Mars 2014 - One Way

Invid Fan wrote:
The fact the colonies created enough wealth to buy imports means they
were profitable. An unprofitable colony would have the parent nation
sending needed goods for free or at reduced prices.


Only if they buythings at non-subsidised costs.

--
Sander

+++ Out of cheese error +++

wrote:
Incidentally, best guess based on spectra is that they are
*outer-belt*
asteroids. Those aren't so easily found in the inner system. (How they
ended up in low circular orbits around Mars is a good question.)

Even the very thin atmosphere at orbital altitudes can circularize any
orbit given enough time. The much higher drag at the perihelian lowers
the aphelion. Mars had a lot more atmosphere 4 billion years ago,
and 4 billion years is a really long time. If simulations don't show
this as enough time, then my guess is their model of the atmosphere is
wrong.


Or you are not taking things rationaly.

--
Sander

+++ Out of cheese error +++

On Tue, 21 Dec 2004 16:51:25 +0000 (UTC), in a place far, far away,
Sander Vesik made the phosphor on my
monitor glow in such a way as to indicate that:

There is no "we" about colonization. It is an individual decision and
also an individual responsibility. A colonist who can't support
himself is not a colonist - he's a welfare recipient living in a very
expensive housing project.

Care to look up at which point the US was able to produce everything
it needed?

Whether it's capable of producing it is irrelevant. The point is that
it's capable of paying for it.

Henry Spencer wrote:
In article ,
Christopher M. Jones wrote:
Ooo, ooo, orrrrr. Maybe, just maybe, Mars! The very same
Mars with a massive ice sheet on one pole and permafrost
deposits (or at least some form of Hydrogen) just a few
meters below most of the surface of the entire planet...

Of course, dirty cryogenic permafrost is not the easiest stuff to mine.
And we are probably talking about mining, not about scooping it up with
a backhoe -- permafrost at those temperatures is hard as rock.

Yes, I am well aware of that. It's not an easy problem
by any means, but comparing the difficulty of getting the
process going vs. the results its a pretty big win at
pretty low input cost, especially when compared to other
alternatives throughout the Solar System. I was mainly
commenting on the difference in ease of processing local
materials for propellant production on Mars vs. on Phobos.
On Mars there are many very robust, relatively low-cost
pathways to propellant manufacture, with permafrost
mining and atmospheric processing represinting a route
that can produce large quantities of propellant with
fairly low initial capital investment using entirely
local materials.

The comparable processes on Phobos are less easy, less
straightfoward, and have a higher entrance barrier (on
Mars you can begin very easily by brining along
Hydrogen, processing CO2 from the atmosphere and producing
LOX/CH4 from mostly, but not entirely, local materials,
there is no similar "back door" to in situ resource
utilization on Phobos). For example, I don't think many
people have fully though out the difficulties of
excavating Phobos. If we just so happen to be
tremendously lucky then there will be a lot of loose,
high-H2O content material on the surface (snow, basically).
More likely, it will be embedded in regolith that may or
may not be hard packed and may or may not be frozen
together in permafrost formations. Even if the ice is
packed (together with other materials) only as loosely
as, say, your average Earthly dirt, that could still be
problematic. The amount of force necessary to excavate
is dependant only on material properties, but the
amount of force available for excavation is often
dependent on weight. And on Phobos there isn't a whole
lot of weight to be had, especially in that we won't be
able to make the equipment itself very weighty. Very
likely excavation equipment on Mars will be fairly
awkward contraptions weighed down, or perhaps anchored,
in place so that they can apply mechanical forces into
the surface. Then you get into issues involving the
efficiencies of the propellant production process, which
favor the Sabatier process pretty heavily over
electrolysis.

Anywho, desnarkify my original comments and the message
is still perfectly accurate, independent of other factors
it will almost certainly be easier to utilize in situ
resources on the Martian surface than on Phobos.


Then of course, you have to consider exactly what must be known before
relying on such resources. You need fairly positive knowledge of what
resources exist at a particular site, not just somewhere in the vague
vicinity -- not information you can easily get from orbit, you have to
actually put a probe with suitable instruments down there. And before
relying on extraction and processing, you really need a pilot run to make
sure your process will actually work, and won't plug up with dirt or wear
down to a wreck or corrode to junk within a week. (Simulation on Earth
won't necessarily tell you these things -- there are too many details it
can't get exactly right because they aren't known very well.)

Interestingly enough, the list of preliminaries you need to attend to is
remarkably similar to what you'd have to do to exploit Phobos.

Quite, but see above on the difficulties. Again, Mars still
has the lead in this regard because of the "back door"
approach. We can ease into fullscale 100% in situ resource
utilization in stages. The first stage would be a technology
demonstration and exploration of atmospheric CO2 usage along
with the Sabatier process and Hydrogen that has been brought
along. This step can be completely robotic and can be
performed at fairly low cost, much less than the cost of the
simplest robotic lander mission. This would provide the data
needed to tweak the design of an Earth Return Vehicle scaled
for a manned mission so that we can be fairly confident of
its operation. The first full-scale Earth Return Vehicle
fueling via in situ propellant production (though also with
brought Hydrogen feed stocks) would provide the proof that
the system was workable before astronauts would ever leave
Earth and put their lives in the hands of the reliability of
the system (or, if it failed, it would provide useful data
to improve so that it could be made to work). Then, the
first manned Martian mission(s) would be able to do the work
necessary to take advantage of local Martian water sources.
Locating prime spots, investigating different methods of
extraction and processing, etc. Which will then put them in
a position to begin propellant production using entirely
Martian feedstocks. The comparable process with regard to
Phobos is slightly more "front-loaded" and may turn out to
take more effort to get into on any level. Though the
lesser delta V requirements on Phobos do to a large extent
help make up for these deficiencies.


The one exception is if all the materials you want are from the Martian
*atmosphere*. You probably still want a pilot run, but the resources are
actually reasonably proven and in a fairly convenient form. It's
unfortunate that there is practically no water vapor in Martian air.

Not to mention the substantial advantage that a pilot run on
Mars can be done entirely robotically.


Plus, Mars also contains carbon dioxide. In fact, the
Martian atmosphere is almost entirely Carbon Dioxide. It
just so happens that with Hydrogen, Carbon Dioxide, the
proper equipment, and a bit of power you can manfucture
both Oxygen and Methane. Which just so happen to make
really quite nice propellants.

At some sacrifice in niceness, you can make CO and LOX from the atmosphere
alone. They don't perform as well but they aren't bad. The conversion is
very simple; the right sort of solid-electrolyte electrolysis cell does it
directly, and is not bothered by moderate impurities. A major bonus is
that the electrolysis cell will also run backwards as a fuel cell -- this
has been demonstrated -- which lets you tap off a bit of your LOX/CO for
keep-alive power at night.


In an enormous bit of luck all of this stuff on Mars just
so happens to be in exactly the same place, Mars, that a
Martian exploration mission would visit, namely Mars.

Yes, that is the place that *a* Martian exploration mission would visit.
One. Program cancelled after first expedition returns. (Maybe the second
if you're lucky.) No question, if you're convinced that the whole thing
is going to die after one or two missions, then getting to the Martian
surface is top priority.

However, a *campaign* of exploration would naturally want to go to Phobos
and Deimos *as well*, and would be willing to adjust the order of events
if this turned out to have practical advantages.

I do not assume a single mission or a campaign but really
a process of exploration and colonization. I will respond
to your points (and others' points) here later in an
omnibus response analyzing the advantages and disadvantages
of Mars vs. Phobos as an early target for manned exploration
taking into consideration different exploration goals.

Henry Spencer wrote:
I wrote:

Even the very thin atmosphere at orbital altitudes can circularize...

Unfortunately, once it's achieved circularization, it then starts quite
briskly lowering the orbit...

Addendum, something I forgot: the *hard* part is not circularization, but
initial capture into an orbit with a low perigee. Purely gravitational
capture doesn't generally get you down that low. Capture by drag very
quickly circularizes the orbit and then drops it into the planet, unless
the atmosphere somehow vanishes almost overnight.
[snip interesting stuff]

There is also the additional bit, which you pointed out, I
think, that Phobos and Deimos are most like outer belt
asteroids. Taken together the odd circumstance lead to
some interesting likelihoods, in my opinion. We already
know that the bodies in the Solar System are not today
where they were when the Solar System formed. I think we
can conclude that Mars almost certainly had a very large
number of encounters with asteroid bodies throughout its
history. Also, we can likely conclude that it had a large
number of encounters with outer belt type asteroids.
Although these are borderline speculative conclusions
without additional corroborating information.

As for circularization, what about ordinary tidal
interations? It seems increasingly likely that Mars had a
more substantial atmosphere (which also contributes to
tidal forces) and likely a substantial covering of water
for geologically significant periods of time. I wonder if
these forces along with the occasional light touch of Mars'
upper atmosphere might have done the trick. I imagine that
the combination of a Martian atmosphere in decline and
the regular Solar cycle could have helped circularize
at least Phobos' orbit without causing it to crash.

I'd be interested to see what sorts of dynamics studies
have been done on this problem and what sorts of things
have been pretty definitely ruled out and which have not.

Paul F. Dietz wrote:
Another thought: if you have a moon in some possibly eccentric orbit,
and it's shattered into many pieces by an impact, those pieces should
(through evolution of their orbital elements and collisions between
the fragments) reaccrete into a body on a much more circular orbit.

Perhaps this happened to Phobos and Deimos, possibly more than once.

I think we have been learning recently (from the origins of
Earth's moon and especially from studies of the Saturnian
system, for example) that cataclysm is very much an operating
principle of the Solar System, and very much more prevalent
than we had previously thought. We know now, for example,
that the Saturn ring and shepherd moon system is rife with
incredibly dynamic and cataclismic processes.

Sander Vesik wrote:

There is no "we" about colonization. It is an individual
decision and also an individual responsibility. A colonist who
can't support himself is not a colonist - he's a welfare
recipient living in a very expensive housing project.

Care to look up at which point the US was able to produce
everything it needed?

Sander, you're confusing being able to support yourself with being
able to produce everything one needs. Presumably, you can support
yourself but (also presumably) you cannot produce all that you need.

Do you appreciate the difference?

Jim Davis

Christopher M. Jones wrote:

The comparable processes on Phobos are less easy, less
straightfoward, and have a higher entrance barrier (on
Mars you can begin very easily by brining along
Hydrogen, processing CO2 from the atmosphere and producing
LOX/CH4 from mostly, but not entirely, local materials,
there is no similar "back door" to in situ resource
utilization on Phobos). For example, I don't think many
people have fully though out the difficulties of
excavating Phobos. If we just so happen to be
tremendously lucky then there will be a lot of loose,
high-H2O content material on the surface (snow, basically).

Unless I'm mistaken, you can't get snow in the earthly sense
on Mars. Not even if you had a source where it might come from
(and there isn't).

--
Sander

+++ Out of cheese error +++

Henry Spencer wrote:
wrote:
Even the very thin atmosphere at orbital altitudes can circularize
any orbit given enough time. The much higher drag at the
perihelian lowers the aphelion...

Unfortunately, once it's achieved circularization, it then starts
quite briskly lowering the orbit.

Another cause of circularization is tidal drag. For this to work in
a reasonable amount of time on such small moons, it would probably
require them to dissipate a lot more tidal energy than a solid rock
would. But perhaps not more than a rubble pile would.
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.

Sander Vesik wrote:
Christopher M. Jones wrote:

If we just so happen to be
tremendously lucky then there will be a lot of loose,
high-H2O content material on the surface (snow, basically).

Unless I'm mistaken, you can't get snow in the earthly sense
on Mars. Not even if you had a source where it might come from
(and there isn't).

If you couldn't tell, I was noting that the probability of
snow *density* water-ice deposits on *Phobos* was rather low
(though the same is true on Mars). Snow is definitely out of
the question. But impacts of icy bodies might create similar
density water ice deposits, though there's little reason to
assume that later non-ice impacts would not thoroughly mix
the ice with regolith. And, worse yet, pack it.