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ARMADILLO – SHOT II

The University of Texas at AustinPost-flight Analysis

Travis ImkenShaina Johl

Christopher McBrydeTravis Sanders

July 1st, 2012Boulder, CO

Mission Overview

The ARMADILLO SHOT II payload will verify the systems-level functionality of multiple subsystems on ARMADILLO1. CDH computer boots and interfaces with subsystems2. Flight software executes and stores data to SD card 3. COM uplinks and downlinks4. EPS provides constant and steady power5. GPS collects data and calculates position6. NVS (camera) collects pictures of the flight7. Magnetometer measures Earth’s magnetic field8. Pressure/temperature sensor collects flight data

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Expected Results

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From the mission objectives:1. CDH computer boots in 120 seconds with automatic

interface to subsystems2. Flight software executes all code and data is recorded3. COM internally indicates downlink *(ground radio deaf)4. EPS provides power for whole flight5. GPS has a position fix and records all visible satellites6. Camera takes pretty pictures7. Plausible magnetic field measurements8. Relevant pressure and temperature measurements

Quick Recap

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ARMADILLO systems integration flight was a mixed success:• Four complete successes (and the pressure sensor too)• Two partial successes and one failure, all with understandingMany ARMADILLO lessons learned… and we’re still smiling!

Results: Success and Failure – 1

1. CDH Computer and Kraken• First log file created after 90

seconds (Linux boot complete) and no hardware restarts– Matches flatsat and SDL results

• Log files created for all interfaced subsystems. Software logs indicate interfaces with COM, NVS, GPS, and magnetometer were established with no errors

2. Flight Software and SD Card• Flight software automatically

executed on boot launching four separate executables

• Data streams established with all data collecting subsystems and recorded to SD card

• SD card data parsed after flight on ground station computer with no errors

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Results: Success and Failure – 2

3. COM Downlink and Uplink• COM software enabled radio and

transmitted packets as shown by collected log file

• No packets were received or transmitted by ground station handheld radio due to handheld hardware failure before SHOT– Tests prior to SHOT departure

showed GS radio deaf at 20 feet – UT Austin ground station antenna

(200 feet away through building) received packets perfectly.

• Results as expected, but unable to independently verify success.

4. EPS Power Distribution• Power provided for flight and

field-sitting – 2.4 hours!• Components used a peak of 15

watts (COM transmit) and averaged 10 watts on 3.3 and 5V

• Voltage drop from 8.04V to 7.33V (~65% power capacity used) and is much better than expected

• 5V current limit may have been reached (next slide) by EPS protection design

• EPS heaters were not activated

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Results: Success and Failure – 3 5. GPS Data and Analysis

• GPS powered on, interfaced by CDH, and created log files• Log files were not populated with data indicating no satellites seen• All antenna connections good and GPS still operational• Lab tests (on power supply) indicated all hardware functionalFailure Analysis – Most Likely Scenario:• GPS assembly nominally draws 5V 1.5A but occasionally spikes to 1.7A• EPS limits 5V to 2.5A. Sum of other components and GPS likely caused

limit to be hit, resetting the GPS and preventing fix from being establishedARMADILLO Impact and Lessons Learned• Balloon GPS assembly had additional interface boards to process data and

communicate with the old CDH interface board. This board consumes an additional 2.5W (0.5A) and is not for flight.

• ARMADILLO power budgets cycle GPS modes and power to prevent this (Power-current budgets established pre-PDR and kept up-to-date) 7

Results: Success and Failure – 4 6. Camera taking pictures for the presentation

• NVS operated as expected on in-house software and took 264 pictures, but…Flight pictures looked like this: And should have looked like this:

• Contrast settings in software made everything white due to sunlight• Camera software configured from SDL star tests (lots of black pictures)ARMADILLO Impact and Lessons Learned• Easy in-house software fix to make aperture/contrast controllable for using

flight camera for star tracking, visual navigation, and pretty images

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Saturday room picture

Results: Success and Failure – 5 7. Magnetometer Measurements

• 110 minutes of magnetometer data collected at 10 Hz.• Magnetic field magnitude within 3% of expected values from National

Geophysical Data Center

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Results: Success and Failure – 6 7. Magnetometer Measurements Continued

• Three axis measurements are plausible but will require analysis• Appears to have little interference from other electronics. ARMADILLO

flight is more isolated and includes shielding.

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Results: Success and Failure – 7 8. Pressure Measurements

• Ground pressure measured to be 14.4 psia – very plausible!• Max altitude pressure measured to be 0.35 psia – very plausible!• Temperatures varied inside:

– 26C at launch– 10.4C minimum inside– Up to 50C in the field – toasty!

• Would have been nice to correlate with GPS altitude data from ARMADILLO or EOSS

• Altitude correlation could be compared to atmospheric pressure and temperature models of the atmosphere

ARMADILLO Impact and Lessons Learned• Interior was warm with ~50% of the flight hardware in the box• CubeSat thermal control is important and iterates the need for analysis

(already part of the UNP deliverables!)11

Results: Success and Failure – 8

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LAUNCH

POW

ER

ON

BURST?

TOUCHDOWN

TEMPERATURE

PRESSURE

GROUND COOKING

Conclusions

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The ARMADILLO SHOT II payload was an overall success.• All subsystems were operational with mixed data success• EPS provided power longer than expected• Flight-like software and flight-like CDH hardware configuration

performed exactly as planned with no errors• All hardware recovered in working order for continued EDU

development and PQR preparations• Plenty of things to go back to Austin and work on after

catching up on sleep!

Actions for ARMADILLO

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Action Items:• Diagnose GPS unit health and performance upon return to UT• Perform similar Flatsat test with EPS and monitor current and validate

against current budgets• Incorporate various software tweaks for camera and flight software• Diagnose our handheld ground radio for future testing• Continue work on thermal analysis to look at internal heatingImpact to UNP-7 ARMADILLO:• GPS Investigation – the unit will still fly!

– GPS unit flew successfully on sounding rocket earlier in 2012– No interface boards used in flight; Kraken v2 has SPI interface– Different and better antenna (L1 + L2 frequencies) is used in flight

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Happy Canada Day