Interstellar travel to the potentially life supporting planet K2-18b.

Space Travel

Figure 1: NASA’s Kepler Space Telescope in an Earth Trailing Heliocentric orbit

NASA’s Kepler spacecraft  discovered a planet named K2-18b in 2015 and according to data analyzed from the Hubble Space Telescope there is presence of water vapor in its atmosphere. This has certainly given goosebumps to science enthusiasts, general public and alien conspiracy theorists alike. It has created a buzz in the media. This shows our scientific progress but we are not ready to celebrate yet. How do we reach there?

Figure 2: Hubble Space Telescope orbiting the Earth

Even if we get one hundred cent percent sure about the planet K2-18b being suitable for human habitat, the find is of little use if we are not going to make it to that planet. Let me give you an idea. K2-18b is 111 light years away from earth. Don’t get yourself confused by the term “light year”. It’s a unit of distance not time, as it sounds. One light year is the distance traveled by light in one year and believe me! that is a huge number. Simply speaking, if you travel at the speed of light, it is going to take you 111 years to reach the planet K2-18b.

Figure 3: Unlike in this image , K2-18b is relatively a lot more farther 

A spacecraft cannot get to the speed of light. Special Relativity bars us from attaining speed of light but getting even to one percent of the speed of light is unthinkable today. The fastest artificial spacecraft till date is Helios 2 which was launched in the year 1976 to study solar processes. It managed to achieve a speed of 252,792 km/hr. Compared to 1,080,000,000 km/hr (the speed of light), the Helios 2’s speed is merely 0.0002 %, let alone achieving 1 %. Disappointed?? You should be.

Let us assume, somehow we manage propel a spacecraft at 1 % of the speed of light. In that case, it will take us 11100(eleven thousand) years to reach K2-18b. Eleven thousand!!  That is way beyond a normal human life span. In eleven thousand years we may even cease to exist as humans, we might evolve into some other beings. Who knows!! We might turn back into apes. Well, that would not surprise me. The point is given the current technological capabilities it seems unlikely that we will be able to land on K2-18b anytime soon.

The Voyager 1 spacecraft is the most distant human made object till date. It was launched into space in the year 1977 and in the year 2012, it managed to exit our solar system. Voyager 1 has been travelling for 42 years and has managed to cover a distance of almost 22 billion kilometers. It took 42 years for Voyager 1 just to cross our solar system and our solar system is like a needle in a haystack when we talk about a distance of 111 light years.

Bored of hearing disappointing stuffs? Let me give you two cases where we can make it to the planet K2-18b but they come with “only if” clauses.

Figure 4 : Spaceship moving at 99 % of the speed of light (c)

First case is where the humans have managed to develop a revolutionary propulsion system that can push a spacecraft near to the speed of light. If that happens, we see Special Relativity come into play. For the astronauts travelling in that spacecraft, the time will slow down (Time dilation) relative to Earth and the distance of 111 light years will be shortened (Length contraction). Suppose the spacecraft manages to get a speed of 99 % of the speed of light. Then according to observers at Earth, these astronauts will take a little over 112 years to reach K2-18b but for astronauts inside the spacecraft, it’s going to take only about 16 years to reach K2-18b. 16 years is well within the limit of a human life span.

If we fail to achieve high speed as mentioned in the first case, we have another option. This option is deep rooted in biology. It’s hibernation. Science fiction movies have always toyed with this concept. If humans are able to create a device which can help them hibernate as long as there is the supply of electricity, Eleven thousand years of travel might not be a bad idea. For this, the size of the aircraft needs to be huge and we will assume the speed of the spacecraft to be 1 % of the speed of light as mentioned in the 3rd paragraph.

Figure 5 : Spaceship moving at 1 % of the speed of light(c)

Then we can send a good number of astronauts abroad the spacecraft. These astronauts must come in a pair of male and female so that they be able produce children. The responsibility to steer the spacecraft for the first 25 years will be assigned to a pair and rest of them are put into hibernation mode. The pair will produce two children. These children will grow to learn the art and science behind steering the spacecraft to the planet K2-18b. After 25 years, the parents will go to sleep in hibernation mode. These children will spend another 25 years steering the spacecraft and before they go to sleep, they will wake up another batch of pair (originally from earth) other than their parents. The new batch of pair will take over for another 25 years before handing down the steering responsibility to their children.

Figure 6 : Some awake astronauts aboard the spaceship and others in hibernation on their way to K2-18b.

This process will go on until they reach the planet K2-18b. If each of the pair and their children is to survive the planet K2-18b, we will need about 600 astronauts (300 male and 300 female) from the earth and a total of their 600 off-springs (born on the spaceship). The only biggest challenge will be to arrange a food supply sufficient for 4 people at a time for Eleven thousand years.

Figure 7 : Spaceship landing on the planet K2-18b.

When we reach K2-18b, almost all of the astronauts will be biologically about 50 years old except the few lucky ones who were never woken up during the course of journey.

It seems very unlikely that we will start our journey to the planet K2-18b any time soon but you may never know what we might be able to discover or invent for transportation. Teleportation and traveling via a worm hole has been subject to many fantasy movies and comics . We are not sure if those concepts will ever turn into a reality . I have skipped these two topics here but I will get back to them very soon.  Till then, let’s keep on imagining and  hope for the best .


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Surya Kiran Yadav

I write on Physics, Space Travel and military technologies
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Last modified: September 17, 2019

2 Responses to :
Interstellar travel to the potentially life supporting planet K2-18b.

  1. yuwaraj says:

    Good analysis. worth reading

    1. Surya Kiran Yadav says:

      Thank you 🙂

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