Presentation on theme: "Space Weather Effects and Consequences. The case of MOPITT on board of Terra spacecraft. Florian Nichitiu Department of Physics, University of Toronto,"— Presentation transcript:
Space Weather Effects and Consequences. The case of MOPITT on board of Terra spacecraft. Florian Nichitiu Department of Physics, University of Toronto, Canada July 2004-Frascati
Space Climate/Weather Space Climate/Weather refers to changes in the space environment and effects that those changes have on Earth and mankinds activities. These affect Earth climate on various temporal and spatial scale as well as communications, navigation and many other space and ground based systems. Space Climate or Climate in near-Earth space is characterized for long-term observations of space environment. Space Weather refers for short-term, very dynamic and highly variable conditions in the geo-space environment. Impact on Solar Physics ( with consequences even for fundamental particle physics; for example neutrino oscillation problem: SNO, Canada) It is important in order to improve our understanding of the Earths climate and weather in relation with (some time) controversial problem of signatures of solar activity variability in meteorological parameters, Earths atmosphere chemistry and long term trends in Earths Climate. Big impact on space technology.Need to have Space Weather nowcast and forecast. The very complex radiation effects on spacecraft systems and instruments, end even on Earth technology are influenced by Space Weather induced variations in the Earths space environment
Sun - Geospace environment Sources of Space Weather Sun : EM radiation & particle radiation Galactic Cosmic Rays
Indicators of Solar activity Solar and geomagnetic indices are used to describe the activity levels of the Sun and the disturbance of the geomagnetic field. Sun Spot Number(SSN) Solar Radio emissions : Flux of 10.7 cm ( Ottawa index). Are essential measurements of the total amount of thermal emissions from chromosphere and lower corona.The F107 index gives a good measure of the UV radiation output ( new E107). There are suggestions that 10.7 cm flux is also an excellent indicator of magnetic activity on the Sun. UV flux, irradiance. Magnetic indices ( aa, Ap, Kp, Dst, etc..).Geomagnetic indices typically describe the variations of the geomagnetic field over a certain time period.They provide a measure of the disturbance of the magnetosphere which has direct consequences for the charged particle space environment. Trapped proton and electron fluxes Galactic Cosmic Rays, protons of very high energy and neutrons fluxes.Flux periodicity correlated with IMF and erosion effect of Earth atmosphere via Solar activity.
Variations and periodicity Solar radiation as main element of space weather, varies at very different time scales. due to solar activity due to Solar-Earth system ~27 days (Solar rotation) ~11.2 years (Schwabe cycle, cycle of solar activity) ~22 years ( Hale cycle) (magnetic cycle : the original magnetic polarity is restored every second 11- year) 80-90 years ( Gleissberg cycle) (seen by an enveloping curve of peaks of sunspot record) ~205 years (de Vries cycle): Sporer minima (AD 1420-1540) Maunder minima (AD 1645-1715) Seasonal variations (related with seasonal variations of geomagnetic activity --> variations of outer belt electron population); due to motions of the Earth around Sun (--> annual changes in the Earths atmosphere introduce seasonal modulation in low-altitude trapped proton population) Daily variations of Earths magnetic dipole (due to axial rotation of the Earth; angle between dipole and rotational axes ~11 deg.) Longer cycles – important for effects related with Earths climate and long term trends
Space Radiation Environment Electrons, protons and ions Trapped by the Earths magnetic field : Radiation Belts ( Van Allen Belts) e E< 2-3 MeV; p E< 200-300 MeV Passing through the solar system : Solar Wind ( e, p He4 ) E< 100 KeV Solar Particle Events mainly protons E = 1 - >100 MeV Galactic Cosmic Rays E up to TeV
Radiation Belts -Oct and Nov 1957 : Sputniks 1 & 2 ( SU) -Jan 1958 : Explorer 1 ( US) Expected rate 30 count/sec (Geiger-Muller counter; J van Allen ) & … zero count/sec ! -Explorer 2 =failed, BUT -March 25, 1958 Explorer 3: 30 /s ; increase to 128 /s (max on tape) then to zero c/s and again to 128. Near the perigee, back to expected 30c/s Ernest Ray : My God, space is radioactive !
1)Circular motions with gyro-radius about the field line : T~ milliseconds 2)Bounce back and forth along a field line.Reversing direction at a mirror point: T~ seconds. 3)Drift of particles around the Earth: T~ one hour. Electrons drift to east, protons drift to west A charged particle became trapped in those regions where the magnetic field lines are closed There are two main belts: I- inner belt : e and p ( up to 2.4 Re) II- outer belt : e (2.8 – 12 Re) Inner & outer belts I III
The Earths magnetic field is not symmetric South Atlantic Anomaly ( also called Brazilian Anomaly or Capetown Anomaly) is a lowest magnetic field region located at 26S, 53W.
SAA is frequently said is due to the The tilt of the dipole axis with respect to the rotational axis And due to the displacement of the geomagnetic axis from the center of the Earth
Electrons AE-8Protons AP-8 Radiation Belt Models
Plasma and Solar Wind Continuous flux of particles ( e, p, He) from sun; (Expanding magnetized plasma generated by the Sun) -characterized mainly by speed and density. Geomagnetic activity is controlled by the solar wind speed and IMF orientation. An important parameter: Bz oscillation and a turn to 5) Electron enhancements- tendency to occur at the solar rotation period (27 days) Strong correlation between electron precipitations (E>30 keV) at polar orbit and solar wind speed at 1 UA. -consequences for physico-chemistry parameters of the atmosphere.
Solar Energetic Particles SEP or SPE (Solar Proton Events) ( Solar Cosmic Rays) Origin : Solar flares and Coronal Mass Ejections (CME) p, e & He emitted by the sun in burst during solar storms -energies > 10 MeV/nucleon -access to open magnetic fields of polar cap. Produce also : X-rays; gamma-rays, UV light burst and very fast wind flow which can inject protons into the trapping region ( even create second proton belt) Fluence: from 10^5 to 10^11 part/cm^2 Duration of event: from one to several days Bastilia Solar Event 14 July 2000
SPE Periodicity: Frequency spectra of solar proton fluence of Energy > 30 MeV periods of ~ 11 years and 3-4 years. Impossible to predict -greater occurrence frequency during maximum solar activity - and during decline of cycle NASA SOHO Image Solar Flare
Cosmic Rays Galactic Cosmic Rays: fully ionized particles of all stable elements (90% p ~7% He) Origin: galactic and extragalactic; Energies up to TeV Energy spectrum max at 0.3-1 GeV/nucleon The incoming charged particles are modulated by the solar wind and IMF which decelerates and partially excludes the lower energy GCR from the inner solar system. There is a significant anticorrelation between solar activity and the intensity of the CR with E< 10 GeV. Variations of proton counts E=80-215 MeV of MEPED detector aboard the TIROS/NOAA spacecraft
Natural Albedo Radiation Is in fact the secondary radiation generated in the inner magnetosphere due to: -nuclear reactions by GCR and SPE interactions with : - protons of the inner belt - and atoms of the atmosphere -secondary CR decay ( pions, muons..) This radiation component consists mostly of: - neutrons - e- and e+ - protons ( and antiprotons), nuclei There is also an anticorrelation between solar activity and the intensity of secondary radiation as a result of atmosphere expanding ( and increasing of nuclear interaction rate) during high solar activity.
Short term variations of Albedo Radiation -When the Sun releases a large burst of matter and magnetic disturbance a magnetic storm which prevent many cosmic rays from entering the atmosphere. Forbush decrease detected by the Inuvik neutron monitor at 23 Mar 1991. Solar cosmic rays produced by a solar flare are recorded as a sharp increase in secondary neutrons flux. The event of May 24, 1990 seen by Inuvik, Deep River and Goose Bay neutron monitors.
Low energy particles - correlated with SA High energy particles - anti-correlated with SA Solar Activity Effects on Spacecraft and instruments Solar irradiance - correlated with SA Neutron Flux - anti-correlated with SA Neutrons cosmogenic radionuclides (14C,10Be,36Cl) : extend record of Solar Activity : signal of past climate variations Effects on Earth Climate
Radiation effect on spacecraft systems and instruments Spacecraft anomalies: from -------- easily recovered to -------- total mission failure origin: -- engineering (operation fault, mechanism failure and ageing) -- space weather which simulate engineering faults BUT not only Based upon the effect upon the s/c : Surface charging | Photonics noise Deep dielectric charging | Total dose effects Single Event Upset (SEU) | Material degradation Solar radio frequency interference | Spacecraft drag
Surface Charging S/C immersed in a cool, dense plasma e, ions, secondary emitted particles : photoelectrons and backscattered electrons Gives net s/c potential And this lead to discharges noise into the system; false command, change the physical characteristics of subsystems. Occurs predominantly during geomagnetic storms ( for K index >=6) Night Day transitions are especially problematic during storms: photoelectric effect is abruptly present/absent trip discharges There is also a strong local time asymmetry: majority Surface Charging anomalies occur during the night
Deep dielectric charging Is a problem primarily for high altitude s/c Relativistic electrons (E> 1MeV) can easily penetrate s/c shielding and can build up charge where they come to rest ( in dielectrics). For high electron flux during extended period of time abrupt discharges deep in the s/c. Discharges appear to correlate well with long periods of high fluxes. High fluxes of these electrons vary with 11 year Solar Cycle. This variation is dictated by the nature of the suns output and by the character of the solar wind incident on the magnetosphere. Was also found that the equinoctial fluxes of electrons (this is an average over 7 years) were nearly a factor of three higher than the average solstice fluxes. Example: Anik/Intelsat (Ca) : 1994 wheel controller 1998 lost all power from solar panel array
Single Event Upset (SEU) SEU occur when a high-energy particle penetrates s/c shielding and hit a device causing a disruption. Effects can range from simple device tripping to component latch-up or failure. Hitting memory devices result in bit-flip. SEU are normally caused by GCR and SPE and high energy trapped particles. SEU rates increase with high fluxes, but the particle energy spectrum and arrival time seen by satellites varies with the location and nature of the event on the solar disk. Distribution of SEU over entire CRRES mission (launched July 25, 1990; returned data for ~14 months) SEU peak occurrence frequency corresponds to the peak of ~50MeV protons of the inner belt. The shoulder in distribution correspond to the peak of the secondary proton belt (from 23 Mar 1991 solar storm). SEU attributed to Cosmic Rays
MISR camera (3 Febr16 Febr 2000) Before cover opened (proton hits cameras designed to detect visible light) UoSAT-2 microsatellite SEU- (recoverable) memory upsets (from Sept 1988 to May 1992) Satellite anomalies over SAA
SOHO LASCO C2 & C3 Images July 14, 2000 - A powerful X class flare erupted from sunspot region 9077 at approximately 10:24- it was accompanied by a full halo coronal mass ejection that is Earth directed. April 23 2003 Bastilia Solar Event– example of High Radiation Background anomaly
TERRA Solid State Star Tracker anomalies High Background
Device Single Events (DSE) - anomalies – occurring in a piezoelectric accelerometer within the MOPITT ( Measurements Of Pollution In The Troposphere) instrument aboard the Terra spacecraft. - Piezoelectric accelerometer anomalies - Location of anomalies signals - Correlation with big Solar Particle Events - Correlation with Solar Activity ( Solar Sub maximum I and II) - Conclusions and consequences The case of MOPITT
SAA Sun Terra, is the name of the Earth Observing System (EOS) flagship satellite, launched on Dec. 18, 1999. The mission is a vital part of NASAs Earth Science Enterprise, helping us understand and protect our home planet Terra s/c is in a sun-synchronous polar orbit. Orbital period=98.88 min. Altitude=705 Km. 25 Jun 2004 01:41:51.36
MOPITT instrument The vibration level is measured by two piezoelectric accelerometers -Cooler Compressor (vibrations for x,y,z) -Cooler Displacer (vibrations for x,y,z) MOPITT instrument is an infrared gas correlation radiometer.It operates with eight channels : for CO and CH4. Infrared detectors need to be cooled to less than 100 K ( by Stirling Cycle Coolers with two Compressors and two Displacers mounted back to back).
Location of MOPITT accelerometer anomalies Total time: 993 days; Daily rate=1.06 ev/day Total Nr events over SAA=567 ( 54%) SAA rate= 0.57 ev/day MOPITT spend only 6.25% of time over SAA SAA rate=9.14 ev/day South Atlantic Anomaly seen by MOPITT
MOPITT Accelerometer Anomalies are caused by the radiation environment SAA events = 54 % Background = 20.4% Poles ( +/- 65 ) = 25.6 %; North/South (poles) asymmetry=0.43
MOPITT Accelerometer Anomalies in South Atlantic Anomaly region Day – Night Asymmetry SAA: Day/Night = 0.72 During the Night: Lat & Long widths increase with 2-3 deg.
Solar Proton Events Max p Flux [pfu] @ >10 MeV >100 MeV Y1 Jul 14/15: 2000 24000 410 Y2 Nov 09: 2000 14800 347 N1 Sept 25: 2001 12900 31 Y3 Nov 06: 2001 31700 253 N2 Nov 24: 2001 18900 4 -Solar Proton Events ( from ftp://ftp.ngdc.noaa.gov/, ftp://ftp.ngdc.noaa.gov/ http://www.sel.noaa.gov/weekly/) 1 pfu = 1part/(cm^2 s sr) MOPITT Accelerometer detect SPE at 6 Nov (during the second peak of proton flux) even if the Solar Event start at 4 Nov
The Proton Monitor data consists of counting rates in a MicroChannel Plate (MCP). The PM MCP responds to secondaries generated by ions with incident energies > 50 MeV and electrons with incident energies > 2 MeV. CELIAS/MTOF Proton Monitor on the SOHO Spacecraft 4-7 Nov 200122-25 Nov 2001 Seen by MOPITT Acc ( Y3) NOT Seen by MOPITT Acc ( N2)
29 Oct 2003 Solar Proton Event Max Proton Flux (pfu) > 10 MeV > 100 MeV 29/10 : 29500 186 30/10 : 3300 110 MOPITT DSE Total # # /Day 29/10 : 9 2.15 30/10 : 7 2.15 This SPE induced a high daily rate for MOPITT DSE on two consecutive days when, as in previous cases, the high energy component (>100 MeV) reaches a large value. These MOPITT DSEs are also located on the polar regions.
SPE detected by MOPITT. Energy dependence Correlation between number of DSE during SPEs and the SPE proton fluence for E> 15 MeV. Y# and N# refer to SPEs identified in previous Table. The energetic particles detected by the MOPITT (piezoelectric) accelerometer are mainly high energy protons
MOPITT Accelerometer Anomalies during intense SPE - are caused by high energy charged particles precipitating via pole horns. - more events during the Day
During High Solar Activity period ( II sub-max) the relative contribution of trapped particles in SAA decrease from ~70% to ~40%, Background remain almost constant(~20%) and Poles contribution increase (from ~15% to ~40%). This is a consequence of direct injection of more high energy particles (via poles) during High Solar Activity. Correlation with Solar activity There is an overall increase ( ~ two times) of MOPITT DSE daily rate during the time period Nov 2001 – Feb 2002 (second Solar sub-maximum)
Correlation with Solar activity MOPITT Accelerometer anomalies are correlated with Solar Activity as shown by Solar centimetric Radio Flux : Ottawa index F10.7 With Sun Spot NumberWith 10.7 cm radio flux F10.7
Summary and conclusions Analysis of MOPITT anomalous accelerometer signals shows a direct correlation of the DSE daily rate with solar activity, a Day/Night asymmetry caused probably by interaction of trapped particles with the neutral atmosphere, and a direct correlation with high intensity solar proton events (SPEs). The high energy particles – the source of anomalous accelerometer signals- are localized mainly in SAA region, but the polar regions, particularly the southern pole, are also regions of higher risk for satellites mainly during intense SPEs. We have also found that at least during the Solar maximum, there is a correlation of the particle population responsible for DSEs in the piezoelectric accelerometer with solar activity as expressed better by the F10.7 than the SSN. During the second sub-maximum of Solar Cycle SC23, the fraction of events over the poles relative to the SAA region increase, which mean that, probable there are more high-energy particles of non-trapped origin in this time interval, and a good proxy of Solar activity for this purpose is the F10.7 Solar Radio Flux index.
The paper: Solar Particle Events seen by MOPITT instrument by: F. Nichitiu, J.R. Drummond, F.Zou,R.Deschambault has been accepted for publication in Journal of Atmospheric and Solar-Terrestrial Physics MOPITT mission and data analysis are supported by the Canadian Space Agency (CSA), Natural Sciences and Engineering Research Council (NSERC) and the National Aeronautics and Space Administration (NASA) E N D Message : including Space Environment Sensors on satellites is a difficult idea to sell to management (because of cost/weight/power penalty) BUT with very good benefits
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