# Presentation: 522951

## Habitats and EVA

- LWS Radiation Emphasis
- John W. Wilson (LaRC), F.A. Cucinotta (JSC)

## Some Questions to be Answered About SPE’s

- What is the appropriate engineering design criteria to assure astronaut safety.
- What is the probability of exceeding this design requirement.
- Are the biological effects of inadequate design or other accidental exposures serious?
- What medical information and practice is required to adequately treat the astronaut during the mission?
- What operational procedures are required?

## Exposure Levels At Which Health Effects Appear In A Healthy Adult (Single, High Dose Rate Exposures)

*Exposure Constraints (Gy-Eq) to Prevent Early Somatic Effects*

-                               BFO           Skin        Ocular Lens
- 30 day limit            0.25            1.5               1.0

## Assumed Shield Configurations in the Present Study are Spherical Shells

- Spacesuit                       0.3 g/cm2  of Aluminum
- Pressure vessel              1.0 g/cm2  of Aluminum
- Equipment room            5.0 g/cm2  of Aluminum
- Shelter                            10.0 g/cm2  of Aluminum
- Computerized anatomical man (CAM) model assumed using old data.
- Radiation is assumed to be isotropically incident

## Dose and dose equivalent response functions in body tissues within various shield configurations

|  |  | Critical Energy, MeV |
| --- | --- | --- |
| Organ | Fluence, p/cm2 | Space Suit |
| BFO | 5108 |  70 |
| Skin | 2108 |  20 |

*Critical Fluence Levels In  Astronaut Exposures*

- Skin

- BFO

## Integral spectra of several events and measured intensities at 1 AU of the 2-11 August 1972 solar event

## Calculated skin and blood forming organ dose and dose equivalent (~ Gy-Eq)

- Skin

- BFO

- Spacesuit exposures

## DOD Kinetics Model

## Surviving fraction of the stem and stromal cell populations for August 1972 event

- 8 hours in spacesuit

- In a pressure vessel

## Surviving fraction of the stem and stromal cell populations for 2 X August 1972 event

| Event | Space Suit | Pressure Vessel | Equipment Room | Shelter |
| --- | --- | --- | --- | --- |
| Aug. 1972 | 1)a | 1 | 0 | 0 |
| 2 x Aug. 1972 | 12)a | 12 | 0 | 0 |
| 4 x Aug. 1972 | 87)a | 88 | 3 | 0 |

- Pressure vessel

- Equipment room

*Expected Mortality (Percent) Without Adequate Medical Treatment (DOD model)*

## Dose Equivalent And Dose In Critical Body Organs Within A Structure During The August 1972 Solar Event, cSv (cGy)

- Aluminum

- Polyethylene

## Sept 1989 Dose Equivalent to Skin and BFO

- Skin

- BFO

## Sept 1989 Tissue Specific Radiation Components within a Spacesuit 

- Skin

- Lens

- BFO

## Historical GLE and Design

- Feb 1956 GLE is largest observed
- Feb 1956 GLE ~ 10 x Sept 1989 GLE
- Design to 4 x Sept 1989 event will assure
-     larger Feb 1956 event has no significant
-     health consequence

## GCR Induced Martian Surface Neutron Model and Surface Materials

## Mars Surface Neutrons >10 MeV

## Integral LET Environment on Martian Surface (1990)(HZETRN/NUCFRG2)

**Nominal designs follow**

## TransHab exposures for 2.5 year Mars mission (cSv)

- LEO exposure limits for comparison

## Laboratory Validation Is EssentialBNL-AGS/NASA Galactic Cosmic Ray Test Facility

**Beam Port**

**Beam Monitor**

**Transhab Wall Section**

**Beam Diagnostic**

## ISS and SPE

- Magnetic field modeled after November 12-13, 1960 event
- SPE modeled after October 19, 1989 and model shock event
- LOC1 is least shielded Shuttle dosimeter
- LOC2 is heavily shielded Shuttle dosimeter
- Orbit is 51.6o inclination at 450 km

## Improved LEO environments and Solar driven dynamics (modulated neutron albedo and atmospheric loses)

**Table 1.  Comparison of present model with Shuttle flight data.**
**       ****Flight****	****     Date****	**** DRNM*    DLOC         TLD (********Gy/d)       Calc. (********Gy/d)**
**STS-41A****	****11/83         6421****	****  3****	****      64.6****	****	****     59.6**
** ****STS-51D****	**** 4/85****	****6661****	****   4****	****     917.4****	****	****     889.3**
**STS-31       4/90****	****5701****	****  1****	****   2141 ****	****	****   2290**
** ****STS-43****	**** 8/91****	****5894****	****   4****	****      20.7****	****	****      18.6**
** ****STS-62****	**** 3/94****	****6771****	****   1****	****      94.3 ****	****	****      89.2**
** ****STS-65****	**** 7/94****	****6822****	****   2****	****      28.3****	****	****      25.1**
** ****STS-67****	**** 3/95****	****6925****	****   3****	****    250.8****	****	****    238.1**
** ****STS-80****	****11/96         6973****	****   4****	****    264.4****	****	****    256.5**
**STS-82****	****  2/97****	****7074****	****  1****	****   2978****	****	****   3080**
** ****STS-91****	**** 6/98****	****6894****	****   1****	****      89.1****	****	****      83.2**
** ****STS-101****	**** 5/00****	****6460****	****   2****	****    140.8****	****	****    131.1**
** ****STS-92****	****10/00         6417****	****   2****	****    165.9****	****	****    153.4**
- * Deep River Neutron Monitor count rate

## ISS 7A Dosimetry in the SM(omni-directional fluence)

- Method 1: altitudes from prior table
- Method 2: altitudes from 5 minute flight data

## Anisotropy Effects on SM6

- Average of two passes through peak of SAA
-  (ascending node and descending node crossings

## Anisotropy and ISS

**Dose Maps**

**Directional **
**Dose distributions**

- Trapped anisotropy

- Earth’s shadow

## Exposures & Shielding Anytime/AnywhereRASC Example: L1 to Callisto surface operations (30 days) and return

- _4 g/cm__2__ shielding_

- Callisto surface exposures

- Jovian trapped e-
- exposures

- GCR background
- exposures

## Optimized L1 Gateway Singular MissionsSimplified geometry

- Single L1 Telescope Construction Mission:

- Single lunar mission:

- Optimized shield mass for L1 mission

-  Mixed crew of age 40
-  Total mission of 62 days
-  Crew never flies again
-  GCR background small
-  Design to 4Sept. 29, 1989 SPE

-  Mixed crew of age 40
-  Total mission of 47 days
-  Crew never flies again
-  GCR background small
-  Flight near Solar min.

**Very similar to the Apollo mission**

## Optimized Gateway Expeditionary MissionsSimplified Geometry

- L1 Construction missions:
-   Mixed crew of 4
-   Starting age 50
-   **2 missions/year**
**  ****37 day missions**
**  ****10 year career**
-   2 spacecraft

- Shield material key
- 1 aluminum
- 2 Polyetherimide
- 3 Polysulfone
- 4 Polyethylene
- 5 Lithium hydride
- 6 Liquid methane
- 7 H/nanofiber
- 8 Liquid hydrogen

- Lunar expedition support:
-   Mixed crew of 4
-   Starting age 45
-   **2 missions/year**
**  ****30 day missions**
**  ****10 year career**
-   4 spacecraft

**Career space workers**