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Comment Re:Fun Movie, Not Future Reality (Score 1) 122

Your point breaks at "grabbed a bar". No, they didn't grab any bar anywhere where the rotation would act as "simulated gravity". They appeared as if sucked into the tube, which would work with air moving there; moving in freefall they won't be dragged anywhere. They might crash against the wall of the tube and then be dragged "downward", but as long as they don't touch any of the structure, the virtual centripetal force doesn't appear.

Comment Re:Are and storms that fierce on Mars? (Score 1) 122

One thing more:

But at the same time, when light is coming from LED lighting, you have to account for stray lighting (light that's not hitting your grow area) and efficiencies at generating PAR, which are 20-30% for proper grow lights, lower for normal room lights (as the phosphor wastes part of the light energy to make it a comfortable white rather than a painful pink).

Did you account for PAR fraction of sunlight? LED growth lights have a significantly better PAR coefficient than sunlight - which covers much wider "waste" spectrum than normal room lights. And actually, solar panels have a pretty wide absorption spectrum, so, while we aren't there *quite* yet, it may be in the future that grow-light - solar panel combo will be more efficient than direct sunlight over the same area - and especially with extra batteries storing energy above the saturation level and expending it during weaker sunlight.

As for stray light - With large area growth, stray light isn't that much of a problem. The light that doesn't hit the square below the lamp, hits the neighbor square, and the loss is then covered by stray light from the neighbor lamp. As for the rest, I believe LED efficiencies already account for directionality, light absorbed by the LED casing.

Comment Re:Are and storms that fierce on Mars? (Score 1) 122

Not even close. Your solar array too has a capacity factor - in the ballpark of 15% if fixed, maybe 35% or so if tracking. Then you have your panel efficiencies. The best large scale commercial panels are 22-23% efficiency. You might get 30%-ish if you used absurdly-crazy-expensive spectrolab cells. Then factor in dust constantly settling on the panels - say 25% loss even with regular cleaning. And Mars's solar constant is only 588W/m^2 *in space*. Earth's is about 1kW/m^2 *on the surface*, 1,4kW in space.

I went with 50% efficiency reduced to 0.7 by morning/evening angles with lack of tracking (Acidia Planitia is equatorial latitudes). That's 2035 space-quality technology. Dust with daily cleaning is non-factor; Opportunity operated for years within some 40-50% loss due to dust, so with daily cleanings it's really non-issue, maybe 2% loss, your 25% would take months of negligence. Due to thin atmosphere, Mars is only something like 560W on surface.

6kW of power consumption for LED lights on a rover?

Only when it switches all of them on. There's a difference between "driving usage" where it may be 500W, and switching the search-lights for emergency when you, say, search for a lost astronaut. In that case 6KW is reasonable.

How the heck would you even cool a 500W LED spotlight (let alone 1kW, let alone 12 of them) in the near-vacuum atmosphere of Mars?

I'd need to come up with estimate of radiation of the surface of Hab, but it's large, white and in very cold environment. There's a plenty of cooling capacity in environment this cold. Yes, air-cooling capacity is poor, but radiational capacity is pretty good considering the radiating surface and the temperature gradient.

I wish you were here so I could show you what a 600W LED grow light looks like. It's blinding. The whole world looks pink for a while afterward. And they're massive, heavy things. To put it another way: 600W LED is equivalent to about 5000W incandescent.

The area lit by them shouldn't be brighter than sunlit area - actually, 25% of sunlight strength would suffice.

Could have, would have, should have. But as it stands, it's 2-3 orders of magnitude off.

We can agree to disagree, I'd say about an order :) But yes, I can accept the botany part of the book was borked. There are more serious errors. Had Weir played Kerbal Space Program for several days, the whole "blowing up the airlock" would be gone - at 2mm/s^2 making a perfect encounter with target moving 12m/s relative to you is some 8 hours.

Still, I have to give it to him: he tried, he did his best, he only made errors because he failed to research even more even though he researched a plenty. We can now hope for a book more accurate, with better science and less errors, now that he's opened the path and showed there's a demand for accurate sci-fi. Even if his own failed to be very accurate.

Comment Re:Are and storms that fierce on Mars? (Score 1) 122

sh1t, did some serious math, then accidentally closed the tab.
First, 1KW light output is if you want Earth's equatorial sunlight, which is far more than plants need - they saturate their input at far less than that. I arrived at 500W (input) of LEDs to produce the needed output for 1m^2, and about 2.5m^2 of solar panels to power them up.

Still, obtaining the needed lamps - yep, 1m^2 per spotlight, 12 per rover (per movie), 10 from other sources, Hab lighting for another 4 or so meters... weaker sources focused on individual plants not to waste energy on lighting up empty soil... that still runs awfully short of the goal, something like 1/3 of what he planned. Not nearly as bad as you predicted, but not nearly as good as Weir thought.

I wonder how much could be saved by adapting growth density. Say, he could light up all the saplings with 2-3 lights, but as plants grow, they need more space. So instead of one massive harvest, to make it so that the grown plants take half the available light, grown in 3/4 half of the remainder, half-grown half of the remainder of that, and so on.

Alternatively, how lethal would space radiation be to potatoes? An extra "tunnel" from transparent plastic, where mature plants would use direct sunlight.

Comment Re:Fun Movie, Not Future Reality (Score 1) 122

oh, wait. One more thing. As ludicrous you might think the "iron man"...

The only thing really impossible about the whole mission plan is the budget.

A mission like Ares 3 could have been launched today, if NASA budget had never been cut after the Apollo program.

Now, if one of the astronauts was left behind, stranded, getting him back to Earth would be far trickier and quite likely impossible. But the Ares 3 mission plan was sound and doable. It's the events triggered by completely impossible storm that were a serious stretch.

Comment I refuse on grounds of self-incrimination. (Score 1) 257

On my encrypted volume I posess atricles of software and media, which I obtained legally, but I don't possess proofs of the purchase. Some of the original media, receipts and other such were destroyed in an accident. By providing access to contents of my hard drive I would expose myself to copyright lawsuit which would require me to produce these proofs. Therefore, I plead the fifth amendment.

Comment Re:Are and storms that fierce on Mars? (Score 1) 122

Give the habitat spotlights from Rover 1, spotlights from MDV, spotlights from Hab's outside lighting and all the spare bulbs for everything.

The solar panels are hindered by fixed angle and distance from the Sun, but boosted by equatorial latitude and thin atmosphere not dissipating nearly as much light as Earth. Although yeah, 11% is lousy. Let's assume space technology of 2035, and give them a healthy 65%, blaming the 11% on Mark being a botanist.

Remember, individual care of individual plants, optimal temperature and humidity, exploiting the soil to the max, battery power for extended "daylight".

How would the figures look like then?

Saliva causes cancer, but only if swallowed in small amounts over a long period of time. -- George Carlin