august 11, 2009 small satellites conference 2009 1 a new particle detection instrument for space...

August 11, 2009 Small Satellites Conference 2009 1

A New Particle Detection Instrument for Space Weather

Research with CubeSats

David GlaserSpace Physics Research Group

Space Sciences LaboratoryUniversity of California, Berkeley

STEIN (SupraThermal Electrons, Ions & Neutrals)

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Overview• Introduction/Context

• Instrument Overview

• Mechanical Design

• Electrical Design

• Modes of Operation

• Concluding Remarks

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Introduction

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UCB/SSLUC Berkeley Space Sciences Laboratory•Founded in 1959•Extensive Experience in Space Weather

Research• Sounding Rockets and Balloons• Instruments for >100 NASA Missions• PI for EUVE, CHIPS, FAST, RHESSI &

THEMIS

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CINEMA Mission

NSF Funded (Awarded Aug.2009)

CubeSat for Ions, Neutrals, Electrons, and MAgnetic fields

PI Robert Lin

Mission Built Around a Concept for a New Particle

Detector Called STEIN

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CINEMA Mission

As Proposed:•3 Identical 3U CubeSats• 1 NSF Funded• 2 Funded by Kyung Hee Univ.,

S. Korea•High Inclination LEO•Ecliptic-Normal Spinner•Launch Vehicle – TBD•2 Science Instruments• Particle Detector• 3-Axis Magnetometer

(Imperial College London)

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Particle Detectors in Space

• Used For the Majority of Space Missions

• Need Small, Low Power Instruments, Especially for Multi-Spacecraft Space Physics Missions

NASA/JPL

FAST THEMIS Ulysses

NASA/JPL

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Comparison with ESAs

STEIN0.40 kg0.55 W Power

Electrostatic Analyzer (ESA)~3 kg~3 W Power

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STEIN - Scientific Merit

• Measures Electrons, Ions, and Energetic Neutral Atoms

• Very Low Energy Threshold• High Energy Resolution

Cutting Edge Science

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Instrument Overview

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• Low Energy Threshold (1-2 keV)

• ~1 keV Energy Resolution• Sensitive to Electrons,

Ions, and Neutrals (But Can’t Separate)

• 4 x 1 Pixel Array• Flight Heritage: STEREO

Mission STE Instrument

(SupraThermal Electrons)

SSD DetectorNew Silicon Semiconductor Detector

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STE STEIN

STE – SupraThermal Electrons

STEIN – SupraThermal Electrons, Ions, and Neutrals

STE + = STEINElectrostatic Deflection

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How STEIN Works

•Collimator•± 2000 V Field Separates Electrons, Ions, and Neutrals to ~20 keV

•Particle Attenuator

(Blocks 99% of Particles)

Instrument Subsystems

•Mechanical•Electronics

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STEIN Attenuator

Mechanism Heritage from THEMIS Mission

Overcenter Cam

Mechanism

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Assembly

Attenuator Mechanism is

Modular

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Instrument Digital

Electronics(FPGA)

Low Voltage Power Supply

Signal Processing~8 V Bus

Voltage

DetectorElectrostatic

Deflection

150 V±2000 V

5 V

C&DHS

High Voltage Power Supply

Control

Power

Science Data

Electronics Flow Chart

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Signal Processing

Diagram For One Pixel

Only ~1 c/s noise

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Modes of Operation

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Modes of Operation

Mode Description

NormalAll Particle Events Stored and

Downlinked

Decimation~1/N (N = 4,16, 64 etc.) Events

are Downlinked

Attenuation 1% of Particles Reach Detector

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Status & Futureof STEIN

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Status & Future Plans

• Spring 2009 - Attenuator Mechanism Successfully Tested

• Summer 2009 – Instrument Testing Began

• Fall 2009 - Complete Testing of Prototype

• Fall 2009 - Finalize Flight Design

• Early 2010 - Begin Fabrication of Flight Units

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Final Thoughts

• Small, Low Power Particle Detectors Are Needed.

• STEIN is Small and Low Power.

• STEIN Detects Electrons, Ions, and Neutrals, with Low Energy Threshold and High Energy Resolution.

• STEIN will pave the way for Magnetospheric Constellations with many satellites making multi-point observations.

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Visit us at:

http://ssl.berkeley.edu

For more information:

David Glaser – dglaser(at)ssl.berkeley.edu

Science Questions:

Jasper Halekas – jazzman(at)ssl.berkeley.edu

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Back-up slides

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STEIN Specifications

Electrons ~2-100 keV

Ions & Neutrals ~4-100 keV

Energy Resolution ~ 1 keV

Count Rate Up to 30,000/sec

Mass ~400 g

Volume Envelope ~650 cm3

Power Consumption ~550 mW

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Science Objective Measurement

Magnetic Storms & Storm-Time Ring

CurrentENA* Line-of-Sight

Charged Particle Precipitation

Electrons, Ions in-situ

Electron Microbursts Electrons in-situ

Science Objectives

*Energetic Neutral Atoms

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Modes of OperationScientific

Observation

Expected Flux @ ~10 keV

(cm2 s sr keV)-

1

Mode (Electronic

Mechanical)

Avg. Counts/Sec

Ring Current ENAs

~103 *Normal Open

300

Low Altitude ENAs

~104 *Normal Open

3000

Auroral Protons ~105 **Normal Closed

30

Microburst Electrons

~106 † Normal Closed

300

Auroral Electrons ~108**Decimation

Closed

~30,000(before

decimation)

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Data Format

Data Type No. Bits Resolution

Particle Energy

8 ~0.4 keV

Pixel ID 2 -

Time Stamp

6 ~15 ms

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Deflection Modes

Mode Description

Sweep-2000 V to – 600, 0 V, +600 V

to +2000 V(sweep in < 1 sec)

ENA Mode Hold at ±2000 V

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Magnetic Storms

Magnetic Storms and Storm-Time Ring Current

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Magnetic StormsSTEIN Will Measure the Storm-Time Ring Current Via ENA Imaging

Image Credit: SWRI

ENA Image of Ring CurrentNASA IMAGE Mission__ keV

ENA map from STE instrument on STEREO (same detector as STEIN) ___ keV

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Charged ParticlesHigh Latitude Charged Particle Precipitation

NASA/GSFC

• In-Situ Measurements of ~4-100 KeV ion

• Remotely sense ion precipitation with Energetic Neutral Atoms (ENAs)

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Electron microburst observed by Korean STSAT-1

1 SecondElectron Microbursts

Electron Microbursts (0.10 – 0.25 sec)

Cause Unknown

Electron Microbursts

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A magnetically trapped ion capturesan electron from a neutral

hydrogen atom...

…creating an energetic neutral atom(ENA) that is no longer

trapped.

ENERGETICION

ENERGETICNEUTRAL

ATOM(ENA)

Charge Exchange

Image Credit SWRI

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STE ENA Map

Angular distribution as a function of source direction centered at noon (left) and midnight (right ) on Nov. 6, 2006. STE downstream sensors looked in the magnetotail direction close to midnight and detected larger fluxes than upstream sensors looking towards the Earth (the Earth’s horizon is indicated by red curve). The blue curves show the iso-pitch-angle contours of the local magnetic field. The black curves show the magnetic field lines at dusk, midnight and dawn.

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Storm time particle precipitation

- SSL, Berkeley -

Precipitating electrons

ExB drift

Oct 13, 2004

Trapped electrons

Korean STSAT-1

Charged Particles

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Spatial or Time Variation “Is it local acceleration?”

Separation Speed: 1m/min

1 d: 1.4 km

10 d: 14 km

1 m: 42 km

1y: 504 km

Multi-Satellite Science

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Deflection System Design

•Sweeping Voltage Selects for Different Particle Energies

•Plate Size and Gap Selected to Balance Deflection and Sensitivity

•Present Design Separates Charged Particles from Neutrals up to ~20 keV

No Signal in Center Pixel Below ~20 keV

Edge Pixel

Center Pixel

20 keV

Simulated Data

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SSD Detector•Low Capaciance•Thin Window Dead Layer•Passively Cooled•Pulse-Height Detection Electronics

•Detector Area: 4 x 0.1 cm2

•Electrons: ~2-40 keV•Ions: ~4-40 keV•Neutrals: ~4-20 keV•Resolution: ~<1 keV FWHM

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STEIN Housing

Single Piece of Machined Aluminum

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Collimator

•60° x 40° Aperture•Baffles

•Cu plated BeCu•Blackened

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Deflection Plates

Copper Epoxied to G10 Ebanol C Surface Treatment

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• Uses Shape Memory Alloy (SMA) Wire

• Stroke: 3 mm• Rated Force: 125 gf

NanoMuscle Actuator

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Over-Center Mechanism

Over-Center Cam Mechanism

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Testing

STEIN with 3-Axis Manipulator

STEIN

Electronics Box

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Preliminary Test Results

ED Voltage Edge 1(+ V)

Center 2 Center 3 Center 4(- V)

±400 100-120 10-20 10-20 ≤ 20

±300 100-120 10-20 10-20 ≤ 20

±250 80-100 300 10-20 ≤ 20

±200 20-40 400-500 10-20 ≤ 20

±150 0-2 500-600 10-20 ≤ 20

±50 0-2 500-600 100-200 ≤ 10

0 0-3 300-400 200-300 0-3

At > ±300 V All Particles Deflected to One Edge Pixel(Except for Scattering)

15 keV Electron Data Counts/Sec, Angle = 0°