Space Travel: A Moonshot Project
Why we aspire to travel to space, why we’re doing it wrong, and ways we’re heading in the right direction.
Space. It exists, alright.
For the past few years, SpaceX has been at the forefront of talks regarding spaceflight. That reputation was heavily strengthened just a few days ago.
On September 18, 2021, a mission of four civilians aboard SpaceX’s Dragon capsule safely returned to Earth. It was the first all-civilian mission to space ever.
As we reflect on this momentous accomplishment, I raise the following question: why we are even going to space?
We should also recognize that there is still much work to be done when it comes to space travel. However, there are many incredible innovations that can help us achieve our wildest dreams when it comes to spaceflight.
Why Go To Space?
There are four main reasons that are typically agreed on when it comes to justifying why we should travel to space.
1) It Improves Life On Earth
Every year, NASA releases a list of technologies they’ve been working on that improve civilian life on Earth. The publication is called Spinoff, and you can check out this year’s edition here.
Some of the technologies from this year’s edition have created odor-eliminating shoes, improved tankless water heaters, a new air filtration system, and more. An investment in spaceflight is an investment in improving your daily life!
2) It’s A Giant Fire Drill
Why do we have fire drills? It’s to prepare us in case we have an actual fire. The more fire drills, the more prepared you’ll be in case you have to evacuate a building.
Well, what if we took that concept but applied it on a much, MUCH larger scale? What if a large asteroid crashes into the Earth? What if down the line, the sun engulfs the Earth? Then what?
Fear not! If we continue supporting space travel, we’ll have the means to “evacuate” the planet if we need.
3) It Benefits The Economy
Over 17,000 people work for NASA. That means that 17,000 driven individuals are not only working on solving big problems, but also receiving financial return for their work.
Now, some may ask, “Why does the government have to pay these people? Why can’t we just have private companies like SpaceX and Blue Origin control the market of space innovation?”
My answer to that is simple: private companies have different incentives to work on space technologies. They need to work on technologies that will give them a return on investment, like asteroid mining.
Meanwhile, NASA is able to not only work on these problems but also some of the problems we have on Earth. For example, with a completely private space travel industry, there would likely be no National Weather Service.
4) Exploration: It’s What We Do
You’re human (presumably), which means that you are a curious being. You question the world around you and wonder what is beyond where you live.
Humans have always been like this. It’s in our roots as hunter-gatherers. Since those times, we’ve been able to conquer all seven continents. Why stop there?
With space technologies, we are able to even further expand our understanding of the world and discover what the final frontier has to offer.
Chemical Rockets: A Thing Of The Past
It is so exciting to see rockets take off today. However, the rockets of today are not capable of being used as a long-term solution to space travel. Here’s why.
Our rockets are called chemical rockets because they employ chemicals to fuel themselves (which can be seen, as the exhaust is made of hydrogen). They utilize Newton’s Third Law of Motion: for every force applied from one object onto another, there is a force equal in magnitude and opposite in direction acted onto the original object (push exhaust down to move rocket up).
The problem is that for these rockets to leave Earth using Newton’s Third Law, the rocket must carry a lot of fuel. A lot. A rocket’s propulsion system (the engine, fuel, and oxidizer) can take up 96% of a rocket’s mass. Why is this? Because of the rocket equation.
The rocket equation, or the Tsiolkovsky rocket equation, goes as follows.
So, what exactly does this mean for a rocket? I’m going to summarize what I learned from this article.
Let’s assume we want to go the star system Alpha Centauri. The final mass of the rocket will be 0.1 g, let’s just say. We can estimate the exhaust velocity of a chemical rocket to be 5 km/s (which is the most efficient exhaust velocity to date). Our change in velocity will be 26,200 km/s to get there. When we do the math, it turns out the mass (in grams) of the amount of fuel we’ll need to propel the rocket is…
10^2200 * the mass of the observable universe
Yeah, I don’t think that makes sense logistically. While chemical rockets are fine for trips to the ISS, if we want to travel to Mars and beyond, there must be a better way.
Space Technologies To Help Us Reach Mars
Ion Thrusters/Engines
You want to get rid of chemical rockets? Good news, we think we have a replacement: ion thrusters!
Ion engines use electromagnetic fields to eject atoms (Newton’s Third Law), allowing a rocket to accelerate for months at a time instead of the maximum 10 minutes of acceleration a chemical rocket allows for.
Basically, instead of hot gases, ion thrusters eject ions (atoms or molecules that have an electrical charge). These ions are positively charged, meaning they’ve lost an electron.
The ions are actually created by the engine itself. The engine creates a plasma by bombarding neutral atoms of some gas (e.g. xenon), called propellant atoms, with electrons. The collisions release even more electrons, coming from the gas, turning the propellant atoms of the gas into positively charged ions.
The ions are directed into a magnetic field, accelerating them into space with tremendous velocity. Newton’s Third Law takes care of the rest.
Let’s revisit the rocket equation. With a chemical rocket, we can say that the exhaust velocity is 5 km/s. However, with ion engines, atoms can be ejected at a velocity of 90 km/s. This gives the rocket a much more efficient acceleration.
While the thrust of ion engines is relatively small, they can operate for months at a time, making them a promising way to accelerate spacecraft.
Solar Sails
The idea of solar sails is to propel a spacecraft with a sail, just like some ships on Earth. Instead of wind, the sail reflects sunlight, as when sunlight reflects off of the sail, it also gives it a push.
The reason for this is because while light does not have mass while at rest, it does have momentum, since it is a wave in addition to being a particle.
Here’s a potential concern: as you move farther away, wouldn’t you get less sunlight and hence a smaller push? Well, yes. But it doesn’t matter.
Don’t forget, space is a vacuum and thus does not have air resistance like Earth does. This means that the initial push will enable the spacecraft to coast without losing any velocity. NASA is already looking at solar sails as a viable well to propel spacecraft.
Antimatter Propulsion
Let’s quickly discuss what antimatter is. You can think of antimatter as normal matter, but all the particles have the opposite charge. This means that antimatter electrons have positive charges instead of negative charges (hence why they’re called positrons).
Antimatter also has the ability to annihilate if it collides with its own partner particle, like if an electron collided with a positron.
Why am I explaining antimatter to you? Well, it’s because we can actually use it to propel rockets! The idea is that we can take as much of the energy released from an annihilation as possible and use it to heat hydrogen to high temperatures. If we can do this, the hydrogen can be blown out the back of a rocket.
This propulsion would be the most efficient ever developed, as 100% of the mass of the matter and antimatter is converted into energy. An annihilation releases about 10 billion times the energy chemical rockets release.
One main problem that must be addressed before antimatter propulsion becomes a reality is that the matter and antimatter must be kept separate before the propulsion, which is difficult to do.
However, if we can create antimatter propulsion systems, we can attain velocities of 40% of the velocity of light, enabling us to reach the Alpha Centauri star system in less than a decade.
A Moonshot Project
With NASA trying to reach the moon and Mars in the coming years, we must also continue developing the above technologies to help us go beyond in the future. This will not be easy, but the reward can be invaluable.
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