# Presentation: 329877

## Section 28

_***Section 28***_
***Enhanced Formation Flying***

*** ******. . . Dave Folta***
*EO-1 EFF Technology Lead, GSFC Code 572*

## Performance Required

***Performance Required***

***Mission Orbit Requirements***
***Paired Scene Comparison Requires EO-1 to Fly in Formation With Landsat-7. ***
***Maintain EO-1 Orbit With Tolerances Of:***
*One Minute Separation Between Spacecraft*
*Maintain Separation So That EO-1 Follows Current Landsat-7 Ground Track to +/- 3 Km *
***Derived Orbit Requirements***
***~6 Seconds Along-track Separation****** Tolerance (Maps To +/- 3km WRT******  Earth Rotation)***
***Plan Maneuver in 12 Hours***
***Derived Software Constraints***
***Code Size approx. <650Kbytes***
***CPU Utilization approx. <50% Average***
***      ******over 5 Hours ***
***Less than 12 Hours Per Maneuver Plan***

** ****EO-1 Formation Maneuver Frequency Is **
**     ****Ballistic Dependent**

## EFF Design

*Thruster Commanding*

*Command and *

*Telemetry Interfaces*

*Timed Command Processing*

*Propellant Data*

*Thruster Commands*

*GPS State Vectors*

*Uplink*

*Downlink*

*Inertial State Vectors*

**AutoCon Control Flow**

- MG5 & Interfaces

## EFF Verification Approach

***EFF Verification Approach***

***Level-1:  AutoCon-G***
***Using a PC and Workstation Environment to Develop, Test, Provide High Fidelity Simulations, Script Development, and Proof of Concept Fuzzy Logic Rules.  ***
***Level-2:  Software Test Facility***
***Using Mongoose Breadboard With Flight Software, Test All Interfaces to the ACS and C&DH for Telemetry and Commanding.  Utilized Simulated Tensor Data and Noise. ***
***Level-3:  Spacecraft***
***Using Spacecraft Mongoose Etc.,  Test Against “Realistic” CPU Loading, GPS Constellation Simulator and Tensor, Etc.***

## Subsystem Level

***Verify***
*EFF*
*AutoCon-F*
***GSFC***
***JPL***
***GPS Data Smoother***
*SCP*
*Algorithm Flight code Uploads for JPL*

## EFF Verification Matrix

***EFF Verification Matrix***

## EFF Test Results

***EFF Test Results***

***AutoCon-F Numerical Benchmark Testing***
***AutoCon-F Was Benchmarked Against AutoCon-G for Each Build***
***EFF/AutoCon-F MG5 Testing ***
***Will It Fit and Execute on the EO-1 MGV Processor ***
***EFF/AutoCon-F Interface and Numerical Accuracy Testing Performed on the Test String From October 1998 to August 1999***
***EFF/AutoCon-F Testing on EO-1 (>20 Hours of Testing Onboard) ***
***EFF/AutoCon-F Successfully Executed on EO-1 in April 1999***
***Round 1 of CPT in July Found Increasing Time Required for Maneuver Planning and Unacceptable CPU Utilization***
***Round 2 of CPT on September 1 Passed All Test Criteria***
***EFF/AutoCon-F Successfully Executed During Thermal Vac in October 1999***
***GPS Smoother Testing***
***Conducted on the Test String Using Simulated Tensor Data***
***Conducted Spacecraft Test on February 14, 2000 Using Real Tensor Data From Simulated GPS Constellation***

## EFF CPT Test Results

***EFF CPT Test Results***

- _CRITERIA__	__PASSED_
***GSFC Targeter Produces Maneuver Plan******	************	***
***GSFC Targeter Maneuver Consistently Reproduced******	****** ************	***
***JPL Targeter Code Uploaded******	****** ************ ******	***
***JPL Targeter Produces Maneuver Plan******	****** ************ ******	***
***CPU Utilization Within Limits*****	**** ********** ****	**

## CPT Test Timeline

***CPT Test Timeline***

***2353L ******	******EFF_cpt.prc started***
***0004L******	******Table upload complete***
***0016L******	******GSFC targeter produced first maneuver plan***
***0025L ******	******GSFC targeter produced identical maneuver replan***
***0025L ******	******JPL targeter code uploaded started***
***0115L******	******JPL targeter code upload completed and JPL maneuver ******	******	******planning started***
***0200L******	******JPL targeter produced maneuver***
***0201L******	******GSFC targeter tables started being reloaded***
***0208L******	******GSFC targeter table upload completed and GSFC targeting******	******	******restarted***
***0217L******	******GSFC targeter produced identical maneuver replan***
*0220L Test complete.  EFF left running on spacecraft to simulate a heavy load on the spacecraft for the remaining CPT testing.*

## Configuration Changes

***Configuration Changes***

***EFF Tested During S/C CPT***
***Parsing of Execution to Minimize CPU Utilization******	******-******	******Logic Error***
***Code Changes for Step Size Control of Propagator******	******-******	******Code Error***
***Storing of Spacecraft State Table******	******-******	******Initialization  Error***
***GPS Leap Second Sign Change******	******-******	******Logic Error***
***EFF Tested in Thermal Vacuum***
***No Changes***
***Positive Independent Verification Of EFF Made Using Test Bed and Ground Software, AutoCon-G***
***Improvement made to GPS smoother after first GPS constellation sim in December 1999***
***Improvements to EFF targeter resulting from extensive simulation of targeter algorithm performance in AutoCon-G***

## Action Item Status

***Action Item Status***

***High Degree of Confidence That EFF Flight Software Functions Correctly and Will Be Able to Successfully Autonomously Control EO -1 / Landsat7 Formation***
***On-orbit Check Out Procedure Will Allow for Software Adjustment Via Scripts,Table Loads, and Patches***

***Readiness &Residual Risk***

***Action***
***None***