Sounder

(LAWS)

Contract NAS8-37590

Vol. I:

DR-20

EXECUTIVE SUMMARY

June 1992

Prepared for

GEORGE C. MARSHALL SPACE FLIGHT CENTER

MARSHALL SPACE FLIGHT CENTER, AL 35812-

4800 Bradford Blvd., Huntsville, AL 35807

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LMSC-HSV TR F320789-1

DR-20

PHASE II

DESIGN DEFINITION OF THE

LASER ATMOSPHERIC WIND SOUNDER (LAWS)

VOL I: EXECUTIVE SUMMARY

June 1992

CONTRACT NAS8-37590

Prepared for

National Aeronautics and Space Administration

George C. Marshall Space Flight Center (MSFC)

Marshall Space Flight Center, Alabama 35812

Approved by

W. E. Jo/fes/ "

LAWS _ Manager

Date _Cd//_ / _

Submitted by

&

4800 Bradford Blvd., Huntsville, AL 35807
LMSC-HSV TR F320789-1

FOREWORD

This report presents the final results of the 21-month Phase II Design Definition and 18-month

laser breadboard efforts for the Laser Atmospheric Wind Sounder (LAWS). This work was

performed for the Marshall Space Flight Center (MSFC) by Lockheed Missiles & Space Company,

Inc., Huntsville, Alabama, under Contract NAS8-37590. The study was conducted under the

direction of R.G. Beranek, NASA Program Manager, and R.M. Baggett, LAWS Instrument

Project Office, JA92. The period of performance was 24 August 1990 to 30 June 1992.

Subcontractors contributing to this effort are Textron Defense Systems - Everett, and Itek Optical

Systems.

The complete Phase II Final Report consists of the following three volumes:

Volume I Executive Summary

Volume II Final Report

Volume ffI Program Costs.

This volume, Executive Summary, reviews all activities completed during the LAWS Phase II

effort and summarizes results, methodologies, trade studies, recommended approaches, and design

analyses.

ii

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

Section

4

5

6

CONTENTS

Page

Foreword .................................................................................... ii

Contents ..................................................................................... iii

iv Illustrations ..............................................................................

Tables ...................................................................................... .. v

Acronyms and Abbreviations ............................................................. vi

INTRODUCTION ......................................................................... 1

TRADE STUDIES AND BASELINE DESIGN ....................................... 7

LAWS FULL SCALE DEVELOPMENT AND VERIFICATION ................... 16

3.1 Structures and Mechanical Subsystem ........................................... 20

3.2 Command and Data Management Subsystem ................................... 23

3.3 Electrical Power Subsystem ....................................................... 24

3.4 Thermal Control Subsystem ....................................................... 24

3.5 Optical Subsystem .................................................................. 29

3.6 Receiver/Processor Subsystem ................................................... 32

3.7 Laser Subsystem .................................... ,............................... 34

LASER BREADBOARD .................................................................. 45

DOWNSIZED LAWS ..................................................................... 48

SUMMARY .............................................................................. 52

iii

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LMSC-HSVTRF320789-1

ILLUSTRATIONS

Figure

l

3

4

5

6

7

8

9

l0

I!

!2

!3

14

!5

16

17

18

19

20

2!

22

23

24

25

26

27

28

29

30

31

32

33

34

Page

LAWS Baseline Design Hight Configuration ............................................ 2

LAWS Package on Bus Assembly ........................................................ 2

LAWS Shot Distribution .................................................................... 3

LAWS/POP in Atlas IIAS Large Fairing ................................................. 3

LAWS in Delta Large Fairing .............................................................. 4

LAWS Program Organization .............................................................. 4

LAWS Phase II Schedule ................................................................... 5

System Level Trades ........................................................................ 7

LAWS System Functional How Diagram ................................................ 8

LAWS System Diagram .................................................................... 9

LAWS Subsystem Assemblies ............................................................. 9

LAWS Baseline Configuration ............................................................. 10

LAWS Baseline Dimensions ............................................................... 11

LAWS Configured for Delta Large Fairing ............ i.................................. 11

LAWS Signal Flow ......................................................................... 13

LAWS Optical Bench Layout .............................................................. 14

LAWS Development Schedule ............................................................. 17

Development/Engineering Unit ............................................................ 18

Subsystem and Component Qualification Test .............. . ............................ 18

Vehicle Qualification Tests ................................................................. 19

Flight Unit Assembly and Test ............................................................. 19

LAWS Assembly and Test How .......................................................... 20

Overview/Summary of the Structures and Mechanical Subsystem .................... 21

Overview/Summary of the Command and Data Management Subsystem ............ 25

Overview/Summary of the Attitude Determination Subsystem ......................... 26

LAWS PDS Block Diagram ................................................................ 27

Overview/Summary of the Electrical Power Subsystem ................................ 28

LAWS Instrument in Earth Orbit .......................................................... 29

Thermal Radiation Model Plot of LAWS Instrument Showing Passive TCS Surface

Coatings ...................................................................................... 30

Overview/Summary of the LAWS Thermal Control System ........................... 31

Optical Subsystem Functional How Diagram ............................................ 32

Overview/Summary of the Optical Subsystem ............. . ............................. 33

LAWS Receiver/Processor Subsystem Block Diagram ................................. 35

Overview/Summary of the Receiver/Processor Subsystem ............................. 36

iv

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ILLUSTRATIONS (cont)

Figure

35

36

37

38

39

40

41

42

43

44

45

46

47

Page

Laser System Block Diagram .............................................................. 37

Laser Transmitter ............................................................................ 38

Resonator Optics Layout .................................................................... 39

LAWS Discharge/Flow Loop, End View ................................................. 40

Two-Electrode Configuration, Side View ................................................ 40

Energy Discharge Processes ............................................................... 42

Preliminary Layout of Pulsed Power Section ............................................ 43

Laser Transmitter Subsystem Summary .................................................. 44

LAWS Breadboard System Block Diagram .............................................. 46

S/N Performance for 525 km Orbit ........................................................ 48

LAWS Telescope with 0.75 m Diameter Mirror in Delta Fairing ...................... 49

LAWS Instrument Fit-Check in Delta Fairing ............................................ 49

Preliminary Steady-State Temperatures on Downsized LAWS Telescope: ........... 51

TABLES

Table

1

2

3

4

Page

Potential Launch Vehicles ................................................................... 12

LAWS Baseline Mass Properties ..................................... •.................... 15

LAWS Transmitted Requirements and Breadboard Design Goals Compared ........ 45

LAWS Electrical Power Comparison ..................................................... 50

V

" • LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

A/D

ADP

AGC

ARTS

ASE

BDU

BW

CART

CCAM

CCSDS

C&DH

CEI

CG

CIL

.CPCI

CPDP

CTE

CVCM

DPA

DVT

EEE

EI

EMC

EO

EOS

EPS

ESC/ESD

EU

FFT

FMEA

FOSR

GFE

GIDEP

GIIS

ACRONYMS AND ABBREVIATIONS

analog-to-digital

acceptance data package

automated gain control

automated requirements traceability system

airborne support equipment

bus data unit

bandwidth

condition of assembly at release and transfer

collision/contamination avoidance maneuver

Consultative Committee for Space Data Systems

command and data handling

contract end item

center of gravity

critical items list

computer program configuration item

computer program development plan

coefficient of thermal expansion

collected volatile condensable materials

destructive physical analysis

design verification test

electrical, electronic, and electromagnetic

equipment item

electromagnetic compatibility

electro-optical

Earth Observation System

electrical power subsystem

electrostatic compatibility/electrostatic discharge

engineering unit

fast fourier transformer

failure mode effects analysis

flexible optical solar reflector

Government furnished equipment

Government-Industry Data Exchange Program

General Instrument Interface Specification

vi

" LOCKHEED-HUNTSVILLE
LMSC-HSVTRF320789-1

GSE

HOSC

H&S

HST

IARM

IAS

ICD

IMU

LAEPL

LAWS

LC&DH

LO

LOS

MA

MAFrIS

MCS

MLI

MUA

NSPAR

OARM

OR

PA

PCP

PDS

PDT

PFN

PIND

PLF

PMP

POCC

PRACA

PRF

PRL

PSATS

ACRONYMS AND ABBREVIATIONS (cont.)

Ground Support Equipment

Huntsville Operations Support Center

health and status

Hubble Space Telescope

input annular reference mirror

integrated alignment sensor

Interface Control Document

inertial measurement unit

LAWS Approved EEE Parts List

Laser Atmospheric Wind Sounder

LAWS Command and Data Handling

local oscillator

line-of-sight

multiple access

Material Processing Information System

Manufacturing Control System

multi-layer insulation

Material Usage Agreement

Nonstandard Part Approval Request

output annular reference mirror

obscuration ratio

product assurance

platform command processor

power distribution system

product development team

pulse forming network

particle impact noise detection

payload fairing

program management plan

Payload Operations Control Center

parts problem reporting and correcti, ve action

pulse repitition frequency

program requirements list

parallel spacecraft automated test system

vii

- LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

PZT

RCS

rms

R&RR

SA

SBA

SLM

SMS

SN

SNR

SQU

STDN/DSN

ST&LO

STV

TAP

TCS

TDRSS

TML

TWG

ULE

VCRM

WFE

WSMC

ACRONYMS AND ABBREVIATIONS (cont.)

pezio-electric transducer

reaction control system

root mean square

range and range rate

single access

scan bearing assembly

single longitudinal mode

structures and mechanical subsystem

space network

signal-to-noise ratio

Structural Qualification Unit

Spaceflight Tracking and Data Network/Deep Space

Network

system test and launch operations

structural test vehicle

transportation adapter plate

Thermal Control System

Tracking and Data Relay Satellite System

total mass loss

test working group

ultra-low expansion

verification cross reference matrix

wavefront error

Western Space and Missile Center

viii

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

Section 1

INTRODUCTION

The objective of the Laser Atmospheric Wind Sounder (LAWS) Instrument Phase II

Preliminary Design Definition and laser breadboard tasks is to further define in sufficient detail

the selected configuration from the Phase I Concept Definition study to allow initiation of

follow-on full-scale development.

This task has been successfully completed, with the restriction that the specific spacecraft on

which the LAWS Instrument is to fly is yet to be confirmed.

Our configuration satisfies all science requirements and General Instrument Interface

Specification (GIIS) requirements, can be accommodated on the MSFC LAWS spacecraft

concept, and is compatible with potential French CNES configurations (Figures 1 and 2). LAWS

will operate in the gravity gradient mode in a 525 km, sun synchronous 97.497 deg inclination

orbit with the axis of rotation of the conically rotating telescope pointing to nadir. The telescope

rotates at 6 rpm in a 45 deg off axis, full 360 deg scan to measure wind velocities from the

Earth's surface to 20 km, with six shots within a 100 x 100 km grid pattern on Earth during each

scan (see Figure 3). Adequate volume envelopes are available for both LAWS and the spacecraft

in the Atlas HAS (Figure 4) and Titan launch vehicles. With reduction of the telescope primary

mirror diameter from 1.67 to 1.6 m, LAWS can be launched in a Delta vehicle (Figure 5).

The Lockheed LAWS program organization is shown in Figure 6. Lockheed-Huntsville is

the prime contractor with overall program management and technical responsibility. Major

contributors to the program are Textron Defense Systems for the Laser subsystem and

breadboard activities and Itek Optical Systems for the Telescope subsystem. Significant inputs

and contributions were also made by our consultants, particularly Dr. Carl Buczek, Laser

Systems & Research Corp., and Dr. Chuck DiMarzio, Northeastern University.

The Phase II Preliminary Design Definition was a 21-month follow-on to the initial Phase I

12-month study for Concept Definition. Phase I period of performance was from March 1989 to

March 1990 and was documented in Ref. 1. Phase II was initiated on 24 August 1990, with

completion scheduled for 30 June 1992 (see Figure 7).

The laser breadboard was added to the basic contract to develop requirements, design,

fabricate, assemble, and test the laser design to ensure orbital performance requirements can be

met. The 18-month breadboard task was initiated in January 1991, with completion on 30 June

1992 to coincide with the end of the Phase II study. This concurrent effort provided maximum

cross flow of data between the two tasks for maximum impact on the baseline instrument design

and flight fidelity of the breadboard configuration and tests. First laser beam was accomplished

on 21 April 1992, less than 16 months from ATP. Both performance tests and life tests were

performed.

1

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

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Figure 1. LAWS Baseline Design Flight Configuration

Figure 2. LAWS Package on Bus Assembly

2

LOCKHEED-HUNTSVILLE
LMSC-HSVTRF320789-1

Z

Z

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12 o E 140 E !60 tZ 18

Figure 3. LAWS Shot Distribution

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DIMENSIONS IN METERS

T AVAILABLE SPACE

PLATFORM ENVELOPE

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(9055) /

1 i

(t36.22

ATLAS PAYLOAD _ -- -_ ......

ADAPTER ENVELOPE [ I

Figure 4. LA WS/7;'OP in Atlas IIAS Large Fairing

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LOCKH EED-HUNTSVlLLI:
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DELTA 6306 PAF / I

Figure 5.

1 7 METER

(5 4 FT)

r

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LAWS in Delta Large Fairing

LMSC-HSV TR F320789-1

LAWS PROGRAM

W.F- Jones

Program Manager

D.I. Wilson

Deputy Program Manager &

Chief Engineer

SECRETARY

P.G. Porter

SYSTEMS

ENGINEERING

T.K. Speer

Chief Systems Engineer

I

PROGRAM OPERATIONS &

PLANNING

A.J. Condlno

I

I LASER SUBSYSTEM &

BREADBOARD

Dr. S.C. Kun.,ius

L Textron Defense Systems

S. Ghoshroy, PM

Dr. H.P. thou, Sys. Engr.

Br 320789-005

I OPTICAL SUBSYSTEM Dr. W.W. Montgomery

SUBCONTRACTS

ADMINISTRATOR

J.T. Stelgerwald

I

DESIGN

ENGINEERING

W,M. Harrison

L Itek Optical Systems

S.E. Kenddck, PM

C. Robbert, Sys. Engr.

Figure 6.

t UDAR I

LABORATORY

Dr. W.W. Montgomery

I

SYSTEM PERFORMANCE

ANALYSES

Dr. W.R. Eberle

I

CONSULTANTS

_ Laser Systems & Res Corp

Northeastern Unlverslty

Slmpsen Weather Assoc

UAH Center for Applied Optlcs

LAWS Program Organization

4

LOCKHEED-HUNTSVILLE
F320788-29

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• Phase II ATP

• Project Reviews:

- Phase II Kickoff

- Quarterly Reviews

- Phase II Final

• Phase Ih (21 months)

- Analysis/Trades; definition

- Error budget

- Technology/Risk assess.

- Identify/Evaluate interface

requirements

- Preliminary design

- Environmental analysis

- Final report (Phase II)

• Laser Breadboard: (18 months)

- Development & test

- Catalyst required for BB

- Breadboard reqmts review

- Initial BB design review

- Final BB design review

- BB test readiness review

- Data reviews

- Final data reviews

- Final report (Breadboard)

CY 1990

AIsIoINID

•8-24

12-6

V

i

12-6

V

CY 1991 CY 1992

JIFIMIAIMIJIJIAIsI OI NID JIFIMIAIMIJIJ

Intedm GSFC Design

Review Review Review

3-5 5-5 6-27 7-31 12-12

V V VV V

9-5

12-12

10-4

5-23

1-17

ATP

4-23

• 6-9 6-23

(MSFC)'(HQ)

u-30

V

3-10

4-23

• • 6-3o

• 6-;o

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Figure 7. LAWS Phase H Schedule

G3

0

o,
LMSC-HSV TR F320789-1

The results of the Phase II design and breadboard tests are that LAWS full-scale

development, verification, and successful mission operation are state-of-the-art technology. The

LAWS system engineering studies and breadboard demonstration show that our design is able to

accomplish the Science Team's requirements for global wind pattern measurements for the

planned 5-year mission.

6

.. LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

Section 2

TRADE STUDIES AND BASEUNE DESIGN

Utilizing the selected LAWS configuration from the Phase I studies, system engineering

trades were performed to further develop and optimize our baseline configuration. The science

requirements, spacecraft resource budgets and interface requirements, launch vehicle loads and

volume envelopes, and the atmospheric phenomena and variables were all incorporated with the

subsystem's physical variables to ensure that the baseline design would meet all requirements

(see Figure 8). Sensitivity analyses were also performed to optimize the performance

requirements with respect to reliability and costs.

ScienceRequirements

• Troposphericwinds

• _>6 pulses/horizontal

100 x 100 km

• < 1 km verticalres.

• System error

contributionlimits_<1m/s

line-of-sight

• Globalcoverage

• Eye safe

• 5 yr. life

10 g Laser pulses

Constraints _.

|

I

I

I

Atmosphere I I

• Aerosol seeding (10"llm'lsr "1)

• Attenuation

• Turbulence effects

- Coherence decorrelation

time (1,2, - - 5 i_s)

- Velocity variability

over _dd

Platform

• Power Resources

Average

Peak

• Thermal Resources

- Cooling&

Exposure

• InstrumentResources

attitude & position

• Orbit Parameters

Altitude & inclination

• Structure

- Envelope&Mass

- VibrationSpectra

- Deformation

Design Variables

• Laser Parameters

- Pulse length

- Pulse energy

- Pulsechirp

- Pulse spacing

- Pulse spetial

- Wavelength

• Optics Parameters

- Aperture

- Scan rate

- Scan angle

• Receiver Parameters

- Data rate

•Contamination -Dynamic range

• InterfaceL Cooling & Power Req

Mass & Volume

InstrumentPerformance • AttitudeMonitor I

_.[

.... SNR &_ Pointing .... F320789-007

I DataUtility I

Error o r Coverage I,

Figure 8. System Level Trades

During Phase I, the requirements were developed for the LAWS system to enable it to

accurately measure the wind vectors on a global scale for five years. These requirements were

7

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

then allocated to either the entire LAWS system or to a specific element or subsystem (see Figure

9). These requirements include both "given" (from the SOW) and "derived" (lower level

requirements established to implement a higher level requirement, usually based on system trade

studies). They were integrated into a LAWS system diagram (Figure 10), which led to definition

of the six specific subsystems (Figure 11) needed to accomplish the mission objectives. (The

Thermal Control subsystem is part of the Structures and Mechanical subsystem but is discussed

separately in later sections of this document.)

Platform Atbtude/Position LEGEND

Transceiver Determination Allocation

Obtain Orbital Communicate Data

and Commands Parameters, Time,

and Attitude

Right

Memory Processor Instrurnentatlon

Store Process Data and Monitor Health, I

Safety, and Status

Data Commands Data I

TCS Laser

To All

Scan Drive

Control Instrument Generate Laser Control Scan Position

Temperature Beam and Alignment

EPS Distribution Detector

Distribute I Detect and Process Electrical Power Return Signals

TDRSS L._ To All Payload |

Satellite/Ground

Transceivers POCC Developer

Transmit and H Decode and Monitor H Monitor

Receive Data _ data quality I_ 1 Instrument Performance

Te/escope

Expand, Direct, and

Receive Beam

Laser Output

Beam

Beckscatter

Return

Sconce

Dam

Evaluate Instrument I

Science Data

F32OTSg-ooe

Figure 9. LAWS System Functional Flow Diagram

8

- LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

F312569-TKS- 02

Figure 10. LAWS System Diagram

OPTICAL SUBSYSTEM

Telescope Assembly

Momentum Compensator

Azimuth ScanningSystem

InterferometerAssembly

Lag Angle Compensator

RECEIVER-PROCESSOR SUBSYSTEM

Photo Detector Array

Active Cooling Assembly

Analog-DigitalConverter

Down Converter

Preamplifier/BiasElectronics

Interfaces

LASER SUBSYSTEM

TransmitterLaser

Local Oscillator

Seed Laser

Laser Subsystem Interface

COMMAND & DATA MANAGEMENT

SUBSYSTEM

Flight Computer

Software Module -.

Attitudeand PositionDetermination

Transceiver InterfaceModules

Subsystem Interfaces

STRUCTURES & MECHANICAL

SUBSYSTEM

Base Structure

Optical Bench

Attach Mechanisms

Satellite BusAccommodations

Component SupportStructures

ThermaJControlSystem

• Active

• Passive

Figure 11. LAWS Subsystem Assemblies

ELECTRICAL POWER

SUBSYSTEM

Power DistributionUnit

Platform ElectdcalPower Interface

LAWS Electrical Power Interfaces

EMI Control

F320789-010

9

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

The signal flow through the Laser, Optics, and Receiver subsystems, plus the volume

constraints of the candidate Arias IIAS and Delta launch vehicles, led to the baseline LAWS

flight configuration layout shown in Figure 12. The velocity vector is along the X-axis, with the

telescope bearing on the leading side of the Instrument platform, the laser on the trailing side,

and the telescope rotating about nadir. Dual Star Trackers are shown on the cold side of the

Instrument in close proximity to the inertial measurement unit (IMU). This configuration meets

all packaging requirements for the Atlas IIAS launch vehicle and can be accommodated by the

Titan vehicle and, with minor changes, the Delta vehicle. It is designed with clear access for

assembly, installation, checkout, and maintenance of all components before launch. Components

are located either around the perimeter of the Instrument base or on the optical platform. The

laser tank and telescope bearing are mounted to the Instrument base, with critical optical

components mounted to the optics bench, which is isolated from the base. The base is, in turn,

kinematicaUy mounted to the spacecraft. The optical bench provides a thermally and structurally

stable platform for mounting and alignment of critical optical elements. The telescope motorbearing assembly and laser pressure vessel are mounted directly to the base structure through cutouts in the optical bench. Baseline dimensions are shown in Figure 13 for the Arias HAS

configuration. Figure 14 shows the basic changes required for a Delta launch vehicle

accommodation. The LAWS Instrument with telescope can be fitted into a Delta (large) fairing

(Figure 5) by reducing the telescope aperture from 1.67 to 1.60 m diameter. This size reduction

results in a signal-to-noise loss of approximately 0.5 dB.

LRSER PNR

TRRNSMIT LRSER IF_..._--_ _ !L"_: :.'_ 7 RECEIVER "X2_"_ /_ [NTERFRCE !

THERNRL "-'1 _ / i C0HPUTER "'7

• . CORPUTER . -- ._.

: r-J-,,,,-..--.,ONE.II-,.7

l-i ,, ,,,...,,

b... CONTROL

CRTOGEN ,C COOLER_ "_ _ _ 1 _[_ l

HONENTUH CONPENSRTOR "-/

FOR CLRRI T¥

Figure 12. LAWS Baseline Configuration

10

LOCKH EED-HUNTSVILLE
LMSC-HSV TR F320789-1

TELESCOPE OMITTED

FOR CLRRITT 11,7M

OIMENS]ONS IN METERS

(]NCHESI

3.65

(1q3.70!

/

Figure 13. LAWS Baseline Dimensions

//i/'_.i.6METER

(5.3 F,,_

3.5 METER

(I I .5 FT)

Figure 14. LAWS Configured for Delta Large Fairing

Due to the present uncertainty of the specific spacecraft and launch vehicle to be used for the

LAWS mission, Titan launch design load factors were used for all structural analyses for

11

" LOCKHEED-HUNTSVILLE
LMSC-HSVTRF320789-1

conservation (see Table 1). As further shown in Table 1, our LAWS

accommodated by Atlas HAS, Delta, and Titan vehicles, with minor changes.

Table 1. Potential Launch Vehicles

!iiiiiiiii!iii!i!i!i_i_i_i!iii_iii_iiiiiiiiiiiii_i_i_i_!i!_i_i_iiii: iiiiiiiiiiiiii!_!_iiii_iiiiiiiiiiiiiii!ii{i!!i!ii!_iii!iiiii!i!_!ii_!i!i! iiiiii!!!ili!:::::::i ........................... _:::iiiiiiiiiiiii iiiii!iiii!i_ii_iiiiiiiiiiiiiiiiiiiiiiiii_ii_!i!iiiiiiiiii!i!iiiiiiiiiiiiiii!iiii!!i!ii!!iii

Atlas IIAS 4.19 large

Delta 3.0 large

Titan 5.08

6.0 axial

2.0 axial

6.3 axial

3.0 axial

6.5 axial

3.5 axial

Baseline

Reduces telescope

diameter & base

mount height

Baseline

F320789-014

baseline can be

A schematic of the LAWS signal flow through the Laser, Optics, and Receiver subsystems is

shown in Figure 15. Tip-tilt mirrors are depicted for low bandwidth adjustment of the local

oscillator beam; higher bandwidth adjustment is required for the dynamic lag angle

compensation. Telescope internal alignment is maintained by an out-of-band alignment

assembly. Focus/defocus capability at the receiver provides increased field-of-view for initial

acquisition. Figure 15 shows optical paths as dashed, and electrical paths as solid lines. The

twos (2's) are components which have been tentatively selected for redundancy to maintain

higher reliability for mission operations. Actual component layout is shown in Figure 16.

A condensed baseline mass properties table is depicted in Table 2_ The weight values are

based on design, analyses, or vendor data for selected hardware elements. The weight budget of

800 kg is met, but little contingency is presently available. Major emphasis will be placed on

weight reduction when the specific LAWS spacecraft is selected. The CG is located close to the

longitudinal (X) centerline. The telescope rotating mass has been minimized to 161.5 kg. The

telescope mass CG is located on the axis of rotation for minimum inertia effects. The momentum

compensator is included to compensate for telescope rotational momentum.

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"I

l

l

l

I

l-I

J

w

.-I

>

or)

kz

d

w

w

"1"

v

0

_1
Table 2. LAWS Baseline Mass Properties

tO

o

X

I"

m

m

9

C

Z

-t

rrm

System

Structure

Power

Thermal

Telescope

Laser

Data

Received

Detector

Momentum

Comp.

Pointing

Total

Contents

System

Weight

(kg)

C.G. Location (m)

X Y Z

Base, Bench, Environmental Cover, Mounts 127.5

Distrubutor, Cable 13.6

Pump Package 15.5 * ,Heaters, Cable 92.95

EOS Cold Plates 21 .**, Lines, Misc.

Mirrors, Reaction & Metering Structures, 204.6

TCS, Motor/Bearing, Misc.

Laser & Power Supp., Oscillators & Power 212.6

Supp., Seed Lasers & Power Supp., Misc.

Computer, Cables 20.4

Electronics, Cryo Cooler, Controller 52.0

Compressors, Displacers, Bias, Preamp, Misc.

Momentum Compensator, Heat Exchanger 12.9

IMU, Star Trackers 41.0

-0.57 0.03 -0.34

-0.88 0.77 -0.32

-0.82 -0.02 -0.38

0.0 010 0.92

-1.20 -0.05 0.21

-0.79 0.29 -0.28

-0.26 0.62 -0.24

0.0 0./0 -0.62

-0.17 0.97 -0.50

777.5kg-0.55m O.08m 0.16m

* Could be replaced by platform pump if LAWS goes on dedicated platform.

** Could be replaced with 5 kg heat exchanger if LAWS goes on dedicated platform.

Br 320789-017

IGo

9

I

Go

<

o

-,4
LMSC-HSV TR F320789-1

Section 3

LAWS FULL SCALE DEVELOPMENT AND VERIFICATION

The guideline development schedule for the LAWS Phase C/D Full Scale Design,

Development, Test & Evaluation (DDT&E), was specified by MSFC for this Phase II study

contract. ATP was 1 January 1994, with launch scheduled for March 2001. The LAWS flight

unit was to be shipped for spacecraft integration on 1 January 1999, and the integral

LAWS/spacecraft configuration shipped for launch vehicle integration on 1 January 2001 (see

Figure 17).

The LAWS development process includes three units to minimize risk during the 5-year

DDT&E program. An engineering unit, a qualification unit, and a flight unit are used for a

success oriented, minimum risk approach. The engineering unit is maintained throughout the 5-

year orbital mission life for sustaining engineering and trend analysis activities. Initially the

engineering unit is constructed of non-flight components to allow an early start on system

integration, checkout, and performance testing (see Figure 18).

The qualification unit consists of flight configuration hardware to be tested to flight

centrification levels. Subsystem and components are required to pass acceptance level tests

before being subjected to full-up qualification level tests. Upon successful completion of

component and subsystem qualification testing as shown in Figure 19, the LAWS Instrument,

composed entirely of qualified units, will be subjected to vehicle qualification testing, as shown

in Figure 20.

Functional testing, as defined in MIL-STD-1540, will be performed immediately before and

after conducting all environmental testing. Functional testing is divided into two sections:

mechanical and electrical. Operation of the transmitter laser, elector-optical devices, software,

and data processing functions will apply to testing these sections. During mechanical testing, all

mechanical operational modes are fully operated and alignment tests are conducted. During

electrical tests, all primary and redundant circuits, commands, and operational modes will be

activated and sequenced as they will be performed in space.

Thermal vacuum tests will be conducted as a part of the vehicle qualification tests ( Figure

20) and flight unit acceptance tests (Figure 21) as required by MIL-STD-1540. During the first

and the last temperature cycles, a full functional test will be conducted at both the specified high

and low temperature extremes. Functional and operational parameters will be instrumented and

monitored during all test cycles.

16

LOCKH EED-HUNTSVILLE
I--

0

C)

X

"Ira

m

9_

-I- ..a

C

Z

--4

rT"

m

MAJOR MILESTONES

Design and Development

Eng.Support

Software

SW Reqmt Specification

SW #zchitecture

sw Development

SW Test & Implementation

SW Maintenance

Engineering Unit

Fab & Assembly

Sub Sys I & T

Sysl&T

oPs Support

Quantity Unit

lab & Assembly

SubSys I &T

Sysl&T

Qual Test

Right Unit

lab Assembly

Sub Sys I & T

Sys I&T

Bus Int

Bus/Veh Int

Sul)ort Launch/Orbit Fit

F-JeOperations

iiiiiiiiiiii_iii_i_/i_!iii_iiiii_iii_i!ii_iii/_!i! !i_ii !i_i i/!ii!iii_liiiiiiii _/iiiiiiiiiiiiii!_. i!iii!ii:,ili!iil iliiili_i iiiii!iiiiiiiii!!iiii !!iiiiiii!iii!iliiii_iiiiiiiiiii!iiiii_ii liiii!iiiiiii!iiiiiiii!!!_iii_iiil/iiiiiiiiii!! _ili!i!i!!:iliiiiii:i!ii.!i! _iiiiiil/!iiiiiiiLiiiiiiiii_i;ii!iii_/.i:iiiiiiiiiiii:!_: _iil/ii!iiiiii:iii:_i i_ii :/_ii_!ii_i!iiiiiiii_iii_!i_ii_il ,xA z_ z_ ....'........................ 'FO,_ ,. LAw_.usZ__u__??

PRR PDR CDR LAWS Ship FRR

I

7/94

oF==:_

r'--

i 72,_

k

r'-"--'111 i6

r"

1

4/96

r'_

7;g6

I'--

!

ev97

"t

7/I)7

g_7

_ ,.------...--.--I

II'm

I_t

-'-z

I_oT r---t

I

M)7

F320789-018

Figure 17. LAWS Development Schedule

r

tl)

9

I

<

",4
LMSC-HSV TR F320789-1

INTEGRATION

_ _ [ OPT_AL h

_ ] INJECT LASER _ [ CHECKOUT

__ INITIAL CHECKOUT J

EPS J

LASER I

_NS. OPTICAL PATH I

TCS J

I _R II I_ER_REA_RO/ BREADBOARD _]"_1 CHECKOUT !

,

TE_E TELE_E1_ISTROC_RE _

STRUCTURE STRUCTURE .R,NG,

MOCKUP _OCKUPFAa ENCODER;L_SY

DESIGN .........

Figure 18. DevelopmentEngineering Unit

_lDE_,OP.E.T I

I,M_IIT I

DEVELOPMENT I

UNIT I

CH_KOUTj

SYSTEMS I

PERFORMANCE I

TESTS J

BASE_ST,F_.Ess'L STRUCTURE _ TEST_

OPTICAL J BASE STRUCTURAL

BENCH _'--" I ASSY I]-IMECH/U_IC/U- F &C.G. V "I TESTSI -I TESTSI

KINEMATIC SPIN TEST • BASE FIXED

MOUNTS

I,,=1 SIMULATORS

•F_TCOMPUTER• EPS

JTELEscopE SHROUDI_'n L.__TELESCOPEa ¢---..---JI •

•

INJECTION LOCAL OSCILLATORS LASERS •

° POWERSUPPLY/L_ER TC,S

I _ J ASSY _ --= • RELAY MIRRORS • STAR TRACKERS BEARING

ASSY I-.Ji • MIRROR • LASER " ETC. ""

|

BLANK

• ENCOOER

SIMULATOR

ComponentLevelQualificationTests

BAKEOUT

THERMAL-VAC

SHOCK & VlB

EMI

PE RFORMANCE

Figure 19. Subsystem and Component Qualification Test

]8

LOCKH EED-HUNTSVILLE
LMSC-HSV TR F320789-1

COMPONENT I

LEVEL

QUAL TESTS J

l EMC

ASSEMBLY _ws

FUNCTIONAL TEST

MECHANICAL

OPERATIONAL MODES

ALIGNMENT

ELECTRICAL

CIRCUITS

PRIMARY & REDUNDANT

COMMANDS ALL

SEQUENCE THRU ALLOPERATIONAL

MODES

!

I

I ,.,°_,. o_o° . H F°.O,,o_,. I---'"_" _,_o_!-4

-_lF°"°"°_L J

Figure 20. Vehicle Qualification Tests

t

r

THERMAL VACUUM I

H STIFFNESS

TEST I J_

ISUBSYSTEM

FABBASE / ASSY

I OPTICAl_ FAB / ASSY

KINEMATIC MO_TS }

C&DH ]

All" SYSTEM_T }

RECEIVER DETECTOR / [

l STRUCTURE SHROUD J +LAWS ASSY

ASSY I I FAB#m.SSYI t--

i_,,1 + ,. /

FABMl_O_ / TEST I - IsuesvSTEM/ C_-CK

Figure 21. Flight Unit Asserr_ly and Test

FUNCTIONAL

F32078_021

TESTS I "

I_=,ic I

VACUUM

WEIGHT C,G. & I

19

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

The preliminary assembly/test flow plan is illustrated by Figure 22. Following installation

and tests of Laser and Telescope subsystems and return of the units to LMSC, the qualification

unit and the flight unit will be further tested. The flight unit will be shipped for spacecraft

integration and then to the launch site. The TDS and Itek facilities are located within 30 miles of

each other in the Boston area, which provides for maximum interface and minimum cost during

laser and optical subsystem integration and tests.

The following sections provide a brief summary for each of the LAWS subsystems.

aTICAL BENCH _ f LASER & LASER

SEEO,,SE --- LOOWER

_-- BASE STRUCTURE ASSEMBLE AT TDS TEST

LMSC HUNTSVILLE TDS LASER

TO LMSC

FULL SYSTEM

QUALIFICATION/

VERIFICATION MOHENTUH

COHP

ITEK TO FIRE LASER,

CHECK ALIGNMENT & VIBRATIONS

Figure 22.

ASSEMBLE AT ITEKLAWS Assembly and Test Flow

TELESCOPE WITH SPIN

MOTOR & MOUNT

CRYOGENIC

COOLER/COMP

ASSY

TO

ITEK

3.1 STRUCTURES AND MECHANICAL SUBSYSTEM

Figure 23 describes key analyses, trades, and verification plans for the LAWS Structures and

Mechanical subsystem (SMS). (The Thermal Control subsystem, which is part of the Structures

and Mechanical subsystem, is discussed in a separate section.) The major structural elements of

the SMS are the base platform, the telescope mounting pedestal, the optical bench, and the

telescope structure. The SMS mechanism is composed of the telescope motor/bearings with Vband caging device for offloading the beatings during ascent.

20

LOCKH EED-HUNTSVILLE
_] STRUCTURES & MECHANICAL DDT&E PLAN OVERVIEW

TASKS 1996 1997

MAJOR MILESTONES

Qualification Unit

Base-Design, Fab, Str Test

Bench - Design, Fab, Str Test

Mounts - Design Fab

Base Assembly

Telescope

Telescope Motor Bearing

Telescope Assembly

Mass Simulators

SMS Assembly

SMS Align, Balance, Test

1994

',,/x /x

ATP PRR PDR

3/94

I

8/94 r----'

2/95

1/94

6294

I

1995

/,,

CDR

7/95

"-'1

6/95

10/95

1/96

I

1/96

Flight Unit

Base- Fab. Struct Test

Bench - Fab. Struct Test

Mounts- Fab

Base Assembly

Base Instruments

Base Subsystem Assembly

Laser Subsystem

Bakeout & Assembly

LAWS Assembly

Alignment Tests, Bal, Wt

Telescope

Telescope Motor Bearing

Telescope Assembly & Bakeout

Mirror

Telescope Subsystem Assembly

Alignment Check

ff94

1/95

1/95

4/96

I

9/96

r-----

1/97

3/96

[

7/96

[--

1/97

4F37

7/97

4/97

10/97

1998 Z_, 1999

LAWS Ship

-- 1/98

KEY REQUIREMENT

Launch Vehicle Interface

• Shroud Envelope

• Interface Loads

Contamination

Strength/Dynamic Characteristics

Operational Life

Redundancy Management

Allignment/Stability

• Telescope Rotation

• Laser Pulse

• Thermal Deflections

• On Orbit Dynamics

• IG/OG Distortion

SMS REQUIREMENTS/VERIFICATION :

IMPLEMENTATION

Designed to meet envelope for max ascent loads

Contamination shield material selection

Designed for positive margins with adequate factors of safety & inert structural

frequency/stiffness requirement

Motor bearing design

Redundant motor bearings

Telescope dynamically balanced

Structure stiffness/shock mounts

Thermal covers/control

Structural stiffness design

Structural stiffness design

ATTITUDE DETER

./ FOLDOUT FRAME
2000 / 2001

/_/_ Launch

LAWS Bus

VERIFICATION

Test & Analysis .

Test & Analysis

Test & Analysis

Test & Analysis

Test

Test

Test & Analysis

Test & Analysis

Test & Analysis

Test & Analysis

_ATION SUBSYSTEM

LMSC-HSV TR F320789-1

DESIGN ANALYSES & TRADE STUDIES

ITEM

Optical Bench*

Base Structure*

Telescope Pedestal

Laser Mounts*

SMS*

SMS

SMS

SMS

SMS

ANALYSES

To determine weight/stiffness/strength optimum for Honeycomb or

multiple truss core

To determine weight/stiffness/strength optimum for GE member

size and tayup

To determineweight/stiffness/strength optimum for material

trade ar,d design

To determine laser pulse effects on telescope pointing

To determine sensitivity of telescope imbalance on telescope

attitude & optics alignment

To dete_Tnine the effect of gravitational field alignment at on orbit

conditions

To determine changing structural design effects on dynamic

modes & natural frequencies (thereby, attitude control)

To determine space platform effects on attitude control

To determine thermal distortion effects on attitude control and

optics alignment

*Ongoing analyses begun in Phase B.

PLANNED TRADE STUDIES

TRADE ITEM BASELINE DESIGN

Telescope Support Pedestal

Optical Bench Core

Base Thickness

Titanium vs. Graphite Epoxy

Honeycomb vs. Multiple Truss

Thick, Thin, Medium (completed)

I-_ SMS VERIFICATION SUMMARY

SMA Qualification Structure

w/Mechanism

SMS Flight Structure

in

,4 O O

.-- ¢1 _ ;g

O

¢_ _ ;> 0 0

0 -- 0 E m u)

0 _ "0 t-- _ 0 0

eu. cn :E n- I- '< o.

X X Q Q Q Q Q

X X A A A A A

X = Same Levels Qual/Flight

Q = Qualification Test Levels*

A = Acceptance Test Levels*

* = Levels Per MiI-Std-1540B

Figure 23.

312594-MT-FO

OverviewSummary of the Structures

and Mechanical Subsystem (1 of 2)

_.... LOCKHEED-HUNTSVILLE 21
DYNAMIC TEST PLAN/FEATURES i

Free-Free Modal Test

Measure dynamic stiffness of spacecraft interface via impedance test

Combine results of these two tests to produce fixed base mode shapes and natural frequencies

- Test article suspended by air bearings

- All suspension system modes below 2 Hz

- Pure random excitation

- -50 + acceleration measurements

- Modal curve fitting techniques extract mode shapes, natural frequencies, and modal dam

RISK SUMMARY

RISK ITEM RISK LEVEL RISK REDUCTION APPROACH

Structural Assembly Failures Low

Motor/Bearing Failure

SMS Attitude Control Failure

Optics Alignment Failure

Low

Low/Med

Low/Med

- Large strength margins

- Early identification and control of fracture critical items

- Redundant motor wiring

- Similarity with other flight proven units

- Dynamic analyses with respect to space platform perturbanc

- High rev dynamic balance of telescope

- Deflection analyses supported by tests

- Thermal deflection analyses and testing

- Dynamic analyses with respect to space platform perturban(

REQUIRED SUBSYSTEM EQUIPMENT

COMPONENT SOURCE HERITAGE FLT QUAL MOCKL

Base LMSC New

Bench LMSC New

Telescope Mount Vendor New

Motor Bearing Vendor Modified Flight Proven

Telescope Vendor New

Mirror Vendor New

Test Hardware:

Mass Simulators LMSC New

Test Fixture LMSC New

1 1

1 1

1 1

1 1

1 1

1 0

1 ea

1

/
i!i: :if:i:

ENG

LMSC-HSV TR F320789-1

PLANNED SMS ANALYSES

ANALYSIS TYPE ALL SMS ALL SMS SMS

EQUIPMENT STRUCTURES MECHANISMS

Strength

Dynamics

Thermal

Mass Properties

Producibility

Life Cycle Cost

FMEA

Reliability

Venting

Stress Controls

Performance

Math Model Verification

X

X

X

X

X

X

X

X

X

X

X

X

312594-MT-FO-2 of 2

PHASE B :_ _:;:_:_:_:: _: 1

MICsM_ __

Equipment packages are _/-----/_-_ "X_\_ j-_\

reproduced as point masses _,__%_ \_

(not plotted). /////_ \_ --_ \ _

1454G/iedSents /J'//_ \,/_\_ \/_ ////

Figure 23. OverviewSummary of the Structures

and Mechanical Subsystem (2 of 2)

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

The base structure design is composed of structural edge beams with internal cross beams

covered by top and bottom face sheets. All components are constructed from graphic epoxy for

light weight, high strength, and low thermal coefficient of expansion. Three kinematic mounts

provide the structural interface between the LAWS Instrument and the spacecraft. All

components are sized for the launch loads with the prescribed safety factors.

The base structure is the mounting platform for the laser, telescope, and the majority of the

other subsystem components. The subsystem components are mounted around the perimeter on

the edge beams. The location is based on thermal requirements to take maximum advantage of

passive heating or cooling.

The optical bench is attached to the base structure by three kinematic mounts. The optical

bench is a honeycomb structure with face sheets, and is made of graphic epoxy material for

minimum distortions and light weight. The seed laser, local oscillator, detectors, and all relay

optical system elements are mounted on the bench.

3.2 COMMAND AND DATA MANAGEMENT SUBSYSTEM

The Command and Data Management (C&DM) subsystem is composed of a flight

computer, Star Trackers (2), inertial measurement unit (IMU), and command and data transceiver

interface modules. The flight computer, applying associated software, provides autonomous

direction to the LAWS Instrument, controlling when the laser is to be fired to achieve

measurements for selected wind components. The flight computer also receives and executes

commands from the spacecraft via the bus data unit (BDU) and exercises stored math models to

compute the time associated with the telescope pointing angles for the laser pulses. The Star

Trackers and IMU are located on the LAWS Instrument baseplate. Outputs from these sensors to

the LAWS Instrument are managed by the attitude and position determination elements of this

subsystem. The command and data transceiver assembles and transfers data from the LAWS

Instrument to the spacecraft for transmission via data relay satellites.

All communications with the LAWS Instrument, to and from the spacecraft, and with the

NASA control centers are directed through the LAWS C&DM subsystem via the BDU. The few

interfaces not controlled by this subsystem are related to the LAWS spacecraft electrical,

thermal, and mechanical interfaces. These interfaces, however, are monitored and reported by

the health and status instrumentation sensors.

The flight computer controls laser shot management firing commands, computes orbital

platform position location, collects telescope line-of-sight azimuth angle values for each laser

shot, provides short time storage of wind data for transmission to the spacecraft data management

system and formatting of data into Consultative Committee for Space Data Systems (CCSDS)

format, and performs other command and data management functions.

23

LOCKH EED-HUNTSVILLE
LMSC-HSVTRF320789-1

Figures 24 and 25 describe the key analyses, trades, and verification plans for the LAWS

Command and Data Management subsystem and the Attitude Determination subsystem,

respectively.

3.3 ELECTRICAL POWER SUBSYSTEM

The block diagram of the LAWS power Electrical Power Subsystem is shown in Figure 26.

The spacecraft's two 120 Vdc (GIIS-specified) power buses are labeled Platform +120 Vdc bus 1

and Platform +120 Vdc bus 2. The PDS will derive two redundant 28 Vdc power buses from the

spacecraft's two 120 Vdc power buses. Each of the two buses will be capable of supplying all

power required by the LAWS Instrument. Since both buses will be active simultaneously, each

bus will supply half of the LAWS power load. For clarity, the redundancy of individual

components in the PDS is not shown. The PDS will supply 120 Vdc to the transmit laser and 28

Vdc to the other LAWS subsystems. Only power distribution to the transmit laser, computer,

and receiver is shown in Figure 26. Power distribution to other LAWS subsystems is similar.

As shown in Figure 26, circuit breaker 1 and circuit breaker 2 will protect the spacecraft 120

Vdc power bus from faults in the LAWS system. Circuit breakers 3 and 4 will protect the PDS

dc/dc converters from faults occurring in the individual LAWS subsystems. These circuit

breakers will be remotely resettable. If a circuit breaker trips, it can be reclosed by commands

from the flight computer or spacecraft. The LAWS flight computer will monitor the health and

status of the PDS and issue commands to the PDS.

Figure 27 describes the phase C/D schedule, requirements, components, and verification

summary for the PDS.

3.4 THERMAL CONTROL SUBSYSTEM

On-orbit thermal control for the LAWS Instrument is achieved by a hybrid form of thermal

control subsystem (TCS). An active fluid loop is used to transport the heat from high powered

components such as the main laser, oscillator, seed laser, and azimuth drive. The heat is

transferred through interfacing coldplates to be rejected to space via EOS central thermal bus

radiators. Heat is also rejected passively by radiation from external surfaces of all components

with an adequate field-of-view to space. Components are placed on the LAWS platform such

that, in combination with conventional passive thermal techniques, they are controlled effectively

within their allowable temperature limits by proper orientation during orbit (see Figure 28).

Passive thermal control is achieved by use of multilayer insulation (MLI), thermal coatings and

tapes, thermal covers, and thermal isolation materials. The passive TCS is based on HST TCS

design with a wide application of low t_/E atomic oxygen resistant Ag FOSR (a flexible optical

solar reflector composed of Teflon with vapor deposited silver) designed for a 15 year lifetime.

The TCS for the telescope and mirrors, although primarily passive, will need to be augmented

with heaters.

24

LOCKHEED-HUNTSVILLE
IEll •

TASKS

MAJOR MILESTONES

Design and Development

Eng. Support

Software

SW Reqmt Specification

SW Architecture

SW Development

SW Test & Implementation

SW Maintenance

1994

/x

PRR PDR

C&DM REQUIREMENTS/VERIFICATION

i

1995 1996 1997 1998 /

A

CDR LAWS Ship

7/94

11/94

i'--_--'-ls_ s

r------'_11 _

I_

I

)S

1999

Engineering Unit

Fab & Assembly

Sub Sys I & T

Sys I & T

OPS Support

Quantity Unit

Fab & Assembly

Sub Sys 1 & T

Sys I & T

Qual Test

8/94

r----

1/95

1

4/96

r---1

7/96

r

___._] 6/97

r'--1

9/97

1

7/97

[--------

1

1/99

L..._._ I

Flight Unit

Fab Assembly

Sub Sys I & T

Sys I & T

Bus Int

Bus/Veh Int

1/96

I

6/97

I-----I 7

r---

Suport Launch/Orbit Fit

Eng Operations

.... REQUIRED COMMAND AND DATA MANAGEMENT SYSTEM EQUIPMEN"

Bread- Development Fli

Component Source Maturity/heritage boards* Units U

Flight processor NASA

Observatory bus interface unit

Oscillator Lockheed

So Atlantic anomaly detector

*Number of cards to be bread boarded

Modified NASNESs 2

0 2

Modified HSI 0 0

Modified/HEAO-2 0 1
2000 L

LAWS Bus

2001

Launch

I

Spares

. d

RI=OUIREMENTS

[_ IMPLEMENTATION/'" ' -

.... VERIFICATION _ •

Requirement Implementation Verification

Merge ENG and SCI data FP, BDU T, S

Selectable fixed and FP T

programmable telemeW

formats

Command decoding FP T

witherror detection

Digitalprocessingwith FP A, I

100% margin

Timing accurate to 10"° FP, BDU A, S

in24 hr,time coding Oscillator

to within 100 izsec

of UTC

High energy protect MCU, OBS T, A

BDU, SAAD

*A = Analysis/simulation,I = inspection,

S = Similarity, T = test

r_ PLANNED TRADE STUDIES

Structured vs. object oriented tech.

ADA vs C language

RISK SUMMARY

Risk

Risk Item Level Risk Reduction Approach

Command

processing

TLM format

and rates

Computer

processes

Subsystem

integration

Safe mode

control

Low Utilize existing designs as

applicable. Engineering

Specialist (ES) to monitor

process flow.

Low Utilize existing formats as

available, provide hardwired

conflngenoy format. ES to

monitorprocess flow.

Medium New S/W design - ES to

evaluate HW/SW design.

Low Identified hardware/software

test facility. Critical path

monitored by ES. Assure QA

surveillance of parts used.

Medium Minor modification to existing

design. ES to monitor

standard process flow.

LMSC-HSV TR F320789-1

:t

r-_ vERIFICATION SUMMARY

Development testa

FP development test

Purpose: establish functional FP operation

Equip required: development unit,MCU

development cards, test equipment

Integrated avionics test

Purpose: establishfunctional CDMS

operation of the MCU with BIUs via the serial

bus

Equip required: tested MCU dev unit, a

tested OBS BIU development unit,a tested

St BIU development unit, a non-flight-item

oscillator,a vehicle systems simulator,and

the MCU test equipment

Environment: ambient

ShAD development test

Purpose: establish functional SAAD

operation

Equip required: SAAD dev unit andstandard

digital test equipment

Environment: ambient

Qualification/acceptance testa

On units shown above

Purpose: individualequipment qualification

Equipment required: per unit as shown

above

Environment: ambient, thermal vacuum,

thermal cycle, vibration, and EMI

SCIENCE INSTRUMENT

ACCOMMODATION PLAN

South Atlantic anomaly detectorprovideswarning to

instrumentsbased on software selectable thresholds.

Safe mode power control commands backup primary

science instrument power switching system.

DESIGN MARGINS "

. ._ AND GROWTH _ .

Processor sized to ensure 100% margininworst

case: average processor margin is 240%

Memory sized to ensure 100% margin in worst case;

average margin provided is 260%

Serial bus provide 320% margin at I MHz

Bus design allows for additional BIUs

BlU design allows commandand telemetry to be

added in discrete increments by adding appropriate

cards

Modular design allows the incorporation of new

technologies

Figure 24. OverviewSummary of the Command

and Data Management Subsystem

25 /_

LOCKHEED-HUNTSVILLE
i A'i-rlTUDE DETERMINATION PLAN OVERVIEW

1996 1997 1998 1999

/

TAS KS 1994 | 1995

MAJOR MILESTONES_, Z_ _ A z_

A TP PRR PDR ST& CDR

Design & Devel. IRU

5/94

Inertial Reference Unit _ Delivery

Star Tracker

5/94 1/95

Interface Design I .= 3_4

Software Req'ts i:_57/94194 11951

Software Development

Fabrication !1_s 7195

Mech. I/F I

Elec. I/F I

Thermal Protection j

Alignment IF I

Integration lO_5 11/95

Eng. Qual.Unit Unit ICE3 12/9._ 96

Flight Unit _98

Test support

Eng. Unit

Qual. Unit

Flight Unit

Engr. Support

Bus. Integration

LV Integration

Launch Support

Orb. Verification

12/94

Att. Deter. Simulation r

7/96

r--m

1/97 6/97

m!

LAWS Ship

6/98 12/98

1/99 2/99

12/98

REQUIRED SUBSYSTEM EQUIPMENT

COMPONENT* SOURCE QUANTITY/UNIT ENG. UNIT QUAL. UNIT

Inertial Reference Unit

Star Tracker

Mechanical Interface

Cables

* "S" Parts

AD1

AD2

LMSC

LMSC

1

2

3

6

1

2

3

6

**Engineering Unit Components Used for Spares
LMSC-HSVTRF320789-1

?.000

Z

LAWS

2001

X /X. Launch

/Bus

1/01 2/01

2/01

KEY REQUIREMENT

Operational Life

Performance

REQUIREMENT IMPLEMENTATION/VERIFICATION

IMPLEMENTATION VERIFICATION

5 yr on Orbit Comparison and Test

Analysis and

Simulation

Interfaces and Software

Functions

• Attitude Knowledge:

100 i_rad/Axis, One Sigma

• Receive Transmit Align:

3 _rad/Axis, One Sigma

• Pointing Accuracy:

8 mrad/Axis, One Sigma

• IRU Attitude Update

• Star Tracker Update

• Lag Compensation

• Receive-Transmit Alignment

Loop

Simulation and Test

2/04

,1

PLANNED TRADE STUDIES

TRADE ITEM

No. of Star Updates Per Orbit vs. IRU

Performance

On Orbit Recalibration Procedures for

Attitude Determination

Methodology of Compensating for Space

Platform Jitter; Active vs. Passive

BASELINE DESIGN

10 Updates/Orbit, Scale Factor Error < 75 PPM,

Gyro Drift Rate Uncertainty < 0.01 deg/hr

Use Hard Target Return to Recalibrate LOS of

Outgoing Laser Beam

Passive; Use Isolators Between Base Assembly

and Optical Bench as Required (Need Goddard

to Supply Jitter PSD of Space Platform)

RISK ITEM

IRU Failure

Star Tracker Failure

Misalignment Due to Zero g

312594-RJ-FO and Launch

RISK SUMMARY

RISK LEVEL RISK REDUCTION APPROACH

Low

Low

Moderate

Space Qualified and Demonstrated Unit

with Built-in Double Redundancy for

Each Attitude Axis

Space Qualified and Demonstrated Unit

Develop Methodology to Recalibrate

Using Hard Target Returns

Figure 25. OverviewSummary of the

Attitude Determination Subsystem

LOCKHEED-HUNTSVILLE

f
I-"

O

O

X

"I"

m

m

E3

C

Z

--I

r--

rm

Platform

+120V

Bus 1

-¢

Platform

+120V

Bus2

LAWS

,+_2v

1-711'!!'1[

I

DC/DC

Converter

1

LAWS

+120V

Bus 2

LAWS

+28V •

H*H

Transmit

Laser + 28 V

Computer + 28 V

Receiver + 28 V

Transmit

v Laser + 28 V

Computer + 28 V

"_ Receiver + 28 V

F320789-27

r-

(/)

9

I

(n

<

0

(D

Figure 26. LAWS PDS Block Diagram
E_] ELE(:TRICAL POWER DISTRIBUTION SUBSYSTEM OVER_

TASKS 1995 1998 1999

MAJOR MILESTONES

Design PDU

PDU Procurement

Fabricate PDU

Engineering Unit

Initial PDU Test

Assemble LAWS

Engineering Unit

Test LAWS

Engineering Unit

LAWS Engineering Unit

Support Operations

Fabricate PDU

Qualification Unit

PDU Qualification Test

Fabricate PDU

Flight Unit

Assemble LAWS

Flight Unit

LAWS Flight Unit Tests

LAWS/Spacecraft

Integration and Tests

1,94

1994

1/95

5/94 1/95

r'-'-"-------

1195

1/95 5/95

"--'---1

7/95

I

7/95 1/96

1/96

1996 1997

_96

I

7/96 _97

I

]

5/96

[

1/96 _

5/96

L

1

7i97

I

6/97

J

6/97

L

10/97

I

1/99

1/99

LAWS/Spacecraft/Vehicle

Integration and Tests

Launch

Orbital Verification

1/94

Design Software

Implement and Test

Software

Maintain Software

Write PDU test plans

and procedures

Design PDU Special

Test Equipment (STE)

Fabricate PDU STE

Initial STE Test

5/95

I

10/@5

: • :i:i:i:)i _:iii!i;_i_ii:ii:Jii!iii_i!_ i:!:i_ii!_,REQUIRED SUBSYSTEM EQUIPMENT:Iii;;_;_i!_i_!_

" i:::

COMPONENT SOURCE MATURITY/HERITAGE MOCKUPS ENGINEERING UNIT

Power Distribution Unit

Cables

LMSC Modified/HST

LMSC Modified/HST

1

28

1

28

FOLDOUT FRA_4_

/
LMSC-HSV TR F320789-1

_W ::

2000 2001

1/01

1/01 3/01

3101

O

3/01

I

1/0_

_] REQUIREMENT IMPLEMENTATION/VERIFICATION

KEY REQUIREMENT IMPLEMENTATION VERIFICATION

28 V + TBD Vdc

TBD W of power

Energy storage

Circuit protection

Redundancy

dc/dc Converter output

voltage = TBD Vdc

dc/dc Converter output

voltage = TBD W

Batteries

Remotely resettable circuit

breakers

Multiple parallel components in

power path; two redundant

isolated power busses

I

PLANNED TRADE STUDIES

NT

AfT

NT

NT

A/T

Distributed vs. centralized power distribution units

RISK ITEM

PDU Failure

RISK SUMMARY

RISK LEVEL RISK REDUCTION APPROACH

Low Space qualified parts, redundancy, system testing

r-_ VERIFICATION SUMMARY

Acceptance, development, and verification testing per MIL-STD-1540

I

I

Standard power control ::!:ii_::i ::.:and distribution SI ACCOMMODATION::, interface

I

QUAL. UNIT

1

28 I FLIGHT UNIT

1

28

F320789-02

: DESIGN MARGIN AND GROWTH :

Multiple power buses rated for 20% growth in loads

Figure 27. OverviewSummary of the

Electrical Power Subsystem

2, 3

LOCKHEED-HUNTSVILLE

L,-_/LDOU'I F
/

/

LMSC-HSV TR F320789-1

Y

/

/

Y / LAWS Base

_- / (Z axis towards nadir)

Telescope

Earth Shadow _

¢ f

/ _ Orbit Plane

Figure 28. LAWS Instrument in Earth Orbit

SUN

Figure 29 shows the passive thermal coatings for the telescope and LAWS base components.

Figure 30 presents the Phase C/D summary for the development of the thermal control system.

3.5 OPTICAL SUBSYSTEM

The LAWS Optical subsystem has two major functions. It first acts as a transmitter in the

role of a beam expander, taking the 4 cm output of the 9.11 _tm laser and forming a 1.67 m

diameter beam which is scanned via a bearing assembly across the Earth's atmosphere.

Secondly, it performs the function of a receiver, acquiring the Doppler shifted scattered energy

from the troposphere. The Optical subsystem interferes with the LAWS laser via the transmitter

relay optics and with the LAWS receiver at the tip/tilt mirror, which performs dynamic lag angle

compensation.

The Optical subsystem functional flow diagram is shown in Figure 31. The selected baseline

design for the telescope is a two-mirror afocal configuration operating with a split field. With a

F/1.5 primary mirror, the telescope fits within the current packaging envelope. The transmit

optic axis is oriented off-axis by 0.2 deg in objects space in order to remove the course lag angle

resulting from the telescope scanning in azimuth and the round trip time for each transmitted

laser pulse. Compensator optics are required in the transmit path to balance focus error from

telescope field curvature. The receive channel is oriented on-axis. Pupil relay optics are required

to limit the size of the radiation through the scan bearing over the entire :k-0.3 mrad object space

29

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

field-of-view. The pupil relay also creates a real pupil at which a single tip/flit mirror can correct

for second order dynamic lag angle compensation.

SHOWING PASSIVE TCS FOR TELESCOPE

NADIR

Z y (Se0_nd:prY0rMdlerrp00rsit)

/_"" Secondary Mirror Si

,,,,,,,

, PrlmaryapM0rr°r p0slt)

Secondary Mirror Support Legs

Dtnmtlonof /

Right X /

Note: • T4delcope not shown

for clarity

• FOSR - FlextbleOp(ICSISolar

Reflect¢_(Vapor delx_lted

AI ¢xrAg on back of TsiIon)

AI teflon tape outside)

NOTES:

• Average total absorbed orbital

heat fluxes used as the tetascope revolves.

• Temperaturesshown .re

minimum randrnaxlmum

considering orbitbeta angle

Structure rsnge of sr to 9ooand 3 sigma

orbitalparameters (AI teflon tape)

NADIR

(Ag FOSR) .

(_ FOSR)

(MU - TedIu

o,u_r layer)

(White ZS3Pmt- outskk

AI Kapton - mkle)

Envlronmeltll/Tlltrnlll

Coverlot OpUc=

(*J FOSa)

honeycomb) MM

Figure 29.

(B_)

FlightComputer

(Black)

/

/

Cryo-cookprController

Thermal Radiation Model Plot of LAWS Instrument Showing Passive TCS

Surface Coatings

3O

LOCKH EED-HUNTSVILLE
_1 THERMAL CONTROL SUBSYSTEM DEVELOPMENT, TEST AND EVALUATION PLAN OVERVIEW

1994 1995

Z PRR/XPDR /kcDR

I

leqmts Def. & Allocation

Laser Gas Flowlo Analysis & Design

I I

J

Coolant Loop Analysis & Design

I I

Telescope & Moun! Ana ysis & Design

I I

!

Optical Bench Thermal/Alignment Analysis

I I

!

Telescope Mirror Analysis

I I

Passive Contro ed Components Analysis

I I

I

Pump Life Test (Development)

1996

I

Pump Functional Test

I

Caracitor/Heat Exchanger Test

, I

Inte_luid Log Test

Passive "IV Test

i I

Integrated Active/Passive

[ I

1

1997

Pump Life Test (Qual)

I

Qu al Test Fab

I I

I

Component Level Qual Test

I I

I

"IV TCS Comple :eSystem Test I

Flight Unit Fab

I I

I

Flight Unit TV TCS Test

Flight Compone!t Tes[ ]

I 1 I

1998

Qual Test of all Systems

I

Ship

2001

/x

Launch

Flight Unit to Bus Integration&Checkout

I

Flight Test of all Systems

] I gis to Veh Integration

COMPONENT

Pump Package

Pumps

Cold Plates

Diverter Valves/Controllers

Heat Exchangers

Ag FOSR

MLI

Heaters, Kapton

LIFE ENGINEERING

SOURCE MATURITY/HERITAGE TESTING MODEL

Supplier 1 1

Supplier 1

TBD

Supplier 1

TBD

Supplier 2

Supplier 2

Supplier 3

Space Qual/Space Lab

Space Qual/Space Lab

Same as EOS

Space Qual/Shuttle

Modified/Breadboard

Off the Shelf/HST

Off the Shelf/HST

Off the Shelf/HST

2

1

2

TBD

TBD

TBD

QUAL

UNIT

2

1

2

TBD

TBD

TBD

FLIGHT SPARES

UNIT

1 1

1

2

1 1

2 2

TBD

TBD

TBD

FOLOOUT
-'] TCS REQUIREMENT IMPLEMENTATION/VERIFICATION

KEY IMPLEMENTATION VERIFICATION

REQUIREMENTS

1. Maintain laser gas temp

at all PRF

2. Five year life on active

cooling system

3. Maintain temp limits of

components for all

mission phases

4. Control of thermally

sensitive optical bench,

telescope & mirror/

supports

5. Minimize contamination

of optics

6. Design for 5 year atomic

oxygen environment

7. Decouple optics from

orbit environment

Convective heat exchanger

within active cooling loop

Redundant pumps

_).Maintain struct temp

gradients and changes to

meet pointing requirem"ts

Active cooling and passive

Ag FOSR outer surfaces,

MLI

Controlled by FOSR, heaters,

ULE optics, gold coatings

Optical bench thermal cover as

contamination collector and

spatial separation of fluid lines

from optics

Teflon Ag FOSR, Aa = 0.012

per year based on flight data

Thermal covers, Ag FOSR outer

surfaces, low mE external,

thermal isolators

Analysis, test

Life test

Analysis, TVT

Analysis, TVT

Analysis, Tv'r

Analysis,

LDEF data

Analysis, TVT

8. No single point failure Redundant pumps, valves Analysis

heater systems

9. Maintain hardware and Safe mode developed with Analysis

components above heaters/thermostats to maintain

survival temperatures component above lower survival

limits

Thermal cover, Ag FOSR and

heater system

Analysis, TVT

D_ ::TCS TRADE STUDIES AND ANALYSIS

1. Position of passively controlled avionics components on the base.

2. Compact convective heat exchanger versus back-to-back cold plates for

EOS/LAWS active thermal control interface.

3. Pumped loop versus heat pipe active TCS.

4. Redundant loops versus single loop with redundant pumps for active TCS.

5. Existing space qualified pump packages versus new development

long life pumps.

6. Passive versus active cooling of main laser power supply.

J •

E-_ :_:_il;i:_::iiiZii::!:ii:ii:iiii:_ii,: :::,_:: iil Tcs,:_:RISK RE DUCTION SuM MARYii::ii i.:.:_.:_:< ii_ill ii::::iiiiiiiiiii:: _:_:_:_:_:: iii:_iii ..:_:iiii_iii_i

RISK LEVEL RISK REDUCTION APPROACH

Five year pump life

Five year valve life

Five year life of other TCS compon.

Contamination due to outgassing

Contamination due to coolant leaks

Contamination due to

biological growth in coolant

High Life testing & redundant pumps

Med Cyclic testing

Low Stable materials

Low Material selection, bakeout & design

Low Use of brazed joints and leak

containment devices

Low Sterilization system

LMSC-HSV TR F320789-1

VERIFICATION SUMMARY I

I L°ad ___ I

I Su_ey/Design Mode J

I

Laser

Breadboard

Test

TCS

Component

Tests

Math

Model

TCS

Design

Integrated

Tests

Test VerifiedTCS

I _::_i:_iiiiiii; MARGINS AND GROWTH_i!ili_i;iii:

1. Using hot and cold design cases with 3_ fluxes

2. Range of equipment duty cycles and MLI/thermal coating performance

3. Heaters sized 1.5X required at minimum bus voltage

4. Controlling to levels well within requirements

5.2.0 x pump life

6. Redundant pump controller and power circuits

7. Redundant heaters & heater thermostats 312594-11

Figure 30. OverviewSummary. of the LAWS

Thermal Control System

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

FROM

TRANSMITTER

Tip/Tilt

Lag Angle

Compensator

l

RECEIVER

Transmitter

Compensator Transmit/

Optics Receive

Telescope

'H I

Periscope Receiver

Follower Pupil Relay

Optics Alignment

Sensor

Secondary

Motion

Control

312594-23

Figure 31. Optical Subsystem Functional Flow Diagram

The periscope follower is a two-mirror assembly which rotates synchronously with the

telescope to fold the receive radiation back on axis. Telescope alignment is monitored by

additional active sensors and maintained by actuators controlling the location and orientation of

the secondary mirror. Other design features include a lightweight system with a 90 percent

lightweight ULE primary mirror, silicon carbide fold optics, and graphite epoxy structures. The

low residual waveform error is due to a low sensitivity design, the alignment maintenance

system, and the use of ULE with its virtually zero CTE and variation of CTE.

The Optical subsystem development schedule is shown in Figure 32 (block A). The major

long lead time items are the ULE blanks for the 1.67 m primary mirror. The first primary will

require approximately 9 months to fabricate.

Subassemblies for various units are listed in Figure 32 (block B). Key requirements,

implementations, and verification approaches are also shown in Figure 32 (block C).

3.6 RECEIVER/PROCESSOR SUBSYSTEM

The Receiver/Processor subsystem baseline is summarized as follows:

• Redundant HgCdTe photovoltaic detector arrays with 52 percent effective quantum

efficiency at 100 MHz and 43 percent at 1300 MHz (47.5 percent average)

• Mixing efficiency of 0.33 for uniformly illuminated annular aperture with ratio of

inner to outer diameter of 0.44

32

LOCKH EED-HUNTSVILLE
_] /_:i:! ̧

Design &

Development

Preliminary design

Final design

Fabrication

Engineering Unit

Qualification Unit

Flight Unit

Integration

Engineering Unit

Qualification Unit

Flight Unit

Test Support

Engineering Unit

Qualification Unit

Flight Unit

Engineering Support

Sustaining Engineerin!

Bus Integr. Support

Launch Support

On-Orbit Calibration

& Align Support

5/94

|

6/94

I

OPTICAL SUBSYSTEM OVERVIEW

1996 1997 1998 [

LAWS

Ship

6/96

7/96

I

2/97

3/97

I

2/97

I

1999

11/97

i

8/97

I

12/97

9/97

I

7/97

I

12/98

I

10/98

I

6/98 12/98

I

1/99 I

REQUIRED SUBSYSTEM E( !UIPMENT

COMPONENT* SOURCE QUANTITY/UNIT ENGINEERING.UNIT QUA!

Primary Mirror Assembly

Secondary Mirror Assembly

Metering Structure

Reaction Structure

Transmit Relay Optics Set

Receive Relay Optics Set

Fold Optics Set

Thermal Control System

Azimuth Scanning System

Tip/Tilt Mirror

Telescope Alignment System

Mechanical, Thermal, Electrical,

and Optical Interfaces

* "S" Parts

Litton-ltek Optical Systems

Itek

Itek

Itek

Itek

Itek

Itek

Itek

Itek

Itek

Itek

LMSC

**Engineering unit components used for spares

1

1

1

1

1

1

1

1

1

1

1

5

1

1

1

1

1

1

1

1

1

1

1

5
000 2001

LAWS/Bus _,Launch

6/01

i

=500 I

91_01 1

FLIGHT UNIT**

1

1

1

1

1

1

1

1

1

1

1

5

LMSC-HSV TR F320789-1

I

REQUIREMENT IMPLEMENTATION/VERIFICATION

KEY REQUIREMENT

Operational Life

Maximize Heterodyne

Efficiency

Lag Angle Compensation

IMPLEMENTATION

5 years on orbit

• Wavefront error _<0.07

waves RMS

• Flat field over receive FOV

. Obscuration < 3%

• Round trip pointing stability

_<1.5 prad

• Magnification: 42X

. Format: 2 points separated

in field by 0.185 °

• Dynamic tip/tilt mirror

VERIFICATION

Comparison and test

Analysis, simulation, and

test

Analysis and simulation

PLANNED TRADE STUDIES

Baseline Design

Fully Passive

Control

Tube/

Tripod

ULE

Alternate Design

Partial Heater

Control

hermalized Metering Rods/

Truss Metering Tube

Graphite

Epoxy

I

Passive

Radiator

Fused

SiC Silica

ULE SiC Metal

(Rods) (Rods) Matrix

I FuyPassive I IAOveD° e I

i I No Radiator Heat Pipe

RISK ITEM

Motor/Bearing/Encoder

Optical Coating Fatigue

Telescope Alignment System

F320789-07

•i•71

_. i_ii; RISK SUMMARY

RISK LEVEL RISK REDUCTION APPROACH

Low Space qualified and demonstrated unit

Low Risk reduction testing with LAWS laser

breadboard

Low Risk reduction testing with alignment

system breadboard

Figure 32. OverviewSummary of

Optical Subsystem

33

LOCKHEED-HUNTSVILLE ,_

_ _,_ _ _T F_-_,ME_
LMSC-HSV TR F320789-1

• Signal aligned on central element of array with exterior elements for alignment

monitoring

• Local oscillator beam tailored for central (signal) element for shot noise limited

operation with phase front matched to signal beam; spill over to alignment elements

• Redundant Split Stirling Cycle cryogenic coolers to optimize detector operating

temperature

• Redundant Split Stirling cycle cryogenic coolers to optimize preamp operating

temperature

• Bias supply and preamplifiers space-qualified versions of standard units

• Automatic gain control for wide dynamic range between aerosol and ground returns

• 10 bit 75 million samples per s analog-to-digital (A/D) converter for adequate wind

signal frequency response and dynamic range.

The LAWS Receiver/Processor subsystem consists of a wide bandwidth photo detector

array, active cooling for the photo detector, bias circuitry, preamplifiers, and on-board signal

processing electronics. For each of these components, several options were considered before

the selection of the baseline Receiver/Processor subsystem components.

Figure 33 is the Receiver/Processor subsystem block diagram. The local oscillator optical

source (upper left hand comer of Figure 33) from the master oscillator is expanded to match the

4 cm diameter of the beam received from the telescope before being focused on the photo

detector. The Doppler signal is received from the telescope and optical train, superimposed on

the local oscillator, and directed toward and focused on the photo detector array. Cooling is

provided for the detectors. Outputs from the detectors are amplified and frequency shifted to the

frequency/amplitude range of the A/D converter. The "zero" Doppler (relative to the ground) is

set for the center of the 0 to 30 MHz baseband to minimize A/D frequency span requirements.

The levels of each channel from the detector array are measured to monitor the received optical

signal spot location upon the detector array for optimal alignment. The output of the A/D is

buffered and telemetered to the platform data interface. The Receiver/Processor development

schedule is shown in Figure 34.

3.7 LASER SUBSYSTEM

The CO2 Transmitter Laser subsystem is shown in the block diagram in Figure 35. The

following components make up the Laser subsystem:

• Optical resonator

• Electrical discharge

• Pulse power supply

• Pressure vessel structure

• Gas flow loop

34

LOCKHEED-HUNTSVILLE
I-"

O

O

I

m

m

0

C

Z

--t

<

rrm

F312599-DW-02

Redundant

Receiver Frequency

Synthesizer

From Computer /

Channel #2 Return Radiation (High S/N /

Channel #3 Position on Measurements) /

Channel #4 DetectOr Array /

Channel #5 /

\ /

\ /

Optical /

\

Alignment Control _,. /

Scanner

Position

/

/

I'-

z:

O0

9

I

<

:13

0

",,4

Figure 33. LAWS ReceiverProcessor Subsystem Block Diagram
TASKS

MAJOR MILESTONES

Design & Devel.

Detector Arrays

Electronics

Bias, Amps, SW

A/D, Controls

Optics

Cryo Coolers

Interfaces

Software

Fabrication

Components

Interfaces

Integration

Eng. Unit

Qual. Unit

Flight Unit

Test Support

Eng. Unit

Qual. Unit

Flight Unit

Engr. Support

Bus. Integration

LV Integration

Launch Support

Orb. Verification

Att. Deter. Simulation

RECEIVER / PROCESSOR PLAN OVERVIEW

1994 1995

LA A A

ATP PRR PDR CDR

8_

1996 1997

1998 Z_ 1999

LAWS Ship

r------I

3/94 1195

' I

! I

1/95 7/95

12194

I

I

9/95 11195

r--i

--1

1196

6/96

1/97 6/97

5/98 12/98

1/99 2/99

"-i

12/98

REQUIRED SUBSYSTEM EQUIPMENT

COMPONENT* SOURCE QUANTITY/UNIT ENG. UNIT QUAL. UNIT

Detector Array

Support Optics

Support Electronics

Bias ckt, Amps

A/D Conv., Controls

Cryo Cooler Assembly

Cables

RP 1

RP 2

RP3

RP4

LMSC

LMSC

2

1 set

1 set

2 sets

4

2 sets

2

1 set

1 set

2 sets

4

2

2

1 set

1 set

2 sets

4

2

* "S" parts

** Engineering unit components used for spares

FOLDOUT FRAME
Z_ _.2o01Launch

LAWS/Bus

1/01 2/01

%I

FLIGHT UNIT**

2

1 set

1 set

2 sets

4

2

F320789-01

LMSC-HSV TR F320789-1

REQUIREMENT IMPLEMENTATION/VERIFICATION

KEY REQUIREMENT IMPLEMENTATION VERIFICATION

Operational Life • 5 yr on orbit Comparison and test

• No single point fail Analysis and test

Performance

Interfaces and Software

Functions

• A/C quantum effect

• Closed loop tracking

• Acceptable aging

• Temperature control

• Data handling/control

• Ground retum alignment

• Automated gain control

• Data digitization & storage

• System performance

monitor

Measurement

Analysis, measurement

and simulation

Measurement, analysis,

comparison

Measurement and analysis

Simulation

Simulation and test

I

r_ PLANNED TRADE STUDIES

TRADE ITEM BASELINE DESIGN

Cooled vs. uncooled Amps

Number of pre-amps for signal detector

Redundant vs. nonredundant

Adjustable focus vs. fixed miniscus lens

Dual tip-tilt vs. single for L.O. adjustment

Number of array elements

Cooled where noise figure is improved

Baseline is four switched pre-amps

Redundant detectors and coolers

Adjustable focus

Dual

Four alignment plus central

RISK SUMMARY

RISK ITEM

Detector Failure

Loss of S/N from

misalignment

Cooler failure

RISK LEVEL

Moderate

Moderate/Low

Low

RISK REDUCTION APPROACH

1. Produce several batches of detectors and perform

accelerated aging tests.

2. Design with redundant detectors.

1. Design for graceful S/N loss from misalignment.

2. Design for low BW on orbit alignment correction.

1. Lockheed developing/qualifying under EOS-A

contracts.

I-_ PERFORMANCE ENHANCEMENT TOOLS

ITEM

Detector A/C

quantum efficiency

POTENTIAL ENHANCEMENT

Perform 18 to 30 month development/test effort; anticipate 30 to 60 %

performance improvement.

Figure 34. OverviewSummary of the

ReceiverProcessor Subsystem

36

LOCKHEED-HUNTSVILLE

FOLDOUT F=_.'_
LMSC-HSV TR F320789-1

I

I

I

PLATFD_'_

POWERI

120 VDC _

POwERPLATFORtl ._

120 VDC

LASER

PS.

INJECTION

LASER

P.S. _2

I GAS HANOL ING _ GAS RESERVOIR

LASER HE A0_I_

INJECTION ]_ RESONATOR

LASER • I I

I

INJECTION DISCHARGE

LASER w2

I LOCAL

OSCILLATOR

I OSCILLATOR LOCAL

.__ OUTPUT

DEAN

PULSE POWER FLOW LOOP ,I,

TO

TELESCOPE

H.V. POWER DETECTOR

SUPPLY

CATALYST

COOLING COOLING

INTERFACE SYSTEM

......

OHPUT I

CAVITY MATCHING ALIGNMENT

ELECTRONICS

Defense Systems

FLIGHT PROCESSOR ._

AUTOALIGNMENT

SOFTWARE

MODULE FAILURE I DATA HANDLING I

HANOL ING MODULES

SOFTWARE MODULE MOOULESAND SIGNALCOII'IANO I

Figure 35. Laser System Block Diagram

• Controls and instrumentation

• Injection laser

• Local oscillator.

The physical layout of the Transmitter Laser subsystem is shown in Figure 36. Its general

configuration is fundamentally that proposed in Phase I. Modifications of note are removal of

the resonator optics from the pressure vessel, the addition of a contraction to the flow loop, and

relocation of the catalyst beds upstream of the heat exchangers. The functional interaction

between the Transmitter Laser subsystems is outlined in Figure 35.

The transmitter laser and its power supply are mounted to the LAWS base structure, while

the other components are mounted to the optical bench. This design feature, plus load isolators

used to mount the laser, provide sufficient vibration isolation to the Optical subsystem from the

laser acoustic impulses. Redundant injection lasers and local oscillators are a feature of our

design for high reliability.

37

LOCKH EED-HUNTSVILLE
LMSC-HSV TR F320789-1

!1

f IN,JECTION

VIN_WS

FH/i$ /

/

i i

i .I.

, i

I

, !

I I

t

f

-P------- 24"0

I i

i

i

I . i .

1: I _

"LL.... ..L__..L__J

¢_¢_ SCRAP( / __._¢C nUTPUT

_, )[AM

PZT/GRATING [_]

//

F'LI3V LOOP

/ DtJTLINE

48"

Figure 36. Laser Transmitter

Optical Resonator. The optical resonator configuration, shown in Figure 37, closely resembles

that of the breadboard design. Although some design parameters were modified to accommodate

the interface of the transmitter with LAWS optical bench, care was taken to ensure that

performance parameters such as mode discrimination and sensitivity to misalignment were not

adversely affected. The key resonator parameters are listed below.

• Type unstable

• Equiv. fresnel no. 1.56

• Magnification 2.25

• Cavity length 3.0 m

• Gain length 1.5 m

• Beam size 4x4 cm.

The resonator is of the unstable type, with a conventional concave primary mirror and a

lens/grating combination acting as the feedback mirror. A folded cavity configuration was

chosen for compactness, with both folding mirrors partially reflecting.

The seed laser fight is injected through one of the folds with the single longitudinal mode (SLM)

detector monitoring the light transmitted through the same fold. The intensity of light

transmitted through the opposite fold is measured by a cavity matching detector. Information

from the "finesse" curve thus obtained will be used by the cavity matching electronics to adjust

the piezo-electric transducer (PZT) drive on which the feedback assembly is mounted.

38

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

_. ....... -f,

I

I

I

I

t

I

TRANSMIT LASER

POWER SUPPLT

TRANSH|T LRSER

J

/"

, f

I

!

I

Defense Systems

Figure 37. Resonator Optics Layout

Laser output energy is extracted by a scraper mirror located near the feedback assembly and

measured by the pyrodetector located between the scraper and the telescope. The primary and

scraper mirrors will either be made of copper or dielectrically coated silicon substrates, while the

folding mirrors and pressure vessel windows will be made of ZnSe to allow alignment in the

visible regime.

Flow/Discharge Subsystem. These assemblies have been defined as one subsystem because of

their high level of mechanical integration and functional interdependencY. As Figures 38 and 39

indicate, the layout closely matches that of the breadboard. Differences arise primarily in the

choice of materials and addition of redundant components wherever failure mode analysis and

breadboard lifetime tests indicate a need.

39

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

FLOW

TUBE/FIN HEATEXCHANGER

INLINE CATALYTIC MONOLITH

WINDOW

LOOP SUPPORTS

CONNECTOR

IMPELLER OUTER SHROUD

CROSS FLOW BLOWER

CONTRACTION (PERFORATED)

MUFFLER

CATHODE

HI VOLTAGE FEEDTHRU

CATHODE HOUSING

PREIONIZER

FLOW CONDITIONING

PRESSURE VESSEL

24 IN. OUTSIDE DIA

Defense Systems

Figure 38. LAWS DischargeFlow Loop, End View

IPPORT CENTER COUPUNG & FAN SUPPORT

IMPELLER OUTER SHROUD

:ROSS FLOW BLOWER

PREIONIZER

WINDOW MOTOR&

MAGNETIC

COUPLING

CATHODE

H.V. FEEDTHROUGH

FLOW LOOP

SUPPORTS

PERFORATED PLATE

TUBE/FIN HEAT EXCHANGER

_) Side View PRESSURE VESSEL

24.12 OUTSIDE DIA

VACUUM CONNEC_ON

Figure 39. Two-Electrode Configuration, Side View

40

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

A UV preionized self-sustained discharge scheme was chosen with four electrode pair

modules (two per side) providing redundancy and eliminating alignment and current distribution

problems associated with long electrodes. A modified Ernst profile was selected for the cathode

based on extensive electrostatics code calculations substantiated by the DVT results. A flat

anode profile was chosen for flow compatibility and compactness. Preionization is achieved

through holes in the anode utilizing a dielectric/corona bar assembly. The preionizer housing

dielectric material can be machined and is impermeable. The relevant operating parameters of

the discharge are listed below.

• Gas mixture

• Gas pressure

• Discharge dimensions

• Pulse length

• Specific energy loading

• Discharge voltage

3:1:1 He:CO2:N2

0.625 atm

4.2 x 4 x 150 cm

3.2 - 4.0 l_S

86 J/L

21-23 kV

Flow Loop. The flow loop is designed to accommodate the discharge assembly described in the

previous section. It provides fresh gas to the discharge and moves the used hot gas at the

appropriate speed to prevent arcing. This gas is subsequently reconditioned by the catalyst bed,

where recombination of CO and O into CO2 dissociated during the discharge occurs.

Subsequently, the thermal energy resulting from the inefficiencies inherent in the laser kinetics

processes is removed by a fan and tube heat exchanger. The sidewall mufflers, located in both

sides of the cathode, attenuate the acoustic waves generated by the discharge in order to maintain

the homogeneity of the lasing medium in the cavity below the levels dictated by beam quality

and cavity matching requirements.

Key features of the flow loop design are the dual tangential fans chosen for both

compactness and modularity, the contractions upstream of each discharge which assist in

restoring flow uniformity, and the skewed positioning of the catalyst bed and heat exchanger

which provides compactness and causes a gradual equilibration and cooling of the hot gas. This

last feature minimizes density perturbations to the laser medium which could otherwise affect the

medium homogeneity in the cavity. The relevant flow parameters are listed below.

• Mass flow rate

• Flow velocity in cavity

• Fan speed

• Cavity flush factor

• Available catalyst volume

• Porosity of muffler wall

23 g/s

1.26 m/s

1700 rpm

3.0 at 10 Hz

12.6 L

3 percent - no packing resistance

Backup Design: 30 percent - 1 cgs rayls/cm

41

LOCKH EIED-HUNTSVlLLI=
LMSC-HSV TR F320789-1

Pulse Power. The pulse power system in a discharge pumped CO2 laser is formed by three

primary components: a high voltage dc-dc converter, a pulse forming network (PFN), and a

thyratron. The function of the high voltage power supply is to step up the 120 Vdc prime power

input to the 40 kV charge voltage required by the PFN. The PFN in turn is charged by this power

supply and, upon switching by the thyratron, generates a pulse with the desired length as well as

voltage and current characteristics. The pulse energy is subsequently discharged into the gas by

the discharge assembly described in the previous section. A functional diagram of these

processes is shown in Figure 40.

01$¢,OI_ECT

6_aTC,H

120Vdc+1-10%_

Pt_ITORM

MONITOR

SlGNN.S

&

FAULT

gGNN.S

I_IERFACE

me,-

V"

40Kv

OUTPUT

(

A3Vdc

MOOULE$

TOO_Wt_

V,OOUES

I

I

J 1

I

-I

120Vde

PLA_OflM

Figure 40. Energy Discharge Processes

The configuration of the PFN, shown in Figure 41, will be an E-type, thyratron switched

scheme similar to that utilized in the breadboard. Primary differences will arise in the choice of

lighter weight, space qualified components, particularly capacitors, and the use of redundant

critical components such as the thyratron, capacitors, and diodes. Also, because operating the

PFN in a pressurized environment would result in a considerable weight penalty, vacuum

operation is anticipated. This will require mounting components on a coldplate and active

cooling of the thyratron. The operating parameters of the pulse power subsystem are listed

below.

• Total energy stored in PFN 264 J

• PFN charge voltage 40 kV max

• PFN current <2.5 kA

• Total capacitance 400 nF

• Pulse length 4.5 ps max

• PRF 10-15Hz

The development schedule for the Laser subsystem is shown in Figure 42.

42

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

L

P2518

t

6

I

_t__

1

2_

++ ,

f

6

I

SCREWS

28 MIN.

I" t_°°__°+c

38kV DC

I . . ,

,,

RES._ / i

PLAN VIEW

i J

----f--

6

L

I

GRID PULSER

AND 120V - lkV

CONVERTER

I

ELEVATION VIEW DIM. IN tNCHES

Figure 41. Preliminary Layout of Pulsed Power Section

43

LOCKHEED-HUNTSVILLE
LASER TRANSMITTER PLAN OVERVIEW

TASKS

MAJOR MILESTONES

Engineering Unit

Design & Spec. Prep.

Procurement:

Long Lead Times I"

Assembly/Construction &

Check Out of Components

Functional Tests of Sub- I

Assembly Comp. Chk. Out

Shock/Vibration Tests

Subsystem integration

Laser Tests @ TDS

Eng. Unit Laser Tests

@ LMSC

Qualification unit

Design & Spec. Prep.

Procurement

Construction

Functional Testing of

Laser subassemblies

Subsystem integration

Laser Qualification Tests

@ TDS

Qual. Unit Laser Tests

@ LMSC

Flight Unit

Procurement: Long Lead

Items

Fabricate, Assemble, Wire

Funct. Testing

Subassemblies

Subsystem Integration &

Laser Testing @ LMSC

1994

' ZX ZX

ATP PRR PDR

6/94

10/94 I

I

I

1/95

7/94

r_

1995

/k

CDR

1996

SHIP ENG

UNIT TO

LMSC

6/96

r

1997

5/95

I

6/95 __

!

1/96

4/96

lO_6r-/

LASER

I&T

1/96

QUAL UNIT TESTS 9/97

1998 1 1999

LAWS Ship

I

SHIP FLIGHT 10/96 ] UNIT TO

LMSC 6298

9/97

r-------

REQUIRED SUBSYSTEM EQUIPMENT

COMPONENT* SOURCE QUANTITY/UNIT ENG. UNIT QUAL. UNIT FLIGHT UNIT**

Pulsed Power Laser

Discharge Cavities

Flow Loop/Fans/Catalyst

Pressure Vessel

Pulse Forming Network

Thyratrons

Pulsed Power Supply

Optical Resonator/Bench

CW Injection Laser

Single Mode PZT Controller

CW Local Oscillator Laser

Controls and Instrumentation

Alignment Laser and Mechanism

Laser Thermal Control System

TDS

TDS

TDSNOP

TDS

TDS

TDS

ALE

TDS/LMSC

MPB

BURLEIGH

MPB

TDS

ITEK

TDS

1

2

1/2/2

1

1

2

1

1/1

2

1

2

1

1

1

* "S" parts

** Engineering unit components used for spares

1

2

1/2/2

1

1

2

1

1/1

2

1

2

1

1

1

1

2

1/2/2

1

1

2

1

1/1

2

1

2

1

1

1

1

2

1/2/2

1

1

2

1

1/1

2

1

2

1

1

1

F320789-050

®

Fan Failur

Individual

Catalyst C

Thyratron

PFN Cap_

Feedback

Mirror Dar

FOLDOUT FR_:L_iiE/'
}00 _, 2001 //_ Launch

LAWS/Bus

LMSC-HSV TR F320789-1

REQUIREMENT IMPLEMENTATION/VERIFICATION

KEY REQUIREMENT IMPLEMENTATION VERIFICATION

Operational Life and Reliability • 5 yr on orbit

• 109 Shots

Performance

Interfaces and Software

Functions

• 9.11 lain (C18 02)

• 20 J/Pulse

• Single mode pulses

• 3 p.p FWHM pulse length

• <200 kHz CHIRP

• 4.67 Hz scan mode "1.xrd2

• 10 Hz design mode ] (max PRF)

• Flight P,,ocessor

- Auto alignment SW

- Failure handling SW

- Data handling SW

- Signal & Command SW

• Telescope control system

• Platform Power Control System

• Platform Thermal Control System

• Beam Detector System

• Gas Handling System

I-DI PLANNED TRADE STUDIES

TRADE ITEM BASELINE DESIGN

Extended Life Tests

• Components to > 109

• System to > 3 x 108

Design for;

Robustness and

Key Component

Redundancy

Performance Validation Test

• Breadboard

• Eng Unit

• Qual Unit

• Flight Unit

Simulation and test

Discharge Parameters

• Gas mixture composition

• Gas pressure

• Electrodes/Preionizers materials

• Cavity dimensions/Gain length

• Voltage/Energy Loading

• Flush factor

Resonator Parameters

• Magnification

• Scraper geometry

• Cavity reflectivity

Flow Loop Parameters

• Catalyst configuration

• He : C18 O2 : N2 = 3:1:1

• 0.625 atm

• Proprietary

• 4.2 x 4 cm/150 cm

• 35 kV/80 J/L

• 3.0

• 2.25

• Square (square vs. circular)

• Uniform (uniform vs. graded)

• Dual in-line Beds, 400 cells/in2

RISK SUMMARY

RISK ITEM RISK LEVEL RISK REDUCTION APPROACH

Moderate 1. Dual fans provide redundancy; laser can operate on one fan.

charge Arc or Preionizer Failure Moderate 1. Redundant preionizer and associated discharge modules.

2. Operation at lower discharge voltages to reduce probability of arcing and failure

amination Probably Low (not yet 1. Catalyst reactivation heaters, flushing of pressure vessel laser gas refill,

established) plus pre-launch clean room and bake out procedures.

Moderate 1. Backup provides redundancy.

Jr Short Circuit Moderate 1. Isolate faulty capacitor, switch in backup spare.

rror PZT Drive Failure Low 1. Robust design is essential.

ge or Contamination Risk not yet established 1. Robust design and cleanroom and bake out procedures to minimize effects.

.age or Contamination Risk not yet established 1. As above; also addition of lasing mixture, cope with a small crack.

Figure 42. Laser Transmitter

SUbsystem Summary

LOCKH EED-HUNTSVILLE
LMSC-HSV TR F320789-1

Section 4

LASER BREADBOARD

An 18 month laser breadboard effort was initiated in January 1991 to demonstrate the

performance parameters and shot life requirements of the LAWS system. The breadboard effort

was to be performed concurrent with the Phase II design to provide high fidelity between the

flight configuration and the breadboard and maximum feedback of test results for the design

activities.

The goals of the breadboard program were to demonstrate

• Output parameters at 10.6 I.tm in normal CO2 mixture

• Output parameters at 9.11 _tm in isotopic CO2 mixture

• Lifetime at 10.6 I.tm on the order of 108 shots.

A comparison of the transmitter laser flight design requirements and the breadboard design

goals is given in Table 3. Figure 43 shows the breadboard system in block diagram as it exists in

the Textron Defense System laboratory. To make full use of the available contract funds, all

hardware components were developed and supplied on LMSC and TDS fixed asset funds.

Contract dollars were used for DVT, breadboard setup and integration, system analysis, and

testing and data analysis.

Table 3. LAWS Transmitted Requirements and Breadboard Design Goals Compared

LAWS

Transmitter

Breadboard

Energy Per Pulse

Pulse Width

PRF

Beam Quality

Wavelength

Beam Mode

Chirp

Lifetime

Weight

Wall-plug Efficiency

F320788-33

15J

__2.5 laS

10 Hz (avg); 16 Hz (peak)

1.2

9.11 lain

Single transverse &

longitudinal

<100 kHz

109 pulses

200 kg

> 5%

15 - 20 J

2.5- 3 tts

10 Hz (life test @ 20 Hz)

1.1

10.6 and 9.11 lxm

Single transverse &

longitudinal

<200 kHz

108 pulses (goal)

Not applicable

Demonstrate laser extractior

efficiency and project wallplug efficiency

45

LOCKH EED-HUNTSVILLE

DefenseSystems
O

O

x

I

m

m

o

c

z

.-t

m

<

rrm

DISPLAY UNIT

LASER

CONTROLLER •

VHE CHASSIS-.

ALIGNMENT

TELESCOPE

PHOTODIODE ......

SPECTROMETER

PHOTODIODE

BEAM DUMP

CALORIMETER

P2456

LASER GAS

REPLENISHMENT

SOURCE

/

/

/

/

/

INJECTION.

ELECTRONICS

RESONATOR

OPTICS

SPECI ROMEI ER

\.

F3 t 2599- HC02

HeNe ALIGNMENT

LASER

HETERODYNE

DETECTORS CHILLER

BEAM DUMP

FLOW LOOP/DISCtlARGE

VESSEl_

/

PULSE POWER

UNIT

LASER POWER

VACUUM SUPPLY

SOURCE

Defense Systems

rZ:

Or)

9

-r

(n

<

_o

0

-',4

Figure 43. LAWS Breadboard System Block Diagram
LMSC-HSV TR F320789-1

First laser beam was accomplished on 21 April 1992, less than 16 months after program

initiation. Other major milestones are listed below.

• Demonstrated single mode operation at 7 J and 10 Hz

• Demonstrated 20 Hz operation at 5 J

• Measured low chirp at 3 Its pulse length

• Measurements show very small beam jitter.

The laser breadboard in the first of its kind to reach single mode output at this energy and

pulse rate.

Our breadboard has built-in flexibility without sacrificing traceability to the flight hardware.

It has the demonstrated capability to operate at a variable repetition rate and energy levels, so test

data can be obtained at the LAWS baseline design levels as well as the relevant downsized

LAWS system. A new data base has been established for gain, rate constants, and intrinsic

efficiency of laser operation in isotopic 12C1802 gas mixtures over a wide range of operating

temperatures. Low chirp, which is essential for lidar operations, has been demonstrated near the

baseline LAWS design point. Lifetime in excess of 108 shots has been demonstrated for corona

UV preionizers, which is an improvement of two orders of magnitude over previous life of

corona preionizers.

In the LAWS laser breadboard program, we have built a piece of hardware that represents

the cutting edge of CO2 lidar technology. The close-cycle repetition operation of a CO2 laser

utilizing a self sustained corona UV preionizer and an in-line catalyst has been demonstrated for

the first time. Also, single mode laser operation has been demonstrated at output energy and

pulse length higher than any existing device.

We are confident that, with an extended breadboard test program over the next 18 months,

laser lifetime can be adequately demonstrated to proceed with full scale development of flight

hardware.

47

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

Section 5

DOWNSIZED LAWS

Recent discussions between NASA Headquarters and the LAWS Science Team have led to

the consideration of a downsized LAWS configuration of a 5 to 7 J/pulse laser and 0.75 m

diameter primary mirror telescope. While not satisfying the original Science Team requirement

of measurements to backscatter coefficients to 10-11 m "1 SR "1, this would still provide significant

global wind measurement data in subvisible cirrus, cloud tops, in the boundary layer, and during

significant volcanic events.

Trade studies were performed on the S/N loss to be experienced for various reduced laser

energy levels and primary mirror diameters (Figure 44). For a 5 J/0.75 m LAWS system, a

13 dB loss over our baseline would be experienced.

5

-20

J

1.67 m

1.50 m

1.25 m Mirror

Di

1.00 m (rt

0.75 rn

0 5 10 15 20 25

LASER PULSE ENERGY (J)

Figure 44. S/N Performance for 525 km Orbit

48

LOCKHEED-HUNTSVILLE
LMSC-HSVTRF320789-1

Our downsized configuration is shown in Figures 45 and 46. The volume envelope of the

delta shroud allows adequate space for the LAWS Instrument, with a full length telescope

shroud, and more than 3.2 m of length for the spacecraft.

F'AI:RING

LAWS / OP

INTERFACE

-_ _'_" ,

E 7

-":-_ I /" ii!

I _L-I__.--4-L._ i _

I I[

I il, l'l

.:::L:l"-:.q

DIMENSIONS IN METERS _3.212

SPACE AVAILABLE

FOR BUS

_-OELTA PAYLOAD

= ADAPTER ENVELOPE

Figure 45. LAWS Telescope with O. 75 m Diameter Mirror in Delta Fairing

Figure 46. LAWS Instrument Fit-Check in Delta Fairing

49

LOCKHEED-HUNTSVILLE
LMSC-HSV TR F320789-1

Analyses have shown that the downsized configuration is well within the allocated power

and weight budgets. Initial weight calculations show a total Instrument weight of 599 kg. A

comparison of constant power requirements for the various subsystems is given in Table 4 for

baseline and downsized configurations. A 106 W reduction is possible.

Table 4. LAWS Electrical Power Comparison

iiiii!iiiiiiiiiiiii !! i iii i ii! !i !iiiiiiiiiiii i!iii!!!! ! iiiii i! !! !!ii!i ! i!!ii!i!iiiiii

Constant Power/Thermal Load

Laser

Laser Fans

Thyratron Filament]Reservior

Local Oscillator

40 40

135 135

30 30

_,iDownS_ Electri_ i:,:, ii_iiiiiiii!_

i!;ii!i!iiiiiiiii iiiiiiiiiiiiiiiiiii ii iWi i; iiiiiiiii ili!i iiiiiiiiiil

Seed Laser

Receiver

Optics

Azimuth Drive

100 100

80 80

30 30

20 20

135 135

30 30

70 70

80 80

Moment Compensator

Telescope Thermal Control

Electrical Power Distribution

Thermal Control

Flight Computer

Attitude and Position References

Total Constant Load

Variable Load

Total (fixed and variable)

15 15

40 40

10 10

66 66

15 15

48 48

609 609

1,537 3,333

t 2,146 3,943

10 10

15 15

20 20

4 4

66 66

15 15

48 48

503 503

513 1111

1,016 1,614

Orbital thermal analyses show that the temperature ranges between hot and cold cases are

well within the allowable temperature with the passive thermal control materials and coatings

design shown (Figure 47). The corresponding cost impact of the downsized configuration is

given in Section 6 of this report.

50

LOCKH EED-HUNTSVILLE
LMSC-HSV TR F320789-1

C

(Black AI Teflon)

-6 to +8 °C

Hinge Mech

(AI Teflon)

-44 to -23 °C

Shroud

(Black Inside, AI

Teflon Outside)

-30 to -10 °C

(AI Teflon)

-64 to -50 °C

Cover Lid

Secondary Mirror

(Black Inside, AI (VD Gold on Chrome)

I Teflon Outside) °C -15 to 0 °C -4 to 21

Ring

(Black)

-21 to 4 °C

I Secondary Mirror

Support Legs

(Black)

-21 to 1 °C

_ Cover Support

Bracket

(AI Teflon)

(VD Gold on Chrome)

-22 to 1°C

F32ge_.3g

Notes:

• Average total absorbed heat fluxes

used for the revolving telescope

• Orbit Beta angles of 59 ° and 90 °

considered

• Cold and hot orbit parameters

considered

Figure 47. Preliminary Steady-State Temperatures on Downsized LAWS Telescope

51

LOCKH EED-HUNTSVILLE
LMSC-HSV TR F320789-1

Section 6

SUMMARY

The LAWS Phase I and Phase II studies have been completed on schedule and have led to

significant advances in CO2 laser development. The Phase II Design Definition study has shown

that a large scanning mirror/high pulse energy laser LAWS Instrument is feasible and within the

existing technology. The capability to monitor wind velocities with backscatter ratios of 10"11

m -1 SR -1 is feasible. The weight budget allocated for the baseline LAWS is adequate, and

sufficient reserves exist with the potential downsized configuration.

With the possible decrease in available power from the baseline of 2.2 kW guideline, power

and shot management is critical for the baseline configuration (15 to 20 J). This is particularly

true during the 100 day occultation period each year.

With the downsized configuration (5 to 7 J), power management is still necessary during the

occultation but is primarily limited to shot management over the polar regions.

The breadboard effort has produced significant laser advances for a tight 18 month schedule

and the minimum budgets available from NASA, Lockheed, and TDS. Using the NASA funds

and Lockheed and TDS fixed assets budgets, the breadboard was designed, fabricated, and

brought on-line with first laser light within 16 months after ATP. First laser beam was obtained

on 21 April 1992 at a 5 J power level. Tests since then have been conducted at sustained,

repetitive pulse levels of over 7 J and 20 Hz. This is an increase of over two to three times

greater than any system previously developed from this type laser. Increased power levels and

additional life tests will be accomplished in the next LAWS phase.

The Lockheed LAWS design will operate in the gravity gradient mode on-orbit, and all

possible Instrument vibration and jitter modes have been considered. Adequate pointing stability

and control is state-of-the-art technology for the critical time periods, frequency rates, and

control responses required by LAWS.

Lockheed recommends a 6-1/2 year phase C/D program for LAWS to provide adequate

feedback from the engineering unit and the qualification unit to the final flight unit. Assuming a

one year period for LAWS integration to the spacecraft, followed by a six-month period for

launch vehicle integration, LAWS could be successfully developed and launched in eight years.

Our baseline design or downsized design can be accommodated by either the Atlas IIAS or the

Delta launch vehicles.

Lockheed's recommendation is that, based on the successful Phase II design study and

breadboard program, a follow-on 18 month extended breadboard testing program and additional

system engineering studies, primarily in interfacing with a to be defined platform, be initiated.

This should be immediately followed by the Phase C/D program, leading to a LAWS launch in

late 2001 or early 2002.

52

LOCKH EED-HUNTSVILLE