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DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. 13 April 2015 1

IMESA-R

IMESA-RIntegrated Miniaturized Electrostatic Analyzer – Reflight

USAF Academy

Principal Investigator: Geoff McHarg719 333 2460

[email protected]

Dr. Parris NealCadet First Class Alex Strom

Cadet First Class Nikolas Taormina

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. 13 April 2015

iMESA-R: A space weather constellation

Four inexpensive space weather instruments Each instrument provides two measurements

• Low energy plasma (Electrostatic Analyzer)• Radiation (Dosimeter)

Low size, weight, power (SWAP)• 10x12x4.5 cm• 2.1 W without dosimeter, 2.5 W with dosimeter

DoD Space Test Program (STP) providing flights on four different spacecraft

• Green Propellant Infusion Mission (GPIM)—FY16• Orbital Test Bed (OTB)—FY-16• STPSat-4—FY-17• STPSat-5—TBD

First DoD space weather constellation• 24 degrees inclination—525-720 km (GPIM and OTB)• 51.6 degrees inclination—425 km (STPSat-4)• 97 degrees inclination—550 km (STP Sat-5)

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iMESA-R flight instrument for GPIM

iMESA-R Constellation with four concurrent satellites


Scientific and Military Problem

Big Picture: Operators need to quickly distinguish between environmentally induced and possible hostile anomalies

iMESA-R concentrates on ionosphere and ionizing radiation

Ionosphere: Plasma irregularities (“bubbles”) cause scintillation

• Loss of GPS lock• <50% availability* during severe scintillation

• Loss of SATCOM Radiation: Single event upset, dose effects,

deep dielectric charging Forecasting is a priority—requires nowcast Nowcast requires multipoint measurements iMESA-R provides 4 satellite constellation

Knipp, Understanding Space Weather, 2011

Van Allen Radiation belt image created using data from NASA Van Allen Probes: Note emergence of third

transition belt: Image Credit APL, NASA

* For LPV-200. Seo, J, PhD thesis, Stanford Univ, 2010


Heritage and Future

Technology patented by USAFA Development funded by AFOSR and AFRL IMESA launched on:

• MISSE7(ISS) iMESA 2009-2011 = 1st data collect• STP-H4 MESA launched Aug 2013 = 1st reflight• STPSat-3 iMESA launch Nov 2013= 2nd reflight

Mature hardware, software, electronics• Demonstrated success on three missions

Future:• GPIM Launch Mid-2016• OTB Launch Mid-2016• STP-Sat 4 Launch Read Aug 2017• STP-Sat 5 TBD

iMESA STPSat-3 Credit Ball Aerospace

MISSE7 Credit:NASA


STPSat-3 IMESA-R Data

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Top panel: raw data product: energy-time spectrogram

• Density increases into sunlight

• Energy increases into sunlight

2nd panel down: Ion Temperature

3rd panel down: Ion Density Bottom panel: derived

spacecraft charging• Energy varying over day-

night cycle between 25-40 eV

Issues:• Data drop out over portion of

orbit• Temperatures not well resolved• EMI due to power converters

STPSat-3 Data: iMESA data product for one orbit 17 Feb. 2015


Changes for iMESA-R flights 3-6

New electrostatic analyzer (ESA) design• Improved temperature measurements• Reduces number of plates—ease of manufacture

Switchable range on ESA• Allows for different host S/C charging

Programmable gain amplifier• Assures data collection during entire orbit• Higher transimpedance amplifier gain

New power supply design• Reduces EMI• Change of one power supply allows flights on

many different satellites Added dosimeter

• Allows ionizing radiation monitoring Rewrote software

• Assures modularity and future upgrades

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Single mezzanine bus: -6dB noise reduction

New ESA Design

ions

Collection Anode


iMESA-R Design Philosophy

Multi-disciplinary• Physics—ESA design, calibration and analysis• Physics—Dosimeter modelling and calibration• Electrical and Computer Engineering: Electronics design and test

Use of Commercial Off The Shelf (COTS) components• Reduced cost• East of integration• Requires space qualification

“Good enough” versus “gold standard” measurements• Numbers count in terms of improvement to model output• Small SWAP minimizes host S/C impact and increases

Evolutionary design changes• Pick a basic technology• Develop on-orbit flight heritage—learn as you go• Change when needed, not because you can

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How many measurements are enough?

Modelled three orbital scenarios (Balthazor et al. 2015, Radio Science)

Compared ionospheric model output with and without iMESA on orbit

Collaborative effort with Utah State University A: 10x satellites @ 500 km

• “String of pearls”• 90º inclination• 1 launch

B: 10x satellites @ 350 km• “String of pearls”• 90º inclination• 1 launch

C: 25/5/1 Walker Constellation @ 500 km• 60º inclination• 5 launches• 5 satellites per launch• ~1-10 year lifetime

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Example 25 satellite Walker Constellation


Scenario A,B (“string of pearls”) Vertical propagation of information

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Converges towards “truth” with 10 satellites• Model improvements at all altitudes – not just orbital altitude• Knowledge “moves along field lines”• Can quantify “accepted error” and use to fine-tune orbital parameters

(A) (B)

GPS-TEC only GPS-TEC + Sats @ 500 km

GPS-TEC + Sats @ 350 km


Mean height of F2 peak improvement quantification

∑

1∑ 2

∑ 2

• Various metrics can be used to quantify improvement by adding IMESAs

• Metrics can depend on conditions – position, time, geomagnetic activity

• 25 IMESAs improves RMS to ~10 km

• 25 iMESAs improves Skill score to > 75%

Without IMESA

With IMESA

RMS deviation of hmF2 (global sum) Skill score of hmF2 (global sum)


iMESA-R Mechanical Overview

Fits in a 45mm x 102mm x 126mm envelope (without RBF Cover) Mass is NTE 1kg (including mounting hardware) Mounting interface is six #6-32 Bolts Al 6061-T651 per ASTM-B209 Printed circuit boards (PCBs) are enclosed within the assembly Designed to fit PC-104 boards

• Keying features on boards• Easy integration into CubeSats (for future missions)

Modular structure design to be barnacle mount or panel flush mount• Easily accessible Programming ports in either configuration

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PC-104 Board Size (with Keying Features)


iMESA-R Exploded View

Enclosure Plate

Connector Ring

Brains Board

Lower Mounting Enclosure Heads Board

Assembly

Upper Enclosure

RBF Cover

Programming Port Blanking Plate

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Hardware Simplified Block Diagram

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= Switchable gain amplification chain

= iMESA-R peripherals

= Data and command pathways

=Signal paths


Simple heritage code design Rewritten from scratch for OTB &

GPIM IMESA-Rs Minor changes anticipated to

accommodate μcontroller change

Command processing

Sweep processing

Spacecraft communication

Software Block Diagram


iMESA-R Summary

Unique 4 satellite constellation for space weather Simplified design allows reduced cost, increased numbers of measurements Cadets learn about space by doing a real mission end to end Multi-disciplinary USAFA effort emulates AF space enterprise USAFA is developing the next generation of Space Professionals

GPIM OTB STP-Sat4 STP-Sat5

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