flight results from the merlin space weather monitor on giove-a
DESCRIPTION
Flight results from the Merlin space weather monitor on Giove-A. 3 rd European Space Weather Week 13-17 November 2006, Brussels K A Ryden , P A Morris, D J Rodgers, C S Dyer - QinetiQ C I Underwood, B. Taylor, S Jason - SSTL/ University of Surrey - PowerPoint PPT PresentationTRANSCRIPT
Flight results from the Merlin space weather monitor on Giove-A
3rd European Space Weather Week 13-17 November 2006, Brussels
K A Ryden, P A Morris, D J Rodgers, C S Dyer - QinetiQC I Underwood, B. Taylor, S Jason - SSTL/ University of SurreyH D Evans, E J Daly, G Mandorlo, G Gatti - ESA/ESTEC
Giove-A
• Test-bed for European Galileo GNSS
– obtain frequency filing protection
– characterise the MEO environment
– validate certain critical payloads
– provide representative signal-in-space transmission
• Built and operated by SSTL
• Successfully launched in December 2005
• Orbit 23,260 km and 56 degrees inclination, 27 month lifetime
– electron dominated: charging and total dose hazards
– exposed to solar particle eventsSSTL image
Galileo orbit
• Severe trapped electron environment– Charging effects
– Total ionising dose
• Galactic cosmic rays
• Solar protons and ions GALILEO altitudeGALILEO altitude
Total ionising dose
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1.E+09
0 2 4 6 8 10 12 14 16 18 20Thickness of Al sphere [mm]
GPS Total
GEO Total
GTO Total
Internal charging
• ESD transients can cause anomalies and outages
• Cables, connectors, pcbs etc
High energy electrons from space environment
Dielectric
Shielding
Merlin space weather hazard monitor
• Electrons and charging
• Total ionising dose
• Protons
• Ions (LET)
• 1kg, 2.5W (standard)
Developed from the earlier CREDO and SURF science detectors
QinetiQ space radiation monitors
CREAM Cosmic Ray Effects and Activation Monitor (1986 onward)
• Charge deposition events in Si
• Flights: Shuttle(10 flights) /BA Concorde/Qantas/
CREDO Cosmic Ray Effects and Dosimetry Experiment (1991 onward)
• Ion LET spectra and proton flux
• Flights: UoSAT, STRV1a, Skynet, APEX, MIR, MPTB
SURF (2000 onward)
• Surface charging and internal charging (electron flux)
• Flights: STRV1d
Merlin (2005 onward)
• Charging/LET spectra/proton flux/TiD
• Flights: Giove-A, LWS/SET
Merlin space weather hazard monitor
Electrons & electrostatic charging (3 shielding depths)
Ions (linear energy transfer)
Protons (>40 MeV flux)
Total dose RADFET (x2)
Integral rad-hard computer, data storage, power conditioning and communications
Ion telescope Protontelescope
Total dosemonitor
Internalcharging(electron)monitor
Energydiscriminator
Analogueprocessingand ADC
Microcomputer and memory
Powerconditioningand filtering
RS422 businterface
RS422 bus Power bus
Lower board
Upper board
Merlin block diagram
Sensor suite (CREDO + SURF + Radfet)
Data handling
Merlin-Giove-A
Electrons & charging: SURF experiment
• Novel approach– internal charging current vs depth
measurement
– each plate has unique energy response curve so spectrum can be obtained
• Virtually immune to proton contamination
• Built and flown on STRV1d
• 300g, 0.3W
Space radiationparticles
Satellitetelemetry system
Lid 0.6mm Al
0.5mm Al plate1.0mm Al plate
Satellite exteriorwall
Satellite groundreference
fA fA
.
SURF experiment: internal charging mode
0.00E+00
5.00E-10
1.00E-09
1.50E-09
2.00E-09
2.50E-09
3.00E-09
0 1 2 3 4 5 6
Electron energy (MeV)
Top plate
Bottom plate
SURF results
• GTO orbit
• 500 x 36,000 km
Merlin-Giove-A
• Located externally (under thermal blanket)
• Extra box shielding incorporated (5mm thick walls) due to severity of orbit
• SURF and Radfet set-up for Giove-A:
SURF plates
Housing (lid)
RADFETS
0.4 mm Al
2 mm Al
5 mm Al
0.5 mm Al
1 mm Al
Thermal blanket - 0.1 mm Al eq.
Merlin pre-flight calibration
SURF plates
Housing (lid)
RADFETS
0.4 mm Al
2 mm Al
5 mm Al
0.5 mm Al
1 mm Al
Thermal blanket <0.2 mm Al eq.
REEF Sr-90 source
Realistic Electron Environment Facility
• 90Sr source: 3.7 G Bq• Vacuum chamber• -10 to +40°C temperature
control of thermal plate• Electron current
controlled by variation of source-to -sample distance
• ESD detection system• Surface potential
measurements (‘TREK’ probes)
Electron spectrum comparisons• REEF
capability brackets the average (AE8) and worst-case (FLUMIC) electron environments predicted for GEO
0.01
0.1
1
10
0.1000 1.0000 10.0000Energy (MeV)
Cur
rent
(pA
/cm
2 )
REEF (30mm) REEF (187.5mm)
Average GEO (AE-8min) NASA worst case GEOWorst case GEO (FLUMIC)
Merlin-Giove-A: pre-flight calibration (REEF)
0
0.1
0.2
0.3
0.4
0.5
0.6
0 50 100 150 200
time / s
char
ging
cur
rent
pA
/cm
2
0,5 mm shield, 0.5 mm collector
1.0 mm shield, 0.5 mm collector
1.5 mm shield, 1.0 mm collector
Source position: 0
Source position: 135,000
Merlin pre-flight calibration in REEF
• Two particle telescopes (CREDO)– ion LET spectrum
– protons (400 keV energy deposition threshold)
Pul
se h
eigh
t dis
crim
inat
orCOINCIDENCE GATE
SIGNAL
Si diode, area 3cm2, 300um thick
NON-COINCIDENCE COUNTERS
COINCIDENCE COUNTERS
Merlin-Giove-A
Radiation monitors installed on Giove-A
Picture: SSTL
Launch 28th December 2005
MERLIN-GIOVE A: CHARGING CURRENTS DUE TO TRAPPED ELECTRONS
0.00
0.05
0.10
0.15
0.20
29/12/2005 15:36:00 29/12/2005 20:24:00 30/12/2005 01:12:00 30/12/2005 06:00:00 30/12/2005 10:48:00 30/12/2005 15:36:00
Date
Cu
rren
t (p
A/c
m2)
0
5
10
15
20
25
30
L (
Re)
:
B (
kGau
ss)
Shield 0.5mm, collector 0.5mmShield 1.0mm, collector 0.5mmShield 1.5mm, collector 1.0mmB (model)L (model)
1st day of data: electrons/charging
GALILEO altitudeGALILEO altitude
Jan & Feb 2006: electrons/charging
Jan & Feb 2006: electrons & dose
21 Feb 2006 electron eventMERLIN-GIOVE A: CHARGING CURRENTS DUE TO TRAPPED ELECTRONS
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
21/02/200600:00
21/02/200602:24
21/02/200604:48
21/02/200607:12
21/02/200609:36
21/02/200612:00
21/02/200614:24
21/02/200616:48
21/02/200619:12
21/02/200621:36
22/02/200600:00
Date
Cu
rren
t (p
A/c
m2)
0
5
10
15
20
25
30
L (
Re)
:
B (
kGau
ss)
Shield 0.5mm, collector 0.5mmShield 1.0mm, collector 0.5mmShield 1.5mm, collector 1.0mmB (model)L (model)
6 days laterMERLIN-GIOVE A: CHARGING CURRENTS DUE TO TRAPPED ELECTRONS
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
27/02/200600:00
27/02/200602:24
27/02/200604:48
27/02/200607:12
27/02/200609:36
27/02/200612:00
27/02/200614:24
27/02/200616:48
27/02/200619:12
27/02/200621:36
28/02/200600:00
Date
Cu
rren
t (p
A/c
m2)
0
5
10
15
20
25
30
L (
Re)
:
B (
kGau
ss)
Shield 0.5mm, collector 0.5mmShield 1.0mm, collector 0.5mmShield 1.5mm, collector 1.0mmB (model)L (model)
Jan-May 2006: electrons & dose
April 06 electron event
April 06 electron event
Single belt transit – 17th April 2006
Merlin-Giove-A: Single transit though belt 17 April 2006
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
17/04/2006 09:21 17/04/2006 10:33 17/04/2006 11:45 17/04/2006 12:57 17/04/2006 14:09
day/month/year/time
de
po
sit
ed
cu
rre
nt
/ p
A c
m-2
3.40
3.45
3.50
3.55
3.60
3.65
3.70
3.75
3.80
pro
vis
ion
al
do
se
/ k
rad
(SiO
2)
charging current (0.5mmshield, 0.5 mm collector)
charging current (1.0mmshield, 0.5mm collector)
charging current (1.5mmshield, 1.0mm collector)
dose (3mm Al eq. in +zdirection)
Jan-Aug 2006: electrons and dose
Jan-Aug 2006: electrons and dose
AE8/sectored shielding model of the expected dose.
Sept & Oct 2006: electrons and dose
Giove-A/Merlin charging currents and dose
0
0.05
0.1
0.15
0.2
0.25
28/12/2005 27/01/2006 26/02/2006 28/03/2006 27/04/2006 27/05/2006 26/06/2006 26/07/2006 25/08/2006 24/09/2006 24/10/2006
Date
Cu
rre
nt
pA
/cm
2
0
2
4
6
8
10
12
Do
se
kR
ad
s(S
iO2
)
Shield 0.5mm collector 0.5mmShield 1.0mm collector 0.5mmShield 1.5mm collector 1.0mmRadFET shield 6mmRadFET shield 3mm
Jan-Oct 2006: electrons and dose(D
aily
ave
rag
e)
Jan-Aug 2006: electrons and FLUMIC seasonal modulation function
Giove-A/Merlin: 1-Day Mean Charging Current
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
30/12/2005 18/02/2006 09/04/2006 29/05/2006 18/07/2006 06/09/2006 26/10/2006
Date
Ch
arg
ing
cu
rre
nt
pA
/cm
2
FLUMIC
shield 0.5mm, collector 0.5mm
Jan-Oct 2006: top SURF plate compared to DICTAT worst case
Giove-A/Merlin: 1-Day Mean Charging Current
0.00
0.05
0.10
0.15
0.20
0.25
30/12/2005 18/02/2006 09/04/2006 29/05/2006 18/07/2006 06/09/2006 26/10/2006
Date
Ch
arg
ing
cu
rre
nt
pA
/cm
2
FLUMIC
shield 1.0mm, collector 0.5mm
Jan-Oct 2006: middle SURF plate compared to DICTAT worst case
Giove-A/Merlin: 1-Day Mean Charging Current
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
30/12/2005 18/02/2006 09/04/2006 29/05/2006 18/07/2006 06/09/2006 26/10/2006
Date
Ch
arg
ing
cu
rre
nt
pA
/cm
2
FLUMIC
shield 1.5mm, collector 1.0mm
Jan-Oct 2006: bottom SURF plate compared to DICTAT worst case
Jan-Aug 2006: electron spectrum ‘hardness’
6th July 2006 – minor SPEGiove-A/Merlin
6th July 2006 event
0.001
0.01
0.1
1
10
100
05 July 12:00 06 July 00:00 06 July 12:00 07 July 00:00 07 July 12:00 08 July 00:00 08 July 12:00 09 July 00:00
Date
Flu
x (
cm
-2.s
-1)
0.0001
0.001
0.01
0.1
1
10
100
Cu
rren
t (p
A/c
m2 )
Coincident ProtonsIon channel 1Charging current
Merlin Giove-A Integral LET Spectra 1st Aug - 31st Oct 2006
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
10 100 1000 10000 100000
LET (MeV/(g.cm -2))
Inte
gra
l F
lux (
m -2
.s -1
.sr
-1)
IonsCREME96
Background LET spectrum
Conclusions• Good data from all Merlin sensors
– Electrons/charging rates measured at three shielding depths
– Total dose at two shielding depths
– > 40 MeV protons (500 keV deposition threshold to be sure of protons)
– LET spectrum (background)
• Numerous electron enhancement events have been observed via the charging (electron deposition) and total dose effects
• Clear 27 day interval in electron enhancements (persistent coronal holes)
• April ‘event’ was the most severe so far – ‘worst case’ events are of engineering significance and their magnitude needs to be captured
– April event still produced less than DICTAT ‘worst case’ predicted charging currents for the plates
…..conclusions
• Ionising dose is delivered in surges during the electron events
• From Jan to August 2006, approximately half of the dose was delivered by just one electron event
• Dose at 6mm shield depth (Merlin +z direction) observed is greater than the predicted value (using AE8/sectored shielding models) at this stage: however may not be typical of whole solar cycle
• Post-script
– 2nd Merlin for NASA ‘Living with a Star’ now built & qualified