NEW RESULTS FOR ISS RADIATION ENVIRONMENT OBTAINED BY LIULIN INSTRUMENT IN 2001

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NEW RESULTS FOR ISS RADIATION ENVIRONMENT
OBTAINED BY LIULIN INSTRUMENT IN 2001

• Tsvetan Dachev
• Solar-Terrestrial Influences Laboratory
• Bulgarian Academy of Sciences, 113 Sofia,
  Bulgaria
• www.stilrad.stil.bas.bg

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Outlook

• Why space environment monitoring is important?
• ISS instrumentation
• International Space Station Radiation Environment
• Anisotropy in SAA region
• Incident proton spectra inside of ISS
• Comparison of ISS with aircraft data
• Future space experiments
• Conclusions

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Why space radiation monitoring on near Earth
orbits and on aircraft altitudes is important?
Single Event Upsets on the SEASTAR flight data
recorder at 705 km altitude clearly show the
location of trapped protons in the South Atlantic
Anomaly, by Janet L. Barth
DNA damages by different kind of radiations
Single Event Upsets Observed in Autopilot in
Boeing Commercial Aircraft
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ISS instrumentation
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Liulin-E094 instrument, flown successfully on
American Laboratory module May-August 2001 as a
part of German lead Dosimetric mapping experiment
Liulin Mobile Dosimetry Unit (MDU)
Liulin Control And Interface Unit (CIU)
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Liulin-Mobile Dosimetry Unit (MDU)
Internal view of MDU
External view of MDU
Electronics
Detector preamp.
Battery compartment
SPECIFICATIONS OF MDU - Dose range 0.093 nGy
1.56 mGy - Flux range - 0.01 - 1250
part/cm2s - Energy loss range - 0.0407 20.83
MeV - Pulse height analysis range - 19.5 mV
5.0 V - LET range 0.27- 69.4 keV/m -
Temperature range 0C - 40C - Power
consumption typically 72 mW

• Size (including 70x38x20 mm battery pack of SONY
  NP-F550 type) 100x64x24 mm
• Total mass (including 0.08 kg battery pack) 0.23
  kg.
• Operation time 5 days

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International Space Station Radiation Environment
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American astronaut James Voss working with
Dosimetric mapping experiment on 26.06.2001
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Usual location of one MDU in ISS
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Locations of MDUs in ISS
13 different locations were chosen for MDUs
inside US Lab and NODE 1.
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Orientation of ISS

• During the experiments ISS was in one of two
  attitudes
• XVV - with the x-axis parallel to the velocity
  vector
• XPOP - x-axis perpendicular to plane of orbit
  z-axis constantly pointing toward the Sun

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Overview of the MDUs doses during the whole
experiment
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Comparison of the Liulin-E094 mean daily data
with (Johnson et al, 1993)
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Anisotropy in SAA region
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Anisotropy as observed in the E-T grams from
Liulin MDU1 and MDU2
19 May 2001
19 May 2001
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Spectra anisotropy during SAA crossing at
ascending and descending parts of the orbit
Descending
Ascending
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Analysis of the ascending and descendingspectra
in the Region of SAA
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Dose rate distribution in SAA for 2 different
XVV orientation time span
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Geometry of the MDUs exposition against the
eastward drifting protons in the region of SAA
MDU1, MDU3 and MDU4 detectors are orientated
toward the predominating east-down drifting
protons at descending parts of the orbit MDU2
detector is orientated toward the predominating
east-down drifting protons at ascending parts of
the orbit
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Incident proton spectra inside of ISS
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Shielding and proton anisotropic effects for
various L-shells as a function of ascending and
descending orbital passes through the SAA.
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Calibration curves of MDUs obtained during the
calibrations with protons at the Universite
Catholique de Louvain, Belgium
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MDU2 incident proton spectra inside of US Lab
module recalculated from GEANT code fit of the
Liulin calibration data
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Comparison of AP-8 MAX averaged along the orbit
proton spectrum with the calculated inside ISS
Liulin spectra for L1.32
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Comparison between Liulin MDUs and NASA TEPC data
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Comparisons with aircraft results
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Liulin-Spectrometer for more than 100 days
monitoring of the space radiation at aircraft
altitudes
External view of LS
Internal view of LS
Electronics
Detector preamp.
D-size Li-ion Batteries
SPECIFICATIONS - Dose range 0.093 nGy 1.56
mGy - Flux range - 0.01 - 1250 part/cm2s -
Energy loss range - 0.0407 20.83 MeV - Pulse
height analysis range 19.5 mV 5.0 V - LET
(Si) range 0.27- 69.4 keV/m - Temperature
range 0oC - 40oC - Power consumption
typically 52 mW

• Size 100x100x50 mm
• Total mass 0.33 kg. (including 2x 0.1 kg SAFT
  LSH20 3.6 V Li-ion batteries)
• Operation time 110 days

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Configuration of ISS and CSA aircraft orbits
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Oulu Neutron Monitor Data
After Forbush
Before Forbush
Forbush
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Aircraft data
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Variations of the CSA aircraft dose and flux data
for 30 May and 2 June 2001 on the route
Prague-New York and back
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Simultaneously plotted Flux data from MDUs on CSA
and on ISS from 21 May to 10 June 2001
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Comparison of ISS, aircraft dose and NM data
Normal to Forbush Ratios On CSA aircraft
N/F1.29 On ISS N/F1.21
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Future space experiments
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Liulin-ISS Instrument is a part of Russian
segment service dosimetric system and will work
on ISS for 15 years after the end of 2004
Liulin-ISS, MDU DIMENSIONS Weight 229 g incl.
80 g battery Size 110x80x25 mm Consumption 84
mW
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R3D-B instrument for ESA Biopan-4 facility
outside of Foton M1 satellite. On 15 October
2002 it was unsuccessfully launched. The mission
will be repeated in 2005 and 2006. The
spectrometer is mutually developed with the
University in Erlangen, Germany.

• Channels
• LET spectrometer

Biopan-4 Facility
After the crash
UV-C channel
UV-B channel
UV-A channel
PAR channel
R3D-B DIMENSIONS Weight 129 g Size 82x57x25
mm Consumption 84 mW
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The R3D spectrometer is mutually developed with
the University in Erlangen, Germany and is
expected to be launched first to Russian segment
of ISS in 2006 and next to ESA Columbus module in
2008

• Channels
• LET spectrometer

EXPOSE
PAR channel
UV-A channel
Columbus
UV-B channel
Flight unit mounted in the EXPOSE facility (May
2003)
R3D DIMENSIONS Weight 189 g Size 76x76x36
mm Consumption 120 mW
UV-C channel
Quick look data analysis panel
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Two more experiments are under development
SSD instrument for NASA DSTB (Deep Space Test
Bed) mission 2005/2006 Balloon over Antarctica
up to 40 km altitude for 2/4 weeks Weight 120
g Size 76x76x25 mm Consumption 120 mW
RADOM instrument for Indian Chandrayaan-1
satellite 2007/2008 Satellite at 100 km over
the Moon surface for 2 years Weight 120 g Size
76x76x25 mm Consumption 120 mW
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Conclusions

• Liulin-E094 doses in ISS in May 2001 at altitude
  about 400 km close correspondent with the data
  published in the NASA Spaceflight radiation
  health program (Johnson et al., 1993) and with
  AP8MAX predictions
• Comparison of the Liulin-E094 and TEPC doses
  shows differences, which are in the range of few
  to 50 in dependence of the differences of their
  shielding
• Liulin-E094 trapped proton anisotropy in SAA is
  shown by strong differences in the doses and
  fluxes on ascending and descending parts of
  orbits for the location of MDU2 in ISS. The
  enhanced doses at ascending parts of the orbits
  are explained by different shielding generated by
  the different geometry against the predominating
  eastward drifting protons in SAA region
• The analysis of the spectra in the SAA region
  shows existence of two types of predominating
  incident radiation inside ISS. In the core of SAA
  protons are predominating, while at the
  south-east bound bremstralung, generated by the
  outside electrons
• Using the Liulin MDUs calibration curves we were
  able to calculate the incident proton spectra
  inside of US Lab. Calculated spectra maximum
  moves from about 100 MeV at low L values toward
  50-60 MeV at higher L values. This behavior was
  approved by simultaneous analysis of the Liulin
  and TEPC specific doses distribution
• Comparisons of ISS and aircraft data in May-June
  2001 shows that the Forbush decreases are
  observed in similar way at both altitudes.
  Observed large differences in the average
  specific dose are associated with different type
  of particles building the doses at both
  altitudes.

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Thank you for your attention