Science for SciFi: Astrobiology

Rubber-forehead aliens are basically a meme at this point. They make perfect sense in terms of production costs and limitations imposed by special effects technology at the time. The good news is that writing for print gives us far more options than would be possible otherwise. I think that they make it easier to relate to characters on screen but making all of your aliens look like humans with a few extra bits glued on requires a lot of worldbuilding to explain away. If you try to explain it that is.

The point of this post is not so much to provide an explanation of how life on other worlds could work but rather why it’s so hard to envision what life on other worlds could be like. This is because a) I am not a biochemist and b) it’s somewhat difficult to pin down just what “life” is. Once you’ve wrapped your head around this second idea and thought about some of the strange chemistries that are possible on alien worlds you will feel much freer to imagine strange new forms of life.

At this point, you are probably getting ready to type an angry comment or tweet along the lines of “WHAT DOES HE MEAN? OF COURSE WE KNOW WHAT LIFE IS. I’M ALIVE AREN’T I?” It’s actually a lot more complicated than that. Here on Earth we still have trouble deciding whether viruses are alive. Sure they can infect hosts and they use the same DNA/RNA coding that we and the rest of life here on Earth do, but they lack the machinery needed to make copies of themselves so they have to hijack ours. NASA has a definition of life that they use in the search for extraterrestrials and it’s probably the best one available to us, but there are still likely to be some who disagree with the definition.

“Life is a self-sustaining chemical system capable of darwinian evolution” – NASA

I’d be interested to hear whether readers think that viruses are included in this definition or not.

The reason that the definition of life is so hard to pin down is that we only have our own world to serve as a reference. In our solar system of eight planets and who knows how many planetoids and moons only one body, Earth, is known to support life. Yet there are two other planets, Mars and Venus, that might have once supported life and several moons that could even harbor life this very moment (I’m looking at you Europa).

We can look around at our own planet and describe how life works here. We can explain how DNA works, how organisms obtain energy, and how one organism gradually evolves into another over time. We know all that but we still do not know how life began on this planet. Without knowing how life began it is hard to definitely say whether a planet could support life or not. We tend to get excited when we find planets around other stars that could support conditions similar to those here on Earth, but when we talk about whether a planet is in a star’s “Goldilocks Zone” what we are really saying is that the planet could support life that is like us, and that’s a little arrogant I think.

Fortunately, our knowledge of chemistry and physics allows us to envision other ways in which life might arise. We are, after all, just bags of chemical reactions that happened to develop egos.

Excuse Me, Is This Life Organic?

These days a lot of people think that if something is organic it was produced from “natural” materials or grown without the use of certain fertilizers or pesticides. What they don’t realize is that oil is both organic and naturally occurring, but you wouldn’t want to eat it. When scientists say something is organic all that means is that it is composed of primarily carbon and hydrogen along with a smaller proportion of other elements.1

We and all the living organisms that we know of here on Earth are built out of carbon. Our DNA, our proteins, our hormones, our cell walls. Every bit of biochemical machinery that makes us is built on a scaffolding of carbon. Organic compounds are so prevalent in living things that the distinction between organic vs inorganic chemicals was originally based on whether they had come from a living thing or not.

Carbon is useful in all these ways because each carbon atom can form up to four bonds with other atoms. Carbon can form long chains with other carbon atoms and can also form double and triple bonds not only with itself but with other elements important to Earth life including both oxygen and nitrogen. Silicon is often suggested as a possible substitute for carbon on alien worlds, but silicon is less versatile than carbon and many of its compounds are unstable. This combined with the prevalence of carbon among molecules found in space does not bode well for silicon’s chances. There is however the clay hypothesis that has to do with the beginning of life on Earth.

Another point in carbon’s favor is that by now many complex organic molecules have been detected in space in molecular clouds around stars and on the surfaces of comets. Many of them being the same molecules used by living things here on Earth. With ready-made materials out there in the cosmos, why not take advantage of them?2

Water? I Hardly Know Her

Water is a really great solvent for life on our planet. Besides being everywhere and thus the most logical choice for life solvents, its properties allow both acid and base chemistry to take place. When we begin to consider different temperatures, pressures, and chemical makeup, a number of other solvent options become clear.

All it takes is a solvent that allowed for acid-base chemistry to take place. Water allows this, but there are other solvents that could, under different conditions, or with different commonalities. Waters is ubiquitous on Earth, but it doesn’t have to be on other planets.

Take a look at different solvents. Or familiar gases that would be liquid at other temperatures. The possibilities might surprise you.

Eating Sunshine (And Other Things)

Here on Earth, most ecosystems arise from the energy provided by the Sun. Just about everything either harvests light through photosynthesis or eats something that does. But even on Earth, we know that this is not the only option. In the deepest parts of our oceans, we have found extremophiles that feed off the heat and chemicals released by volcanic vents.

That is just on Earth. There are many sources of energy in the universe including gravity and magnetic fields. Alien life forms could catalyze the synthesis of vital metabolites using alpha and beta particles released by radioactive minerals to catalyze reactions or construct molecular machines on their cell membranes that harvest hydroelectric power.

The Galactic Habitable Zone

It’s weird to think that there might possibly be a shortage of resources on a galactic scale but once you get an idea of how elements are made it begins to make sense.

Basically, there is a band with indeterminate boundaries somewhere between the center of the galaxy and the edge that makes up the galactic habitable zone, a region that is determined by metallicity, the age of the stars, and how often stars in the area go supernova.

The center of the galaxy with its high concentration of stars is considered unsuitable for life, as the frequent supernovae release bursts of radiation that would sterilize nearby worlds and make the development of life difficult, if not impossible. Meanwhile, the edge of the galaxy is full of younger stars that have not had time to transmute the heavier elements that life needs.

All this results in an uncertain band looping around the galaxy where planets are more likely to be habitable. The boundaries of this band are uncertain, but

Turning The Weirdness Dial Up to Eleven

A lot of us tend to base alien species on the species we are familiar with here on Earth. A quick look at some extinct species will show that there are many, many variations on how weird life can get just on a single planet. Just because it didn’t happen HERE doesn’t mean it can’t happen SOMEWHERE.

In all honesty, it just depends on how strictly you want to adhere to known science. You could have aliens with bones like ours with gelatinous flesh or stationary mollusks that spend their days exploring complex algorithms in their minds.

Hard science fiction is all about finding plausible explanations based on what we know now. That doesn’t mean it can’t be weird.

Conclusion

If anything should be clear by now it’s that nothing is. The Milky Way is a big place and we can envision so many possibilities that it is just about impossible to anticipate all the possible variations of life. In fact, I came across so much information while reading this post that I wasn’t able to include it all in this one post. So stay tuned for future posts on the origins of life, panspermia, and whatever else catches my eye in the process.

Notes

  1. Unfortunately for myself and other inorganic chemists. Our field is literally defined as “not organic” which makes it more than a little hard for someone to guess what we do.
  2. I’ve come across a wealth of information on this topic and it’s all incredibly facinating. Enough so that I’ll probably have future posts on both on possible origins of life and on the wonderful hydrocarbons that have been found out there in the universe.

Sources

Some of these resources may be behind a paywall. Consult your friendly neighborhood librarian for help. Or in the case of research papers, it never hurts to email the author, they may just send you a copy!

Astrobiology: The Study Of The Living Universe by Christopher F. Chyba and Kevin P. Hand. Annu. Rev. Astron. Astrophys. 2005

Astrochemistry: From Astronomy to Astrobiology by Andrew M. Shaw

Beloved Wikipedia.

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A Spacers Life (For Me)

Spacers are, in a way, a nation unto themselves. Even with a Bulgarin Drive, journeys between stars take months at best. Away from the rare corridors where local gravity fields align just right they take years.

All this time the spacers are traveling at the speed of light, or faster, within their Bulgarin bubbles. Time passes differently for them, thanks to relativity they age much slower than their planet-bound fellows, and the worlds they return to are often very different from the worlds they left.

These differences have led to spacers developing cultures of their own. Few ever really return home, most sign-on expecting their journey to be a one-way trip, a way of paying their passage to a new world. Others make the conscious decision to leave the society they have known and live the rest of their now extended lives on ships travelling between the stars.

Faced with these long stretches of time, many choose the comfort of a stasis pod when possible, but not every ship has enough space, and at least a few crew members need to be awake at any given time. With all these long periods spent alone, away from companionship and any likelihood of rescue, spacers have learned how to take care of themselves and keep themselves entertained in the vastness of space.

Reading Material

The average ship has thousands of micro floppies loaded with everything from textbooks to the latest smut. Even private ships regularly take on new media at every time they stop. Bulgarin transmitters can only send some much information in a single burst. Spacers get to read the latest from each world they visit, long before the locals at their next destination have ever heard it.

But paper books are expensive. Most media is transmitted of micro floppys or other digital storage media. Spacers (and most locals) choose to use digital books instead, which project the words onto a sheet of transparent plastic.

These devices are surprisingly sophisticated, with buttons that allow the reader to move forward and backward in the book, and to set a limited number of bookmarks.

Spacers are known for their voracious information appetite. Most ships make it a priority to procure more material for their library at every port of call. In this way even privately owned ships serve to keep the disparate segments of humanity connected culturally.

Technical Tools

Space is huge and filled with tech, tech that tends to break from time to time. Portable interface terminals like this one are a spacer’s best friend.

Terminals are small and handheld, able to be clipped onto a belt or other piece of clothing. Each terminal is able to connect to a wide array of machines including satelites, life support systems, reactors, and more through a standard connector. Once plugged in the terminal displays a set of standard metrics like CPU usage, temperature, and error codes. The menu, which can be navigated by the arrow buttons in the bottom left, allow the user to to do a variety of things internally.

These hand terminals even give the user the ability to type custom commands or lines of code, although this is not the most user friendly option. Larger portal terminals with dedicated keyboards and graphic user interfaces are generally preferred for those more complex tasks.

Explorer’s Kit

All ships, no matter what their purpose, carry basic scientific equipment on board including Ultraviolet/Visual Light spectroscopes, mass spectrometers, and nuclear magnetic resonance instruments. Even if it it not their purpose, any ship might encounter unknown environments that they need to evaluate to determine their safety.

A basic spacer’s sample collection kit.

For things that cannot be easily carried back into orbit, spacers often bring handheld units able records local conditions. These units come equipped with a myriad of basic sensors and can be connected to various attachments such as voltage probes. Data collected with these hand-held sensors can be stored and timestamped on microfloppies

A basic handheld sensor package.

For Safety’s Sake

Radiation from distant stars, nuclear weapons, and leaky reactors are a constant danger. Most ships require their crew to wear radiation badges at all times. The badges are painted with specialized chemicals that cycle through colors as the amount of radiation increases. These colors provide a handy guide for spacers trying to quickly assess the safety of their surroundings using a handy guide.

Green = Good

Yellow=Be Careful

Red = Get Out

Black = You’re probably dead already.

The presence of breathable air is also of importance to all spacers. In response to this danger most spacers also carry small atmospheric field tests. The rods inside are chemically treated to change color in the presence of various gases.

NATO Forces in the Independence System

Awhile back I posted about a system named Independence, a part of my retro-scifi setting Red Suns. Independence is important because one of it’s planets, Franklin, is capable of supporting human life.

Because planets like this are so rare, the system is coveted by many factions, several of which maintain outposts in the system and two; NATO and the Neo-SOVIET have agreed to share Franklin. The relations between these two factions are often tense and both sides have dedicated considerable resources to securing their interests in the system.

This is the first of several posts where I provide an overview of the ships, people, and places of the Independence System. Beginning with an overview of NATO military assets in the system.

Ship Weapons

Rotating rings are great for providing consistent gravity but are incredibly vulnerable in combat. For this reason most frontline combat ships are built without rings. “Gravity” is provide by constant acceleration and crew have to deal with frequent shifts in acceleration and orientation.

NATO ship design hides most weapons emplacements inside armored bulbs. Everything from anti-missile counter measures to missile chutes are enclosed in armored bulbs that only open during combat.

These autocannons, suitable only for close-range combat or intercepting missiles, are a vital part of every ship’s defenses. Most combat however, is done with missiles at extreme ranges.

These missiles can carry a variety of payloads good for everything from orbital bombardment to anti-ship slog fests. The one pictured here is a generic load, but NATO armorers are more than capable of switching warheads out at a moment’s notice.

Missiles

Siegfried Class Battleship

The newest, most advanced ship in the NATO fleet, and only a handful are currently available. It takes over a decade to finalize the design of a new battleship, and years more before new ships are fully distributed in all the systems where NATO has interests. The Independence system has an unusually high concentration of these new battleships. Equipped with new, rapid launch missile silos and state-of-the-art target tracking. A Siegfried can make short work of most ships.

Siegfrieds carry close to 2000 personnel, including enough dropships and marines to take over a small surface settlement or large space station. Each ship is a self-contained city. NATO spacers compete fiercely for a posting on a Siegfried because they know that they will spend years, or even decades on that ship and a Siegfried is one of the safest, most comfortable ships to be on in any fleet.

Challenger Class Battleship

There are a bit smaller than the Siegfrieds. Let’s say a crew of about 1000.

Somewhat older than the Siegfrieds but by no means out dated. The armament on modern retrofitted Challengers is similar in almost all ways to a new Siegfried. The main differences in armament come from a less sophisticated guidance computer and a set of four drive cannons mounted at the top of the ship.

These drive cannons fire huge projectiles at enemy ships and moons in medium-range confrontations. These cannons require a dedicated reactor and are placed away from the main hull to increase their field of fire. At the time of the ship’s design it was thought that these cannons would be a part of the ship’s primary armament. Technology had other plans. As guidance computers and targeting systems advanced it became more and more practical to engage enemies at extreme range. Despite this, the Challengers remain competent warships.

Recently, several of the Challengers in the Independence system have been given further refits that have improved their guidance computers. Engineers expect to see a far greater degree of accuracy from the drive cannons as a result. This has not yet been tested in combat conditions.

Marshal Class Destroyer

This is the smallest warship that NATO is likely to assign to long-term missions. Marshal Class Destroyers are often seen far away from NATO systems.

In locales such as the Independence System the Marshal Clase Destroyers are commonplace due to the buildup of forces. They are frequently seen escorting larger ships or leading customs patrols.

Marshal Class Destroyers carry enough firepower to hold their own in a fight and carry multiple Pioneer Class Dropships. Enough to perform small boarding actions and land marines on a surface.

Multi-Vector Attack Unit (MVAU)

Outside of atmosphere fighters are uncommon. The smallest combat craft operated by NATO is the MVAU, a broad class of small vessels crewed by between two and five crew.

MVAUs are an important part of the larger fleet, but their pilots must be carefully selected, as their positions require them to spend many weeks or even months alone.

MVAUs are mainly valued for their ability to go relatively unnoticed. Their small profile makes them difficult to distinguish from the vastness of space and they often go for long periods in a “dormant” state.

In combat MVAUs are limited. Their main armament consists of projectile weapons, useful for intercepting missiles or attacking unsuspecting targets. An MVAU may carry one or two missiles but for the most part are considered the outermost part of a fleet’s defensive screen.

Pioneer Class Dropship

Large shuttles that glide to a safe landing are preferred for ground operations. But not all planets have suitable atmospheres or are safe for shuttles with such drawn out atmospheric trajectories.

Dropships can carry many tons of supplies, or about forty marines, on a meteoric trajectory towards a planets surface. It’s fall is only arrested at the last moment by a set of powerful maneuvering thrusters.

Ground Forces

Forces stationed on Franklin’s surface have the luxury of not needing to carry bulky life support systems and armored exoskeletons. But they do have to content with the possibility of protracted surface combat.

Because Franklin is capable of naturally supporting human life the surface is worth preserving to both sides. This means that large scale bombardments are unlikely and the soldiers stationed there will have to endure a protracted ground campaign if war breaks out.

NATO soldiers on Franklin are equipped with a stripped down version of more standard armor kits painted in shades of white and grey to blend in with the chalky off-white gravel and stone that covers the planet. For the harsh, dry winters a mask with breathing filters also suitable for protection against chemical warfare agents is supplied to each soldier and worn as needed. These masks offer protection from the massive storms that sweep across the surface each winter and pummel victims with showers of dust, gravel, and ice. Also useful in the winter is a bundle of heating circuits incorporated into the uniform that when activated can help to keep a soldier’s core temperatures up.

Most soldiers carry the same service rifle used on other planets and in vacuum. These rifles are deadly, but are mostly small caliber weapons designed to allow soldiers to carry enough ammunition as possible.

For support, ground troops have access to a selection of armored vehicles, all built in local factories. Most of these vehicles are hover craft or have extremely wide treads into order to navigate the mud slurries that cover much of the surface during the wet season.