I used to think it was useless for us to go to Mars, and it still is. However, what’s changing is that we are going to go to Mars anyway, and that’s really kind of a revelation that we will eventually become a multi-planet species.
The problem with Mars, I think, is it’s too small.
The size of the planet means two things: one, the planet’s central core cooled off early on it its history, essentially destroying the magnetic field of the planet, and two, without enough gravity you’d need at atmosphere much deeper than Earth to achieve the same pressure.
There’s a third problem, too. No nitrogen to speak of.
These problems would not be solved by dragging the planet closer to the sun. It is basically, as far as we can tell, a dead planet.
Every heterosexual couple should have no more than 1 child. This would reduce the population and allow us to continue to abuse the environment and enjoy our pleasures of modern civilization at a sustainable level.
I assume you mean over populated by people because there are far more germs and insects than people on Earth.
In fact, we have very few people, but we are a destructive people that are capable of and are in fact changing the environment and not for the better.
Without population control it will just get worse and worse. Every heterosexual couple should have no more than 1 child. This would reduce the population and allow us to continue to abuse the environment and enjoy our pleasures of modern civilization at a sustainable level. However, in absence of that it will not get better and it will come to a point where there is a crunch. Sooner or later things will crash and eventually nature will balance things out.
Proxima Centauri, is our nearest star, about 4 light years away.
A light year is the amount of time light travels in one year, or 9,460,730,472,581 kilometers. That’s 9.46 trillion kilometers, or about 5.88 trillion miles.
The fastest space ship we ever built was the Juno spacecraft, which in 2016 broke all speed records in space with a gravity assisted acceleration up to 164,700 mph.
The problem with going much faster than that is General Relativity and propulsion. Even with all the fuel in the solar system, it would still take an infinite amount of fuel to approach the speed of light. There’s no warp speed or aliens that have somehow “broken” the laws of physics. You can’t approach the speed of light.
If, however, you could go, say 40 times faster than Juno (there’s no existing technology that would come anywhere near this speed), you’d be going about 6.58 million miles an hour. That’s a hypothetical but impossible speed by either humans or space faring aliens, but none the less, for the sake of argument, let’s say you could go that fast.
Light travels at 670,616,629 miles per hour (as a layman and lazy American I think in miles more easily). So your space craft is amazingly, impossibly, traveling slightly less than 1% the speed of light. We’ll round it up for arguments sake. You’re going now 6.7 million miles an hour. Don’t crash into an asteroid at that speed!
How long would it take to make the trip to Proxima Centauri 4 light years away? Well, if you were going 1% the speed of light (6.7 million miles an hour) it would take you 400 years to reach the nearest star.
Unfortunately, you can’t just get up and go 6.7 million miles an hour. You’ve got to build up speed, which conceivably would take years burning some kind of fuel source that would weigh as much as the Moon because you’d need so much of it (which would slow your acceleration). The problem is the faster and longer you want to burn fuel, the more fuel you need, which increases your weight and decreases your acceleration. Remember, also, as you approach any percentage of the speed of light at all, the amount of fuel required to accelerate your spacecraft any faster begins to increase exponentially because of the law of General Relativity.
At the other end of the trip you’d need the same time and fuel to slow down so you don’t overshoot your target.
People have thought about using light propulsion. From somewhere in Earth orbit, shooting a powerful laser at a reflector at the back of the outgoing spaceship. It would be slow, but eventually it would increase in speed. They’d still need fuel at the other end to slow down.
It’s difficult to know how to figure in that acceleration and deceleration process, so I usually, for the sake of argument, just double the time, which probably isn’t far off.
That would mean it would take you about 880 years to start out, accelerate to 6.8 million miles per hour, and then slow down at the other end. That’s how long it would take to reach our nearest star.
As far as we know, there’s not even any interesting planets over there. If you want to go somewhere more interesting you’d probably have to go farther out in a different direction to the Trappist-1 system, which is 40 light years away.
That would only take you 8,000 years each way. We’re talking eight thousand years. You’d need generational spacecraft, where entire civilizations lived and died for thousands of years before they reach where they’re going, and would these descendants of the original pioneers have any idea what to do when they got there?
These, depressingly, are only the closest stars, right around our neighborhood. There are many more stars in our local group, and billions more in the galaxy, and millions of galaxies.
All we can do is watch them, study them, wonder about them and so on. We will, however, never be able to visit them, and those aliens out there unable to visit us.
A thoughtful question. No simple answer but we can give you cool information!
Actually, it doesn’t really matter whether the star you are going to is 100 light years away or 1 light year away. These are just incredible, inconceivable distances, and although 99% the speed of light sounds nice, we’re not going to get even a hundredth of 1 percent the speed of light. We just don’t have that technology now or ever, as you’ll see below!
There would be no fuel that could power a spaceship faster and faster toward the goal. At a certain point acceleration would have to stop. You would need to save half of your fuel for slowing down at the other end.
So what you’d have to do is accelerate until half your fuel is burned. Then wait. If that fuel got you half way, then you’d start the retro burn immediately and it would take the same amount of fuel to slow down. If half your fuel took you 1/10 of the way then you’d have to coast for 8/10ths more then the last 1/10 burn the last of your fuel to slow down. To get you going 99% the speed of light would require an almost infinite amount of fuel according to Einstein’s theory of relativity – and then you’d have to slow down too!
It would be a one way trip and you wouldn’t know until you arrived if there was anything out there that could be habitable.
Our closest star, Alpha Centauri, is about 4.4 light years away. That number “4.4” misleads us to think that’s not very far, but it’s further away than you can imagine, and that’s just the closest star. This is a distance of about 5.88 trillion miles away, and there’s another number we can deal with: 5.88 (trillion miles).
The fastest we’ve ever gone was on July 4, 2016, when the Juno spacecraft, assisted by Jupiter’s gravity got up to approximately 165,000 miles per hour (265,000 km/h), breaking all previous space speed records. But even if we could increase that speed 81 times faster than Juno, even if we somehow could come up with the incredible propulsion to both speed up and slow down, that would give us the fantastic speed of 13.3 million mph! Can you even imagine that speed? That happens to be about 2% the speed of light, and it would take us 2,200 years to get to Alpha Centauri without even taking the acceleration or deceleration into account at all. So maybe about 4 or 5 thousand years each way, what to speak of 100 light years like you are asking about would take about 44,000 years each way at 81 times faster than we’ve ever gone before.
Your question was if we could go 99% the speed of light for 100 light years. You did correctly identify that there would be a period of acceleration and an equal period of deceleration at the other end of the trip, but honestly not even a fraction of 1 percent of the speed of light is ever going to be achievable. The weight of the fuel alone would be impossible to move.
We can’t give a number for an answer because we’re never going to get that fast anyway. I did try to put the distances into perspective. We are all living in the world of science fiction and don’t want to accept the numbers. Interstellar travel isn’t in our future.
While it is true that building a city under the ocean would be easier than going to Mars, going to Mars isn’t going to stop oceanographic research. One does not cancel out the other. It’s not like we are pulling out funds from researching the ocean so we can go to Mars. There are things still to be discovered under the sea. There are things still to be discovered in space. Both will go on because we have billions and billions of people and some people like studying the oceans and some people like studying space!
Exactly the disappointing truth. It can’t. Since Mars is too small, the core cooled down long ago and therefore the organized magnetosphere doesn’t exist. Put as much atmosphere you want and it will still be blown away and not protect us from dangerous rays from the sun. We can only “colonize” the same way we “colonized” the Moon or the International Space Station: staying indoors!