Given the news of the finding of an Earth-like planet around one of our nearest stars, as described here, it is interesting to see if we could ever actually get to this planet. I am going to start a small series on the idea of getting to another star. I will cover a few topics such as the problem with getting to another star with our current technologies, what new technologies we could use, and why getting some satellites to another star might not even help.
Right then. Why can’t we get to another star now?
Let’s say that we want to get to a star that is about 4.5 light years away. A light year is actually a distance – it is the distance that light travels in an Earth year (as opposed to a Martian year). It is roughly 9.5×10¹² km. That is a long distance. To give some perspective, it takes just over 8 minutes for light to get from the sun to the Earth. To reach Pluto, it takes light 5.3 hours. Given that it took New Horizons 9.5 years to get to Pluto, you can see that it will take us a fair bit of time to go all the way to another star.
But, let’s try.
How would you get a satellite to another star? Well, you would have to accelerate it up to some speed, then cruise for a long time, and then decelerate it once it gets to the other star. Ideally.
Since we would want to actually see what this thing measures in our lifetime, let’s assume that we can get it up to about 1/3 light speed (a nice round number of 100,000,000 m/s), and let’s assume that we can accelerate at roughly the gravity of Earth, which is about 10 m/s². If we do a tiny bit of math, we can see that it will take us 10,000,000s to reach this speed, which seems like a huge amount of time. But, considering that there are 86,400s in a day, this is only about 116 days or about 4 months.
So, if we wanted to get to another star, we would take about 4 months to accelerate up to about 1/3 the speed of light, cruise for about 12 years, and then decelerate for about 4 months, with a total trip time of about 13 years total. Not that long! Why aren’t we packing our backs now (or building a satellite for the 13 year journey)?
The problem with this is that we don’t have the technology to accelerate something at 10 m/s² for 4 months. If you watch a rocket launch, you will see that the rocket accelerates for only a few minutes – like 10. In fact, to reach orbital speeds (7,600 m/s) , if you accelerate at 10 m/s², it will take about 13 minutes. To break away from the Earth, which is much harder, it will take about 20 minutes. Even with math, that is significantly shorter than 4 months.
One of the reasons that I brought up New Horizons before is because it is one of the fastest satellites ever launched. It left our orbit going about 36,000 MPH, which is about 16,260 m/s.
Let’s put this speed in the context of getting to that other star which is 4.5 light years away. 16,260 m/s is about 0.0000542 times the speed of light. So, to get to another star, New Horizons would take about 83,000 years. That, my friends, is a long time, and why no one is packing any bags.
It will be a long time before we can make this journey in any reasonable amount of time. Next time, let’s talk about why we will never be able to get to another star using our current rocket technology. I am not even joking here. Using modern rocket technology, it would more mass for fuel that there is matter in the entire universe to accelerate us up to anywhere close to the speed of light. But, let’s talk about that next time.