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  • - I'm taking this week off. Standing in for me is Tom Carroll

  • from the incredibly stylish Aspect Science

  • who sent one of the best guest video pitches I've had in a long while.

  • And it said, "hi Tom, I've got 12 kilos of Martian soil simulant

  • "and I'm trying to grow a salad."

  • - Can we grow crops in Martian soil?

  • That's a question I asked in a recent video of mine,

  • and the answer actually turned out to be: yeah.

  • Or at least that it's probably possible with a bit of tweaking of the soil

  • and assuming you figured out

  • where to get a good supply of liquid water from,

  • and that you're growing the crops in a controlled indoor environment.

  • What's pretty cool is that Martian soil has actually been found to contain

  • all of the nutrients needed for a plant to grow.

  • But how do we know this?

  • I mean, unlike the moon, no samples of Martian soil,

  • which is technically called regolith, have even been returned to Earth.

  • Orbiters, landers, and rovers like those of the Viking and Pathfinder Missions

  • gave us our first understanding of what Mars's surface was made of,

  • and they led to NASA JPL developing

  • the JSC Mars-1 Martian soil simulant in 1998.

  • The aim to closely mimic what was found on the Martian surface.

  • Simulants have a range of uses, like testing out new tools,

  • testing out new handling methods,

  • and testing out ways to make use of the material itself.

  • But after a while some experiments with the Martian soil simulants

  • showed that they lacked certain properties of Martian soil,

  • which led to the development of newer simulants.

  • And which leads me to these boxes.

  • Inside these boxes are 12 kilos

  • of Mojave Martian Simulant, or MMS,

  • provided by the Martian Garden in Texas.

  • So having made a video previously about

  • if it's even feasible to use Martian soil to grow crops,

  • the next logical step is to try to actually grow something.

  • So I'm going to try to grow a Martian salad here on Earth.

  • Now whilst I'm getting everything set up

  • now would probably be a great time to ask the question:

  • how do they even create this stuff?

  • Simulants are basically crushed blends of Earth materials.

  • So the whole process really revolves around

  • finding places on our planet with a good supply of material

  • that has similar properties to Martian soil.

  • The Martian surface is covered in soil that has a key ingredient of basalt,

  • which is a dark, iron-rich volcanic rock.

  • The original Martian soil simulant

  • used weathered volcanic ash from an area near Mauna Kea in Hawaii.

  • But this stuff, MMS, uses basalt rock

  • that's found in an ancient volcano in the western Mojave Desert,

  • which has a very similar mineral makeup to what's found on Mars.

  • They take boulders and rocks of this basalt,

  • which are then crushed into smaller and smaller particles,

  • resulting in a range of sizes from fine powder to gravel.

  • It's then sifted multiple times to separate it

  • into coarse, fine, and superfine grades of simulant.

  • The simulant is missing an important component

  • of Martian soil, though, toxic perchlorate compounds.

  • Now on Mars these could be lethal to crops and to the humans that eat those crops.

  • But luckily for us there are a range of different methods

  • for getting rid of them.

  • All right, now I've got everything set up and ready to go.

  • I've got two germination pod trays split into four columns.

  • Column one contains MMS with a bit of fertiliser.

  • Column two contains MMS with nothing added.

  • And for comparison we've got good old Earth soil in column three.

  • And column four contains nothing

  • but a water-retaining sheet.

  • I'm using four different varieties of micro green plants,

  • which are essentially just plants that could be harvested really early on.

  • I've got pea plants, sunflowers, cress, and radish.

  • And now it's really just a waiting game.

  • But let's face it, even if these things grow,

  • they really wouldn't be keeping me full.

  • If we're wanting to stay on Mars for extended periods of time,

  • we're going to need to figure out a way to generate some high-calorie food,

  • seeing as it will just be too heavy to bring with us.

  • Some researchers like Dr Weiger Wamelink

  • of Wageningen University have managed to use

  • Martian soil simulant and grow a heap of different vegetables,

  • like tomatoes, carrots, and green beans.

  • And after having a quick chat with him, I found out that they've even managed

  • to grow some proper potatoes.

  • I'm just growing micro greens because they're quick and they're easy

  • so if I screw up it'll be cheap and easy to try again.

  • But hopefully it will be good and they'll actually grow,

  • which it looks like they might.

  • It's a few days since planting the seeds now,

  • and look what we've got.

  • Everything has started to germinate,

  • and I can already taste the sweet, sweet salad of victory.

  • And what led to this stage is actually pretty fascinating.

  • The seeds I planted a few days back

  • were lying dormant, where their growth has stopped

  • and metabolism has almost completely stopped as well.

  • Seeds that are dormant stay that way

  • until conditions are right for them,

  • or they receive a specific environmental cue.

  • For instance, in areas where wildfires are common,

  • seeds can require intense heat or smoke,

  • which acts as a sign that other competing vegetation

  • has probably just been cleared by fire.

  • When germination begins they take in a large amount of water

  • in a process known as imbibition.

  • And the seeds expand and rupture their outer coats.

  • Metabolic changes inside the seed are triggered

  • and enzymes begin digesting food stores,

  • leading to the plant embryo resuming growth.

  • The embryonic root makes an appearance first to access water.

  • Then the shoot tip needs to break through and emerge from the soil.

  • Now different plants do this in different ways,

  • but once they do, the first true leaves can develop and start photosynthesizing,

  • allowing the plant to grow more and more.

  • And eventually, this will lead to a full grown plant.

  • But I'll be harvesting my micro greens at a much earlier stage than that.

  • At a stage that they're actually getting pretty close to now.

  • It's a few more days later

  • and now we've got shoots properly growing

  • and can start to see the differences in everything.

  • What's interesting is seeing that the seeds in the fertilised simulant

  • seemed to not be doing well at all.

  • Now there are a few reasons this could be happening,

  • but really what this probably means is that I screwed up

  • and used way too much fertiliser.

  • But what's really clear is that the plants in the Martian soil simulant are growing

  • a lot slower than the plants in the Earth soil.

  • And this is something I expected

  • and something that we would probably expect from real Martian soil.

  • You see, even though Martian soil has been found

  • to contain all the nutrients needed for a plant to grow,

  • some of them are probably not going to be very abundant,

  • or even in accessible forms.

  • So it'll have to be tweaked

  • by adding in micro and macroscopic organisms

  • and probably using some forms of fertiliser

  • to ensure proper nutrient availability and nutrient cycles.

  • This'll lead to long-term, sustainable use of soil.

  • And will lead to plants that are nice and healthy

  • when you're about to harvest them.

  • Which is what I'm about to do with my micro greens right now.

  • It's now 14 days since I planted all of these micro greens,

  • and here they are.

  • All right, so it might not look all that impressive,

  • but it's still time for me to make my Martian salad.

  • But wait, I've got to try and make this look good.

  • Okay, so it's not exactly the biggest feast,

  • but I'm actually pretty happy about this.

  • I mean, I grew this in a Martian soil simulant.

  • And now I'm about to taste it.

  • Hmmm, I mean it's pretty leafy...

  • with a little bit of pepper.

  • I probably wouldn't recommend it.

  • Now clearly this was not a real experiment,

  • and clearly I made some mistakes in my methods.

  • But there are some real scientists working hard

  • trying to make growing crops on Mars a reality.

  • A lot of these experiments are less about

  • "can we stick a seed into the Martian soil and just grow a plant"

  • and more about, "okay, what's our starting point

  • "and what do we need to tweak to make it better?"

  • Even though we might still be at least decades away

  • from even landing on Mars,

  • let alone settling on it for long periods of time,

  • research done now will make sure that we're as ready as we can be,

  • and it can even lead to better agricultural practices here on Earth.

  • So I'm probably going to try this whole experiment again,

  • but I think I'm going to try to grow something

  • maybe just a little bit bigger this time.

  • Tom, thank you so much for this opportunity.

  • I massively appreciate it.

  • And thank you for watching.

  • Now I'm going to get back to my absolute feast.

  • - Go and subscribe to Aspect Science! I'd recommend starting with his video

  • about what would happen if a micro meteorite

  • hit an Apollo astronaut on the moon.

  • I'm back next week and I'll see you then.

- I'm taking this week off. Standing in for me is Tom Carroll

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火星のサラダを地球で育てる方法 (How To Grow A Martian Salad On Earth)

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    林宜悉 に公開 2021 年 01 月 14 日
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