Space radiation and tourism beyond LEO

I got an account on SPENVIS at http://www.spenvis.oma.be/spenvis/
and have generated some radiation shielding data and graphs.

You tell it what orbit apogee and perigee you want, how many orbits,
what thicknesses of shielding, etc. and you get some data. It is
very easy to use.

I generated data for a single geo transfer orbit to simulate a tourist
going to a GEO hotel and then back. This is through the Van Allen Belts
each way and so a lot of radiation.

I also generated data for a year stay in a GEO hotel.

So far my graphs are just for Van Allen Belt radiation and not
cosmic radiation or solar particle events.

The graphs can be seen toward the end of:

http://spacetethers.com/radiation.html

-- Vince

"Vincent Cate" wrote in message
om...
I got an account on SPENVIS at http://www.spenvis.oma.be/spenvis/
and have generated some radiation shielding data and graphs.

You tell it what orbit apogee and perigee you want, how many orbits,
what thicknesses of shielding, etc. and you get some data. It is
very easy to use.

I generated data for a single geo transfer orbit to simulate a tourist
going to a GEO hotel and then back. This is through the Van Allen Belts
each way and so a lot of radiation.

I also generated data for a year stay in a GEO hotel.

So far my graphs are just for Van Allen Belt radiation and not
cosmic radiation or solar particle events.

The graphs can be seen toward the end of:

http://spacetethers.com/radiation.html

-- Vince

I'm lousey at this kind of thing. Any idea what kind of dose an astronaut
would get if they travelled on a low thrust trajectory (say a 30-60 day
spiral orbit) on their way to escape velocity?

I'm thinking of a moon/mars mission that can only use ion-drive.

Ta.
Nathan

"Vincent Cate" wrote in message
om...
I got an account on SPENVIS at http://www.spenvis.oma.be/spenvis/
and have generated some radiation shielding data and graphs.

You tell it what orbit apogee and perigee you want, how many orbits,
what thicknesses of shielding, etc. and you get some data. It is
very easy to use.

I generated data for a single geo transfer orbit to simulate a tourist
going to a GEO hotel and then back. This is through the Van Allen Belts
each way and so a lot of radiation.

I also generated data for a year stay in a GEO hotel.

So far my graphs are just for Van Allen Belt radiation and not
cosmic radiation or solar particle events.

The graphs can be seen toward the end of:

http://spacetethers.com/radiation.html

-- Vince

I'm lousey at this kind of thing. Any idea what kind of dose an astronaut
would get if they travelled on a low thrust trajectory (say a 30-60 day
spiral orbit) on their way to escape velocity?

I'm thinking of a moon/mars mission that can only use ion-drive.

Ta.
Nathan

"Blurrt" wrote in message . au...

I'm lousey at this kind of thing. Any idea what kind of dose an astronaut
would get if they travelled on a low thrust trajectory (say a 30-60 day
spiral orbit) on their way to escape velocity?

I'm thinking of a moon/mars mission that can only use ion-drive.

With or without shielding? As I understand it, you'd get a lethal dose
quite quickly (a day or a few days) in spacecraft with a similar
amount of protection to current vessels (like Soyuz, Apollo and the
shuttle).

With heavy shielding (a foot+ of aluminum around the crew section) to
survive a slow spiral through the belts...well, I suspect that it'd be
a lot easier to use that adequate shielding mass for fuel and chemical
rockets to zip through the radiation belts.

The usual suggestion for ion-powered flights to Mars/Moon is to let
the spacecraft spiral away from Earth without a crew. Once the
spacecraft is out of the radiation belts, the crew is sent to the ship
on a small, light capsule launched by a fast chemical rocket.

Mike Miller, Materials Engineer

"Blurrt" wrote in message . au...

I'm lousey at this kind of thing. Any idea what kind of dose an astronaut
would get if they travelled on a low thrust trajectory (say a 30-60 day
spiral orbit) on their way to escape velocity?

I'm thinking of a moon/mars mission that can only use ion-drive.

With or without shielding? As I understand it, you'd get a lethal dose
quite quickly (a day or a few days) in spacecraft with a similar
amount of protection to current vessels (like Soyuz, Apollo and the
shuttle).

With heavy shielding (a foot+ of aluminum around the crew section) to
survive a slow spiral through the belts...well, I suspect that it'd be
a lot easier to use that adequate shielding mass for fuel and chemical
rockets to zip through the radiation belts.

The usual suggestion for ion-powered flights to Mars/Moon is to let
the spacecraft spiral away from Earth without a crew. Once the
spacecraft is out of the radiation belts, the crew is sent to the ship
on a small, light capsule launched by a fast chemical rocket.

Mike Miller, Materials Engineer

"Mike Miller" wrote in message
m...

With heavy shielding (a foot+ of aluminum around the crew section) to
survive a slow spiral through the belts...well, I suspect that it'd be
a lot easier to use that adequate shielding mass for fuel and chemical
rockets to zip through the radiation belts.

The usual suggestion for ion-powered flights to Mars/Moon is to let
the spacecraft spiral away from Earth without a crew. Once the
spacecraft is out of the radiation belts, the crew is sent to the ship
on a small, light capsule launched by a fast chemical rocket.

Mike Miller, Materials Engineer

But wouldn't you need that shielding anyway, in case of a solar storm?

"Mike Miller" wrote in message
m...

With heavy shielding (a foot+ of aluminum around the crew section) to
survive a slow spiral through the belts...well, I suspect that it'd be
a lot easier to use that adequate shielding mass for fuel and chemical
rockets to zip through the radiation belts.

The usual suggestion for ion-powered flights to Mars/Moon is to let
the spacecraft spiral away from Earth without a crew. Once the
spacecraft is out of the radiation belts, the crew is sent to the ship
on a small, light capsule launched by a fast chemical rocket.

Mike Miller, Materials Engineer

But wouldn't you need that shielding anyway, in case of a solar storm?

"Roger Stokes" wrote in message ...

But wouldn't you need that shielding anyway, in case of a solar storm?

Short answer: Yes and no. Yes, you'll need some shielding for a
(brief) solar storm, but no, it's not necessarily the same as
shielding for an extended journey through the radiation belts.

Long Answer:

Remember radiation applies over time.

Consider a ship with a storm shelter. It has a 60-day journey through
the belts versus an 8-hour solar storm, both radiation sources
delivering the same average amount of radiation per hour [1].

The shelter is going to thin down the radiation by approximately the
same amount in both cases. Therefore, because the 60-day journey
through the belts lasts 180 times as long as the solar storm, you end
up with 180 times the dose of radiation from the belts as you do from
the storm.

But there's more to it than just dosages over time.

Consider the area that needs to be shielded in both cases.

For a "storm shelter" that is occupied for no more than, say, 24
hours, you can make the shelter small and out of existing materials on
the ship - water and LOX tanks, food stores, etc. Think of how long
you can cram into a subcompact car when your life is on the line (or
you're a bunch of college students on spring break sharing a car ride
to Daytona Beach). When NASA rings up your ship and says, "We just saw
the x-ray pulse from the sun. You got a charged particle storm coming
your way," you have hours (I think) to get into that little shelter.

On the other hand, a shielded compartment fit for holding an entire
ship's crew for 60 days needs to be rather larger than a 24-hour storm
shelter. A slow mission to Mars might actually need to carry enough
consumables to form a 24-hour shelter without using additional
shielding mass. But to enclose 60-day crew quarters (size of an RV,
perhaps, or small mobile home) with the equivalent of a couple feet of
aluminum?

And then there's the issue of radiation direction. I think belt
radiation is omni-directional, or at least multi-directional. You need
to shield all sides of the protected area. On the other hand, I think
solar storm radiation comes from more or less one direction: the sun.
You can minimize storm shelter needs by relying on existing ship's
equipment: just aim the ship's stern at the sun. Between the engines
and remaining fuel, you should have quite a bit of shielding mass. You
can concentrate the heaviest shielding of the small shelter on one
side, minimizing the needs elsewhere.

[1] I dunno if storms and belt radiation are actually comparable, but
that'll work for sake of argument.

Mike Miller, Materials Engineer

"Roger Stokes" wrote in message ...

But wouldn't you need that shielding anyway, in case of a solar storm?

Short answer: Yes and no. Yes, you'll need some shielding for a
(brief) solar storm, but no, it's not necessarily the same as
shielding for an extended journey through the radiation belts.

Long Answer:

Remember radiation applies over time.

Consider a ship with a storm shelter. It has a 60-day journey through
the belts versus an 8-hour solar storm, both radiation sources
delivering the same average amount of radiation per hour [1].

The shelter is going to thin down the radiation by approximately the
same amount in both cases. Therefore, because the 60-day journey
through the belts lasts 180 times as long as the solar storm, you end
up with 180 times the dose of radiation from the belts as you do from
the storm.

But there's more to it than just dosages over time.

Consider the area that needs to be shielded in both cases.

For a "storm shelter" that is occupied for no more than, say, 24
hours, you can make the shelter small and out of existing materials on
the ship - water and LOX tanks, food stores, etc. Think of how long
you can cram into a subcompact car when your life is on the line (or
you're a bunch of college students on spring break sharing a car ride
to Daytona Beach). When NASA rings up your ship and says, "We just saw
the x-ray pulse from the sun. You got a charged particle storm coming
your way," you have hours (I think) to get into that little shelter.

On the other hand, a shielded compartment fit for holding an entire
ship's crew for 60 days needs to be rather larger than a 24-hour storm
shelter. A slow mission to Mars might actually need to carry enough
consumables to form a 24-hour shelter without using additional
shielding mass. But to enclose 60-day crew quarters (size of an RV,
perhaps, or small mobile home) with the equivalent of a couple feet of
aluminum?

And then there's the issue of radiation direction. I think belt
radiation is omni-directional, or at least multi-directional. You need
to shield all sides of the protected area. On the other hand, I think
solar storm radiation comes from more or less one direction: the sun.
You can minimize storm shelter needs by relying on existing ship's
equipment: just aim the ship's stern at the sun. Between the engines
and remaining fuel, you should have quite a bit of shielding mass. You
can concentrate the heaviest shielding of the small shelter on one
side, minimizing the needs elsewhere.

[1] I dunno if storms and belt radiation are actually comparable, but
that'll work for sake of argument.

Mike Miller, Materials Engineer

In article ,
Roger Stokes wrote:
With heavy shielding (a foot+ of aluminum around the crew section) to
survive a slow spiral through the belts...

But wouldn't you need that shielding anyway, in case of a solar storm?

Not really. Solar storms are infrequent and brief, so you can use a
relatively small "storm shelter" area during them.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |