Why the large differential in trips to Mars?

well they might be able to create gasses and run a engine to power a mars base

In article ,
says...

well they might be able to create gasses and run a engine to power a mars base

What are you babbling on about now? Who are "they"?

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

mars society had that proposal for mars direct including in situ production of fuel for the return trip to mars.

now that same fuel could be used tp power the station?

On Fri, 17 Aug 2012 15:05:52 -0700 (PDT), bob haller
wrote:

mars society had that proposal for mars direct including in situ production of fuel for the return trip to mars.

now that same fuel could be used tp power the station?

Circular reasoning. In-situ production requires power.

"My base has power to make in-situ fuel production, therefore I can
use that in-situ fuel to make power for my base."

Nope. Doesn't make sense.

Brian

In article , bthorn64
@suddenlink.net says...

On Fri, 17 Aug 2012 15:05:52 -0700 (PDT), bob haller
wrote:

mars society had that proposal for mars direct including in situ production of fuel for the return trip to mars.

now that same fuel could be used tp power the station?

Circular reasoning. In-situ production requires power.

"My base has power to make in-situ fuel production, therefore I can
use that in-situ fuel to make power for my base."

Nope. Doesn't make sense.

The only possible way it makes sense is if you're using solar power and
using some of the fuel/oxidizer to produce power for the base at night.
But as others have noted, solar doesn't make much sense on Mars,
especially if you need a lot of power (e.g. to make fuel and oxidizer
for the return trip).

If your base is nuclear powered (which seems likely), then you're
absolutely right, you won't need any fuel/oxidizer to power the base.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

fuel production is a function of time and power...

realtively low power solar for a number of years could create enough
fuel to run a station for a time.....

it would be a juggling act to decide how many years solar would have
to create fuel for base operations for 2 years.......

ideally the fuel would be on site complete before the crew left earth

In article 4d1800c4-528d-4dbb-872e-
, says...

fuel production is a function of time and power...

realtively low power solar for a number of years could create enough
fuel to run a station for a time.....

True, but irrelevant.

it would be a juggling act to decide how many years solar would have
to create fuel for base operations for 2 years.......

ideally the fuel would be on site complete before the crew left earth

Possibly, but if your problem is how to power the base, why not size the
power plant to the base requirements in the first place?

Engineering solutions come directly from the problems to be solved. I
don't see a problem statement which leads to the solution you're
proposing. What problem are you trying to solve here?

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article m,
says...

Is Solar truly useless on Mars ? Wouldn't it just be a question of
larger solar panels ?

With new flexible solar panels which are quite light, why would this not
be a viable solution ?

Couldn't this provide at least a minimum of power to sustain life in
some ground modules ?

Dust storms can coat the panels, reducing output. Since dust storms are
unpredictable, output from the arrays will be unpredictable as well.
Adding any sort of cleaning mechanism introduces complexity and the risk
of failure either of the solar panels or the cleaning mechanism.

And if there is an orbiting expedition ship, would solar also be out of
the question for it (and its journey back to earth) or would solar be
workable for it ?

Solar in orbit is at least predictable.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On 21/08/2012 1:36 PM, JF Mezei wrote:
Is Solar truly useless on Mars ? Wouldn't it just be a question of
larger solar panels ?

With new flexible solar panels which are quite light, why would this not
be a viable solution ?

Couldn't this provide at least a minimum of power to sustain life in
some ground modules ?

And if there is an orbiting expedition ship, would solar also be out of
the question for it (and its journey back to earth) or would solar be
workable for it ?


The problem with flexible panels is just that - they flex - remember the
winds on Mars are up to 200km/h - while only being 1% of Earth's
sea-level air pressure, that's still enough to make those panels into sails.

Jeff points out that dust is a problem, but the dust can be blown off -
a small 'air' compressor would be used to compress Martian air and use
that to clean the panels.

Fixed panels are better for Mars.

For an orbiting ship, solar is fine - you just need twice as much in
Martian orbit compared to Earth orbit due to the lower solar levels that
far away from the Sun.

No, solar is not out of the question for use on the Martian surface,
especially if linked to fuel cells for a regenerative system. It would
just take twice as much area as those on Earth. Dust is _still_ the
main problem with that, but the solution I suggested above would work.
Afterall, the panels in the Mojave desert at SEGS (Solar Electricity
Generating System - look it up on Wikipedia) are washed with water - why
not use Martian air on Mars for the same thing?

I think Zubrin's idea of using a small reactor is quite a good one, but
there's the issue of getting it there and all the socio/political
problems of launching a nuclear reactor, despite the power source for
Curiosity (which seems to have gone largely un-noticed by the greenies etc).

On 24/08/2012 03:06, Alan Erskine wrote:
On 21/08/2012 1:36 PM, JF Mezei wrote:
Is Solar truly useless on Mars ? Wouldn't it just be a question of
larger solar panels ?

With new flexible solar panels which are quite light, why would this not
be a viable solution ?

Couldn't this provide at least a minimum of power to sustain life in
some ground modules ?

And if there is an orbiting expedition ship, would solar also be out of
the question for it (and its journey back to earth) or would solar be
workable for it ?


The problem with flexible panels is just that - they flex - remember the
winds on Mars are up to 200km/h - while only being 1% of Earth's
sea-level air pressure, that's still enough to make those panels into
sails.

Jeff points out that dust is a problem, but the dust can be blown off -
a small 'air' compressor would be used to compress Martian air and use
that to clean the panels.

Fixed panels are better for Mars.

For an orbiting ship, solar is fine - you just need twice as much in
Martian orbit compared to Earth orbit due to the lower solar levels that
far away from the Sun.

No, solar is not out of the question for use on the Martian surface,
especially if linked to fuel cells for a regenerative system. It would
just take twice as much area as those on Earth. Dust is _still_ the main
problem with that, but the solution I suggested above would work.
Afterall, the panels in the Mojave desert at SEGS (Solar Electricity
Generating System - look it up on Wikipedia) are washed with water - why
not use Martian air on Mars for the same thing?

I think Zubrin's idea of using a small reactor is quite a good one, but
there's the issue of getting it there and all the socio/political
problems of launching a nuclear reactor, despite the power source for
Curiosity (which seems to have gone largely un-noticed by the greenies
etc).


Using Solar will mean -

.. Sending large and heavy batteries to Mars for storing electricty
in the day for usage during the night.

.. Dust storms last for weeks (sometimes) cutting Solar energy output
drastically. Sure you could store energy during sunny periods for
use during dust storms - though you'd need absolutely gigantic
batteries for that purpose.

.. The most useful scientific experiments generally require megawatts
of power to provide conclusive results. Not sure at all solar could
provide this science power - and power our life support systems at
the same time.

If there was a safer option that existed instead of nuclear I'd be
all for it and give it a big thumbs up. If we had to launch a human
mission to Mars today unfortunately nuclear seems to be the only
option.

Still, as somebody else mentioned we're many decades away from doing
that so hopefully there will be an energy breakthrough in the time
it takes. Just like I'm hoping there will be a propulsion
breakthrough that will let us go to Mars in just a few weeks. If
we could do that then we could launch a mission much sooner.

--
T