Molecular Monday: Top 5 Chemicals on Mars

January 29, 2018

For today’s Molecular Monday post, I thought I’d try something a little different. I’m counting down my picks for the top five chemicals on Mars. These are chemicals that, in one way or another, are important to helping us understand the Red Planet better.

#5 Possible Methane
Several robotic probes have detected burps of methane on Mars, which could indicate ongoing biological or geological activity—either one of which would be a huge surprise on a world long thought to be both biologically and geologically dead. However, the methane could also be a contaminant leaking from the robots themselves. We’ll have to wait and see with this one.

#4 Hematite
Hematite is a rusty red colored mineral, also known as iron oxide or iron (III) oxide. Almost the entire surface of Mars is covered in hematite, giving the planet its distinctive color. But questions remain about where all this hematite came from. One thing we can be certain about is that Mars’s red color is only skin deep. When the Curiosity rover drilled a hole in the ground, it found the underlying layer was grey.

#3 Carbon Dioxide
Mars’s atmosphere is almost all carbon dioxide, which should help keep the planet warm, but the air is too thin to produce much of a greenhouse effect. As a result, Mars is a little too cold for human comfort. There’s also plenty of frozen CO2 (also known as dry ice) at the poles. Maybe someday we can release all that excess CO2­ and do to Mars what we hope not to do to Earth.

#2 Perchlorate Salts
The most noteworthy perchlorates on Mars are calcium perchlorate and magnesium perchlorate, but there are plenty of other flavors besides those two. Based on data collected all over Mars, it seems these perchlorate salts make up 0.5% to 1.0% of the Martian regolith; that makes the regolith extremely toxic to humans, and we need to figure out what to do about this problem before we can begin any serious colonization efforts. On the other hand, in the unlikely event that life already exists on Mars, perchlorates might (might!) make a good source of chemical energy, similar to the way oxygen is a good source of chemical energy for us.

#1 Water
Humans on Mars will not suffer from a lack of water. There are vast quantities of H2O frozen at the poles and buried in underground glaciers. And there’s little doubt that liquid water once flowed over the planet’s surface, carving river channels and chemically altering the rocks. However, a wet and watery Mars would have looked very different from modern Earth. Rather than standing lakes and rivers, Mars seems to have experienced violent flash floods, perhaps caused by melting and refreezing glaciers, followed by long periods of dryness. Still, the liquid water was definitely there, and there’s a distinct possibility that microorganisms could have started to evolve before the planet dried up completely.

So those are my picks for the top five most interesting and/or important chemicals on Mars. Let me know what you think of this list in the comments, and if people like it, maybe I’ll do something similar for other planets.

P.S.: Honorable mention to the polycyclic aromatic hydrocarbons (PAHs) from the Martian meteorite ALH84001. Like those methane burps, PAHs could either be an indicator of Martian life or a hugely embarrassing scientific mistake.

Sciency Words: Triangular Trade

January 26, 2018

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 I’m really stretching my conception of science-related terms so we can talk about:


When I was a kid, I had an extensive collection of cards from Star Wars: The Customizable Card Game. At one point, I was trying to trade with a friend to get his Millennium Falcon card, but I didn’t have anything my friend wanted. So we got a third person involved and set up a three-way trade. My extra Princess Leia card went to this third person, who then gave a rare star destroyer to my friend, who then gave me the Millennium Falcon I needed to complete my rebel fleet.

This was sort of like what happens in triangular trade. Like nerdy kids trading Star Wars cards (or non-nerdy kids trading, I don’t know, baseball cards or something), cities or regions or countries set up three-way trade arrangements for their exports. This kind of arrangement served as the basis for much of the world economy in the 18th and 19th Centuries, during the Age of Colonialism.

The most commonly cited example (unfortunately) is the slave trade, where the trade routes between Europe, Africa, and the Americas actually traced out a big triangle across the Atlantic Ocean. European nations exported manufactured goods to their African colonies, which then exported slaves to the American colonies, which then exported things like sugar, cotton, tobacco, etc to Europe.

Obviously triangular trade is more of a historical term than a sciency thing, but much like the word thalassocracy, I feel like this old, history-related term might become applicable again in a far-out, Sci-Fi future where humanity is spreading across the Solar System. And the reason I think that is because Robert Zubrin, one of the foremost Mars colonization advocates in the U.S., wrote about triangular trade in his book The Case for Mars and also in this paper titled “The Economic Viability of Mars Colonization.”

To quote Zubrin from his “Economic Viability” paper:

There will be a “triangle trade,” with Earth supplying high technology manufactured goods to Mars, Mars supplying low technology manufactured goods and food staples to the asteroid belt and possibly the Moon as well, and the asteroids and the Moon sending metals and possibly helium-3 to Earth.

So everybody wins! The people of Earth win, the colonists on Mars win, and all the prospectors and mine workers in the asteroid belt win! Even our moonbase wins (this part might seem counterintuitive, but the delta-v to reach Earth’s Moon from Mars is actually lower than the delta-v to reach the Moon from Earth). And this time, slavery isn’t involved!

Unless the high technology being exported from Earth includes robot slaves who then… hold on, I have to go write down some story ideas.

A House on Earth or a Ticket to Mars?

January 24, 2018

Whenever someone says something will happen in the next twenty years, you can take that as code for “I have no idea when this will happen, but I really hope it’ll happen soon!”

With that in mind, in the next twenty years the cost of sending a human being to Mars will become affordable for the average person. Or at least that’s the promise made by Elon Musk in his scientific paper/personal manifesto “Making Humans a Multi-Planet Species.”

In that paper/manifesto, Musk says, “In fact, right now, you cannot go to Mars for infinite money.” That’s a blunt way of putting it. Musk goes on to say that if Apollo-era technology were revived, it would cost about $10 billion per person to send humans to Mars. But Musk believes his company, SpaceX, can reduce the cost to a mere $200,000 per person.

That’s still a whole lot of money. Who can afford that? But before you dismiss what Musk is saying, consider this: the average person heading to Mars would not be going on a whim or as a tourist. Choosing to travel to Mars would be a major life decision. You’d be going there to stay, to help colonize the Red Planet, to start a new life on a new world.

That $200,000 price tag is comparable, according to Musk’s estimation, to the median average cost of buying a home in the U.S. So the choice we’d all have can be framed this way: would you rather buy a house on Earth or a ticket to Mars?

If I could ask Musk one question, it would be can I get a mortgage on my Mars ticket? Based on some of the other things Musk says in his manifesto, I suspect the answer would be yes, something like a mortgage would be possible.

I have to admit I’d have a hard time deciding what to do in this future Mr. Musk envisions. I’d probably choose to go to Mars, but I also really like my house on Earth. It would be hard for me to give that up. Hard, but not impossible.

So if we were all living twenty years from now, which would you choose: a house on Earth or a ticket to Mars?

Sciency Words: Chemofossils

January 19, 2018

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:


On Wednesday, I made up a bunch of numbers for the odds that we will find life on (or bring life to) Mars. The odds, in my inexpert judgment, are pretty low for finding anything presently alive on Mars, but I’d say there’s a 50/50 chance we’ll find the fossilized remains of life that existed there in the past. Now if only our rovers were equipped with digging gear!

But after writing Wednesday’s post, I learned that there are, in fact, many different kinds of fossils, including body fossils, trace fossils, ichnofossils, and chemofossils. And according to this article by Claire Cousins, a planetary scientist working on the European Space Agency’s upcoming ExoMars rover, it’s these chemofossils that will probably be our first real evidence of ancient Mars life.

The word chemofossil is, as you may have guessed, a combination of the words chemical and fossil. I was unable to find out who coined the term, but it seems to have happened fairly recently. According to Google Ngrams, it starts appearing in literature in the 1970’s.

Chemofossils are the telltale chemicals left behind by dead and decaying biomaterial. Even if an organism becomes totally decomposed, there may still be a sort of residue that suggests some sort of past biological activity. A good example, which Cousins cites in her article, are amino acids that share the same chirality.

Finding amino acids on Mars would be mildly interesting, but amino acids can come from just about anywhere. However, if those amino acids all have “left-handed” chirality (or “right-handed” chirality), well… the only natural phenomenon we know of that picks and chooses the chirality of amino acids is life.

Now since I’m still in the mood for making up numbers, I’m going to say there’s a 99% chance someone will announce they’ve detected chemofossils on Mars, BUT we will spend the following decade or two arguing about whether or not they really did. As Claire Cousins writes, discovering life on Mars “[…] will be a gradual process, with evidence building up layer by layer until no other explanation exits.”

In other words, I doubt that discovering chemofossils will definitively prove that life once existed on Mars. But I do think chemofossils will be the first “layer of evidence” we find.

Life on Mars: What Are the Odds?

January 17, 2018

So… is there life on Mars? I don’t know, but after everything I’ve read and seen and learned about the Red Planet, I feel like making up some numbers.

I’m going to say there’s a 10% chance that life exists on Mars today. Mind you, this is not intelligent life. It’s not even complex, multi-cellular life. No, I’m just saying there’s a 10% chance that some kind of microorganism is there, eking out an existence near the Martian R.S.L.s or in the permafrost near the Martian poles. And maybe we’ve already detected the first signs of these microorganisms’ activity.

But the odds of that are pretty low, in my opinion. I think there’s a much better chance—let’s say a 50% chance—that Mars supported life at some point in the past, and that we’ll find the fossilized remains of ancient Martian organisms preserved in rock. We’re probably still only talking about microorganisms (or rather microfossils), but given that Mars hasn’t been geologically active in a long time, those fossils should be extremely well preserved.

Lastly, I think there’s a 90% chance that, regardless of whether or not Mars supported life in the past or present, it will support life in the future. Human life, to be specific (as well as plant life and maybe some edible bugs). Maybe it’ll be nothing more than a small research station, or maybe it will be a full-fledged colony. But I’m 90% sure we’ll get there. I say this because a lot of very smart people (and a handful of very rich people) seem to be pretty determined to make it happen.

Anyway, these are my best guesses about the odds of finding life on (or bringing life to) Mars. Do you agree with my rough estimates? Do you think I’m way off? Let me know in the comments!

Molecular Monday: Jarosite on Mars

January 15, 2018

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.

Over the last few months, I’ve been trying to get to know the planet Mars better. There’s some pretty clear evidence that Mars used to be a different kind of planet, a wetter and more watery sort of world… but perhaps not in the way you might have expected.

Many of Mars’s rocks seem to tell a similar story about that wet, watery past. That story usually begins something like this:

We’ve already looked at Mars’s sedimentary basaltic rocks. Such a thing would be almost a contradiction in terms on Earth. Sedimentary rocks are made by flowing water; basalt is destroyed by water. So how could a rock be both basaltic and sedimentary?

Now let’s take a look at another rock that’s almost self-contradictory: jarosite. Jarosite is a potassium/sulfur/iron-containing mineral with the chemical formula KFe3(OH)6(SO4)2. It typically forms in wet, acidic environments by the oxidation of iron sulfides. If you don’t understand what that means, that’s okay; I don’t fully understand it either. The important thing is that jarosite forms in water; but jarosite is also destroyed by water. It breaks down into simpler compounds if exposed to water for long periods of time. That makes jarosite pretty hard to find on Earth, but of course it’s surprisingly common on Mars!

In 2004, the Opportunity rover discovered jarosite—lots of jarosite—in the Meridiani Planum region (incidentally, the same region where Airy-0 is located). According to a NASA press release at the time: “Jarosite may point to the rocks wet history having been an acidic lake or an acidic hot springs environment.”

But whatever was happening in Meridiani Planum, the region must have dried up pretty quickly. According to the abstract of this paper, also from 2004, “[…] the presence of jarosite combined with residual basalt at Meridiani Planum indicates that the alteration process did not proceed to completion, and that following jarosite formation, arid conditions must have prevailed.”

Before I started all this Mars research, I imagined ancient Mars as a very Earth-like place, with standing oceans and lakes and gently flowing rivers. I guess there still could have been a time like that in the very beginning, but most of Mars’s history with water seems to have been far more sporadic and violent than that, with lots of flash flooding (perhaps caused by melting glaciers) and very brief wet spells followed by long periods of dryness.

At least that’s my impression at this point in my research.

Sciency Words: Airy-0

January 12, 2018

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:


Airy-0 is a small crater on Mars. There’s nothing particularly strange or noteworthy about it. Mars has lots of craters. Or at least, Airy-0 wouldn’t be noteworthy if not for some arbitrary decisions made on Earth over the course of the last few centuries.

In the 1830’s, Earth-based astronomers wanted to know the length of a Martian day, so they picked a dark, easily-identifiable surface feature and used that as a reference point to determine the planet’s rate of rotation. 19th Century astronomers also decided to use that dark surface feature to calculate latitude lines on the Red Planet. In other words, that dark feature (now known as Sinus Meridiani) became the reference point for the Martian prime meridian.

Then in the 1970’s, when NASA’s Mariner 9 space probe began sending back the first detailed maps of Mars, a specific crater within the Sinus Meridiani region was chosen to serve as a better, more precise reference point for the prime meridian. That crater was named Airy-0 in honor of George Biddell Airy, the astronomer who built the Airy Transit Circle telescope at the Greenwich Observatory in England.

I find this extremely fitting. The location of Airy’s telescope is used to define Earth’s prime meridian, so it makes sense that Airy’s crater on Mars would be used to define the prime meridian of Mars. But unfortunately, there seems to still be some uncertainty about Airy-0’s exact location.

Apparently the crater is small enough that space craft can have trouble locking onto it from orbit, and according to this paper from 2014, it turns out Airy-0 is approximately 47 meters east of where it was previously estimated to be. That’s a discrepancy of 0.001º latitude, which may not seem like much, but it’s enough to be problematic for science.

Three pictures of Airy-0 in increasingly high resolution over the past few decades. Airy-0 is the large crater in the top of each picture. Image courtesy of Wikipedia.

So Airy-0 will continue to be subject to intense scrutiny by us Earthlings, not so much because of anything intrinsically special about it but because, for the purposes of Martian cartography and Martian timekeeping, we really, really need to know exactly where Mars’s prime meridian is.