Solar Storm Radiation Model (SStoRM)

Solar Storm Radiation Model (SStoRM)Solar Storm Radiation Model (SStoRM)Prepared by: Joshua Lande–Marlboro College, VT and Ron Turner–ANSER, 2900 South Quincy Street, Suite 800, Arlington, VA 22206

Overview The Solar Storm Radiation Model (SStoRM) is a JAVA applet that

estimates the radiation exposure of an astronaut from a Solar Particle Event. SStoRM is useful as a teaching and illustration aid in understanding the severity of SPEs as our nation embarks on future missions to the Moon, Mars and beyond.

SStoRM can be used to help establish how the time evolution and spectral character of an SPE, not just the total fluence, impacts the astronaut, enabling investigators to expand beyond case studies of a limited number of historical events.

It provides an accessible Graphical User Interface, allowing the user to specify

– The character of the SPE (fluence and energy spectrum)

– The time evolution of the SPE It produces radiation exposure estimates:

– Absorbed Dose and Dose Equivalent

– Skin, Eye, BFO

– In free space and on a simplified lunar surface There is an “Exercise Mode” of a simulation of an astronaut on

EVA on the lunar surface

Details Input to SStoRM: 8,500 BRYNTRN-3 runs,

each with six products:

– Dose Equivalent (Skin, Eye, BFO)

– Absorbed Dose (Skin, Eye, BFO) Human represented by CAM to account

for body self-shielding Five Aluminum shielding configurations

– 0.3 g/cm2 (spacesuit)

– 1.0 g/cm2 (nominal rover)

– 5.0 g/cm2 (heavy rover/light spacecraft)

– 10.0 g/cm2 (nominal spacecraft)

– 30.0 g/cm2 (nominal shelter) Solar Energetic Particle spectra

represented by:

Input to SStoRM: 8,500 BRYNTRN-3 runs, each with six products:

– Dose Equivalent (Skin, Eye, BFO)

– Absorbed Dose (Skin, Eye, BFO) Human represented by CAM to account

for body self-shielding Five Aluminum shielding configurations

– 0.3 g/cm2 (spacesuit)

– 1.0 g/cm2 (nominal rover)

– 5.0 g/cm2 (heavy rover/light spacecraft)

– 10.0 g/cm2 (nominal spacecraft)

– 30.0 g/cm2 (nominal shelter) Solar Energetic Particle spectra

represented by:0/)( EEeEKEFluence 0/)( EEeEKEFluence

Choose the Energy Spectrum SStoRM allows the user to specify

the K, , and E0 parameters of the event

They also get to specify Emin, or the minimum energy value to integrate from when finding the integral flux

When the calculate button is pressed, the flux is graphed along with the spectral curve of several historical SPEs

The integral flux for all the graphed curves is compared in the chart to the right

Choose the Time Evolution Here, the user can select A,

B1, and B2, the parameters of the time evolution curve

C is calculated automatically to ensure that the integral flux of the time evolution of the event is the same as the integral flux of the energy spectrum of the event

Once the calculate button is pressed, the C factor and the graph of the time evolution of the event are displayed

The Estimated Dose(or “How Bad is Your SPE”)

SStoRM gives total event dose to the Skin, Eye, and BFO

It does so for thicknesses 0.3, 1, 5, 10, and 30 g/cm2

The radio buttons let the user select absorbed dose or dose equivalent

Also, exposure is either for free space or on the lunar surface

The difference is that the dose on the lunar surface is half of the dose in free space (no explicit allowance for backscattered particles)

Lunar EVA Exercise This exercise allows the user to

simulate an astronaut working on the moon during an SPE

The user can select a warning time that an astronaut would receive prior to the onset of the event

– A negative value means that they are warned about the SPE that many hours after the event has started

They then take a given time to pack up and enter the rover

They then drive back to the base Once at base, they stay under a

heavy shielding for the remainder of the event

Shielding for spacesuit, rover, and base can be varied