New Mars Forums

Louis,

When I talk about cost, I'm only looking at the cost of transporting whatever we're transporting to Mars.  The cost of the equipment isn't even a consideration when compared to transport costs.

The thickness of the thin film product you linked to is 1.5mm, so I'm not sure where you're getting the idea that we're going to decrease its weight by a factor of 4.  For that to happen, you're talking about a product that is literally thinner than human hair, which will affect durability and deployability.

The efficiency of thin film is mediocre compared to silicon wafers, and the output wattage of the panel you linked to only confirms that fact.

You wind up with something that's very similar in weight to what I proposed, but nowhere near the efficiency, so you end up doubling the associated panel weight as a result.

There's no magic in 1.9kg/m^2 vs about 2.25kg/m^2 for the solution I proposed.  In short, there's no commercial technology that performs better than cutting edge aerospace photovoltaic technology.  That was readily apparent to me from the beginning, which is why I proposed the most performant solution in terms of efficiency, durability, weight, and therefore transportation cost.  The downside to my proposed solution is that production cost is much higher, but that's unavoidable given the performance requirements.  Thin film is great for aircraft supplemental power, but not-so-great on every other performance metric.  If the efficiency gets improved, then we can revisit this.

Despite choosing the most performant solution, I couldn't come up with a mass figure anywhere near that of a nuclear solution, which is why I stopped the exercise.  There's no solar solution that isn't at least an order of magnitude heavier than an equivalent nuclear solution, using existing technology.  For colonization to occur in the next 5 to 10 years, such a mission will use existing proven technology, not something that might one day become available.  New solar technologies are being created with regularity, but very few of them see commercial production and that happens on time scales of 10+ years.  NASA is just now deploying the next generation of MegaFlex, for example, as well as some new thin film technologies.  The agency likes thin film for ease of deployment in microgravity environments, but none of the papers on the research indicate that the panels are more performant than competing silicon wafers in terms of power output per unit weight.

Anyway, this city of a million people won't be built using today's technology, because it's so wildly impractical, so I'm not too concerned with what the colonists will have to work with, which has yet to be defined.

louis wrote:

Flisom - proven technology: less than 2kgs per square metre.

https://www.flisom.com/wp-content/uploa … -BL_CH.pdf

You example is absurd.

There is no need for the early missions on Mars to have PV systems that last for 20 years.

I think we can probably get down to 0.5 Kgs per sq metre with current technology because we won't need to think of a long term system and because the weather on Mars is so clement. As long as the systems can deal with the temperature shift, then there is not much else to fear apart from dust deposit. However, I am happy to live with 2 kgs per sq metre for now and see what Musk comes up with...because he will have been working on this. Cost will not be important for the first few missions, so he can go with the most expensive solutions.

Louis,

The panel you posted about is 1,021mm by 419mm and weighs 0.8kg without an adhesive backer.

1.021m Long * 0.411m Wide = 0.419631m^2

1m^2 / 0.419631m^2 = 2.383

0.8kg * 2.383 = 1.906kg <- Only just under 2kg/m^2, but power-to-weight is the figure of merit here

35W per panel * 2.383 = 83.4W/m^2

The nominal output wattage of that thin film panel is less than half of the space-rated PV that I proposed using, which explains why NASA doesn't use thin film panels on their solar powered rovers, because they'd have to more than double the panel surface area to achieve the same level of output, thus more than double the associated panel weight.  There's no benefit to doing that.

Pix of landing
https://twitter.com/TheMarsSociety/stat … 2180183040
Space agency of China releases photos

China is banned from the ISS, while Europe, Brazil, Japan, Russia and the United States use the Space Station. Now the Chinese have released High resolution images from the surface of Mars. There might be some type of Water under the soil and seem to be different types of rocks in the immediate vicinity of the lander, the Zhurong Rover has interesting science instruments. I hear rumors they have taken scientists from the Lunar Exploration Mission and Chang'e program to give more attention on Mars, there is also a Rover currently in operation on the Lunar surface but Moon is on hold while China gives Mars its full attention?

there might be other types of soils and sands and clays, different rocks and perhaps crater rim here on Mars next to the Rover.

Does the Rover have some kind of A.I software, perhaps by itself move using the avoidance cam and photos just as NASA gave its Rovers a level of intelligence?

The first guys building a human base on Mars perhaps wont be people, maybe it will probably be Robots and Artificial Diggers working hard to make a base before the Arrival of people

Louis,

There won't be any city of a million people on Mars using photovoltaics and chemical rockets.  It's wildly impractical, and mandating the use of solar power only makes it an order of magnitude, or two, more wildly impractical than it would be with nuclear power.  Weight matters, cost matters, simplicity matters, labor availability matters, and simple physics will remain undefeated by anyone's ideology.  It's a bit like arguing over why we don't make aircraft out of Lead.  No amount of insistence on ignoring basic math will ever change the math.  That's why we don't have any cities on Earth that are entirely powered by photovoltaics and batteries, and why we don't ship cargo using chemical powered rockets.

India is another hot spot in the world where conditions are being stressed due to the poor economy and income levels. The US has or will send vaccines to them in hopes to give aid to their nation and of its people.
We still do not know enough about the vaccines or how well it will work for all of the variants that have come from the original...

The medical profession needs to stop labeling and start testing to see what it is before giving out medical advice or labels.

(th)-

I was hoping for some commentary and input on my latest post of the 17 astronaut crew thread.

An observation by RobertDyck at post #161 of the topic cited below stayed with me.  It was a caution that trees need wind to stress them.

http://newmars.com/forums/viewtopic.php … 45#p178745

SearchTerm:trees need wind
Searchterm:wind needed by trees to develop strength

Failures of Biosphere II

(th)

Going to a gun range with your fellow employees in Texas is like going to a bowling alley or baseball game.  Whether or not the finger waggers on the east or west coast recognize that shooting sports are a national past time or not, they are.  One of my past employers, we went to a gun range, we went to ball games, we went to bars, we went to karaoke, we played putt-putt golf.

In a place where everyone has a gun, if not several, it's just something else to do.  No more thought was ever given to it than that, because we don't personify inanimate objects, we don't view ownership of finely machined pieces of steel / wood / plastic as good or bad, and we're there to have a good time, not to make a statement about politics.

Louis,

This city of a million people will use solar, wind, and Hydrogen for energy storage, not batteries, and it will cover some 10,000 square miles.  The high speed train that connects all nodes in the city to achieve the design goal of moving from one end of the city to the other in 20 minutes would have to move at a speed of 512kmh, but no high speed train is currently capable of doing that.

Will this city be built with solar powered electric trucks and excavators, or will the construction equipment use diesel engines?

Are all of the building materials produced using solar power?

Where is their food source coming from, and will that be entirely powered with wind and solar (seed planting to market, without oil and gas)?

Are they using solar power to desalinate sea water?

That's quite literally what we're talking about doing.

What I want to see is a city built using nothing but wind / solar power.  The machines need to be battery or corded-electric powered, the materials used should be made using wind / solar power, and the energy storage medium, whatever that is, can't be supplied by oil and gas wells or coal.

At that point, how much tonnage do we need to ship, can that realistically be done using chemical rockets, and do we have a practical operating model going forward?

I can already guarantee that it's more for solar than it is for nuclear, and not by a little bit.  The question is whether or not we go far outside the realm of what is practical or reasonable.

For example, if half of every ton of materials we ship is solar panels or batteries, then how practical is that for building out the colony?

It's not that it's utterly impossible, it's that it's so impractical as to beg the question of why we're continually trying to fit a square peg into a round hole.

Solar power is not the solution to all energy problems.  Power storage remains humanity's greatest weak point when it comes to energy delivery.  We don't have scalable methods for storing energy, except in the form of liquid hydrocarbons that can be burned in an oxidizing atmosphere that Mars clearly lacks.  We either come up with vastly more energy dense batteries than what we currently have, or we admit that we've reached the technological limit of batteries and have to consider alternatives, whether fuel and oxidizers or nuclear power.  In terms of total tonnages processed in-situ or delivered from Earth, nuclear materials provide orders of magnitude more energy density over fossil fuels and batteries, so more energy can be devoted to growth or less delivered (from Earth) tonnage is required.

I think you're demanding more of technology than it can presently deliver.  If energy storage changes drastically over the next ten years, then we can revisit the practicality of using nothing but solar and batteries, but until then, it's not a realistic plan, and that's not being dismissive of SpaceX's plans, it's merely restating what's plainly obvious to engineers who understand the mathematics behind current energy technologies.

Re post #12:
We do know a fair bit about how bones work. Osteoblasts are cells that build bone, osteoclasts dissolve bone, releasing calcium into the blood. The human body needs calcium, and bones are a storage mechanism. Quoting Wikipedia:

Osteoblasts are cells with a single nucleus that synthesize bone. However, in the process of bone formation, osteoblasts function in groups of connected cells. Individual cells cannot make bone. A group of organized osteoblasts together with the bone made by a unit of cells is usually called the osteon.

Osteoblasts are specialized, terminally differentiated products of mesenchymal stem cells. They synthesize dense, crosslinked collagen and specialized proteins in much smaller quantities, including osteocalcin and osteopontin, which compose the organic matrix of bone.

In organized groups of connected cells, osteoblasts produce hydroxylapatite - the bone mineral, that is deposited in a highly regulated manner, into the organic matrix forming a strong and dense mineralized tissue - the mineralized matrix. The mineralized skeleton is the main support for the bodies of air breathing vertebrates. It is an important store of minerals for physiological homeostasis including both acid-base balance and calcium or phosphate maintenance.

One known mechanism is when bone is stressed, it stimulates nerves. Yes, bone has nerves. I once broke a finger bone, the doctor inserted a needle right into the broken end of the bone. Damn it hurt! It tell you, there are sensitive nerves in there. If you have ever jumped from a height a little too high onto something hard like pavement, you will feel your shins hurt. That means you just shocked the bone. It didn't break the bone, but it simulated the nerves in your shin bones. (It hurt.) Those nerves start a cascade of chemicals that cause osteoblasts to build bone, specifically where the nerves were stimulated. The fact nerves in the bone were stimulated means your bone at that point isn't strong enough, so osteoblasts will build more bone specifically there, to make your bone stronger.

Meanwhile, osteoclasts dissolve bone to release calcium into blood. In a healthy person, your bones are a balance of osteoclats dissolving bone while osteoblasts build them back up. This will optimize your bone so you have strong bone just where you need it. Several things can interefer with this. If you have nerve damage in your bones, then stress cannot be detected, and nerves will not start the chemical cascade that causes osteoblasts to strengthen bone. Many people think osteoporosis is a chemical thing, but nerve damage can cause it. Metabolism of senior citizens slows down. If metabolism slows too much, osteoblasts cannot build bone quickly enough to respond to stimulus. This can result in osteoclasts dominating, causing net bone loss.

Zero gravity can have many effects. Cells are membranes filled with liquid. Without gravity, convection within cells cannot happen. Loss of convection within cells can cause liquid currents within the cell to slow or stop, causing various chemical processes to not work correctly. This is one reason people like me think partial gravity will have profound effect on the human body. Even Moon level gravity should be enough to cause liquid convection within cells. This must be tested though. Lower gravity might cause slower liquid currents within cells, causing zero-gravity effects to be only partially mitigated.

Then there's the question of how groups of cells coordinate? Does gravity affect movement of groups of cells? I don't even have a hypothesis about that.