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:

REGOLITH

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!


Sciency Words: Telerobotics

November 10, 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:

TELEROBOTICS

This is a pretty easy one, I think. Telerobotics refers to controlling robots from a distance, usually a great distance. This is in contrast to robots that function autonomously or machines that require direct human control.

The word comes from the familiar Greek root tele-, meaning “far away,” and of course the word robot, which originally comes from Czech and means something like “forced labor.”

A wide variety of fields use telerobotics, but for the purposes of this blog we’re most interested in its use in space exploration. At this point most if not all spacecraft are telerobotic in nature. They receive instructions from mission control on Earth, carry out their instructions, and then transmit their status back to Earth so that mission control can decide what to make the spacecraft or space vehicle do next.

The problem, of course, is that this back and forth communication is restricted by the speed of light. In the case of the Mars rovers, this means that even performing the simplest tasks can take hours and hours. It’s very frustrating, especially for the rovers.

This is one of the biggest reasons Buzz Aldrin and others say we should send astronauts to Phobos (one of Mars’s moons) before sending anyone to Mars itself. From a small Phobos base, astronauts could telerobotically control the rovers in real time. The speed-of-light delay would be negligible.

The rovers could cover a lot more ground that way, dramatically speeding up our exploration of Mars. Also, when the time comes, the rovers could be used to quickly prepare a landing site and assemble habitat structures in advance of the first human colonists arriving on Mars.


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.


Sciency Words: Delta-v

October 27, 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:

DELTA-V

Okay, it might be a bit foolhardy of me to try to tackle this term. This is actual rocket science, and I’m nowhere close to being an actual rocket scientist. But this is still far too important of a concept for me to ignore, so I’ll do my best.

The simplest definition of delta-v (often represented mathematically as ∆v) is that it equals your total change in velocity. So if you’re driving along at 25 miles per hour and then accelerate to 65 mph, your delta-v equals 40 mph. And if you decelerate from 65 to 25 mph, your delta-v once again equals 40 mph.

Things start getting interesting when you consider delta-v to be cumulative. So if you start off at 25 mph, accelerate to 65 and then drop back down to 25, your total delta-v equals 80 mph (40 mph + 40 mph).

In rocket ship design, the term delta-v is used as a sort of proxy for how much thrust your engines are capable of and how much fuel you’re carrying. You might also consider the kinds of gravity assists or aerobraking maneuvers you can use to augment your delta-v without expending additional fuel.

This is where the math starts to get complicated, but if you can calculate how much delta-v your spacecraft is capable of, then you’ll know where you can go in space. And if you know where you want to go in space, you can figure out how much delta-v it’ll take to get there and build your spaceship accordingly.

I first learned about delta-v from a video game called Kerbal Space Program. It’s a fun and sometimes frustrating spaceflight simulator that does a reasonably good job approximating how real life space exploration works. Unfortunately I was never very good at it. The scenario in the comic strip above… I made that mistake a lot.

But hopefully I’ve learned my lesson well. I’d hate to run short of fuel during my upcoming totally-for-real, I’m-not-making-this-up trip to Mars (stay tuned!).

Links

The Tyranny of the Rocket Equation from NASA.

Can Kerbal Space Program Really Teach Rocket Science? from Scott Manley (well known for his YouTube tutorials on K.S.P.)

How to Use Kerbal Space Program to Teach Rocket Science from Digital Media Academy.

Six Words You Never Say at NASA from xkcd.


Sciency Words: Aldrin Cycler

October 20, 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:

ALDRIN CYCLER

The term cycler can refer to two different but related things in orbital mechanics: an orbital trajectory that continuously and perpetually cycles between two planets, or a spaceship that’s been set on such a continuously, perpetually cycling trajectory.

The mastermind behind this idea is none other than the famous Buzz Aldrin, astronaut extraordinaire. Turns out Dr. Aldrin is more than just a pretty face. In 1985, Aldrin proposed using cyclers to transport equipment and personnel to and from the planet Mars. After crunching the numbers, physicists at NASA’s Jet Propulsion Laboratory confirmed that Aldrin’s idea would work.

The cycler trajectory Aldrin proposed is now known at the Aldrin Cycler. Aldrin’s plan would actually use two spaceships, one for outbound journeys to Mars and another for inbound trips returning to Earth.

According to Aldrin’s book, Mission to Mars: My Vision for Space Exploration, the outbound cycler ship would take roughly six months to reach Mars from Earth; the inbound ship would take about the same amount of time to reach Earth from Mars. Both ships would then spend the next twenty months looping around the Sun to catch up with their home planets and start the cycle again.

Presumably the ships would only carry human passengers during the shorter six-month legs of their respective journeys. The rest of the time, they could just fly on autopilot or remote control.

If the Aldrin Cycler proposal or something similar were implemented, traveling to and from Mars would be sort of like catching a train, with boarding taking place regularly every twenty-six months. I’ve even found a video showing what these cyclers might look like.

Okay, that’s actually an anime that I liked when I was a kid. We don’t have to make cycler ships look like trains (though we totally should).

The major drawback with the cyclers is that the upfront cost of building them will be enormous; however, if we’re serious about establishing and maintaining a permanent human presence on Mars, these cyclers would easily pay for themselves in the long run. The laws of orbital mechanics keep them going, so they’d require little to no fuel.

And since a cycler could keep cycling for decades or centuries or even millennia (in theory, they could go on forever, or at least until the day the Sun explodes), we Earthlings would always have guaranteed access to Mars, and our Mars colonists would always have a guaranteed means of getting home if they needed it.


Sciency Words: Island of Stability

October 13, 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:

ISLAND OF STABILITY

According to Star Trek: Voyager, in the 24th Century there will be 246 elements on the periodic table. In one episode, the Voyager crew discovers element 247, and to their astonishment that element is stable.

Here in the 21st Century, on modern day Earth, there are only 91 naturally occurring elements. Element 43, technetium, and everything above element 92, uranium, have to be produced artificially. And these artificial elements are all unstable. Some of them, especially the really, really high numbered ones, are so unstable that they’re effectively useless.

When an atomic nucleus gets too big, the so-called strong nuclear force is no longer strong enough to hold the whole thing together. You can also run into problems if you don’t have a comfortable balance of protons and neutrons. At that point, when atoms are too big or improperly balanced, they start shedding nuclear particles until they can stabilize themselves. This process is called radioactive decay.

If you want, you can draw a chart with the number of protons in an atom along one axis and the number of neutrons along the other. But charts are boring, so let’s draw a map instead.

Physicist Glenn Seaborg (for whom element 106, seaborgium, is named) was apparently a big fan of maps. I imagine he and J.R.R. Tolkein would have gotten along well. In the 1960’s, Seaborg started referring to groups of atomic isotopes by “geographical” names, and these names have stuck.

On the map above, the landmass stretching up from the bottom left corner represents all the stable and semi-stable isotopes. This “Peninsula of Stability” is surrounded by a “Sea of Instability.” But somewhere out in that sea, according to Seaborg and others, certain very large atoms might theoretically become stable. These atoms would have just the right balance of protons and neutrons to hold themselves together despite their extreme size. These “magically” stable isotopes are represented by the Island of Stability.

Physicists have been trying to find the Island of Stability for decades now, but it seems to be perpetually just over the horizon. It was once predicted that elements 110 and 114 might be stable. They’re not. I remember reading that element 118 might turn out to be stable. It didn’t. Now there’s a prediction about element 120. We’ll have to wait and see about that one.

Also there’s a possibility that we’ve been skirting along the island’s coast, so to speak. Maybe if we just add a few more neutrons to some of the unstable elements we’ve already found, they’ll stabilize. Maybe. More on that in next week’s Molecular Monday post.

Personally, I think Star Trek: Voyager was on to something. My prediction is that the Island of Stability will be found all the way out at element 247, and I recommend the IUPAC name it Janewayium.


Sciency Words: Brainjacking

October 6, 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:

BRAINJACKING

This is the kind of word you’d expect to find in one of those young adult Sci-Fi dystopia novels. Instead, I first encountered the term in a recent issue of Scientific American.

The word brainjacking is formed by analogy with hijacking. One possible definition involves a parasitic organism taking control of a host’s brain, perhaps altering the host’s brain chemistry in some way. A well known example is the zombie ant phenomenon, which is caused by a parasitic fungus.

But Scientific American was actually talking about humans, not ants—humans with medical implants in their brains, implants which may be vulnerable to hacking. Deep brain stimulation (D.B.S.) systems are sort of like pacemakers for the brain, and they’ve proven to be effective at controlling the symptoms of neurological disorders like Parkinson’s.

According to the abstract for this paper from World Neurosurgery, electronic brainjacking could come in two forms:

  • Blind attacks, which require no patient specific knowledge. Hackers could incapacitate or kill patients, or they could steal data from D.B.S. devices.
  • Targeted attacks, which do require some knowledge about the patient and how, specifically, the D.B.S. system is being used. Hackers could attempt to induce pain, control motor functions, enhance or repress emotions, or manipulate the brain’s rewards system.

Apparently these D.B.S. devices do not have a lot of security features built in, and what’s more they’re deliberately designed to be accessed and programmed wirelessly. That might at first seem like a serious design flaw, but it’s actually a necessary feature. In case of an emergency, E.M.S. personnel may need quick and easy access to your device.

Based on what I’ve read about brainjacking, there are zero documented cases of hackers actually attempting to do this… yet. But it’s clearly something both neuroscientists and cyber-security experts are worrying about.

And if there ever is a future where brain implants become ubiquitous, for both medical and non-medical purposes, then brainjacking may be a word everyone needs to know.