New Mars Forums

...can the same furnace or ovens for metal refining be used for glass?

Re. greenhouse pressures, what are the limits for bees?

...insects, like plants, can survive low pressure closed-loop ecosystems. Reductions of pressure that can be tolerated by plants can be tolerated by a wide variety of insects and insect life stages. Although many insects possess different respiratory capabilities, most insects can tolerate pressures down to 100 mb and will operate between 200 mb and 1 bar without major loss of function. Between 500 mb and 1000 mb the insects we studied showed no pressure effects at all.

I was think of a multiple strand fiber optic glass molded with lensing on each end...

...Lake Matthew Team - Cole that said we were thinking to small, I do remember a time when that our discusion where much along the same lines as what Lake Matthew Team - Cole was thinking, one where we had unlimited power to spare with all the down mass to our hearts desire. Of which the members here did try to reign in the big idea of grandure in that a touch of reality that we are really still small with limits of cash and size for the dreams of Mars.

How thick would we need the insulation to be, to keep constant production in a greenhouse? How many layers of argon-filled bubblewrap are we talking about?

Theres a nice big set of domes in Cornwall, UK. They are built in a former quarry and are known as "The Eden Project". Quite a visitor attraction. See loads of images by googling it.

Tom Harris  "How the Eden Project Works" 3 May 2001.
HowStuffWorks.com. <http://science.howstuffworks.com/enviro … s/eden.htm> 6 January 2017

I am reminded in the greenhouse topics that mars is cold and that it will suck to heat out of things so we will want multiple domes, layers with hard vacumn and of different gasses to allow for the heat to stay in the dome that we live with in.

Lake Matthew Team - Cole wrote:

Tools

Oldfart1939 wrote:

One of the best small pieces of equipment we could consider for transport to Mars to lighten the workload is a small tractor-frontloader known as a Bobcat. Fitted out with a suite of accessories, it would sure make the work easier than digging and moving regolith by hand...

True, but a tractor-drive has limited mobility on rough ground.  You'd want a more versatile loader, like the Caterpillar P-5000, for greenhouse construction.  Feature demo at the link.

What?

A Bobcat has very good mobility for the intended purposes. On the other hand, a caterpillar or tracked vehicle is an order of magnitude higher maintenance requirement. Trust me--I've owned several hundred thousand dollars of farm implements. A Bobcat is normally a 2 WD front wheels only powered, but that's where the weight being moved is concentrated. A special unit could be constructed by a number of manufacturers to run on methane and oxygen, which will be available at the base. Rocks in the way? Fine, move them with the front loader.

The tracked model you illustrate would be fine, but unnecessarily complicated for the intended usage of greenhouse construction, and moving regolith to fill said greenhouse.

Oldfart1939 wrote:

Reinventing the wheel?

Almost all the concern over radiation hazards is succinctly discussed in Dr. Zubrin's book, "Entering Space."

What he said!

Could I suggest a list of basic books for someone new to Mars?
Amazon books - sponsor the Mars Society

US nuclear reactor workers are allowed 5 REM/year, and radiation from a reactor will be almost exclusively neutron.

There is a paper from Curiosity, but I don't have a current subscription to the journal Science.
Mars’ Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover

To be clear to the new guy, the painting of Mars Direct depicts sand bags filled with Mars regolith. It's radiation shielding. A permanent settlement requires 2.4 metre thick regolith for complete radiation shielding, but a science/scouting mission will use sand bags.

I talked directly with Dr. Penelope Boston about polymer film for an inflated greenhouse. She wrote a paper in the "Case For Mars" papers before the founding of the Mars Society. I found PCTFE, sold by Honeywell under the brand name Clarus. It becomes embrittled at -240°C. The coldest location recorded by Mars Global Surveyor at the south pole during southern winter was -140°C, so this material handles 100° colder than the coldest spot on Mars.

We also talked about radiation. According to papers published by the team for the MARIE instrument on Mars Odyssey, Mars atmosphere blocks 90% of heavy ion galactic cosmic rays. That's 90% at a high altitude location such as Meridiani Planum where Opportunity landed. It blocks 98% to 99% at low altitude locations such as the bottom of the dried up ocean basin in the northern hemisphere. What gets through is proton radiation which comes from the Sun. Atmosphere blocks some light ion GCR, but the lighter the radiation particle the less atmosphere blocks it.

Plants can withstand radiation much better than humans. The surface of Mars receives 50% as much radiation as ISS. And I already gave the difference regarding types of radiation. So plants don't need radiation shielding on Mars. The best Mars greenhouse uses ambient light.

As for temperature, Mars atmosphere is so thin that atmospheric heat loss is minimal. And the same spectrally selective coating that NASA currently uses for space station and spacecraft windows will be applied. That blocks UV, and controls IR. It can reflect more long wave IR from warm things like the floor, and less short wave IR from extremely hot things such as the surface of the Sun. That traps heat in. The majority of heat loss will come from the ground. Besides, we also want to use 2 pane windows, or 2 layers of polymer film, with argon filling the gap. That helps prevent heat loss.

Studies on space effects on plants
A comparison of various studies has clarified how space effects are deeply influenced
by plant characteristics (e.g. species, cultivar, stage of development, tissue architecture
and genome organization) (Holst and Nagel 1997). In relatively short-term space-flight
experiments, it has been pointed out the space environment causes chromosome aberration
and changes in the cell cycle of plant cells. This may be due to either microgravity or
increased cosmic rays in space or resulting from unfavorable growing conditions in the
plant growing unit. Structural and functional changes in the DNA molecule are responsible
for most of the damage expressed after exposure to ionizing radiations, at both the
cellular and the systemic levels. DNA modifications range from single base alterations,
base substitutions, base deletions, chromosomal aberrations to epigenetic modifications.
In general, radiation exposure can induce both negative and positive effects on plants,
and the mutations at the base of these effects can also be transmitted to the progeny
(Mei et al. 1998; Yu et al. 2007). Apart from reduced germination, among the detrimental
effects, there is often reference to embryo lethality, dwarf architecture, modification
of floral morphology with altered occurrence of fertile floral elements (Kranz 1986;
Sah et al. 1996). On the other hand, stress conditions, like the exposure to ionizing
radiations, can have stimulatory effects on specific morphological parameters and can
increase the yield of the plants in terms of growth, reproductive success and ability to
withstand water shortage (Maity et al. 2005; Yu et al. 2007; Melki and Dahmani 2009).
A few space-flight experiments have attempted to test the effects of the space environment
on plant reproduction. For instance, Arabidopsis thaliana and wheat plants were
grown in space for different durations (Mashinsky et al., 1994; Salisbury et al., 1995). 
They were found to produce and develop flowers, but the flowers produced more sterile
seeds than did ground control plants. These experiments could not specify the cause for
such failure in seed production.