Is There Really No Planet B?
It’s a popular theme in science fiction: the quest for a new Earth, because the old one is becoming uninhabitable, usually due to human interventions. Sometimes the idea is elaborated in a somewhat ironic manner, like in the unsurpassed Dutch series Missie Aarde (Mission Earth), in which the Netherlands take the lead because it’s the only country not under water thanks to its dykes. Sometimes it’s dead serious, as in the movie Interstellar, in which drought, dust storms and crop failures make the need for a new world urgent.
When you realize how much effort it takes to get a few astronauts into orbit, you wonder how one could get billions of people to another planet. But an even more important question is: what are the chances of finding such a spare world somewhere?
The average environmentalist has little faith in it; at every climate march, signs are carried with variations on the phrase There is no Planet B. The Dutch Party for the Animals has even made it its campaign slogan: Plan B – because there is no planet B. But is that really the truth? Can’t we really go anywhere if it gets too hot under our feet here on Earth? Let’s explore the possibilities.
Around the sun
We first look around in our own cosmic neighborhood: the solar system. Of the seven planets that, like Earth, orbit the Sun, Mars is by far the most hospitable. Elon Musk has good reasons to want to go there. On Mars you have solid ground under your feet, unlike on the gas giants Jupiter, Saturn, Uranus and Neptune. You are not roasted alive like on the sunny side of Mercury. And you don’t get squashed like in the ridiculously dense atmosphere of Venus.
But the comfort of Mars is relative. Occasionally the temperature rises above zero, but usually it is much colder, down to -140 C. The atmosphere is very thin and, moreover, unsuitable for human lungs. Not to mention the dust storms and cosmic radiation.
There are beautiful desert landscapes on Mars with spectacular volcanoes, craters and gorges. But we will only be able to see that beauty through the visor of a space helmet or the windshield of an all-terrain vehicle.
Is there nothing that can be done about those flaws of Mars? Yes, which brings us to another common theme in science fiction. Terraforming, modifying a planet to allow terrestrial life to thrive.
We are currently proving that terraforming is possible. Raising the temperature on Earth a few degrees in a few centuries is quite an achievement, especially when you consider that it happens by accident. We don’t even do our best; it simply happens as a side effect of our activities.
Such a thing is, of course, also possible on Mars. Requirements: a good amount of greenhouse gases, a lot of patience and maybe some water and nitrogen to be imported from elsewhere. The result: a higher temperature and a denser atmosphere, suitable for plants and ultimately for humans and other animals.
Don’t expect tropical jungles, because Mars is a lot further from the Sun than Earth. But a mixture of Iceland and Tibet with a touch of Cornwall, that should be feasible. Sounds like a great place to go hiking .
However, it is a very long-term project, with a lot of uncertainties. Before you have transformed Mars into a dependency of the Earth, a few centuries, or millennia, have passed.
And even if you could terraform Mars at the touch of a button (Arnold Schwarzenegger does something like that in Total Recall), there’s another inconvenient truth: Mars is a lot smaller than our home planet. It still has a lot of square kilometres, but if we move all we have to Mars, things become a bit cramped.
Venus, that other close neighbor, is a lot bigger; almost as big as the Earth, in fact. But terraforming Venus, with its surface temperature of 462°C and its showers of sulfuric acid, is even more complicated and time-consuming than modifying Mars.
If you’re optimistic (which I like to be), there are a few more terraforming candidates in our Solar System. For example, Jupiter’s moons Ganymede and Callisto or Saturn’s moon Titan and maybe even our own Moon. But those are all, like Mars, tiny worlds. They are more likely to become exotic holiday destinations than second Earths. And we are talking about dreams for the very, very distant future.
In other words, the Animals are right, there is no planet B in our Solar System, at least not now and not in the next few centuries.
And if we look further away, to planets orbiting other stars? After all, there are many more of them than eight. Since 1991, nearly 4,500 so-called exoplanets have been discovered. And that’s just the tip of a very large iceberg. Since many, if not all stars seem to have some kind of planetary system, the number of planets in our Milky Way alone runs into the many hundreds of billions.
The vast majority of these are probably too big, too small, too hot, too cold, too light or too heavy. Or they get a constant bombardment of deadly radiation from their star. Or they lack a decent amount of water. Or they have an atmosphere in which we, atmospheric connoisseurs that we are, cannot breathe.
But it’s quite conceivable that among all those billions of planets there are a few where you can step out of your spaceship in casual clothing. Where clear mountain streams flow, where a gentle breeze brings sweet scents and where exotic but harmless life forms produce soothing sounds.
Speed of light
The only question is: how do you reach such a paradise? Because the distances within our solar system can drive you insane, but beyond it they become really unimaginable. And almost unbridgeable. Even light takes four years to reach the nearest star. And our very fastest spaceships travel ten thousand times slower than light.
Someday faster ships will be invented. But the speed of light looks like a hard limit. Don’t count on a warp drive that will make the Milky Way something as travelable as the Greek islands.
In other words, also here there’s only one conclusion possible. There is no planet B to go to.
Whatever it takes
So there’s no time to lose. Let’s start planting trees, greening our cities, traveling smarter, building better, generate sustainable energy, develop vegan chicken bones. Anything that can help keep planet A beautiful. Whatever it takes. So that our proverbial grandchildren can also enjoy it, a hundred years from now.
So should we ignore the rest of the universe? Should we solve all the problems on Earth before we send humans or robots to Mars? No, that’s like solving all the problems in the Netherlands before we go to Belgium.
If you are repairing your house, it is good to take a walk around the neighborhood every now and then. For the adventure, for the challenge and for the science.
On Mars, we can find out how unique Earth’s life really is. On Venus, we can learn what it looks like when global warming really gets out of hand. On the moons of Jupiter we will encounter something we cannot yet imagine. And if terraforming really takes that long, we shouldn’t wait too long to get started.
The bottom line is: there are many things to discover in the cosmos. But a ready-made new world to move to will not be one of them.