Humanity has always dreamed of going to the stars, but it’s only in the last 100 years that it has become a real possibility in the minds of many people. While it is exceptionally challenging to achieve, many scientists now believe it may be possible for humans to leave the Solar System and perhaps even reach the nearest neighbour star, Proxima Centauri, which is 4.2 light-years away. What’s needed to make this shift, and what could possibly allow humans to venture beyond their own solar system and maybe even colonise another planet?
Advanced propulsion systems capable of relativistic speed
One significant development would have to be the introduction of advanced propulsion systems that can reach relativistic speeds. Once speed gets closer to the speed of light, the relative passage of time on the spaceship compared to the surrounding environment declines, making it possible for humans to travel vast distances in a single lifetime.
Whether that happens remains theoretical, but there are plans in development. Unfortunately, a conventional chemical rocket like the ones produced by NASA or SpaceX would take around 75,000 years to reach the nearest star, so those are obviously impractical. For interstellar travel, spacecraft need to be reaching 20% or 30% of the speed of light.
One option is to use nuclear propulsion. The idea is to use nuclear reactors to heat a propellant, which then powers ion thrusters. Interestingly, NASA is already trying to develop this concept in the form of its SR-1 Freedom project. The goal is to test this device on the way to Mars by 2028 to see if it’s viable for long-range travel in the future, perhaps to the outer solar system or beyond.
A more advanced option is fusion rockets. These would harness the power inside stars themselves to provide thrust and high efficiency. Technical analysis suggests that these rockets could perhaps reach 20% of the speed of light, but maybe not any faster.
The final option is to use directed energy or laser sails. Here, human beings would board a spacecraft, and then lasers would push them rapidly into the interstellar medium. The problem with this system is that it’s very difficult to slow it down. Once the initial push has been given, no additional propulsion can be added from Earth. It would have to be added from other celestial bodies, potentially requiring additional lasers on planets in the outer solar system.
Closed loop bioregenerative life support
At the same time as engines are developed, there’d also be a need for closed, bioregenerative life support. These systems would have to support astronauts for decades and be 100% efficient in their recycling, just like the Earth is. Achieving these artificial ecosystems is challenging. It would require equipment similar to the ISS Water Recovery System, which includes hydroponics and algae to scrub CO2 and produce oxygen while also generating food.
The Earth has proven that such processes are possible, but it would be essential to maintain them synthetically and indefinitely on any spacecraft, perhaps with the inputs of additional energy from the propulsion system. There would also be a need to turn waste into resources. Human waste would have to become the organic building blocks for new materials or nutrient-rich soil to grow more crops. Nothing in the payload could be wasted, so everything would have to be kept on the ship.
Active radiation shielding
We would also see a need for advanced aerospace composites to provide astronauts with effective radiation shielding. Unfortunately, space is full of cosmic rays, which are high energy and can damage human DNA. Over time, especially periods of more than three months, astronauts’ bodies would become very damaged, and they would age and develop diseases faster. Radiation shielding would have to counter this 99% or more to be effective and keep them safe for multi-year travel.
Unfortunately, the technology to do this without adding significant weight to spaceships is simply not available right now. However, it could become cheap and easy to access in the future if composite material technology advances sufficiently. Many companies are currently looking into improving how they manufacture and produce composites, especially to make them more robust and perhaps even to enable them to deflect incoming cosmic rays.
Artificial gravity
Long-term microgravity is bad for astronauts’ bones, muscles, and general health. Many astronauts come back to Earth and feel incredibly weak for the first few weeks of living normal lives again outside of space.
The easiest solution to create artificial gravity is to use centrifugal force by rotating the entire spacecraft and providing a large habitation ring. This could effectively simulate gravity, although it wouldn’t quite feel the same as regular gravity on Earth. When you walked forward, it would be more like walking uphill.
You could also try creating something similar to a vomit comet. The solution is to create a rotating structure that can simulate gravity without generating motion sickness from the Coriolis effect.
Interestingly, artificial gravity is probably the technology most within reach right now, especially if it’s done using centrifugal force. Experimentation in space is already underway, and NASA is looking at adding this concept to the next space station.
Hibernation chambers
Depending on when advanced propulsion systems come online and how good they are, it may be necessary to provide crew with hibernation chambers. Instead of allowing them to work and age as normal, it may be necessary to put them into a kind of stasis where their body systems slow down.
The problem, of course, with space travel is that the human life span simply isn’t long enough. It may be necessary to put humans to sleep for hundreds of years and then wake them up once they arrive at their destination. Furthermore, putting humans into stasis or hibernating them reduces the need for living space, oxygen, and food. This could potentially lower the complexity of any interstellar travel project.
So there you have it. Those are the tech advancements needed for human explorers to go beyond the outer solar system.
