Why Our Solar System is Perfect for Exploring.
Updated: Dec 27, 2019
A family portrait of our Solar System, all ready to help us on our way to the stars. (Credit:NASA/Jenny Mottar)
This past summer, I was fortunate enough to sit on a panel at the Silicon Valley Comic Con with Andy Weir, the author of The Martian, among other distinguished guests. Our panel was about how we can use storytelling, both with art and science, to connect us to the journey to Mars. One question, often asked was, ‘Why do you explore Space?’. I answered, as I always do, with the ‘because I can’. Because life has existed for 4 billion years, complex life for 500 million years and humans for 300 thousand years. In all that time, we, you and I right now, exist at a point in time that gives us the option to look beyond our world and actually go, with humans and robots.
We hope that the journey to space becomes easier in the future as technology advances, but we are always a natural or human-made disaster away from losing that opportunity forever. The knowledge and infrastructure that makes space exploration possible may exist only now. This drives me to take advantage of this opportunity while we can and work to build it for the generations to come. However, our luck goes beyond this fortunate timing. At the panel, Andy added that in his wildest imagination, he would be hard-pressed to dream up a believable solar system, more conducive to exploring space than ours. Now let's see just how lucky we are to be humans on Earth, in our particular solar system at the dawn of a space-age.
2019 Silicon Valley Comic Con, Panel - Mars: Transforming from a Point to a Planet with Emerging Technologies. Left to Right: Andy Weir, J.R. Skok, Kitty Yeung, Yvonne Cagle. (Photo Credit: Grace Tang).
“Space is hard”. That is a statement you often hear from scientists and engineers whenever a spacecraft crashes. While there is truth to that, it could have been so much harder. To explore space, first, we need to leave Earth, a perfect planet to start on the journey. Often termed the ‘Goldilocks’ planet, Earth is neither too hot nor too cold, too young or too old, too big or too small. Earth is large enough to support our atmosphere, oceans and resource diversity. It is large enough to support plate tectonics which drives long-lasting hydrothermal systems that create high-grade metal ore deposits rich enough to refine into rockets and spacecraft. Earth is large enough to support the processes and biosphere that lead to oil and gas deposits that contain high density, transportable chemical energy that we can use to build and fuel spacecraft. Can early-stage rockets be designed, built, and operated on a planet without fossil fuels? We don’t know, we haven’t had to figure it out yet, though we probably should. Earth is big enough for all of that.
Earth is also small enough to escape. Every planet has an escape velocity, a speed that spacecraft must reach to escape the gravity well. This is a function of the mass and radius of the planet. Earth escape velocity it about 26,000 mph (11 km/s). This is very fast. This is why rockets are big. It takes a lot of energy to accelerate a kilo of mass to that speed, even more for a human or spacecraft. However, this velocity is possible with our fuels and rocket technologies. If Earth was larger, this number would be higher, making escaping even tougher until the limits our or rockets and ingenuity are reached and we are stuck. Life on larger planets might be able to see the universe around them but unable to venture out to explore. We are fortunate to start our journey in a world that we can leave with just the resources that we can find here.
Once we leave the Earth, we quickly encounter the Moon. The Moon might just be the reason we survive on Earth anyway. Its gravity keeps the Earth’s orbit more stable than any other planet and might be a major reason why we could evolve. The Moon is a four-day rocket ride away. Once we are able to leave Earth, getting to the Moon is not too much of a stretch. Only 12 years after the first rocket left Earth, humans were on the Moon. Now that effort was not easy, or cheap. It took a technological, political and financial commitment that was nearly unparalleled in the history of humanity, but it was done. If the next rocky surface was as far as Mars, if the trip took 2 years rather than 2 weeks, we may never have stepped on another surface. Luckily the Moon is where it is. We can go there when we, the collective ‘we’, or at least the insanely rich ‘we’ decide to go. When we get there, we find a good size planet in its own right. It is often portrayed as barren but has a lot going on for it. While dry compared by the standards of Earth, we know it has massive deposits of water, trapped in the permanently shadowed craters of the north and south pole. Water is interwoven into the minerals of volcanic deposits around the Moon. Water, so important for life on Earth, is like gold in space. If broken into hydrogen and oxygen, it becomes a source of rocket fuel to take humans on to their next step. The Moon also contains huge supplies of basalt, that can be turned into fabrics and composites for building, rare earth element deposits needed for electronics, ilmenite to source iron and oxygen and a unique supply of Helium-3 embedded in the regolith that might just be a fuel source for future fission reactors. With the exception of the Helium-3, all these things exist on Earth, however, on the Moon, they exist on a world with an escape velocity of 5300 mph (2.38 km/s), one-fifth of Earths. This is why the rocket from the Earth to the Moon was so much bigger than the rocket from the Moon to Earth. This sort of well-stocked, ‘practice’ planet, just a few day ride from home, would be hard to imagine in a fictional solar system if it wasn’t for our good luck to grow used to it.
The 363 ft (110 m) tall Saturn V rocket was used to launch 10 three person missions from Earth to Space, 6 of which landed on the Moon. Most of the rocket was used to accelerate the Apollo Spacecrafts off of Earth. Only the single accent engine on the Lunar Module was enough to launch from the Moon.
As we look to leave Earth, our next step beyond the Moon is the planet Mars. Mars is yet another gift of our solar system. It is a planet that, from the surface, can be easily confused with some views of our own paradise Earth. It has mountains, volcanoes and lake deposits. This big difference is that Mars has no liquid water on the surface and an atmosphere too thin to realistically ever breathe. However, despite the lack of liquid water, it is teaming with ice. Ice at the poles, ice underground, and molecular water bonded in the rocks throughout the planet. Once we figure out how to get away from the Earth-Moon system, we will be welcomed by a planet that would remind us of home and provide many of the most important resources we need to build. Living and building on Mars are just hard enough to help us get good at surviving in space without making it impossible. Learning to build from the materials on Mars is exactly what people like me spend our days on at Made of Mars. A few more years of development, some great rockets, and a few brave explorers and we will be well on our way.
NASA's Curiosity rover of layers in Mount Sharp, a view that would be familiar to desert dwellers all over Earth. Image credit: NASA/JPL-Caltech/MSSS
Once we have figured out how to live on Mars, we will have solved the major challenges of surviving away from Earth. We can then apply that knowledge and technology to the outer solar system, where the worlds get weirder and life gets harder. As we move beyond the Asteroid Belt, the Sun gets so dim that it is not a viable power source. However, water becomes easier to find on comets and icy moons, opening up options if we can improve hydrogen cell technology. Or we can learn to painstaking concentrate the Uranium found in meteors for more traditional reactors. The methane deposits on Titan provide a tantalizing prospect for energy, but hopefully, we are beyond the need for hydrocarbons by then. The distances, the radiation from Jupiter and the strangeness of the outer solar system make it a difficult place to explore. This is true for robots and even more for humans. We are lucky to have the opportunity to practice first on the Moon and Mars before taking on these challenges.
J.R. Skok, PhD is a planetary scientist with the SETI Institute, Chief Science Officer of AstroReality and Founder of Made of Mars. His opinions are his own.