New Mars Forums

Nano-Greenhouse

A 6-man crew, packed onto a FH and carrying such a tiny equipment payload, would be only a scouting mission, or precursor to settlement.  There's no compelling reason, and precious little payload, for greenhouse gardening in that scheme.  Neither is there need to cripple greenhouse designs under those crushing mission-design constraints, which are your own.  Or if you want it, maybe you should develop a nano-greenhouse design in another thread, so that this thread can explore production greenhouses.

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Trying to steer topic back to just the crop and only the crops

ZLD is just water treatment.  How would you expect the crews to treat raw freshwater or brine, anyway?  It's a core task requiring efficient, reliable tech.  ZLD seems appropriate.

And when you consider the fact that ZLD output gives a series of useful fertilizers, well, I don't know why you'd design a Mars greenhouse - even the first greenhouse - without it.

Flow

Would it make sense to start with a high-level ZLD water flow chart?  Many of the greenhouse's essential products, starting with water itself, could be made efficiently by a ZLD plant.  A water flow chart concisely relates the various ZLD solution inputs, outputs, devices and modes, with brief annotations and maybe color-coding.  Example:  Figure 3.  Water Flow Chart. 

Some of the ideas we've discussed at NMF have already been implemented commercially in ZLD plants.  For example, perchlorate removal - so important to Mars regolith/brine treatment - is actually a well-known commercial process:  insert an electrodialysis stack into the ZLD chain and the problem is solved.  Adding each vital component to the ZLD water flow chart, where appropriate, could pull NMF ideas together, and in a form that's easily communicated.

After, something similar might be done for the gas/cryogenic plant, and perhaps the ECLSS plant (which might be too complex for more than a partial chart of the most vital ECLSS flows).

When summer ends and LEDs go dark and sprinklers dry out and bees and drones nap, it's just a field of wheat.  Close-packed wheat on sandy ground.  The harvesting of this hydroponic wheat field introduces no "impractical" drama, as far as I can see.  Are you sure you're not introducing the impracticality yourself?

Which doesn't answer my questions to you.  Why pack ITS cargo ships with stone wool, or else with a monstrous furnace and factory for making stone wool? 

The product isn't needed as hydroponic substrate because sand also serves as substrate, and the product isn't needed for fertilization because it's inert, without inherent nutrients.

So, why?

The world's most productive crop plant doesn't need that symbiosis, obviously.  What crops did need that symbiosis, in your personal experience, and why?

To your knowledge, do any of these notional LMT greenhouse crops need it?

Coals to Newcastle, Basalt to Mars

No, stone wool is just granulated basalt fibers, no better than sand (i.e., granulated basalt) for this purpose.  And the cost!  Stone wool substrate for a single acre would fill the better part of a cargo ITS. 

For no reason.

"Containers"?  That's a misapprehension.  The LMT scheme grows half-acre plots.  No containers.  It's only hydroponic because it uses inert bedding substrate.  There's no obvious need for a complex soil.  Or is there?

No, it's an application of Bernoulli's principle; electrostatic charge wouldn't increase it. 

And just in case anyone is thinking to use electrostatic charge for any transportation purpose:  note that the martian atmosphere's electrical conductivity is two orders of magnitude greater than Earth's.  Implication:  electrostatically-charged surfaces quickly discharge. 

KZOT. 

It's not an event you want to amplify on a balloon, or on any delicate transporter surface.

Known Unknowns, Etc.

There are some very creative ideas in those threads.  Focusing on soil, I find that many of the creative ideas for soil manufacture seem to introduce more unknowns than they remove.  For example, the idea of blending waste streams into the soil could introduce unpredictable fluctuations in toxins, microbes, pH and nutrient loads.  On Earth, soil microbes are diverse and abundant, and their metabolisms help the soil manage fluctuations.  But on Mars, most of the beneficial soil microbes would be absent unless explicitly cultivated.  Perhaps fluctuations could be managed by the greenhouse crew, but it would seem to be a worrisome job.  It's just more unknowns.

Hydroponics removes unknowns by simplifying the soil down to an inert substrate, such as pH-neutral rinsed sand.  In a greenhouse with ISRU fertilizer, sterile nutrients are added in a controlled manner, again removing unknowns.  A microbiome isn't required and can be suppressed, to remove even more unknowns.  For example, a plasma nitrate plant makes hydrogen peroxide as a byproduct.  That hydrogen peroxide is added to the liquid nitrate fertilizer to kill off soil pathogens without harming the plants.   (Conceivably this treatment could remove a further unknown:  hypothetical Mars exo-pathogens.  Microbes evolved under martian anoxic conditions really shouldn't like sudden peroxide oxygen baths.)

To my mind the removal of unknowns is a main reason to aim for a hydroponic greenhouse, one having no more organic matter in the substrate than may be necessary for water retention.  A little cellulose could be adequate.

But am I missing something?  Is there good reason to convert sand substrate into a soil that's rich in organics, microbes, worms, etc., in this unique circumstance?

Mars Magnus Aerobot

It's not obvious from the conceptual illustrations that the balloon is attached.  See the gap?  Ravindran's drive train might be connecting across that gap via magnetic linkage.

That would cause turbulence on the upper surface, killing lift.

It's a super-pressure balloon:  constant volume and shape.  Therefore heating doesn't increase lift.  Conversely, constant volume makes constant-elevation travel much easier.  Also the constant volume and shape hold the balloon's lower surface constantly close to the bodyshell.  According to the original Ferguson patent, this reduces drag and improves maneuverability.