# Presentation: 164749

## Operational Aspects of Space Radiation Analysis

**October 18, 2005**
**Mark Weyland**

## 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

## 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

## 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

## 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 Equivalent_
- 25 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 %**

## REAL TIME SUPPORT

**Notes:**
NOAA SEC in Boulder, CO   (EASY Mike)
L-30, and L-3 day briefings
And daily briefings when on console during real time support (discuss in a minute)

## 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

**Notes:**
Examine available space weather data, reports, and forecasts for trends or conditions which may produce enhancements in near-Earth space radiationenvironment
Tag-up with NOAA SWO Solar Forecaster for “big picture” of space weather conditions
Check vehicle status and crew timeline for the potential for unscheduled EVAs
Report crew exposure status and space weather conditions to flight management

## SPACE WEATHER

## SPACE WEATHER

## SPACE WEATHER

## REAL TIME

## REAL TIME

## REAL TIME

- Solar Active Region Display System (SARDS)

## REAL TIME

## REAL TIME

**Notes:**
What do we do during contingency situation (usually middle of night)

## 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 called
- 20 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 called
- 20 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 called
- 20 Jan 2005 07:05z 	Energetic SPE (>100MeV) Exceeded 400 Level: 07:00:00 426.760010; pager called
- 20 Jan 2005 07:01z 	Energetic SPE (>100MeV) Exceeded 200 Level: 06:55:00 217.960007; pager called
- 20 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 called
- 20 Jan 2005 06:47z 	Flare Exceeded X1 Level: 06:46:00 - X1.50; pager called
- 20 Jan 2005 06:46z 	M Flare Start (Crossed 5.000000e-05 Threshold): **06:45:00** - M9.04; pager called

## 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.

## CONTACT INFORMATION

- srag.jsc.nasa.gov

**Notes:**
P339 – Treadmill (more shielded area)
P327 – Next to R-16
P307 – Workstation (and at other end of module)
Window 14 – Thinly shielded area on front end

Doses rates change with attitude and altitude lately, and will approximately double at solar min

Vary more than 35% in SM

## CONTACT INFORMATION

## 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

## 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

## 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](slide24.xml)_ 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

## 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

***To design a flying machine is nothing; ***
***building it is not much; ***
- Otto Lilienthal

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