[ RadSafe ] Mission to Mars

[Brennan, Mike (DOH)]

Though it is not my field, I have been paying some attention to this for
some time.  

According to a presentation I attended last year, we could probably
build a ship that could go to Mars and not exceed dose limits for a crew
of 50+ year-old men, but we could not build one that wouldn't exceed the
limits for a woman of child bearing age, and that is who it has to be
designed for.  This assumes that the ship must be built on Earth and
launched: things become easier if you can assemble a much larger ship
with more reaction mass in orbit.  This is why a much cheaper system for
getting mass into orbit is the first step.

The Moon missions too between one and two weeks, as I recall, which kept
the total dose down.  A Moon base would almost certainly be built
underground, which provides as much shielding as you feel like digging
through.  

We are only scratching the surface of what can be done with robots, and
I think that for some time to come most of the serious space science
with be done by unmanned vehicles, be it in space or on a body.
Eventually, when the cost of transportation comes down, it will be
economical to have people go out and see with eyeballs, but we have a
lot to keep us busy until then.

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of
JPreisig at aol.com
Sent: Thursday, June 30, 2011 8:53 AM
To: radsafe at health.phys.iit.edu
Subject: Re: [ RadSafe ] Mission to Mars

Hi Again,
 
      This is from:    _jpreisig at aol.com_ (mailto:jpreisig at aol.com)    .
 
      Sure, a manned mission is probably quite  expensive right now.  
However, we are not starting from
zero knowledge for a spaceflight to Mars using reactor power.  See
Nerva, 
Prometheus, etc.
The government is far ahead of what we common folks know, and for
tactical  
reasons, we cannot hear
about much of the work.  Similarly for plasma physics.  Yes,  unmanned 
missions should occur to MARS
first.  Hey, haven't we already had some unmanned missions to  Mars???  
Will NASA scientists
continue to work on Prometheus???
 
      Yes, Maury, we are protected here on Earth  via the Van Allen
belt, 
the Earth's magnetic field, etc.
See Accelerator Health Physics by Patterson and Thomas for information  
about early work on 
cosmic rays,  Then look at NASA documents, Health Physics, Journal of  
Geophysical Research
(in the area of Earth magnetism etc.) for articles on this subject.
For a 
human crew on a Mars bound
spaceship, one bad solar flare can ruin your whole day (it could kill
all  
the members of such a space
crew.)   See also Brookhaven National Lab's website about the
accelerator 
there that is used for
NASA studies of space radiation  Earth  accelerators approach  perhaps
some 
of the particle energies  of
cosmic rays.  Clearly we have some understanding of sunspots,  solar
flares 
and the like.
 
     Nothing ventured, nothing gained  The space  flights to the moon 
weren't shielded by the VanAllen
belt and Earth's magnetic field.  Those Moon explorers made the trip
and 
survived.  How long did the 
Moon missions last????  Several weeks or months????.  Aren't we  now in
the 
same time ballpark 
with a trip to Mars in travel time????  NASA, Russian crews etc.  take 
risks.  They are aware of the risks and
go forward.  They are brave.  Very good ground based Engineers  and 
Scientific ground crews 
support the flight efforts.  Von Braun and company had many failed  
launches before
launches started to work fairly routinely.
 
     Hope the floodwaters recede in Nebraska.
 
     Now back to work????
 
 
     Regards,     Joseph R. (Joe)  Preisig, PhD
 
 
 
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