Robin van Spaandonk wrote:
In reply to Wesley Bruce's message of Fri, 04 Nov 2005 19:14:02
+1100:
Hi,
[snip]
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
Wouldn't this be going pretty fast as it passes the Earth, and
would that make it hard to catch up with it?
Yes quite a delta t but your transfering only crew, baggage and some
cargo not the mass of living quarters, power systems etc.
I favor faster craft.
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.
How long would it take if you accelerated then decelerated?
That is the time if you accelerated for half the time and decel for half
the time. no coasting.
Is there an online trip calculator?
Not to my knowlage.
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. ;-)
[snip]
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 should think that a space station orbiting Mars would be quite
useful. It could function as a planetary observatory, and as a
relay station for both information and supplies. A.o. it could
provide regular weather updates for ground crews.
The Mars mission, should not be seen as a "one shot", but rather
as the beginning of an ongoing program. Viewed in that light, a
space station in orbit makes a lot of sense. It could also
function as a staging post. Multiple shuttle trips between Mars
and the orbiting station could be then be made using fuel
manufactured on the surface.
[snip]
You don't need to resupply and crew swap a Mars net robot sat. The
russian are concidering a base on phobos. The delta t equations make
phobos easyer than the moon. You dont have to land you just dock woth
the big rock. That said the Japs are trying to dick a rover/hopper with
an asteroid and it's prooving tricky.
What's the lifting capacity of the Russian's largest rocket?
You missed this one.
Sorry I don't really know. There are two or more Russian programs, all
semiprivate now, the numbers change regularly and I'm not up to date.
Energia is retired. The medium sized craft are their strenght.
[snip]
How many satellites are already in Mars orbit, and is there any
[snip]
There's at least three and one on the way but there are
incompatibilities and other problems in the current constellation.
Doesn't sound like a lot of forward thinking went into that little
lot.
Yep and they prang half the stuff they send into the planet or in on
case the moon.
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.
If you have a constant real time link, then you don't need store
and forward capability, just a transfer capability. The storage
capability can exist on the main orbital vessel.
It's a back up option. It means that if all but one breaks down then
you've still got comms.
Also their clocks are optimized for limited gps type navigation.
Not so critical. Inertial navigation is currently pretty advanced,
so there is no real need for anyone to get lost.
True for a rover but a good system for a man on foot with limited life
support is required.
[snip]
BTW I don't think the Hafnium reactor is for real.
You think it was a misinformation program or some thing.
No, but AFAIK the initial indications that it worked haven't been
replicated.
Thanks I thought there was at least a replication.
[snip]
The half life must
change as a consequence.
I believe the idea was indeed to trigger the decays through x-ray
stimulation.
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.
What's wrong with a simple reactor?
[snip]
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.
Then you had better make sure that you have a video camera that
can actually see the fuel in the tank (sensors can be fooled). You
also need to know that the fuel is not contaminated.
Good call The mars society has someone looking at such things.
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.
You might also consider a nuclear rocket for Mars takeoff. It
could initially use compressed CO2 for reaction mass, then operate
as a ram jet as it gained velocity. That way you wouldn't have to
make any fuel.
Its already been designed and published. The papers in "Nuclear Rocketry
using Indigenous Propellants: The key to the solar system. by Robert M
ZubrinAnalog March 1990 pages32-49
I'm working on a cold fusion powered version using a plurality of small
cold fusion cells, thermal transisters and radiowave heaters to replace
the nuclear rockets.
See: http://www.marssociety.org/ and http://www.marssociety.org.au/
and http://www.marshome.org/ for all the details.
Actually, I think a large cave would probably make a much cheaper
abode. You need then only seal off the entrance(s). There are
bound to be a few lava tunnels somewhere.
I'll have two please but the odds of finding Ice and a lava cave in the
same place is low. The jackpot would be ice in a lava cave.
[snip]
Regards,
Robin van Spaandonk
http://users.bigpond.net.au/rvanspaa/
Competition provides the motivation,
Cooperation provides the means.
