Finding a Twin Earth

Part One

In this blog and the next, I’m going to discuss the process of finding a twin Earth. What are the chances of finding a twin Earth? How are humans going to power the ships that escape to other planets? How fast will they go? How long will it take to get there?

As we learned in Prometheus Blue, the Earth is doomed to the fate of a rogue star and as I have proven, there’s no way to stop it. Our only option is to get out of Dodge. We’ve got to go about finding a twin Earth and evacuate our poor planet well before the end comes in 2713.

I’ve gone into a fair amount of detail below and in the next blog entry, Odds of Finding a Twin Earth – Part Two. There are a score of factors that could be wildly wrong, but I estimate that our chances of finding a twin Earth, suitable for thriving human life and within our “local space” of 100 light-years is about one in 2.4 million.

Follow me on this epic journey of twisted logic.

In an earlier blog post, I listed out a few of the challenges associated with getting off planet and finding a twin Earth among the stars. Here’s where I keep a running tab on those challenges and our discussions:

Finding, Getting To and Living On a New Earth

• The ExoPlanet Search – How are we going about finding a twin Earth;
• Finding a Twin Earth – What’s the likelihood that we will find a planet that humans can actually thrive on, as NASA and many other organizations go about the search?
• Drive Technology – Developing transport technology to get there, including fuel type;
• Testing and Simulation – How to best prove out our theories? Start with Mars;
• Sustainability – Carrying and manufacturing enough food, water, air and fuel for the journey. Surviving cosmic radiation;
• Ship Design – What is the best design for long term travel? How to survive micro-collisions?
• Funding – Who is going to pay for it?
• Getting Around – Traveling around the local system when we get there – the fuel, engine type we used for long distance travel may not be suitable for in-system maneuvering;
• What if we’re wrong? Confirming we have the right place (when we get there). Can we detect all critical factors from Earth?
• Establishing a Home. Building a sustainable life once we get there – grow food, build shelter, manufacturing, technology, 3D printing, etc.;
• Who Goes and How Many? Considering skills, age, health, propagation and the gene pool. Attrition during voyage and after we get there.
• Back home – Closer to impact date, implementation of birth controls, long term managed selection process.

This blog will explore all of these issues and more over the coming weeks and months.

In an early post — The Exoplanet Search — we discussed the methods that NASA is using to find other planets. It’s all wrapped up in their Exoplanet Search. There we examined the many methods of search and how successful each method has been – so far.

Conditions for a Thriving Human Colony

Today we’ll discuss the actual conditions that we are searching for in a new home, along with an attempt at putting a probability of finding a twin Earth. This isn’t going to be easy because our search criteria are going to be tough: we want to find a planet like ours where humans can thrive and enjoy in the open, breathable air, drink the water, be safe from predatory monsters and organisms, grow food, not be roasted to death by cosmic radiation, etc. Scientists call this, the “Goldilocks Zone”.

Sure we could live on the moon, or on Mars, but for this search, we want to find something that could truly be a second home without having to resort to artificial means to keep us alive.

There are so many factors involved here. Let’s take a look at a few of the big ones that have to be correct to hit the Goldilocks Zone:

1. Temperature Profile (TP). This is so important. Sure, on Earth we often have to wear warm clothing, or maybe it’s just too hot out there, but we want a temperate client that we can run naked through the grass if we want – at least for part of the year. Think about our nearest neighbors: Venus 462C. Mars -80C. Meanwhile, Earth’s average temperature is 15 deg C.;
2. Liquid Water (LW). Because it’s so much a part of us. It’s been proven that the presence of liquid water multiplies the chances for life many fold;
3. Lack of Predators (LP) that will destroy us. Let’s say we find the perfect world where everything is in balance. But

–          It’s full of raptors and Gigantisaurus Rexes. I guess we could kill or capture them all but is that really what we should be doing?

–          Or worse, the world is infested with trillions of poisonous insects, or hordes of fist sized attack spiders that make life miserable;

–          Or maybe even worse, the world is rife with microscopic alien viruses that attack human life like ebola and we have no cure.

4. Planetary Stability (PS) – so we’ll not be overcome with earthquakes and tidal waves;
5. Solar Stability (SS) – Our central star must be calm and stable, without continually bathing our planet in life-killing radiation and flares;
6. Single Star System (SSS) – There’s a lot of debate out there about what percentage of the stars in our galaxy are actually binary stars, i.e. two stars that orbit each other closely. I’ve seen estimates as high as 85%. The potential problem with occupying a planet with a binary star system is that the orbital path may be quite wonky, subjecting the planet to pulls from complexly changing directions, resulting in earthquakes, rip tides and other instability;
7. Ozone Layer (OZ) – Space, especially space near a star (like our Sun) is filled with ultra-violet radiation, which if in high enough concentrations, destroys bacterial life, causes skin cancer and pre-mature aging. Our ozone layer filters out much of the UV radiation. Without it, that SPF50 sunscreen wouldn’t be close to enough to protect you from harmful rays. Some scientists speculate that the presence of an ozone layer on a planet is very rare;
8. Magnetosphere (MS) – Earth is blessed with an iron-rich core with flowing magma which turns our planet into a gigantic magnet. The Sun emits powerful solar winds – charged particles of electrons and protons – which if left unchecked would strip away our ozone layer and leave us unprotected from UV radiation. However the magnetosphere interacts with the solar wind and dissipates much of it. Many scientists believe that Mars, which does not have a magnetosphere, lost much of its atmosphere in the exact mechanism.
9. Our Moon (MN) – Our satellite gives us many benefits. Many scientists believe that without a moon, our day would be 4 hours, not 24. The moon gives us tides that create tidal pools that spawn life and recycle our water continuously. The moon also helps to stabilize our 23 degree tilt to the Sun and this gives us our seasons. So while not absolutely vital to survival, the moon definitely contributes to our quality of life and may have aided its creation;
10. Gravity Range (GR) – It’s hard to imagine Earthly colonists surviving well on a planet with 3 times the Earth’s gravity. Most of the planets found to date in the Exoplanet search have been very large, massive, high gravity planets. This is intuitive because those are the planets we would detect most easily. So we have to find a planet that is similar in gravity range to Earth – say 0.5 to 2.0 at the top end;
11. Diversity of Life and Food Chain (DIV) – If we are to maintain a self-sustaining existence, we have to be able to live off the land. Either a plant based diet, or a combination of meat and plants is vital to a thriving community. We can’t live for millennia on pre-manufactured food; we have to be able to grow it on our new home planet. Clearly most planets will not have the soil / water / chemical compositions to grow food suitable for human consumption and growth;
12. Jupiter and Saturn (JS) – Think of these planets as the solar system’s vacuum cleaners. Their immense gravities pull in tremendous amounts of space junk daily, from small particles to huge mountain sized asteroids and comets. Without this protection of our outer layer, many, many more planet killing impact events would have wiped out life many times over on Earth. How many other planets have this big brother and sister guarding them from wandering interplanetary interlopers?

So that’s 12 major categories of factors. Each and every one of them has to be in that narrow zone that supports human life. When you look at them all together, you get a sense of how rare and precious our planet truly is. There is a multitude of variations to many of these factors – chemical composition for example – which lead us to believe that the number of sub-factors is in the thousands.

So what are the odds of finding so rare a combination of such diverse factors?

That’s in Part Two, coming soon.

Follow me