Cosmic Radiation

On Thursday, September 25, 2003, at 11:57 AM, Lucio de Souza Coelho

> "The effect of the blocking from atmosphere 'down under' is trivial
> compared to the blocking by 6,000 miles of rock. The reason you need
> double the atmosphere is that I assume *no* cosmic radiation comes from
> under your feet on Earth. Thus, on a colony, you get cosmic radiation
> from twice as many directions, requiring twice the shielding provided
> by the atmosphere."
>
> That is, you were assuming that if you have some atmosphere-equivalent
> shield
> in both sides (like in my membrane example) then you get radiation at
> Earth-surface levels.

Hm. No. Exactly the opposite. It says, in the first sentence, that
the Earth blocks far more than the atmosphere which is why you get 'no
cosmic radiation ... from under your feet'.

However, others have pointed out a couple of things: The atmosphere
seems to block most cosmic radiation (99% is best number I've seen, but
the jury is still out). Also, the Earth itself emits quite a bit of
radiation. On this front, how much comes from the last few meters of
the Earth? I would expect radiation coming from lower down would be
blocked, but perhaps I've got this wrong.

>
The International Space Station (ISS) most important legacy may be
jump-starting space tourism. Consider: the first space tourist, Dennis
Tito, was supposed to go to the Soviet era Mir space station. Under
pressure from NASA, Russia de-orbited the Mir which resulted in Mr.
Tito going to the ISS instead. Now the Mir was old, smelly, crowded and
probably not all that nice. The ISS was brand new, shinny, much more
roomy, etc. Mr. Tito came back to Earth with glowing accounts of how
great space is. Would his experience have been as good on Mir?

Al Globus
CSC at NASA Ames Research Center
http://www.nas.nasa.gov/~globus/home.html

Views expressed in this email are only my opinions and are not the
position of any organization I'm familiar with.