[nicwolff]

From the poster that gene-h linked:

> Why Aerogel?

> - Individual fuel particles must be micron sized to permit fission fragment escape

> - Accumulation of critical mass of micron dust particles presents a challenge (levitation not feasible)

> - Embedding in solid material could solve this, but need very low density to allow FF escape

> - High temperature, low density, IR-transparent aerogel is an ideal matrix for fission fragment engine core

[iwwr]

Thanks!

So basically the fragments are escaping through the aerogel.

[db48x]

Yep. Then, because they are electrically charged and inside a magnetic field, they are accelerated out of the core and become propellant. If the magnetic field is strong enough, it seems they can reach quite a high speed. 5% of the speed of light even. It would be pretty cool to go to Mars and back on 20kg of fuel.