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Study: Potatoes can grow on Mars

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Re: Study: Potatoes can grow on Mars

#111

Post by averagewall »

ars wrote: post #94
averagewall wrote: post #84

Earlier quoted context omitted.

A difference in temperature has the same numerical value in both degrees C and K. Often differences in temperature are all we're interested in so C is often interchangeable with K. If you use Fahrenheit, then you lose that easy relationship unless you also use Rankine for absolute temperature. But nobody, not even Americans, has even heard of Rankine so it would be a far bigger challenge to get anyone to use that tha…

> A difference in temperature has the same numerical value in both degrees C and K. I know, I used them basically interchangeably in my post. > unless you also use Rankine If people used Fahrenheit more often they would use Rankine more often as well (and yes, I was aware of it before this discussion). > which would be joules in SI Joules is a unit of energy, not temperature. You need to multiply by entropy to get te…

Isn't temperature an energy scaled by the Boltzmann constant? That means it's proportional to the energy of something. Why not just use that energy directly instead of converting it to another unit? That's what I means about using Joules for temperature - divide kelvins by Boltzmann's constant

Why on earth would you make absolute zero anything other than 0? That's the major problem of Fahrenheit and the reason Celsius is not the SI unit. Instead, you could put a human-level temperature at a round number like 1000 new degrees so everyone always has the leading 1 in there for everyday values.

Re: Study: Potatoes can grow on Mars

#112

Post by TeMPOraL »

piker wrote: post #83
adrusi wrote: post #47

Earlier quoted context omitted.

Martian gravity is lower than earth gravity, and if the test was run in earth like gravity there could be concerns that that variable would have an effect. By conducting the experiment in lower gravity than Mars's, it's hard to doubt that martian gravity would pose a problem.

Practically speaking, honest question, how do we simulate lower gravity for extended periods other than orbit? Seems hard.

Technically, what you're doing in orbit is free fall ;).

I've seen devices used to simulate microgravity in cell research. Devices like these:

http://www.grimm-space-research.com/RPM/RPM.html

As far as I understand, the basic idea is to spin the sample in such a way that over time that the forces acting on it (including gravity) average out to 0. Apparently the processes they're interested in occur slowly enough that they behave as if in free fall.

Re: Study: Potatoes can grow on Mars

#113

Post by simonh »

_rpd wrote: post #43
JohnJamesRambo wrote: post #10

Earlier quoted context omitted.

https://www.newscientist.com/article/dn22520-mars-is-safe-fr... I didn't know the answer so I googled it. Apparently it isn't that high. "Readings from NASA’s Curiosity rover suggest radiation levels on the Red Planet are about the same as those in low Earth orbit, where astronauts hang out for months on the International Space Station."

> radiation levels on the Red Planet are about the same as those in low Earth orbit ... which coincidentally is where the experimental potatoes in the article were grown.

Unfortunately not, looks like they never got round to launching the cubesat.

Re: Study: Potatoes can grow on Mars

#118

Post by david-given »

clinton wrote: post #52
david-given wrote: post #11

From the article: "The box mimics the day-night patterns of Mars, as well as its temperature, air pressure and atmospheric composition." Wait, really? They're growing plants in what's practically a vacuum and at subzero temperatures? Really? That seems... stupendously unlikely... to me. Not that I wouldn't love to be wrong, mind. Anyone have a link to actual data? Everything linked to is just press fluff. Update: Act…

I ran a similar experiment at home, albeit with a fern rather than potatoes and without simulating martian light. My fern started to perish (and it was a well established plant). The biggest problem I'm facing at the moment is that Mars is extremely nitrogen deficient. https://reprage.com/post/marsarium-9 https://www.reddit.com/r/Colonizemars/comments/5vi52v/inspir...

That's awesome. I want to do that.

It'd be interesting to measure the gas composition inside the chamber --- although I suspect the bodging together a gas spectrometer is going to be a bit problematic.

This all at at one atmosphere, though, isn't it? I see you have a vacuum pump, but that enclosure doesn't look like it'd be safe to evacuate. I'd like to try low pressures. Intuitively I'd expect hard-skinned plants like cactuses to cope better --- but intuition is frequently wrong. Another interesting thing to try would be to use one atmosphere of absolute pressure but have accurate partial pressures of carbon dioxide and nitrogen to simulate the Martian atmosphere...

Re: Study: Potatoes can grow on Mars

#119

Post by david-given »

freeone3000 wrote: post #51
astrodust wrote: post #50

Earlier quoted context omitted.

Celsius at least has a family of units that mesh with it precisely. To heat one cubic centimetre of water up 1°C takes 1 Joule. It also essentially weighs 1 gram at normal temperatures. How many BTUs does it take to heat up one cubic foot of water by one degree Fahrenheit?

It takes one BTU to heat one pound of water, one pint, one degree Fahrenheit. The units may be arbitrary, but they still line up.

Is that a US or a UK pint?
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