Re: Improved lunar landing architecture



Cardman wrote: 
On Fri, 12 Aug 2005 21:11:00 -0700, Hop David
<hopspageHATESSPAaMmM@xxxxxxxxxxxxxxxxxxxxx> wrote:


Cardman wrote:

Well I do know that 27km up it is only 2% the surface level. So
launching from on top Mount Olympus seems to make a lot of sense. I
think that you could well come close to removing this need to go up
before aiming to achieve orbit.

Sounds like a good plan to me.

Mount Chimborazo sits near earth's equator and it's air pressure is about a 1/3 that of sea level. Sounds like an ideal site for a launch pad. Gosh, why hasn't any built a facility there?


Maybe it is because it is in Ecuador.

? Why is it less feasible to build a launch facility in Ecuador than French Guiana?

Apart from that I do not know 
the landscape to see how well heavy equipment can be moved up the
slope.

Yes, it is a little problem to do construction work on the top and sides of large mountains.


The best place of build a Mars base would be in flat areas, low altitude & near water (who knows, Marsis may even find liquid water beneath some parts of Mars' surface) 


Liquid water? There is already tons of ice blocks around that only
need a little heat.


Mining permafrost is more difficult than just adding a "little heat".



The top of a super volcano doesn't seem the best choice for a base. 


Well the thing about Olympus Mons is that apart from it being three
times higher than Mount Everest, then it is also huge. So I am sure
that you can get a very long road going up there.


Oh, the bigger the mountain the easier it is to build a road?


Better yet in that low gravity you could just make a huge lift or a
cable car system.

A base on Olympus Mons plus the road to the flatlands would be a larger construction project than a Deimos base.


And this is not the "base". After all in my plan it would be like 20
to 30 years even before they start launching from Mars. In using their
own Mars made hardware at least. So they would already have a large
well established base, that could be considered as a small town,
before they pick their ideal launch site.

The goal is to replicate the most important science, research and
industry fields on Mars.


The moon and asteroids are also of scientific interest.

Also having many people on Mars will change 
the "search for life" into grouping them by species.


Earth launches do a burn sending the rocket nearly straight up. When it reaches the apogee of its suborbital path that's where it does the major burn, where it's safely above the most destructive atmosphere. 


Stating the obvious then. And it does this because Earth has a very
thick atmosphere that creates drag, friction and heating. So it is
better to depart this atmosphere ASAP.

Obviously Mars is very different. Less than 1% the atmosphere at
ground level, where achieving any worthwhile elevation strips that
atmosphere away to almost nothing.


Martian atmosphere is about 2 microbars at 100 km vs Earth's 3 microbars. Their mesospheres are at comparable altitudes. I believe Martian launches would still need to do a suborbital hop before they do their major burn. 


From my calculations this seems doubtful. Certainly the Martian
Atmosphere goes up a long way, but for a long time it is very thin.


www.terrapub.co.jp/journals/EPS/pdf/5003/50030247.pdf
http://www.ux1.eiu.edu/~cfjps/1400/atmos_struct.html

Care to show your calculations?



Methane seems questionable. There is not that much in the Martian
atmosphere. Only 10 ppb it seems. And Hydrogen would seem like a much
better option.

Well then, hydrogen is also questionable by your logic since it's not common in the Martian atmosphere. 


Obtained from good old water. And you cannot question this seeing how
that is exactly how your Mars moons plan aims to make fuel.


Of course the methane would be made from Martian resources.

You seem to be a Mars Direct fan. I will quote from page 102 of Robert Zubrin's _Entering Space_":

"The hydrogen brought from Earth can be quickly reacted with the Martian atmosphere, which is 95 percent carbon dioxide gas (CO2), to produce methane and water, thus elimnating the need for long-term storage of cyrogenic hydrogen on the planet's surface."

Hydrogen is a bitch to store, methane is much easier to work with. I believe Zubrin would've carefully weighed the pro and cons of hydrogen before advocating methane. 


That guy was on drugs. So not only do you take this vast volume of
hydrogen with you, instead using what can already be obtained from
Mars, then you produce a fuel that is not very efficient anyway.

Zubrin is as passionate about Mars direct as anyone. He also has some degrees and actual industry experience. What are your credentials?



First is that I know that escape velocity from Mount Olympus is 5.0027
km/sec, but then you have to go into a Hohmann transfer orbit from
that. I guess that works out around 5.5 km/s.

More like 5.7 km/s 


You may care to note that your previous calculation from the surface
was 5.6 km/s. And since I added 27km to the launch site, then I
thought that I would be generous and to improve this to 5.5 kb/s.


This generosity reveals your ignorance.
velocity at 27 km: 5.6608 km/sec
velocity at  0 km: 5.6783 km/sec


And so in your questionable mathematics this more efficient launch
site is now worse than the surface.


My spread*** is at http://clowder.net/hop/railroad/Hohmann.xls

The mathematics is based on what I've read in "Fundamentals of Astrodynamics" by Bate, Mueller and White and "Orbital Mechanics" by Prussing and Conway.

It is possible I've made a mistake on the spread***. If you can find a flaw, I would appreciate you pointing it out to me.

Almost like I said that it was 
27km into the ground.


Well I make it 2.8, where that does not seem bad when fuel is easy
enough to come by. And since you have to launch from Mars anyway, then
you just turn your inefficient launch system into a more efficient
launch system.

For the sake of argument I'll grant your 4.5 km/sec exhaust velocity 


Well that is real life numbers in what those SSMEs already do.


and your .3 km/sec atmospheric delta vee penalty. 


Since I desired further debate over the efficiency of launching higher
up in the atmosphere, then I aimed for a safe 0.5 value. Still, it is
true to say that this number could well be reduced depending on what
the most efficient flight path actually is.

I see no reason why on Mars you need to climb higher into the
atmosphere, when the real thicker atmosphere is much lower down, and
where going up more causes it to thin much more slowly.


Leaving Mars and entering Hohmann orbit isn't your total delta vee. You also need to exit the transfer orbit and enter earth orbit. If you're parking at, say, the Earth Moon L4 orbit, this costs about 2.26 km/sec. 


Yes, well. Since both of our systems need to do this anyway, then this
aspect can be mostly put aside.


So 6 + 2.26 km/sec makes a total of 8.26 km/sec delta vee

e^(8.26/4.5) - 1 = 5.26


Launching from Deimos: e^(2.4/3) - 1 = about 1.2 

2.4 + 2.26 = 4.66

e^(4.66/4.5) - 1 = 1.82


Launching from Phobos: e^(1.8/3) - 1 = about .82. 

1.8 + 2.26 = 4.06

e^(4.06/4.5) - 1 = 1.46 


Fair enough. And now lets see you add in what an additional array of
ion engines can do to make your 7 month trip somewhat shorter. :-]

After all the faster that you can move between planets greatly reduces
your requirements for food, water and oxygen. This would increase
safety and decrease launch mass.

I think that you have to face the fact that this rocketry system is
all well and good for launching from planets, but in terms of moving
between planets then it sucks.


For some reason I highly doubt that these two moons contain much
methane.

And for some reason I highly doubt Mars has much O2. Guess you can't use Lox with your hydrogen. Hope you drop this silly argument. 


My point was that there should certainly be a more efficient launch
system than with using methane. After all I achieved a complete 50%
thrust improvement over using your cow farts plan


Radiation shielding? I see no reason why your interplanetary craft
would not come well shielded as it finished construction.

Because that would make it substantially heavier. Presumably it's initial construction would be of earthly materials and it costs a lot to lift stuff from earth's steep gravity well. This is the reason Zubrin suggests the Earth Return Vehicle (ERV) be flown to Mars with it's two methane/oxygen-driven propulsion stages unfueled. Getting fuel from Mars in-situ resources substantially reduces mission requirements.

Water has been suggested for radiation shielding. Passengers could live within hollow walls filled with water. 


Water does not seem like the best choice these days when compared to
some plastics. All a question of mass.

As I said, within my plan, this larger craft can be built at a later
stage. This can be from Earth, Moon, or some Mars resources, depending
on your starting point.


If the ERV were sent to Phobos or Deimos, it could be supplied with oxygen, fuel and water mined from the Martian Moon. 


Obviously.


Yes, oxygen, fuel and water would need to be done as extra launches
from Mars under my plan. However, you still need to add in your Mars
launches of people, cargo and no doubt food.

Sorry, I don't follow you here. Your Earth Return Vehicle would have to have all of those in one package that would be sent off in a single launch. 


My point was that you would still have to bring people and equipment
up from the surface of Mars, when this is all about the best end way
to colonize Mars. Growing food on Mars also seems likely.


Well NASA seems to want to do that in the one craft that you land on
the surface and just wait until it fills up.

Could you give a cite? I had heard that NASA's possible Mars missions had become more Zubrin like, but to be honest I'm not up on that right now. Anyway, not long ago NASA thought Zubrin was nuts. They could change again before the missions become reality. 


Sorry, but I no longer seem to have that link.

I recall that it was reports from their appointed science advisers in
recommending what kind of missions NASA should do in support of their
new objective to ultimately land people on Mars.

Having a craft land in the polar region and to start making rocket
fuel was one of their top recommendations.


I do not see why it would

be that hard though, and where you also have to make fuel in orbit
under your plan.

The difference I've mentioned several times. You don't have to launch the fuel and a larger craft up a steep gravity well and through an atmosphere. 


Except when you advance past your "fuel station" in the main objective
of the colonization of Mars.

No. If Martian colonization is achieved, you still wouldn't have to launch a large craft and the fuel for an interplanetary journey up the Martian gravity well and through an atmosphere. Those leaving Mars could take a small craft to Deimos and then leave for Earth in the Earth Return Vehicle parked at Deimos.

It is all well and nice having an 
efficient fuel production system, and a couple of other refining jobs,
but until you start landing people on Mars then you are overlooking
why they came of this location in the first place.

Please don't change the rules of this debate. 

?



Mars does not have that much of an atmosphere. Like where Earth is 100
kPa then Mars is about 0.8 kPa. And launching from Mount Olympus at
only 2% this pressure would be 0.016 kPa.

Almost like a vacuum before you even launch, which is why I believe
that you can take a much more direct route to orbit. After all that is
only 1/6250th of Earth atmospheric pressure at sea level.

I had thought it was around 6 millibars. I think you mean 6.25/1000. As mentioned earlier, the earth's mesosphere, where meteors burn up, is much less than that. I don't think a 6 millibar atmosphere would be kind to something going mach 18. 


Well I was just using available information. The Mars atmospheric
pressure at the surface varies between 0.7 and 0.9 kPa, depending on
how deep you go. Less than 1% of Earth's sea level 100 kPa value in
other words.

It is also known that the atmospheric pressure on top of Mount Olympus
is just 2% of this surface value. Using an average 0.8 kPa for the
surface means that this would be 0.016 kPa.

And that obviously is 1/6250th of Earth's atmospheric pressure at sea
level. 

Since I have no idea how to convert kPa to millibars, then all I know
is that this very thin Mars atmosphere seems negligible. So I see no
reason why you cannot do mach 18 at what would be a pressure of even
less than this, when drag, friction, and heating, should be minor.


Also I am sure that such a craft could make use of large ion engines
to get that extra zip between planets. I can say that Mars has Xenon
at 80 ppb in the atmosphere. Sounds like a better fuel system to me,
but that nuclear generator could be a bit dodgy.

Ion engines do not have enough thrust to lift off from the Martian surface. 


Notice my words "extra zip between planets", when trying to use them
for launch would be insane. So it is your normal rocket fuel for
launch, where your ion engines could well save months from your trip.

And in the future this system will greatly speed up trips further into
the solar system.


Ion engines have higher exhaust velocities but tiny thrust. Although SMART-1 made it to lunar orbit with a tiny amount of fuel it took it more than a year to arrive there. 


That is because SMART-1 has a tiny ion engine.

I guess that you also missed NASA's project that successful created
the world's first large ion engine. I would have to look up its thrust
value, but it can certainly whip SMART-1's metallic ass.

The only reason why this large ion engine has not flown yet is due to
NASA having problems with their other project, in order to create a
mini-nuclear reactor to provide the power that this ion engine needs.

However, once that problem is solved, then a complete array of these
ion engines would certainly produce a massive thrust. In terms of ion
engines at least.

In fact I am thinking that this could be enough to break Mars orbit
within a reasonable time, which would remove all need for this craft
to have two large propulsion systems.

I am not sure what the travel time for such a system would be between
planets, but I would estimate that this long 7 month trip could be
reduced to about 2 to 3 months.

"I am thinking", "I would estimate" etc. etc. You throw out these B.S. phrases with no math. Give some numbers and show how you figure them.



Ion engines may be way to achieve a lot of delta vee with a small amount of fuel. But I'm not so sure they'll shorten trip times. 


The problem with current ion engines is simply lack of power, when
solar power does not produce much to run an engine off. However, not
only can a large ion engine produce a much larger thrust, but this
engine was created within a very efficient time. In other words even
larger engines should be easy enough to do.

They only now have to get a nuclear reactor to power it.

The other thing about ion engines is that they use xenon. And xenon is
one of the rarest and most expensive elements on Earth. Although 80
ppb in the Martian atmosphere may not sound like much, but this is
certainly a large wealth of ion engine fuel.

A power plant able to give an ion engine would be quite large as would be the ion engine. You have three large masses, The nuclear power plant and ion engines, traditional chemical rocket & fuel plus the ERV payload.



Not to forget the cargo and maybe food.

What cargo? 


How can you possibly say "What cargo?". As it like your brain just
fell on the floor and all knowledge of this debate went with it.

Colonizing Mars won't send to price of copper up high enough to make Martian copper profitable to an earth market. Nor even platinum.

You haven't described any profitable exports.


I seem to recall your desire to make "profit" out of all this, where
you had quite an interest in mining these two moons for whatever you
could get out of them. So obviously you cannot use Harry Potter's wand
to move these ores to where ever you want them.

You also have passenger luggage to deal with.


Food for a trip less than a day.


I meant the 7 month trip between Mars and Earth. 

Food could be grown on Deimos or Phobos.


Since I trust that they would be beyond growing food enroute at this
point, preferring commercial prepacked food, then this is a lot of
food and oxygen that your passengers would get through.

Shorten the trip and this helps out in so many ways.


You would be surprise when you come to fill up and it reads "Xenon
Only" on the tank. :-]

And I'll be surprised to see Harry Potter wave his wand and lift off a Xenon only ship from Mars' surface. 


Another case of denial because you do not wish to see the truth. Your
conventual rockets are fine for launch, but they suck big time for
moving through space.

So I have a dual fuel production system. That is hardly hard.


I have yet to see your idea return a profit. And you have all this
extra infrastructure to support. I have not even heard your mention
what happens when your widget breaks.

And I have not even heard you mention of what happens when your Martian widgets break. 


Lots of available Martian resources available to see if they can fix
it locally. If not then it can be imported. The point here is that
Mars has far more resources than these two moons to deal with any
broken widgets.

Earth copper, iron, zinc, etc. mines, and manufacturing are brought together by a huge infrastructure that took a long time to build even with a large population in a hospitable environment. Martian widgets aren't going to be a snap to make.

And you still haven't demonstrated Phobos lack of resources.



All space plans seem like that. I mean like NASA is really going to
get any return from their Moon Base. Nothing that you could make some
$$$ from at least.

If no return is realized, the moon base will be abandoned when the political wind turns. 


Financial return is only one of many options. And I cannot say that
the US government is hot on making a profit. More like they will aid
and advance society.

So that is why their Moon Base will go on.


And how do you intend to do that? I have already wrote off the space
solar power plan, when nuclear is already more cost efficient.

I recall you saying nuclear plants are OK since the U.S., EU and China will be restrained by mutually assured destruction. 


No one is yet that stupid.


How about nuclear plants in Korea? Pakistan? 


I believe that they are already nuclear powered. Both North Korea and
Pakistan have nuclear weapons as well, according to reports.


All the nations of Africa and South America? 


In progress.


Will hundreds of diverse nuclear powers all be sane and restrained? 


You should not create technology if society is not responsible in
their use. Nuclear weapons have had a good history to date.


I'm not even sure U.S. will be restrained. I believe the Bush administration wants to resume nuclear testing to develop bunker busting weapons. 


You are quite correct.


It seems more about achieving an internal market I would say. And then
all these Earth folk can profit from stocks and bonds. So there does
seem like a good way to profit from space.

Chinese can use U.S. currency to buy stuff from the U.S. What profitable exports would the Martian colony have? 


Exports?

Lets turn that around with what exports from Earth can make a profit
on Mars? None I am sure. So lets all pack up and await death shall we.

In other words Mars will soon establish it's own economy, where money
can be made (and lost) within that internal market.


So you would be spending trillions on your cow and never getting any real meat beyond several flags and lots of footprints. 


And humans living on Mars with a profitable Martian economy.

The Xenon market should be a good one for Mars, when not even the Moon
has Xenon.

Xenon is only 800 parts per million in an atmosphere that's six millibars. 


That is 800 parts per *billion*. And for xenon that is a lot.

Within Earth's atmosphere it is not even listed in the main and minor
atmospheric list.


And the market for xenon will be ships lifting off from planetary surfaces 


No.


to make quick interplanetary trips? 


Yes.


I would call it a more focused approach. Under whatever scheme you
would still need infrastructure on Mars.

Near earth asteroids plus the main belt and Jovian asteroids have far more surface area and available resources than Mars. It would be a more focused approach to concentrate on the small bodies and ignor Mars.


NASA are not going to do that though are they. 

Nice to know you have a crystal ball.


You are thinking along the line of commercial profit. NASA more thinks
about development, construction, science, exploration and even one day
colonization.


As the one thing that your Phobos and Deimos plan most overlooks is
that this is yet one more location to support with additional food,
hardware, repairs and other required resources.

A phobos base could also become more self sufficient with improved use of in situ resources. 


That seems highly questionable. The list of things that you would not
have on Phobos is a long one. That list begins with xenon, the world's
best interplanetary fuel.

Cardman. 


--
Hop David
http://clowder.net/hop/index.html

.

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