The discovery of seven Earth-like planets orbiting a nearby star has really gotten everyone thinking about space colonization again. Found by NASA's orbiting Spitzer Space Telescope and the ground-based TRAPPIST Telescope, there seems to be at least seven Earth-sized planets orbiting the star TRAPPIST-1.
The biggest surprise is that three or four of these planets are in the Goldilocks Zone - not too far from the star, not too close, not too big for a planet, not too small – a sweet spot where liquid water is stable on the right-sized planet with an atmosphere on which life could develop or survive if transplanted.
All these planets are similar to several planets in our own Solar System, but the fourth planet out, TRAPPIST-1e, seems the most favorable for life.
Suddenly, we are talking about intelligent life elsewhere in the Galaxy, and travelling through space to get there. Is this desirable? Is it even possible?
In this case, nearby means just under 40 light years away, a mere 230 trillion miles. Such a journey would take only a few years at 99.9999% of the speed of light or about 600,000 years at the fastest speeds we’ve recently attained with some clever slingshots around big planets.
So we just have to make a ship that can travel close to the speed of light. Over the years, many ideas have emerged to do that, mostly from nuclear fusion, like the Bussard Ramjet of Niven’s series that is powered by collecting interstellar hydrogen to fuse. Whatever method you chose, the absence of friction in space means you just have to give continuous pulses of thrust, even tiny ones, that eventually accumulate to push the vessel to near-light speeds.
TRAPPIST-1 is a small M-type ultracool dwarf star that has a mass, luminosity and radius about a tenth those of our Sun. It has a surface temperature of 2,550 K (4,130°F) and is young, not much over 500 million years. Our Sun is G-type yellow star with a surface temperature of 5,778 K (9,941°F) that formed 4.5 billion years ago.
TRAPPIST-1 is metal rich, meaning it formed from a gaseous nebula rich in metals accumulated from past supernovae. Supernovae are the only explosions large enough to form metals heavier than iron. The TRAPPIST-1 star is barely bigger than Jupiter, but the TRAPPIST-1 worlds are very much like some of the smaller planets in our own solar system, like Earth, Mars and the icy satellites of the outer Solar System.
The Goldilocks Zone is essential to the origin of life on any planet. For life to develop, you need water as liquid (year-round), an atmosphere, carbon and a few common elements like sulfur and nitrogen, and some common energy sources like lightning, volcanic heat, ultraviolet radiation, ocean wave impact, or a few others.
Carbon is essential since it is the only element that can bond with itself almost an infinite number of times to form increasingly complex compounds. Water is necessary since it is the only compound with the right boiling and freezing points, thermal and electrical conductivities, density of its solid with respect to its liquid, is the most effective solvent, has great acid-base properties, and forms hydrogen bonds, all properties necessary for life to develop.
We know these things from many experiments that recreated early Earth conditions in the laboratory and formed the organic compounds needed to evolve into life. The most famous were performed by Stanley Miller in the 1950s and refined later by many researchers (including yours truly) after we learned more about the conditions that existed during the first billion years on Earth. The early Earth was not reducing but was anoxic from outgassing during continuous volcanism. So there was no free hydrogen but lots of carbon dioxide.
If you take a sterile mixture of pure water, some gases like CO2, H2SO4, NH3, Cl and some sterile volcanic dirt (all components that come from erupting volcanoes on Earth), and spark some lightning through it, within only 2 days a slew of complex compounds form, turning the mixture into a veritable organic soup.
Forty years ago, as a young planetary geologist with a specialty in extraterrestrial biology, my particular soup yielded simple sugars like glucose, various amino acids and polypeptides, lipids, oils and tars, complex sugars like ribose, and very complex purine and pyrimidine bases. All of which are the building blocks of cells and key components like ribonucleic acid.
And all created by well-known chemical reactions that were later harnessed by reactive proteins called enzymes which would eventually become the biochemical engines of living cells.
Of course, going from the building blocks to actual living organisms took another several hundred million years of slow chemical evolution. Not random, just slow.
If it’s so easy to create the building blocks of life, then there should be plenty of life on the billions of planets that exist just in our own Galaxy. And there should be intelligent life on some of those, too, given sufficient time.
Carl Sagan calculated this possibility about 40 years ago using the Drake equation. Conservatively, there are millions of planets in our Galaxy that have life, and thousands of planets that have intelligent life.
However, if TRAPPIST-1 is only 500 million years old, then it is unlikely sufficient time has occurred for intelligent life to have developed on one of its planets.
On the other hand, we might be able to terraform one of these planets. It took microbial life about 2 billion years to turn Earth’s anoxic atmosphere to one with free oxygen, but seeding the right planet with the right microbes could work much faster.
So assuming there is life out there, can we reach it? Can it reach us? If we go fast enough, maybe.
The speed of light really is the Universe’s speed limit. At 671 million miles/hour, it can only be achieved if you have no mass, like a wave of light. Subatomic particles can get close, but when something like humans in a spaceship approach the speed of light, things go weird.
General Relativity tells us that interstellar space travel at near-light speeds also involves a bit of time travel as well, at least relative to the residents of Earth that would be left behind. As you approach light speed, time slows down, space contracts and your mass increases to infinity. But only relative to outside the ship. Inside the ship everything seems normal. Even the radiation dose to the crew would only be that of years, not decades.
This effect even has an equation to describe it – the Lawrence Transformation Equations. If the ship is traveling at 99.9999% of the speed of light, it will take about 40 years in Earth time to get there, but only about 21 days will have passed on the ship! If there are people on board and the ship is limited to one G of acceleration, then the ship will take about 42 years to reach TRAPPIST-1 in Earth time and 7.2 years ship time (3.6 years to accelerate and 3.6 years to decelerate. (Note- thanks to Timothy Weaver who noticed my LTE calculations were backwards! Also see The Relativistic Rocket and I2M)
This gets to the heart of investing in such a venture. There is no real return on the investment for individual investors. If a ship traveled to TRAPPIST-1, then came back, 80 years would have passed on Earth.
Who would invest in this? Altruism for the future of the species just may not be enough. Also, that money might be better spent on fixing what’s wrong on Earth. On the other hand, it's not too different from oceanic exploration of 500 years ago when many explorers didn't expect to ever return home.
But TRAPPIST-1 is rich in metals, which means the planets orbiting TRAPPIST-1 are also rich in metals, hundreds of times more so than Earth. So if Platinum Group Metals, Rare Earth Elements and Noble Metals like gold are of interest to you, boy, do I have a planet for you!
Of course, the same issues exist with another civilization wanting to visit Earth. There certainly is life elsewhere in the Galaxy. But General Relativity says those things you're seeing are not UFOs, you’ve just been smoking too much.
James Conca, Contributor
Dr. James Conca is a geochemist, an energy expert, an authority on dirty bombs, a planetary geologist and professional speaker. Follow him on Twitter @jimconca and see his book at Amazon.com