Space Weather Effects and Applications Eamonn Daly ESA Space Environments and Effects Section ESTEC Noordwijk The Netherlands eamonn.daly@esa.int

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

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]

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

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 www.esa.int/spaceweather 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.

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

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

Radiation in space The principal particles: Protons 0.1-300MeV {radiation belts, solar particle events, cosmic rays} Ions 0.1-300MeV {cosmic rays, solar particle events, (radiation belts)} Electrons 0.01 - 10MeV {radiation belts, (other planets) ((solar))} The main interaction mechanism is ionisation but other processes can be important

“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

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

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

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

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 2000 - 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 http://sohowww.estec.esa.nl/

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.

XMM: Radiation Damage to Detectors Detectors (5 arrays) Spectrometer gratings mirrors Orbit 48-hr Highly eccentric Apogee: 115000 Perigee: 7000km Inclination: 40o Leads to potential degradation of CCDs and to background from soft protons entering the mirror shells

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

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

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

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…

“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

“Internal” electrostatic charging MeV electrons penetrate material and build up an electrostatic charge Meteosat 3 (1988-1992) had many disturbances On average, environment was seen to get severe before an anomaly

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

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

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

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

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

Radiation Enhancements in the Atmosphere -Altitude & latitude variations Courtesy Clive Dyer (see IEEE TNS Dec. 2001 paper)

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”

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

Example Service: Human Spaceflight Radiation Warning for ISS

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.

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

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)

Requirements Analyses have been made since ESA system studies

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.

Requirements Analyses: See poster of Glover et al.

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)