Sciency Words: Special Region

March 30, 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:

SPECIAL REGION

It’s been several months now that I’ve been focusing almost all my research efforts on Mars. During that time, I’ve read a lot about those very special regions of Mars that might be home to alien life, but I didn’t realize until last week that “special region” is, in fact, a technical term.

Not only that, it’s a term whose precise definition has been and continues to be in dispute—exactly the kind of term most worthy of a Sciency Words post!

According to this paper from the journal Astrobiology, a special region is any region on Mars where “terrestrial organisms are likely to replicate” or where there is “a high potential for the existence of extant martian life forms.” By international agreement, NASA and other space agencies are not allowed to risk contaminating these special regions with our Earth germs. Since our current Mars rovers may not be 100% germfree, they’re all banned from exploring those areas.

But where are these regions, exactly? What are their boundary lines? This is where the definition of this term gets murky. We just don’t know enough about Mars to know which regions are special and which are not.

Initially I assumed it would be up to the International Astronomy Union (I.A.U.) to sort this out. They claim to be the sole authority on naming, categorizing, and defining space stuff. Even if you’ve never heard of the I.A.U. before, I can almost guarantee you’ve heard about at least one thing they did.

But in this case, I guess because this is a matter of international law, it’s a different organization that has to define what is or is not a special region. That organization is called COSPAR (Committee On SPAce Research), which is part of the International Council for Science. And COSPAR has been understandably reticent about setting any official definitions or drawing any official boundaries on a map. Like I said, we just don’t know enough about Mars yet.

Instead, COSPAR recommends evaluating potential landing sites on Mars on a case-by-case basis, keeping the latest scientific data in mind, to avoid contaminating any regions that might possibly someday turn out to be special (whenever we figure out what that means). According to this article from NASA, COSPAR reviews and updates the definition of “special region” every two years. Their next formal meeting is scheduled for July of 2018.

P.S.: Wait a second… who put that sign there? They better have decontaminated it first!


Mars Rovers Must Rove Responsibly

March 21, 2018

We’ve sent several robotic space probes to Mars already, and several more will be heading to the Red Planet in the next few years. Mars is already the second most heavily explored planet in the Solar System, after Earth.

But our robots are forbidden by international law from entering regions where Martian water appears to be flowing, or regions where Martian life could hypothetically exist. Why? Because there’s a chance that microorganisms from Earth hitched a ride aboard our space probes, survived the journey to Mars, and might start to grow and reproduce if they’re exposed to Martian water.

Yesterday, we talked about a paper in the journal Astrobiology which argued that the risk of contamination is minimal, and we should let our Mars rovers do their jobs. Go explore, and if there’s Martian life, go find it! Today we’re looking at a response to that paper, also published in Astrobiology, in fact in the same issue of Astrobiology. A response which raises several concerns, such as:

  • In the last few decades, we’re learned that Earthly microorganisms can be far more resilient than we ever imagined. Some of them very well might survive—and thrive—on Mars.
  • We’ve also learned that Mars is far less hostile to life than we previously assumed. Quite a few microbes from Earth might find Mars a rather comfortable place to live.

Taken together, these two points suggest that we have not overestimated the risk of contaminating Mars. In fact, we may have drastically underestimated the risks, and we need to be more careful, not less careful, about where we let our Mars rovers go. Otherwise:

  • We might destroy the very Martian life forms that we’re so desperately hoping to find.
  • We might make Mars’s water undrinkable for future human settlers.
  • We might end up misidentifying a stowaway microbe from Earth as a new form of life native to Mars, and the authors of this response paper argue that even our best gene sequencing technology might not be able to clear up the potential confusion.

Even if our Mars rovers keep their distance from Mars’s potentially-habitable or potentially-inhabited areas, there’s still a lot of valuable science they can do, especially when they’re investigating areas that used to be lakes or rivers, areas that could have supported lots and lots of alien life in the past, even if they’re bone dry and very thoroughly lifeless in the present.

So let’s take things slow. Let’s stick to the original plan (and current international agreements) and continue to explore Mars in a responsible and methodical manner.

Or maybe not. Gosh, I don’t know. After reading these two papers back to back, I really don’t know what to think.


Let a Mars Rover Rove

March 20, 2018

In the near future, human beings will probably set foot on the planet Mars. Human beings will likely do a lot of other things on Mars too: coughing, sneezing, peeing, pooping… it won’t be long until Mars is thoroughly contaminated with our germs.

We may have contaminated Mars already, at least a teeny bit, with our robotic space probes. You see, these probes may not have been as thoroughly cleaned and sterilized as they were supposed to be before they left Earth. Consequently, our Mars rovers, like the Curiosity rover, are forbidden from entering or even approaching sites where liquid water may be present.

This is to ensure that we don’t endanger any native Martian life that could hypothetically be living in those watery areas. It’s also to ensure that we don’t misidentify Earth germs as native Martian microbes at some point in the future.

But according to this paper published in the journal Astrobiology, we really should lighten up and let our Mars rovers do their jobs. We’ve spent billions on these robots, and we’re not using them to their best. While there is some risk of contamination, it’s only a small risk, or so the authors of the paper claim.

First off, the Martian environment is extremely cold, there’s lots of radiation, and an abundance of harsh, oxidizing chemicals in the soil. In short, Mars can do a better job sterilizing out space probes than we can. The very few Earth germs that might have made it to Mars thus far wouldn’t be able to spread far.

As for misidentifying an Earth germ as a Martian microorganism, the authors of the paper claim this wouldn’t be a problem. At this point, we have a pretty good idea which Earthly bacteria could have hitched a ride to Mars, because we know which bacteria were later found in the clean rooms where our space probes were built. Those bacteria can be easily identified with gene sequencing.

So let’s send the Mars rovers in. Let them do their jobs. Let them study Mars’s recurring slope lineae and other watery features, or any other areas where life could possibly exist. Let’s do this now, while the risk of contamination is still relatively low, because the humans are coming, and they’re bringing a whole lot more germs with them!

Or maybe not! As I’ve said before, these kinds of scientific papers should be understood not as final declarations of fact but as part of an ongoing conversation among scientists. In tomorrow’s post, we’ll talk about the other side of the argument.


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:

ASTRO-PALEONTOLOGY

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.


Sciency Words: Geologic Periods of Mars

November 3, 2017

One of the reasons I write this Sciency Words series is to introduce you to terms that I know (or at least suspect) we’ll be talking about in upcoming blog posts. Right now, I’m just getting started with my special mission to Mars series, so I think this is a good time to introduce you to not one but four interesting scientific terms.

Today, we’re looking at the four major periods of Mars’s geological history (based primarily on this article from ESA and this article from the Planetary Society).

PRE-NOACHIAN MARS (4.5 to 4.1 billion years ago)

This would have been the period when Mars, along with the rest of the Solar System, was still forming.

NOACHIAN MARS (4.1 to 3.7 billion years ago)

This period was characterized by heavy asteroid/comet bombardment, as well as plenty of volcanic activity. Most of the major surface features we see today formed during this time: the Tharsis Bulge, Valles Marineris, several of the prominent impact basins in the southern hemisphere, and also the vast northern lowlands—or would it have been the northern oceans? Also valley networks that formed during this time look suspiciously like river channels.

HESPERIAN MARS (3.7 to 3.0ish billion years ago)

Around 3.7 billion years ago, it seems asteroid and comet impacts on Mars died down, and volcanic activity kicked it up a notch. We also see a lot of surface features called “outflow channels” corresponding to this time, rather than the river-like valleys that appeared during the Noachian. These outflow channels may have been created by sudden and violent floods, which may have been caused by melting ice dams releasing lake water.

AMAZONIAN MARS (3.0ish billion years ago to today)

The Amazonian Period began when the northern lowlands, specifically a region called Amazonis Planitia, was “resurfaced,” covering up any impact craters or other surface features that may have been there before. Mars experts disagree about when this happened, but most estimates seem to be in the neighborhood of three billion years ago. Any obvious volcanic or geologic activity ceased during the Amazonian, and for the most part all of Mars’s water has either frozen solid or evaporated into space.

On Earth, if you want to talk about the age of the dinosaurs, what you’re really talking about is the Mesozoic Era, which is subdivided into the familiar Triassic, Jurassic, and Cretaceous Periods. And so if you’re looking for dinosaur fossils, you need look for Mesozoic Era rocks.

At this point we only have a rough sketch of the geologic history of Mars. We don’t know enough to make the kinds of divisions and subdivisions that we’ve made for Earth. But if you want to go looking for Martian dinosaurs (by which I mean fossilized Martian life of any kind, even if its only microbial) then I can tell this much: look for Noachian and Hesperian aged rock formations. Those are the rocks that would have formed back when Mars still had oceans and lakes and rivers (or at least random, violent floods).

At least, landing near some Noachian and/or Hesperian rocks seems to be a high priority for NASA’s Mars 2020 rover.


Molecular Monday: Boron Isn’t Boring

October 2, 2017

Welcome back to another edition of Molecular Mondays, a special biweekly series here on Planet Pailly combining two of my least favorite things: chemistry and Mondays.

At some point long, long ago, I read a book about the periodic table of the elements. Chapter five was about boron, and what I remember learning was that boron is kind of useless. Certain boron-containing compounds are used in cleaning detergents, and while boron is not particularly toxic to humans, it’s deadly to insects, so it makes a good insecticide.

And that was basically it. Nothing more to know. Time to move on to chapter six: carbon.

So when the news came out that the Curiosity rover had detected boron on the surface of Mars, my initial reaction was “who cares?” But then I read more, and I soon realized that I’d been grossly under-informed about the fifth element from the periodic table.

First off, finding boron on Mars posed a real challenge. The Curiosity rover used an instrument called ChemCam, which basically zaps rock samples with a laser and performs a spectroscopic analysis on the resulting rock vapor.

According to this paper published in Geophysical Research Letters, scientists were looking for two spectral lines, both in the ultraviolet part of the spectrum, which are characteristic of boron: 249.75 nm and 249.84 nm. Annoyingly, iron also produces a spectral line at 249.96 nm, so ChemCam can only confirm boron’s presence in samples that have low iron content, which are hard to come by on Mars. Iron oxide is basically everywhere.

But despite this difficulty, boron was detected. Why should I or anyone else care? Because it was detected in veins of sedimentary rock, meaning that at some point long ago when Mars still had lakes and rivers and oceans of liquid water, boron must have been mixed into that water (likely in the form of borate, a compound of boron and oxygen).

Again, why should anyone care? Because some of the fragile molecules necessary for life decompose in open water, but borate can help stabilize those molecules, allowing them to combine to form RNA. Boron itself is not incorporated into our modern DNA, but its presence here on Earth may have helped life get started—and if boron was present on Mars, mixed into ancient Martian waters, it could have helped life get started there too.

Could have. We still don’t know for sure, but as I’ve hinted previously I am planning a little trip to Mars aboard my imaginary spaceship. Stay tuned. I’ll be sure to let you know if I find anything.


Sciency Words: Tardigrade

August 4, 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:

TRADIGRADE

Tardigrades, a.k.a. water bears… there’s just something lovable about them. They’re kind of cute for microorganisms (or kind of horrifying, depending on which picture you’re looking at). And they’re absurdly tough. They can survive almost anything. They can even survive in space.

There have been several experiments now where tardigrades were taken to low Earth orbit and exposed to the vacuum of space for prolonged periods of time. Most of them survived the experience. In the absence of food, water, or oxygen, tardigrades can enter a state of suspended animation, and their cells have the ability to repair their D.N.A. if it gets damaged by solar or cosmic radiation.

In fact tardigrades seem to be so well adapted to the hazards of space that it’s sometimes suggested (usually not by serious scientists) that these little guys might come from space.

German pastor and zoologist Johann August Ephraim Goeze is credited with discovering tardigrades in 1773. Goeze called them Kleiner Wasserbär, which is German for “little water bear,” because the way they walk on their eight pudgy, little legs reminded Goeze of the plodding movements of bears.

In 1777, Italian biologist/Catholic priest Lozzaro Spallanzani made further observations of these creatures. Spallanzani called them il Tardigrado, meaning “slow walker,” again because of the slow, plodding manner in which they walk. The English words tardy and tardiness are closely related, etymologically speaking.

Today we’ve retained both tardigrade and water bear as common names for these creatures. Apparently some people also call them moss piglets, which is just adorable. Over a thousand species of tardigrade have been identified, all classified under the phylum Tardigrada.

As for the question about where tardigrades came from—are they native to this planet, or did they immigrate to Earth from someplace else?—I can only say this: if tardigrades do have an extraterrestrial origin, they must have arrived on Earth a very, very long time ago. The oldest known tardigrade fossils date back to over 500 million years ago (meaning they may have been here since the Cambrian explosion).