New Mars Forums

Ah, but the lack of personal space is directly related to the conditions creating the isolation. 

Still, we should indeed fear a lack of personal space.  Personal space is desperately important for two reasons: 1) It's one of those "minor" issues that, if neglected, can devastate a mission by lowering morale and creating interpersonal conflicts; and 2) It's something that we can control.  We'll be kicking ourselves if we don't worry about personal space.

Never neglect privacy in an isolated, confined group.  Privacy generally has the last laugh.

As for telecommunications being able to alleviate isolation, I'm not sure that they would have the same effectiveness if the responses were significantly delayed.  I understand that the Mars Society has conducted some experiments along these lines at their Mars Analog stations.  Were there any relevant results?

CME

Hello All.

Using electrolysis to split water into hydrogen and oxygen wouldn't produce much thrust at low temperatures, but at very high temperatures this could perform very well.  The water could be cracked electrolytically, as in an electrothermal rocket, or using masers and/or lasers.  Only electrolysis would work at low temperatures, but at high temperatures (>5000 K) the water will dissociate regardless of the source of heat, so if you're pushing for plasma a maser will work just fine.  A VASIMR system would probably run just fine on water.

Natrium (boro-hydrides, magnesium hydrides, whatever) doesn't look like it would be a useful substitute for liquid hydrogen in chemical rockets, because the liquid hydrogen contains more hydrogen per pound.  But a plasma rocket is so much more efficient than a chemical rocket that it could make up some of the difference.  It needs less fuel, so if there's less hydrogen available per pound then that's just fine.

CME

Hello Shaun.

This website explains the mathematical relationships between concentration/molality, vapor pressure, freezing point and melting point for aqueous solutions.

http://wine1.sb.fsu.edu/chm1046/notes/S … Collig.htm

The important point to note is that these relationships are roughly linear over broad ranges.  The concentration required to lower the vapor pressure of water below the mean atmospheric pressure of Mars is not quite attainable.  The brine becomes saturated before that and becomes unable to hold more salt.  However, it's very close, and liquid brines could exist in high pressure pockets just inches below the surface if the temperatures ever got high enough.

Some other points to note: 

Distilled Water freezes at 0 degrees Celsius even in near vacuum, but will Franklin boil at 0 degrees once the air pressure falls below its vapor pressure.  So, once the pressure falls below the vapor pressure of a solution, it can no longer exist as a liquid.

Most chemicals that dissolve in water reach saturation points, beyond which molality cannot be increased just by adding more solute at constant temperature & pressure.  However, some chemicals, such as alcohol, have no saturation limits.  If you add enough alcohol to water, you reach a point where it's more convenient to talk about water disolved in alcohol. 

Freezing salt water concentrates the salt because the salt ions are excluded from the forming water crystals.  Thus, the portion that freezes first is relatively pure ice, or at least at a lower concentration than it started.  This effect can gradually purify the water out of the solution over time (which is why you can drink water melted off of icebergs).   It also means that if you freeze salt water in an ice cube tray, the water pressure in unfrozen portion shrinks rises as more and more salt is forced into it.   Ultimately, the internal pressure can rise high enough to force a miniature geyser of water up through the ice cube's surface. 

This pressure buildup is a natural consequence of the freezing process and would handily raise the water pressure of a brine above its vapor point.

The same could happen in a frozen salt lake, contaminating the frozen surface with salt.  Unfrozen water at the bottom of the lake would become concentrated with salt excluded from the upper layers, raising its pressure and ultimately causing it to burst up through any weaknesses in the ice layers. 

Thus, the surface of a frozen lake of brine would likely be contaminated with salt, making it difficult to determine the age or nature of the formation from orbit. 

But it would still look like a frozen lake.

CME

Whoa, ya'll! 

I just finished watching "The Lord of the Flies" on TV!

I'm not so sure I want to go to Mars anymore!   :0

CME 

Hello Canth.

Sounds like my old car. 

Actually, as someone who's used to travelling around in ratted-out vehicles, I can safely say that the cost of trying to upgrade an existing vehicle that has reached the end of its usefulness typically costs more than it's worth.  "The end of its usefulness" is usually a euphemism for "broken down".

However, I take issue with your statement that it's always better to send up new ones than to use what's there, because it implies that: a) the only satellites that anybody will sell, rent or abandon are already broken; and b) there are no broken satellites worth recovering. 

I submit that needed materials that it is not within our present capacity to lift would be economically viable to salvage and recover.  For example, much is made of RLV's, but a lot of the convincing designs I've seen have payload capacities far less than the size of some space station modules.  If you're a private company that suddenly has cheap access to space but lack the ability to put up heavy modules, you might look seriously at buying used instead. 

I suspect that nuclear reactor fuel will also become a viable prospect for salvage.  Many of those reactors in space have orbits expected to decay in the next few centuries.  It's possible that it may become economically viable to go get them even if they're never used, just to keep them out of the atmosphere.

Hmm...

CME

Interested in reactors in space?  Check this out!  It's a rough analysis of the amount and location of radioactive material in orbit.

http://www.globenet.free-online.co.uk/ianus/npsm1.htm

Surprise!  Almost nothing is in an unreachable "doomsday orbit".  These devices can be recovered, some (in principle) by Soyuz or Shuttle missions.  Some of the material is not worth the price of recovery (such as the RTG's launched to the Moon with Apollo), and other satellites are too risky to capture (such as the unshielded, obviously leaking/disintegrating RORSAT's).  However, I believe a recovery mission could be viable. 

Multiple reactors are up there for the taking. 

CME

Ever invaluable, Shaun.  I hadn't considered the consequences of yearly dust dispersal in Mars' arid environment. 

As for the current exploration act, I hadn't previously considered the necessity of nuclear power for small outposts on Mars, but apparently there is a big one.  (See the forum discussions on life support and power systems.)  This one fact, coupled with the inevitability of squabbling and compromise over nuclear power, could lead to the removal or neutering of the items calling for manned missions to Mars.

We should still throw behind this bill if we expect to get anything from it.  But I have a grave fear that it will not be sufficient to take us to Mars.

CME ???

Hello All.

Like the old Mir space station, the international space station Alpha has a limited planned operating lifetime, possibly followed by some unspecified mission extensions.  After that, it?s expected to be de-orbited and splashed into the ocean ? destroyed.

Instead of discarding it, what would be required to retrofit it, convert it to function as an Aldrin-style Space Bus, and launch it on a cycling trajectory between Mars and Earth? 

A lot, no doubt.  NASA probably won?t put it up for grabs, even internally within the agency, until they?ve gotten all they can out of it.  The limits of its operating lifetime are partly determined by degrading materials, all of which would have to be replaced for safe use far from Earth.  Then there would be fuel, supplies, engines, etc.  Still, it could be done.  It would be a better fate than ending up as space junk, IMHO, and cost less than building a cycler from scratch.

Speaking of space junk, it stands to reason that there is a lot of useful salvage out there in orbit.  For example, I hear there are two or three Russian-built nuclear reactors flying on satellites.  If it?s so politically impractical to launch new ones, could these existing reactors in space be salvaged for a trip to Mars?  Is their fuel expended, or were they shut down for other reasons?  These alone could be worthwhile for a salvage mission. 

Expended boosters are likely no longer usable as such, but may contain useful parts.  And there?s all sorts of other equipment flying around up there that can no longer fulfill its primary mission but still retains some function.

Then there are fully functioning satellites.  A working communications satellite could be purchased from its owners, recovered by a separate (much smaller) vehicle and launched to Mars without costly return to Earth.  Certain designs should be sufficient for Mars-Earth relay as is.  Other satellite designs, such as weather satellites, could also find favorable employ. 

Perhaps a large part of the infrastructure we need to get to Mars is already up there, waiting for us to come back to it.

CME

PS: I don't know what would happen if Russia or the ESA wanted to sell its ISS components and NASA didn't, but I would not be adverse to finding out. 

(* My previous message -- about how I'm always right about everything in the universe -- has been moved to a more appropriate forum. *)

Actually, Tom, the statement "If a rocket has twice the ISP of another rocket engine using the same reaction mass, that rocket has half the thrust or less" simplifies to

    v.1 = 2 * v.2

    m'.1 = m'.2

    m'.1 * v.1 = 1/2 m'.2 * v.2

                   = 1/4 m'.1 * v.1

which is a false statement. 

Oops! 

CME

PS: I still stand by the rest of my rant... I think.

  ???

Hello Lars.

If you would like to provide help with the Beanstalk, you can reach Allen Meece at:

Navigaiter2002@aol.com

He can probably tell you all sorts of things that need doing.

(The Beanstalkr@aol.com address you may find listed at the site is likely to be ignored due to excessive spam.) 

Currently, IMHO, the project status is somewhere below "sure thing" and somewhere above "glorified research paper."  The dynamics have all been largely worked out by Allen, myself and others -- it can work, and work well.  However, we still have a pressing need for scale models (Allen's elevators, etc.), so that we can find the best ways to do things.  At this point, we are still operating without funding, so we're having problems with some basic milestones: realistic market surveys, getting people to take us seriously enough to give us quotes, etc.  There are also numerous engineering details that have yet to be settled, many of them only valid below the freezing point of propane.

However, despite remaining obstacles, I think that this can be done.  For example, for less than US $3000000, a largely automated platform with a simple repeater station could be put up near San Juan and take cell phone calls from the Virgin Islands.  And that's just one of the purposes you could use systems like this for.  Anything a high altitude station-keeping aircraft can do, a stratospheric beanstalk can do, without a drop of fuel or even a single turn of a motor. 

A beanstalk could even be made to launch orbital payloads.  We estimate that the largest cargo one could carry on its way up is about 40T to 60T, large enough to carry small rockets like the old Scout series.  The main limitation to cargo capacity is the effect of midlevel winds on the balloon, but if you can get one to work, you can get two or more.  Thus, loads larger than 60T can be lifted.  The ability to raise multiple beanstalks also means that a stable "tower" could be constructed to receive a descending space tether. 

CME

What is the largest cargo a modern jet aircraft can carry to higher than 20km (65000ft)?  It seems to me, if you were going to make a small RLV, it would be wise to start with a size that would could lift today. 

CME

Hello Canth.

There are several goals enumerated in the act in question.  Earth RLV?s, Mars RLV?s, Lunar surface-to-orbit RLV?s, OTV?s all around? (Sounds a bit like the old 90-day report they gave President Bush, Sr.?  :[ )  So many, in fact, that I think it would basically leave us with the same circus of competing systems we have now, except the focus would change to high thrust propulsion systems.

As such, I personally think it?s bad legislation in its current form, but bills like this often get torn apart and reassembled a lot before their final fate is determined.  Keep watching.  The US Congress may yet rise above quiet desperation. 

I think nuclear-electric propulsion is a wonderful idea for re-usable orbital craft.  I prefer chemistry for my surface-to orbit propulsion on Earth, because it?s safer and can evolve more thrust than nuclear systems. 

Question:  If a nuclear thermal rocket had a meltdown in the Martian atmosphere, would there be as much damage from radioactive dispersal in the thinner air?

Hmm.

CME