Robin van Spaandonk wrote:
In reply to Wesley Bruce's message of Thu, 03 Nov 2005 15:09:42
+1100:
Hi,
[snip]
Firstly the ISS is the dry dock not the ship. It is actually doing quite
a lot of quiet science; learning to live in space *was* the original
objective.
The ISS would not survive a trip to Mars. It would not survive the
required acceleration,
I think that if you put the modules in line, rather than in their
current configuration, it wouldn't have any problem with the
acceleration. However I'm more curious about how long the trip
would take using a nuclear reactor and an ion engine at low
acceleration as opposed to the high acceleration chemical thruster
you appear to be considering.
About the same. The time frame is not acceleration limited. Its limited
by orbital windows. Some have proposed making a cycler using ISS
modules. The minimum fuel option is a cycler. A cycler is a craft that
orbits the sun in such a way that it takes a crew to Mars in three
months and then swings around the sun unmanned to pick up a new crew. A
second cycler going in the opposite direction would take three months to
drop someone home from mars and then spend a year going around the sun.
Ion engines are too slow for manned flight we want to go faster than
three months for manned missions. That gives us three options. Avoiding
solar flares, we have more than three months warning but less than six I
believe. Some say we have more than a year but we've only looked at a
years data from the new sats in close to the sun. Ion engines are OK for
dead cargoes but solar sails can match ion engines and plasma sails beat
them. The best sail design is at:
http://www.ess.washington.edu/Space/propulsion.html
2nPa is good thrust, better than Ion and you are not burning fuel. Also
you can combine robotic craft with manned craft in a way they
accumulates momentum in six unmanned craft. And then bounce them off the
manned crafts fields. This takes a months acceleration from the solar
wind and packs it into a few minutes of field interaction. This is my
reusable reaction mass drive. Not yet published.
If you could run a drive at one g continously Mars is 3 to 5 _days_ away
but you'd need a hell of a bumper bar.
Nuclear salt water rocket 0.1 g ~ 3 -5 weeks, a good plasma drive 0.01
g ~4 to 7 weeks, The best sail 0.005 ~6 to 9 weeks.
Reactionless drives rule. Too bad about newtons laws. ;-)
and it would not carry enough supplys to make the
round trip of three to five years.
It need not be the whole ship.
About 30% of its mass would not be
required on a trip to Mars but can't be removed.
What mass would that be, and why can't it be removed?
Lab racks with power and cooling. Their not much use on mars because
there systems are optimized for zero g.
On mars you want your lab on the ground or better still in the rover.
I'm in the Australian
Mars society and the National space society NSS. We're doing the design
work that Nasa keeps claiming the credit for.
Excellent, then you should be able to answer all my questions! :)
Dou now I'm in trouble.
Space exploration would be simpler if we had the heavy lift craft the
National Space Society NSS has been talking about for years and Nasa has
just announced it now will slowly design and build the thing./ /That's
called reinventing the wheel; given that volunteers in the NSS did a
full design a decade a go. The heavy lift ship could lift the remaining
ISS components in two shots. It can lift ~100 tons. We could do one lift
if all the bits fitted in one bundle but they don't. *Dou!*
What's the lifting capacity of the Russian's largest rocket?
[snip]
* An Orbiting network of data relay sats and navigation beacons.
Mars Net. It's been designed awaiting funds. This means that a
How many satellites are already in Mars orbit, and is there any
reason they can't talk to one another, and thus be used as relay
satellites? I know there is at least one, if you count the trip
vessel as a second, then you need only one other small satellite
to form a triangle, and that could be taken along on the trip.
There's at least three and one on the way but there are
incompatibilities and other problems in the current constellation. Mars
Net is store and forward email, much bigger data streams and the sats
can talk to each other in the same language so you can send 'live'
video. Also their clocks are optimized for limited gps type navigation.
You need 6 to 18 sats for a minimal navigational system, I believe. The
system we have uses many more sats but we do not need to more than half
a mile accuracy on mars. We don't have streets to find and buildings to
bomb over there yet.
crew or robot on Mars can call earth at any time from anywhere on
Mars and no-one can get lost. It also means a team on Mars can
teleoperate a robot anywhere on the planet in real time at any
time.
We have 3 fission options. Pebble bed, a and
neutron bombarded isotops. That's safer than EVA's.
By the time this mission gets off the ground, you may have a CF
option as well.
Why do you think I'm in both CF and the space societies?
BTW I don't think the Hafnium reactor is for real.
You think it was a misinformation program or some thing. It cold be. I
have two papers on it and they seem real. Yes its not really fission but
its still nuclear binding energy being used up. The half life must
change as a consequence.
Perhaps you could explain the "neutron bombarded isotopes" - where
do the neutrons come from?
A a two kg neutron gun fires into a cavity lined with isotopes normally
found in medium grade nuclear waste. They fission but they don't make
enough neutrons to chain react. It can be turned off quickly. I'll
check my source on that one the web page has moved on me.
Also, if by "Hafnium reactor" you are
referring to Hf-178, then that's not really a fission option.
[snip]
* Mars fuel plant launch. A robot rover equipped unmanned mars
lander that makes fuel from Martian atmosphere. Powered by some
kind of reactor. Cold fusion would be nice. We need 50 kw.
Why not land the reactor portion of the main ship on Mars? Then
you can use the power from the main reactor to create all the fuel
you need in a short period of time. It would save the whole fuel
plant trip. It could also make enough fuel for it's own launch for
the return trip. The fuel plant could be taken along on the main
ship. Might be better than landing only to discover that the
previous fuel plant mission didn't quite work, and you now have no
way of getting back. If the crew + fuel plant landing doesn't
work, then the crew are probably dead, and not very interested in
coming back anyway.
[snip]
Yes thats been thought of but if we have a big reactor on Mars then we
can do anything. But would you go to mars with a reactor and fuel plant
not knowing it will absolutly work. Send a robot. Make fuel to come
home. check it worked and then go. That way you garantee you'll get
back. That said my moneys on cold fusion. But I would still make fuel
with a fusion powered robot factory while I watched from the safty of earth.
* Permanent base, probably part underground, part in multistory
buildings and part in modular glass houses. It needs to be placed
near a multi-ton water ice deposit. Pressure domes, farm designs
and other system are either in testing or on the drawing board.
See: http://www.marssociety.org/ and http://www.marssociety.org.au/
and http://www.marshome.org/ for all the details.
Given that the Martian atmosphere is so thin, wouldn't you expect
the radiation hazard on the surface to be greater than on Earth?
If so, can you really afford to have part of it in a multi-story
building? (or is that just for the farms?)
(Do the current Mars rovers have radiation detectors on board?)
Not a problem Solar flares don't get through the atmosphere. Cosmic rays
decay products do but the flux is perfectly vertical. Cosmic rays decay
products can be stopped by several millimeters of lead on the rovers.
Three to six cm of concrete or two feet of Mars dirt. The top floor of
the multistory buildings will have plant and equipment or green houses
not living space. The average airline pilot gets a cosmic ray dose in 5
years that is about the same as the Astronaughts would get in a year.
Its not lethal and we can take stem cells from them before they go so we
can fix them when they get back. PS the lifetime radiation dose of a
Tibetan is greater than anyone in the space program. At high altitude
the cosmic ray stuff gets to millions. The longest lived people in the
world are all at high altitude so it can't be that bad.
[snip]
BTW it might be an idea to have 2 smaller reactors rather than 1
large one. Then one can be left in orbit, while one lands. On the
trips out and back, both can be used in tandem.
Regards,
Robin van Spaandonk
http://users.bigpond.net.au/rvanspaa/
Competition provides the motivation,
Cooperation provides the means.
