giove-a 3 rd euro space weather meeting, 13-17 nov 2006 ©sstl/university of surrey giove-a...
TRANSCRIPT
GIOVE-A ©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 2006
GIOVE-A Radiation Environment Study Regime and Instrument Description
B Taylor, C Underwood (University of Surrey)S Jason, S Fellows, E Rooney (SSTL)
K Ryden, D Rodgers, P Morris (QinetiQ)G Gatti, G Mandorlo, H Evans, E Daly (ESA)
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20062
Outline
• The MEO Radiation Environment• Galileo & the GIOVE-A Spacecraft• GIOVE MEO Environment Goals• Radiation Monitors onboard GIOVE• Timeline
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20063
The MEO Radiation Environment
• Cosmic Rays– Constant background flux of
protons and heavy ions– Well defined energy spectrum
up to ~1020eV
• Solar Proton Events– Predominantly encountered
at solar maximum, few at solar minimum
– Geomagnetic field provides varying protection
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20064
The MEO Radiation Environment
• Outer radiation belt– Significant proton fluxes
confined below ~4 RE– Outer Belt composed of
Electrons – Extends between 3 - 7RE– >1 MeV flux peaks at
around ~4-5 RE at ~106-107 electrons cm-2s-1
GIOVE-AOrbit
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20065
The MEO Radiation Environment
• Environment Models– AE-8
• Standard for engineering use
• Mostly empirical, little physics
• Based on data from satellites from 60’s & 70’s
• Static, long term average model
• Covers entire range of belt
• Versions for Solar Max & Solar Min
– CRRESELE• Based on 2 years of data from GTO at Solar max
Electron Belt model comparison
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
0 1 2 3 4 5 6 7
Altitude/ Earth Radii>1
MeV
Ele
ctro
n Fl
ux
CRRESELE
AE-8 MAX
AE-8 MIN
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20066
The MEO Radiation Environment
• Environment Variability– Distribution varies greatly
due to solar cycle– Spatial distribution varies
due to geomagnetic field variation at higher altitudes
– Injection events due to geomagnetic storms can enhance environment by orders of magnitude
– Closely linked to Solar activity
GOES >2MeV Electron Flux
0.00E+00
1.00E+09
2.00E+09
3.00E+09
4.00E+09
5.00E+09
6.00E+09
7.00E+09
8.00E+09
9.00E+09
1.00E+10
0-Jan-00 14-May-01 26-Sep-02 8-Feb-04 22-Jun-05
Date
Flu
x/cm
^-2
s^-1
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20067
The MEO Radiation Environment
• Environment dangers and effects– Total Ionising Dose (TID) caused by energetic particles
(electrons, protons and heavy ions)– Single Event Effects (SEE) caused by energetic heavy
ions and protons– Electrostatic Discharge (ESD) – caused by penetrating
electrons
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20068
The MEO Radiation Environment
• Previous MEO Spacecraft– Combined Release and Radiation Effects Satellite
(CRRES)• Launched into Geostationary Transfer Orbit (GTO) in 1990• ~1 year mission
– Space Technology Research Vehicles (STRV)• Two satellites launched into GTO in 1994• ~2.5 year mission
– GPS• Multiple spacecraft carry radiation detectors• Data is property of US DoE - limited access
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 20069
The MEO Radiation Environment
• Solar Cycle Coverage– GIOVE-A lifetime is
over solar minimum– GIOVE combined with
STRV gives data on two consecutive solar minima
– CRRES data at solar maximum
1985 1990 1995 2000 2005 2010
Year
Sunspot Number
STRV
CRRES
GIOVE-A
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200610
Galileo
• Galileo- The European Global Navigation Satellite System (GNSS)– Independent, commercial
system– Two test bed spacecraft –
GIOVE -A & -B– Four In Orbit Validation
(IOV) spacecraft– Final constellation to consist of
30 satellites, 27 active, 3 spare in 3 orbital planes
– Total cost of system: ~€3-4 billion
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200611
GIOVE-A Spacecraft
• GIOVE-A– Precursor to Galileo Programme– Objectives
• Secure frequency filing• Demonstrate key payload
technologies• Provide Signal-in-Space for
Experimentation• Measure MEO environment
– Requirements • Two year mission lifetime• Low cost, rapid schedule• Kick-Off - July 2003 and Launch – 29th December 2005
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200612
MEO Environment Goals
• Optimise the design of the Galileo satellites– Confirm requirements are correct, modify if necessary
• Are existing models a good enough description of the environment?– LET spectrum– Electron Fluxes– Total Ionising Dose– Dose rates
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200613
Radiation Monitors on GIOVE-A
• MERLIN – QinetiQ– Cosmic-Ray LET Spectra– Proton Flux– Total Ionising Dose– Electrons/ Deep Charging
Currents
• CEDEX – UniS/SSTL– Cosmic-Ray LET Spectra– Proton Flux– Dose-Rate Induced
Photocurrents
Proton fluxHeavy ion LETspectrum
Total dose B
Total dose AElectrons &deep charging
MerlinSpace Weather Monitor
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200614
Radiation Monitors on GIOVE-A
CEDEX
Merlin
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200615
Radiation Monitors on GIOVE-A
Radiation Monitors
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200616
Radiation Monitors onboard GIOVE-B
• SREM- ESA – Due for Launch late 2007 on
GIOVE-B– Three precision particle detectors
• Electrons & Protons
– Internal total dose measurement
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200617
Timeline – Initial Operations
• CEDEX & Merlin turned on - 29th December 2005– Second contact after launch– Operated near continuously since first switch-on
• Environmental Readiness Review (ERR) 06/04/2006
• Environmental Payloads Commissioning Phase– Setup of download and processing chain
• Initial Operations Phase– Initial analysis of data with simplified shielding models
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200618
Timeline – Main Operations
• Main Operations Phase – Part 1– Simplified 1D Mulassis, and 3D GEANT-4 model of the
payloads/ spacecraft. – Results compared to AE8/CRRESELE
• Main Operations Phase – Part 2 – Electron response of Merlin using Geant4, SREM data
expected (but now delayed)– Data compared with static and quasi-static models (AE8,
FLUMIC, CRRESELE, ESAMEA, etc). – Results used to validate modelling performed in MOP-1– Pile-up induced responses to electrons in Proton Flux
measurements from Merlin investigated to derive further data on electron environment
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200619
Conclusions
• Merlin and CEDEX have been operating since December 2005
• Initial commissioning activities are complete• Data analyses continue to be refined• The following two papers will describe the units in
more detail and present the in-orbit results
©SSTL/University of Surrey 3rd Euro Space Weather Meeting, 13-17 Nov 200620
Thank you foryour attention
For further information contact :Dr Elizabeth Rooney
Surrey Satellite Technology Limited
Tycho House, 20 Stephenson Road,
Surrey Research Park, Guildford, Surrey, GU2 7YE, UK
Tel: +44 1483 803803, FAX: +44 1483 803804
Email: [email protected] Web: www.sstl.co.uk