1. Space Weather Effects and Applications
Eamonn Daly ESA Space Environments and Effects Section
ESTEC
Noordwijk The Netherlands

2. Review Effects (roughly divided between):
Outline
Defintions
Review Effects (roughly divided between):
Effects on space systems
Effects on communications and terrestrial effects
User requirements
Services
Conclusions

3. What is “Space Weather”?
conditions on the sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health
[US National Space Weather Programme]

5. User Sectors Affected by Ionospheric Disturbances
Affected by Local Space Environment
Navigation Services
Communications Services
Spacecraft Operations Services
Air Transport Services
Launcher Support
Human Spaceflight Support
Others
Science Missions Operations Services
Tourism
Spacecraft Development
Affected by Geomag. Induced Currents
Air Transport Services
Other SSA Services
Power Industry Services
Survey, Oil & Gas Services

6. see www.esa.int/spaceweather
Effects
Space Weather Effects result from complex interactions between the environment and the affected systems:
Satellites affected by radiation, plasma, atmosphere, particulates;
Radiation hazards to astronauts on ISS, future exploration missions;
Radiation hazards to crew and avionics on aircraft;
Disruption to communications relying on the ionosphere;
Disruption of navigation satellite signals (GPS - Galileo);
Ground power outages from currents induced in lines;
Others (Geological Surveys, Climate, Tourism,…);
see
While our interest here focuses on space weather radiation effects, space weather affects a wider community, by interfering with communications, disrupting magnetic-based surveying, disrupting power systems, etc.

7. Effects on Spacecraft Courtesy G. Ginet, AFRL
before
after
False stars in star tracker CCDs
Outside inner belt
Inside inner belt
Surface degradation from radiation
Solar array power decrease due to radiation damage
Electronics degrade due to total radiation dose
Solar array arc discharge
Single event effects in microelectronics: bit flips, fatal latch-ups
1101  0101
Spacecraft components become radioactive
Electromagnetic pulse from vehicle discharge
Induced
Voltage
Courtesy G. Ginet, AFRL
Time

8. Spacecraft Effects Radiation Effects are caused by:
Total integrated ionising or non-ionising dose (energy absorbed/unit mass)
a problem for electronics, solar cells, materials, man
Single event effects, including single event upset (non-permanent error in a bit), single event transients; latch-up (destructive); detector interference;
a problem for electronics, detectors and man
Plasma Effects due to:
Electrostatic charging causing electrostatic discharge →EM pulses;
a problem for electronics
Plasma interactions with “exposed active” systems – solar panel interconnects; electric propulsion; payloads; tethers
Neutrals Cause:
Drag, depending on atmospheric density
Erosion of surfaces – the residual Oxygen is non-molecular and corrosive
Contamination

9. Radiation in space The principal particles:
Protons MeV {radiation belts, solar particle events, cosmic rays}
Ions MeV {cosmic rays, solar particle events, (radiation belts)}
Electrons MeV {radiation belts, (other planets) ((solar))}
The main interaction mechanism is ionisation but other processes can be important

10. “Single-event” effects (SEE’s)
a particle crosses (“hits”) a (small) sensitive target
the energy deposited causes a noticeable effect:
ionisation free charge causes a bit to “flip”
pixels of a CCD are “lit up” by creation of free charge
DNA is damaged
SEEs are becoming extremely difficult to evaluate in complex modern chips

11. SEUs on UoSAT-3 microsatellite memory
Oct ‘89
Mapped
Time behaviour
SEUs are from:
Cosmic rays and solar ions at high latitude
Radiation belt proton nuclear reactions in south Atlantic

12. An Aside: The South Atlantic Anomaly
500km
Earth’s magnetic field is an offset tilted and distorted dipole
This brings the radiation belt down in the South Atlantic

13. Radiation Effects on SOHO
Cosmic ray background varies with solar cycle
Errors in on-board memory
Solar array degradation

14. SOHO Image “snowing” on 14 July 2000
These pictures are examples of some of the splendid images returned by SOHO. They are of the events of 14 July the famous “Bastille day event”. The left image shows the image of the sun in the extreme UV from the EIT camera. A flare is clearly seen. The centre images show pictures from the LASCO coronograph. Here, the instrument’s circular occulting disk blocks the sun’s surface and allows the extended corona to be seen. Here, in the lower of the views , the “snowing” of the image is due to the energetic particles generated in the event hitting the camera’s CCD detector ~50 minutes after the flare. A particle hitting a CCD pixel will render it “bright” temporarily. If it passes through the CCD at a shallow angle, it can generate an image of its path. Other instruments were similarly affects and many SOHO images [1] show the CCD “radiation background” response to solar energetic particle events.
The upper right image is from the CDS instrument which provides detailed information about the spectral characteristics of specific regions on the sun. The bottom right is an image of the solar magnetic field as produced by the MDI instrument. Knowledge of the solar magnetic field can give clues to the imminent onset of energetic events.
______________
[1] ESA’s SOHO web site

16. Error rate increases in small solar event
ISO Star Tracker
Error rate increases in small solar event
provided software can cope, this phenomenon should not lead to problems
but there are several cases of attitude stabilisation loss
Effects were also seen on ISO in other systems. During the small April 1998 event, effects were seen in the star tracker. The red, blue and white curves are measurements of the particle fluxes during the event made by the GOES spacecraft for energies of 10, 50 and 100MeV respectively. The yellow stepped curve is the error rate of the star tracker system.

17. XMM: Radiation Damage to Detectors
Detectors (5 arrays)
Spectrometer gratings
mirrors
Orbit 48-hr Highly eccentric
Apogee:
Perigee: 7000km Inclination: 40o
Leads to potential degradation of CCDs and to background from soft protons entering the mirror shells

18. Manned Missions Away from LEO Risk High Doses (prompt radiation sickness at ~100 REM (1 Sv); death at 400)
Apollo 16
Apollo 17
104 REM skin dose
103

19. What is done to avoid radiation problems?
“radiation hardness assurance” in design process
Conservatism; design against worst cases
Space weather effects on operations designed in to operations procedures if necessary

20. Spacecraft Interactions with Local Plasma Environment
Hot plasma causes electrostatic charging of outer surfaces
Potential differences can lead to discharges → spacecraft failure (rare) or “anomalies”
Also caused by energetic electrons getting inside materials and stopping
High electric fields lead to breakdown discharges

21. Spacecraft-Plasma Interactions
Main engineering issue is high-level electrostatic charging
27 February 1982: interruption (ESR) on Marecs-A Maritime Com. Sat.
Main anomaly & other small ones coincident with geomagnetic “substorms”
Anomalies caused by electrostatic charging -> discharge
large areas of dielectric thermal blankets
large differential charging
Marecs-A and ECS-1 satellites had power losses on sections of solar arrays
Telstar 401 failure on 10th Jan 1997 following storm on 7th
ANIK-E1 & E2 failures in 1994 and 1996
Many other examples…

22. “Surface charging” is result of currents to a surface
High level (negative) charging occurs because “hot” electrons dominate
Often only possible in shadow
Depends strongly on material

23. “Internal” electrostatic charging
MeV electrons penetrate material and build up an electrostatic charge
Meteosat 3 ( ) had many disturbances
On average, environment was seen to get severe before an anomaly

24. Charging-Induced Anomalies
Anomalies on the morning side during storms MP
GEO
Hot plasma 6
Statistical Survey (Rodgers et al.) of Meteosat-3 anomalies and their local time distribution
Meteosat Anomalies

25. Failure of Equator-S Spacecraft due to “killer electrons”
December 97
Primary CPU Fails
April 98
Back-up CPU Fails
Enhanced Hot Electrons

26. Canadian experiences (800 events over 25 years, courtesy Telesat Canada*)
Anik-A’s
11 uncommanded mode switches of telemetry encoders.
Anik-B
One earth sensor mode switch, believed to be caused by optical solar reflector discharge.
Anik-C’s
C1 and C2 had only a few phantom commands (i.e. mode changes, unit turn-on/off);
C3 had more than 100 such events.
Anik-D’s
D1 had only 3 events (uncommanded mode switches);
D2 suffered a major service outage on 8 March 1985, when multiple events occurred simultaneously.
Anik-E’s
Many phantom commands, especially RF amplifiers;
On 20 Jan 1994 both momentum wheel electronic units failed on E2, one failed on E1;
Several RF amplifier failures.
MSat
Many phantom commands;
Very large number of RF amplifier failures.
Nimiq
A few phantom commands (as of Oct 1999)
Anik-E momentum wheel electronics provide an excellent example of an unambiguous space-weather-related failure **. Conversely, the investigation of the March 1996 Anik-E1 power failure showed that, although initially suspected of being so, it was in fact not related to space weather.
** Evans, J. and Gubby, E. R., “Ground Loop Attitude Control System for the Anik-E Satellites” International Union of Radio Science XXVIth Assembly, University of Toronto 16 August 1999
* SPACE ENVIRONMENT EFFECTS AND SATELLITE DESIGN, Robin Gubby & John Evans, JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS, 1999

28. Communications/ navigation effects
RF signals through ionosphere experience phase errors due to plasma effect on EM propagation
Signal delays lead to GPS navigation errors - a large sector of space weather services

29. Geomagnetically Induced Current Effects
Strong ionsopheric currents induce geoelectric fields on the Earth’s surface (Faraday’s law of induction)
Fields can cause currents to flow in power lines - transformer damage, network “tripping” and induce potential differences between pipelines and the ground, accelerating corrosion
Magnetic field perturbations on Earth’s surface disrupt geological surveying that relies on magnetic/electric field sensing

30. Radiation Enhancements in the Atmosphere -Altitude & latitude variations
Courtesy Clive Dyer (see IEEE TNS Dec paper)

31. Space Weather Services
Provision of information (data, tailored information, warnings) driven by user requirements.
Most established is US NOAA SWPC
Many services in Europe addressing various “market sectors”

32. ESA’s Space Weather Applications Pilot Project
Aim to support investigation of maturity of the “market”
~30 CO-FUNDED services established;
esa-spaceweather.net

33. Example Service: Human Spaceflight Radiation Warning for ISS

34. Reliability of forecast is a major obstacle
Operations
Manned example already well established: NASA-JSC system uses NOAA resources
Science mission instrument shut-off e.g. ESA’s XMM and Integral take action if hazardous conditions are detected
Launch authorities can delay launches (e.g. rapid decision taken for Cluster-II launch on July 16 ‘00)
Reliability of forecast is a major obstacle
If space weather services can provide good quality, rapid and reliable information (current conditions of forecasting), operators can take steps to protect systems. Some examples are listed here, two of which have been addressed earlier in detail: manned missions and science operations. Launch authorities are also becoming increasingly interested in space weather warnings.

35. Some Examples of Current Resources
GNSS Scintillation Network (CLS)
Ground Based Magnetometers L1
Ionospheric monitoring (GPS TEC)
ESA/NASA SOHO
ESA-EU Giove
Aurora
NASA/POLAR
NASA ACE
NOAA/SEM
NOAA GOES

36. Applications needs differ from Science data needs
Data type
Coverage
Timeliness
Continuity
Quality
But science data remain a crucial resource for applications in the short-medium term
(CLRC-RAL, Space Weather System Studies 2000)

37. Requirements Analyses have been made since ESA system studies

38. SSA SW Services Addressing User Needs
Monitor
the Sun
solar wind
radiation belts
magnetosphere
ionosphere
surface B field
Provide
reliable local spacecraft (/launcher) radiation, plasma & electromagnetic data for re-construction, nowcast & forecast of hazardous conditions
timely and reliable ionospheric disturbances nowcast and forecast important to Galileo signal and service quality
thermospheric density for spacecraft drag calculation
timely and reliable ionospheric density profile nowcast and forecast
results of ground-level magnetic field variations monitoring and forecast
* nowcast = re-constructing in real-time the present environment based on data, proxies & models.

39. Requirements Analyses: See poster of Glover et al.

44. Conclusions
Space weather effects are increasing;
Interactions that lead to effects can be very complex – requires considerable effort to analyse and mitigate;
Services and affected users may need information of different types to science users;
Development of coordinated space weather services in Europe is foreseen within “SSA”;
(Note: ESA young graduate trainee, research fellowship and PhD partnering programmes)