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Dr. Robert C. Singleterry Jr.

NASA Administrator's Fellow (Cohort 6)

NASA Langley Research Center

HPC User’s Forum, Stuttgart, GM

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Overview

Simulation at NASA for Space Radiation

What are Our problems?

Am I (we) Unique?

Possible Solutions?

No Real Conclusion!

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What is Space Radiation?

One of the top 5 problems that must be solved for extended space travel

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Simulation at NASA for Space Radiation

Just solve the Boltzmann Equations:

Easy as pie …… there’s pie?

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Simulation at NASA for Space Radiation

Not so Easy!!

Stochastic Methods

Monte Carlo is the most prevalent

Deterministic Methods

Discrete ordinates is the most prevalent

Now can use finite elements for the geometry solution

Straight ahead method (what we use now)

Dozens if not hundreds of other methods exists also

Possible solutions for space radiation?

Physics allows the straight ahead method

Many ways to even solve with this method

Interpolation

Ray-by-ray

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Simulation at NASA for Space Radiation

Today’s method of choice for us

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As vendors move towards a multi/many core environment, the individual cores slow down to beat thermal limits

The NASA Space Radiation code is a physics research code with a web based front end

Last thing thought about was execution time

Physics code was written from 1970 to present

Legacy does not begin to explain it

It is serial!!! (We have added dynamic memory allocation)

All is not lost, just limited

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What are Our Problems?

Interpolation – not much to do here

Thread the mathematics

Course parallel over interpolation points

Ray-by-Ray

Since the rays are independent, each ray can go on a core

Thread the mathematics

Still hit a wall at about 1000-2000 cores

Would take more money than we have to rewrite our code for a cluster environment

Latest NASA machine: 43,008 cores!!!

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- Simulation at NASA for the Space Radiation Effort
- Simulation at NASA for Space Radiation
- What are Our Problems?
- Possible Solutions?
- No Real Conclusions

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