# Presentation: 019533

## Section 24

_***Section 24***_
***Lightweight Flexible Solar Array***

*** ******. . . John Lyons***
*EO-1 Lightweight Flexible Solar Array Lead*

## Team Members

***Team Members***

***John Lyons******	******GSFC LFSA Lead******	******>20 years space solar***
***	******	******array experience***
***Gene Fosness******	******AFRL LFSA TO******	***
***Bernie Carpenter******	******LM-Denver LFSA Lead******	******>10 years ***
***Jerry Draper******	******LM-Denver Mechanical******	******>10 years******	***
***Kristi Mederos******	******LM-Qual Testing, Verification******	******4 years***

## Description

***Description***

***Copper Indium Diselenide (CuInSe2 or CIS) Thin-Film Solar Cells ***
***Deposited on a Flexible Kapton Blanket suspended in a Composite Frame***
***Frame Deployed Using Shape Memory NiTi Alloys and a Launch Restraint Device***
***Advantage: Increase solar array w/kg (from typical 40 w/kg to >100 w/kg), increase science payload mass fraction ***
***Partners: AFRL (Kirtland AFB, NM), NASA/LaRC, Lockheed Martin (Denver, CO)***

## Description (continued)

_***LFSA FLIGHT UNIT***_

_***SMA - DEPLOYED***_

_***SMA - STOWED***_

***Description (continued)***

## CIS I-V Curve Sweep Block Diagram

## Shaped Memory Deployment Heater Block Diagram

## Validation

***Validation***

***Demonstrate Controlled Deployment ***
***Use Shape Memory Actuation to release launch retention mechanism followed by activation of shape memory hinges***
***Material is heat-treated in deployed position during fabrication, then low-temperature material (martensite phase) is deformed into stowed shape. When material is heated (as during deployment), the original heat-treated shape is recovered. After heater is turned off, heat-treated shape is maintained.****** ***

## Validation (continued)

***Validation ****(continued)*

***Evaluate Photovoltaic Performance ***
***Monitor LFSA current, voltage, temperature trends to determine on-orbit degradation in Vacuum, Thermal Cycle, Radiation, Atomic Oxygen Environments***
***Determine if degradation is consistent with ground test results; if there are any synergistic effects due to combined environments, isotropic particle irradiation (rather than monodirectional, monoenergetic)***
***Critical to have this data before building and flying an operational LFSA with CIS***

## Lightweight Flexible Solar Array Operations

***Lightweight Flexible Solar Array Operations***

***L&EO Operations***
***Performed at around Launch plus 7 days***
***Deploy LFSA array via commanding the release of a stow pin, which in turn allows shaped memory hinges and deployment systems to deploy the LFSA***
***Deployment should take ~30 seconds and will be done during eclipse exit during a pass while instrument operations are not occurring***
***Weekly On-Orbit Operations***
***Perform LFSA I-V Curve Sweep data collect***
*Use stored commands to: enable storage of LFSA data, start I-V Curve Sweep mode, change mode back to normal, and disable LFSA data storage*
*I-V Curve Sweep takes 10 seconds*
*Performed in sunlight, with the preference that the spacecraft be in a position where the sun is at an optimal angle on the array (i.e., near 90****)*
*Provide data (FDSS STK data) from which LFSA validation team can derive sun angle during data collect*
*Provide LFSA validation team a time history of LFSA raw and calibrated telemetry gathered during I-V curve collects in tabular and plot forms via Excel*
***Special On-Orbit Operations***
***Perform additional I-V Curve Sweep data collects (up to 3 / orbit) – as requested ***

## LFSA Verification

***LFSA Verification***

***Tests at Lockheed Martin***
***Thermal (non-vacuum)***
***Random Vibration (15 grms, 3 min/axis)***
***Thermal Vacuum (8 cycles, -40 to +80°C)***
***Functional Tests***
*Deployment*
*PV Output*
*Electrical Performance*

## Functional Testing

***Functional Testing***

***LFSA***
***Launch Restraint Release and Deployment***
*Verifies working of shape memory release mechanism and panel hinges*
***CIS Solar Panel I-V Curve Sweep***
*Verifies working of photovoltaic array*

## LFSA Test Flow

***Note:  LFSA included in S/C vibration test (mechanical only)  but not powered on (except for thermistor readings) during Thermal Balance/Vacuum Testing.***

## Reviews

***Reviews***

***Telecons******	******	******	******	******Peer, periodically***
***Box CDR, PSR (telecon)******	******	******	******Peer***
***CDR******	******	******	******	******	******System***
***Delta-CDR******	******	******	******	******System***
***PSR******	******	******	******	******	******System***

## Critical RFAs/PRs

***Critical RFAs/PRs***

***PR #:***
***839-30-7******	******     Only 3 screws are mated to the LFSA ******	******	******	******     electronics box. 17 screws appear to be ******	******	******	******     missing.***
***Disposition:***
***LM was aware of it, this was not a final delivery of LFSA.******(All screws were in place for final delivery).******	***
***PR #:***
***889-30-2, 889-30-6******	******     Switch status reads "Deployed"******	******	******	******	******	***
***Disposition:***
***Switch position affected by gravity. Does not affect LFSA performance. However, shims were installed so the switch would be closed while LFSA is stowed in 1 g.******	******	******    ******	***

## Special Topic:

***LFSA Repair, Modification, and Re-Integration***

*** ******. . . John Lyons***
*EO-1 Lightweight Flexible Solar Array Lead*

## LFSA Power Interface Issues

***LFSA Power Interface Issues***

***Post S/C environmental testing and final integration of LFSA with S/C indicated problem with readout of I-V data, which was diagnosed as power up sequence error  in software code within the LFSA microcontroller***
***Further examination of power interface logic from S/C to LFSA indicates that a “smart short failure scenario” in LFSA might result in degraded power services (+5V,15V,******-15V) to main S/C processor, putting mission at risk. ***
***Decision made on 11/24 to modify LFSA power interface to accept unregulated 28V input rather than current (+5,-15V, +15V) interface.***
***Plan developed with LM to modify current power interface and correct  microcontroller software:***
***Delta CDR (modified power, re-qual requirements) held Dec 3rd***
***Functional testing with S/C on Dec 20th***
***Environmental requalification (vib, thermal, EMI) Dec 20- Jan 15th***
***Reintegration with S/C on Jan 17th***
***Revised interface allows LFSA microcontroller to be powered up separately and turned off if it causes any problems.***

## Lightweight Flexible Solar Array(Revised Power Interface)

## LFSA Power Interface Issues

***LFSA Power Interface Issues***

***1)******	******Develop and present Delta CDR - Dec 3rd******	***_***Complete***_
***2)******	******Lockheed Martin to modify LFSA to ******	***_***Complete***_
***	******accommodate new power interface and ***
***	******functionally test unit with new ***
***	******micro-controller software at LM - 12/17/99***
***3)******	******Swales to modify and test S/C harness******	***_***Complete***_
***	******to new interface (before Dec 16) ***
***4)******	******Lockheed Martin to functionally test LFSA ******	***_***Complete***_
***	******with S/C at GSFC 12/21 ***
***5)******	******Lockheed Martin to perform environmental ******	***_***Complete***_
***	******re-qualification of LFSA at LM and GSFC  ***
***	******(thermal cycle, vibration at LM, EMI at GSFC)***
***	******Dec 27- Jan 12***
***6)******	******Reintegration of LFSA with EO-1 S/C - Jan 13******	***_***Complete***_

## LFSA Mechanical Issues

***LFSA Mechanical Issues***

***Mechanical/Structural Issue - Oren Sheinman***
***Concern raised that LFSA may inadvertently deploy during launch.***
*Took part in S/C vibration test, no problems*
*Re-performed random vibration test on all three axis as per original EO-1 Swales Environmental specification after rework to requalify it for launch, no problems*

## LFSA Summary

***LFSA Summary***

***Recent reintegration and test demonstrated no residual risk to spacecraft***
***No Redbook candidates***
***LFSA ready to fly***