Dining on Mars, Part 2: Lettuce

December 12, 2017

A few years ago, NASA astronauts started growing lettuce aboard the International Space Station. This was a big deal. The day the astronauts finally got clearance from mission control to eat their lettuce, it made headlines.

Except I remember there was something about this story that really didn’t make sense to me at the time, and honestly still doesn’t. Supposedly getting to eat fresh lettuce was a huge morale booster for the I.S.S. crew. Look, I get this was an important proof of concept, demonstrating that it is possible to grow food in space. But lettuce… a morale booster?

Speaking as someone who’s currently living on the surface of Mars, I can assure you that lettuce is just as exciting here as it was back on Earth.

Of course the reality of living on Mars is that you have to stick to a vegan diet. You simply don’t have the room or resources to raise livestock (although as our presence on Mars grows and our habitat structures expand, it may be possible to bring some animals over… but that’s a topic for future posts).

Fortunately experiments back on Earth using Mars regolith simulant have shown than a great many vegetables should be able to grow in Martian soil, not just lettuce. We’ve already talked about potatoes and sweet potatoes. Also according to this article, the research on tomatoes, peas, spinach, and several other crops looks promising.

That’s encouraging news, but that same article also warns that Martian regolith contains elevated levels of metals, such as iron, arsenic, and lead. This is a “further research is required” thing, but it’s possible that plants could absorb some of those metals, meaning my Mars lettuce might end up giving me lead poisoning.

I wish someone had mentioned that to me before I started growing all these crops in Martian regolith.

Sciency Words: Astro-Paleontology

December 8, 2017

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


This may be a first for Sciency Words. Usually I discover new words to share with you during the normal course of my research, but this time I thought to myself, “astro-paleontology has got to be a thing by now,” and then went and found that it is.

Or at least it almost was. Back in the 1970’s, astronomer John Armitage wrote a paper titled “The Prospect of Astro-Palaeontology,” officially coining the term. And then it seems nobody followed up on the idea.

The word paleontology comes from several Greek roots and means the study (-logy) of that which existed (-onto-) in the past (paleo-). It think we’re all familiar with what this really means: digging up the fossilized remains of dinosaurs and other organisms that died long ago. By adding the Greek word for star into the mix (astro-), Armitage created a term for the search for and study of the fossilized remains of life on other worlds.

The blog Astro-Archeology did several posts about Armitage’s work. I recommend checking out all three of these posts:

To be honest, I don’t have a whole lot to add to what Astro-Archeology already wrote on this subject, except that the search for alien fossils on Mars is about to heat up.

None of our current Mars missions are equipped to search for life on the Red Planet, either living or dead. But NASA’s next rover, the Mars 2020 Rover, will be. Specifically, Mars 2020 will be designed to hunt for fossilized microorganisms.

So maybe the term astro-paleontology is due for a come-back.

P.S.: You may have noticed that John Armitage and Astro-Archeology spelled this term as astro-palaeontology and I’m spelling it as astro-paleontology, without the extra a. This is a British spelling vs. American spelling thing.

Molecular Monday: Basalt as a Sedimentary Rock

December 4, 2017

I had a rough week last week, which disrupted my regular posting schedule. But I’ll talk about that on Wednesday for IWSG.

Today I’ve returned to Mars and I’m ready to continue my exploration of the Martian surface. I considered calling today’s post Mineralogical Monday, but really minerals are just a special kind of molecule, so I’ll stick to the Molecular Monday series I already have going.

Before I was so rudely brought back down to Earth, I was visiting Gale Crater. I wanted to meet the Curiosity Rover and maybe get an autograph, but I got distracted by some peculiar rocks.

It’s hard to put into words what was so odd about these rocks. They have the look and feel of sedimentary rocks, but in terms of chemical composition they’re more like basalt. But basaltic sedimentary rock is a contradiction in terms.

Sedimentary rocks form (typically) when sediment accumulates at the bottom of a river, lake, or other body of water. Over time, the sediment becomes compacted or cemented together, and thus a new rock is born.

Basalt is an igneous rock, meaning it forms from cooling magma, and it is chemically vulnerable to water. Basalt tends to include a lot of iron, magnesium, and calcium; water tends to leech these elements out of basalt, leaving a silicon-rich clay behind. So as a sediment sitting at the bottom of a lake or river, basalt wouldn’t last long enough to turn into sedimentary rock.

Fortunately for me, I’m not the only one who’s struggled to find the right terms to describe these weird Martian rocks. Emily Lakdawalla, a well respected science journalist writing for the Planetary Society, wrote an article about this and summed up the inherent contradiction well: “Sedimentary rocks say ‘Mars was wet.’ Basaltic composition says ‘Mars was dry.’”

So how did these basalt-like sedimentary rocks form? I can think of three possibilities:

  • Windblown Sediment: Sedimentary rocks can be created by wind rather than water, but as Emily Lakdawalla shows in her article, not all of these Mars rocks can be explained that way.
  • Liquids Other Than Water: It’s possible the sediment was deposited by a liquid other than water. That explanation makes more sense to me on a super-cold planetoid like Titan, where water is a rock and rivers are full of methane; however on Mars, water still seems to be the most likely working fluid.
  • Flash Floods: Maybe basaltic sediment was only exposed to water for a short time, perhaps during the flash floods that seem to have occurred during Mars’s Hesperian Period.

Most of the rock formations in Gale Crater are already believed to be Hesperian-aged, so the flash flooding idea makes the most sense to me. But of course the Curiosity Rover has been here a lot longer than I have, so I’ll be eager to ask her opinion on the matter.

Magnets on Mars

November 21, 2017

Today I’m continuing my totally-for-real, I’m-not-making-this-up exploration of Mars. I’m really here on the surface of Mars, walking around and doing science—or rather bouncing around in the low gravity and gawking at cool Mars things.

Last week we talked a bit about my efforts to grow potatoes in Martian regolith, based on experiments conducted by the International Potato Center back on Earth using a “Mars regolith simulant.” I ended up doing a bit of research about what, precisely, a Mars regolith simulant is. Turns out these’s a pretty long history to this stuff.

The earliest simulant appears to have been developed at NASA’s Johnson Space Center and is know as JSC Mars-1. It was made using volcanic ash from Hawaii and the recipe was based on data collected by NASA’s Viking and Pathfinder missions.

As we’ve learned more about Mars, there have been several newer generations of simulant, such as JSC Mars-1a, MMS-1 and MMS-2 (which have been made available for sale to the general public), and most recently JMSS-1, which was developed by the Chinese.

But going back to the original JSC Mars-1, I read something in this article that surprised me: “Approximately 25 wt% of the sample can be lifted with a hand magnet.” Since I’m here on the surface of Mars, that gave me an idea….

Given how much iron is contained in Martian regolith, what happened next shouldn’t have come as too much of a surprise. When I touched my magnet to the ground, most of the Mars-dust didn’t stick, but some of it did.

This is consistent, by the way, with the findings of the Spirit and Opportunity rovers. Magnets attached to the rovers’ Rock Abrasion Tools (R.A.T.) accumulated dust particles as the rovers chipped away at Martian rocks. It’s noteworthy that the R.A.T. magnets collected different colors of dust at different locations, indicating that there are many different kinds of magnetic particle on Mars. Spirit and Opportunity also conducted what’s known as the Magnetic Properties Experiments (M.P.E.), which used magnets to draw stray dust particles out of the Martian atmosphere.

It seems like you’ll find magnetic particles just about everywhere on Mars. Again, this shouldn’t come as much of a surprise. There’s a lot of iron, mostly in the form of hematite and magnetite, on the Martian surface. But still, this is a weird and awesome thing to see in action, at least from an Earthling’s perspective.

Sciency Words: Regolith

November 18, 2017

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


For a long time, I assumed this was another example of having one word for something here on Earth (soil) and a completely different term for the same thing on another planet (regolith). But no, we have regolith here on Earth too; however, other planets and moons do not appear to have soil, strictly speaking.

American geologist George Perkins Merrill is credited with coining the word regolith back in 1897. The term is based on two Greek words meaning “rock blanket.” I don’t know about you, but that conjures up a strange mental image for me. I mean, who’d want to snuggle up under a blanket of rocks?

But after doing further research, I think Merrill was being pretty clever with this one. Regolith is defined as a layer of loose gravel, sand, or dust covering a layer of bedrock.

As for the distinction between regolith and soil, I think it’s best to define soil as a special kind of regolith: regolith that contains enough organic ingredients to support plant life.

By that definition, Earth has both regolith and soil while places like the Moon and Mars only have regolith. That being said, a lot of people (including professional astro-scientists) go ahead and talk about Martian soil when they really mean Martian regolith.

Unless, of course, Martian regolith turns out to have more organic matter in it than we thought!

Dining on Mars, Part 1: Potatoes

November 15, 2017

Good news everybody! I’ve safely landed on the surface of Mars. I’d already constructed my habitat dome through the magic of telerobotics, so all I had to do when I got here was settle in and get comfy. The next order of business: what am I going to eat?

You may remember that fictional astronaut Mark Watney survived for over a year on Mars on a diet of potatoes and multivitamins. The potatoes provided Watney with the calories his body needed, and the vitamins provided everything else (well, almost everything else).

Watney grew his potatoes in a mixture of Mars dust and “fertilizer.”

So I guess the real question is: can this work in real life? Can potatoes grow in Martian regolith if the regolith is treated with some kind of fertilizer? According to the International Potato Center (C.I.P.) in Peru, yes. At least that’s what it says in this press release from earlier this year.

C.I.P. researchers used soil collected in a southern Peruvian desert, soil which is said to be the most Mars-like soil on Earth. This “Mars analog soil” was mixed with a bit of more traditionally Earth-like soil and then hermetically sealed in a test chamber that simulated Martian environmental conditions (O2 and CO2 levels, air pressure, and temperature).

Unfortunately I can’t find anything peer reviewed concerning this experiment, and I’ve learned to be skeptical of science-related press releases. However this press release refers only to “preliminary results,” so I have to assume a more substantive paper is on the way, and I’ll be eager to read it once it’s published.

In the meantime, I’ll do my best to grow my own potatoes here on Mars. Also I found this paper saying that sweet potatoes would make an ideal crop for long-term space missions. The sweet potato, according to the paper, “grows rapidly, has a higher yield, and greater nutritional values than other crops.”

That makes me even more excited about this Mars mission than ever. I love sweet potatoes!

Molecular Monday: Why is Mars Red?

November 13, 2017

Today’s post is part of a bi-weekly series here on Planet Pailly called Molecular Mondays, where we take a closer look at the atoms and molecules that make up our physical universe.

Okay, so I took a little detour on my mission to Mars to visit Phobos, Mars’s largest moon. But now it’s time I headed down to the surface of the Red Planet itself. Which brings us to today’s Molecular Monday question: why is the surface of Mars red?

In ancient times, the answer would probably be something like Mars is drenched in the blood of his enemies. A more modern, more scientific explanation would involve iron oxide, specifically iron (III) oxide with the chemical formula Fe2O3, which is more commonly known as rust. As a mineral, it’s also known as hematite, which is what I’m choosing to refer to it as from now on.

But it’s a little too easy to just identify a chemical substance. A far more interesting question is this: where did all that hematite come from? No one knows for sure, but there are (as far as I can tell) three possibilities:

  • Ancient Water: Maybe Mars simply rusted the same way rust generally forms here on Earth. Martian hematite could have formed when iron and water mixed together, with hydrogen gas being released as a byproduct. This would have had to happen billions of years ago during a time when liquid water was more readily available on Mars.
  • Meteor Impacts: Back in the 1990’s, following the Mars Pathfinder Mission, a scientist at NASA’s Jet Propulsion Laboratory proposed that meteor impacts may be responsible for depositing all that iron on the Martian surface, and that carbon dioxide (split apart by solar UV radiation) provides the oxygen to oxidize that iron. Click here for more about that possibility.
  • Dust Storms: In 2009, researchers at the Aarhus Mars Simulation Laboratory in Denmark showed that the abrasion of grains of quartz (which contains oxygen) and magnetite (which contains both iron and oxygen) can produce hematite. Both quartz and magnetite are present on Mars, and Mars’s global dust storms might be enough to grind quartz and magnetite together. Click here for more about this process.

The Martian water hypothesis might seem like the obvious explanation. At least I assumed so until I started researching this post. But when the Curiosity Rover started drilling holes in the Martian ground, it found that the underlying layer is sort of grey, not red. This seems to be consistent with what the Mars Pathfinder Mission found: that iron and other metals are more present in the Martian topsoil than in the rocks.

That may suggest that Martian hematite formed only in the recent past, or perhaps that it forms continuously in the present. If so, that would cast doubt on the ancient water hypothesis and lend credence to either the meteor impact or dust storm hypotheses, or perhaps a combination of the two.