18-OCT-2005 Lyndon B. Johnson Space Center space radiation analysis group 1 Operational Aspects of Space Radiation Analysis October 18, 2005 Mark Weyland.

1 18-OCT-2005

Lyndon B. Johnson Space CenterLyndon B. Johnson Space Centerspace radiation analysis group

Operational Aspects of Space Radiation Analysis

October 18, 2005

Mark Weyland

2 18-OCT-2005


BACKGROUND

• The SRAG was established at the NASA – Johnson Space Center in 1962

• SRAG provided 24-hour support for all manned missions until 1994

• Pre-flight, in-flight, and post-flight support

• Legal and moral reasons require NASA limit astronaut radiation exposures to minimize short and long-term health risks

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ALARA

• Adherence to ALARA (As Low As Reasonably Achievable) is recognized throughout NASA’s manned spaceflight requirements documents

• Radiation protection philosophy-- All radiation exposure, no matter how small, increases the health risk to that individual (Linear Non-Threshold Theory)

• Astronaut exposures are much higher than the typical ground-based radiation worker

• Space radiation more damaging than radiation typically encountered by ground-based workers

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BACKGROUND

Acute affects» Affects range from mild and recoverable to death

» Risk of acute affects during LEO missions is very small

Long-term risks» Cancer risk increase

» Cataracts

» Genetic affects

» Heart risks

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Limits

30 Day:

NASA BFO (NCRP 98)

Eye (NCRP 98)

Skin (NCRP 98)

Annual

NASA BFO (NCRP 98)

Eye (NCRP 98)

Skin (NCRP 98)

Dose Equivalent25 cSv

100 cSv

150 cSv

50 cSv

200 cSv

300 cSv

30 day and annual and limits serve to protect against deterministic effects

Career limits serve to protect against long-term deterministic and stochastic effects, most specifically to limit additional cancer mortality less than 3 %

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REAL TIME SUPPORT

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REAL TIME

•Nominal support on console from Mission Control Houston (MCC-H) is 4 hours per day

•In MCC-H continuously during significant space weather activity and all EVA's

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SPACE WEATHER

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SPACE WEATHER

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SPACE WEATHER

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REAL TIME

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REAL TIME

Nov 8 2000 SPE - First Day

Nov 9

15:00 17:00 19:00 21:00

Dos

e R

ate

(G

y/m

in)

0.01

0.1

1

10

100

1000TEPC SPERTAlarm setpoint

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REAL TIMESolar Active Region Display System (SARDS)

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REAL TIME

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REAL TIME

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SRAG Space Weather Alarm System Log

20 Jan 2005 17:18z SPE (>10MeV) Decreased Below 1000 Level: 17:05:00 645.6; pager called

20 Jan 2005 08:35z X-ray Flare Event Ended at 08:34:00 - M4.85/ Peak at: 07:01:00 - X7.12/ 1.805278 hours; pager called

20 Jan 2005 08:34z Flare Decreased Below M5 Level: 08:33:00 - M4.95; pager called

20 Jan 2005 07:28z Energetic SPE (>100MeV) Has Peaked at: 07:10:00 652.359985; pager called20 Jan 2005 07:28z SPE (>10MeV) Exceeded 1000 Level: 07:15:00 1113.5; pager called

20 Jan 2005 07:28z X-ray Flare Half Peak Event Ended at 07:27:00 - X3.43/ Peak at: 07:01:00 - X7.12/ 0.690000 hours; pager called

20 Jan 2005 07:18z X-ray Flare Has Peaked at: 07:01:00 - X7.12; pager called20 Jan 2005 07:17z Flare Decreased Below X5 Level: 07:16:00 - X4.93; pager called

20 Jan 2005 07:15z Energetic SPE (>100MeV) Exceeded 600 Level: 07:10:00 652.359985; pager called20 Jan 2005 07:05z Energetic SPE (>100MeV) Exceeded 400 Level: 07:00:00 426.760010; pager called20 Jan 2005 07:01z Energetic SPE (>100MeV) Exceeded 200 Level: 06:55:00 217.960007; pager called20 Jan 2005 06:57z Energetic SPE (>100MeV) Start (Crossed 1.0 Threshold) 06:50:00 21.980000; pager

called

20 Jan 2005 06:53z Flare Exceeded X5 Level: 06:52:00 - X5.34; pager called20 Jan 2005 06:47z Flare Exceeded X1 Level: 06:46:00 - X1.50; pager called20 Jan 2005 06:46z M Flare Start (Crossed 5.000000e-05 Threshold): 06:45:00 - M9.04; pager called

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ISS Crew Dose Summary From January 2005 Event

• Due to fortunate orbital phasing, crew only received around 2 days worth of additional dose (~0.035 cGy).

• If ISS had begun the high magnetic latitude passes during the start of the event, the doses would have been a factor of 10 higher for this event.

• If the Shuttle were on the way to the moon, the doses would have been around 6 cGy in the first 2 days. This is more than a ground based worker is allowed in a year.

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CONTACT INFORMATIONsrag.jsc.nasa.gov

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CONTACT INFORMATION

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Constellation Vehicle Shielding

• Radiation specific shielding on Exploration vehicles is unknown

• Already push-back on adding mass for radiation protection

• Best case scenario’s still leave short duration vehicles and EVAs (low shielding) vulnerable to SEPs

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New Challenges for SRAG

• Train Space Wx Officers for each mission

• Implementation of design ideas (shielding, materials)

• Education (design engineers, management, crew)

• New models and tools

• Concept of Operations

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SRAG Wish List

• Recommendations of the NASA Sun-Solar System Connection Radiation Working Group Report – July 2005

• Real time data from spacecraft for operational purposes, (NDAs)

• Additional real time measurements in proton flux (50's &100's, but also 300's to 500's)

• Integration/transition from research models to configuration controlled V&V operational tools (CCMC?)

• Satellite data sent directly to future Constellation vehicles as well as the ground

• Quiet time forecasts

• Active/electronic personal dosimeters with well characterized charged particle/neutron sensitivities

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FINAL THOUGHT

Of all the risks encountered by astronauts during

space flight, the increased risk of cancer induction

from radiation exposure is one of the few that persists

after landing

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To design a flying machine is nothing; building it is not much; flight testing it is everything.

Otto Lilienthal

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To design a model is nothing; building it is not much; testing (V&V) is everything.

18-OCT-2005 Lyndon B. Johnson Space Center space radiation analysis group 1 Operational Aspects of Space Radiation Analysis October 18, 2005 Mark Weyland.

Documents

space weather slide

nasa johnson space center

real time slide

real time support slide

system sards slide

mark weyland slide

real time nominal support

skin ncrp