Thread: If what Spaceship shape is best for flying in space?

If a UFO from another planet came to Earth, which shape do you think it would be? (considering the fact that it contains aliens and oher electronics)

In movies it had been a disk, but I don't know if it really is the best one, and why.
If you have any idea please tell and explain briefly.

Thanks!

As sharply pointed/streamlined as possible so that you reduce the number of impacts with matter in space (small rocks).

Impossible to say without knowing their technology. Although a realistic design would be a large ship that stayed in space and wasn't aerodynamic, along with smaller ships that are aerodynamic.

Traveling through the interstellar medium is no easy trick. Smacking into stray hydrogen atoms at near the speed of light would create a very deadly irradiation of your ship’s hull. One solution is to instead move your whole planet. Even with mere fusion power, the oceans of the Earth could provide enough fuel to propel our planet for thousands of years. When we got to our destination, we could ‘refuel’ at a gas giant like Jupiter. Fusion reactors would keep the Earth warm in transit and our atmosphere would protect us from interstellar radiation. There’s really no place like home.

Originally Posted by Arch2008

Traveling through the interstellar medium is no easy trick. Smacking into stray hydrogen atoms at near the speed of light would create a very deadly irradiation of your ship’s hull. One solution is to instead move your whole planet. Even with mere fusion power, the oceans of the Earth could provide enough fuel to propel our planet for thousands of years. When we got to our destination, we could ‘refuel’ at a gas giant like Jupiter. Fusion reactors would keep the Earth warm in transit and our atmosphere would protect us from interstellar radiation. There’s really no place like home.

The problem is that we'd have to take the Sun with us....otherwise we'd just freeze to death.

"Fusion reactors would keep the Earth warm in transit"

Originally Posted by Arch2008

Traveling through the interstellar medium is no easy trick. Smacking into stray hydrogen atoms at near the speed of light would create a very deadly irradiation of your ship’s hull. One solution is to instead move your whole planet. Even with mere fusion power, the oceans of the Earth could provide enough fuel to propel our planet for thousands of years. When we got to our destination, we could ‘refuel’ at a gas giant like Jupiter. Fusion reactors would keep the Earth warm in transit and our atmosphere would protect us from interstellar radiation. There’s really no place like home.

I would like to see some numbers. How much energy could we get from fusion? In any case, by the time we have the technology to do something like move the planet around, we will surely have the technology to build really cool starships that could get to another star a lot faster.

The Sun fuses hydrogen and produces a million times humanity's annual energy requirement every second.

Don't forget that the passengers of these cool spaceships need to survive the radiation produced by moving through the hydrogen atoms in nearly 300,000 km of space every second. The best shape is the Earth.

Originally Posted by Arch2008

The Sun fuses hydrogen and produces a million times humanity's annual energy requirement every second.

Ok, lets do some math. There are 1.5E18 kg of water in the oceans. That gets you about 1E44 protons. The proton fusion cycle produces 25 MeV/proton used up. So if we fused all the protons in the ocean, we get about 2.5E51 eV, or 4E32 J. Yeah, that's a lot of energy. But the mass of the earth is about 6E24 kg, so if you magically dumpped all 4E32 joules from fusing the oceans into the earth as kinetic energy, you could accelerate to about 11600 meters/sec. At that speed, it would take you over 100 thousand years to get to the nearest star. But of course we would need to slow down when we got there, so really we could only use half of the energy to speed up - meaning it would take about 200 thousand years. Which seems like too long a time to make it worth while, especially since you could get a starship there in just a few decades. Of course I might have made a calculation mistake, so feel free to run the numbers yourself and see if you get a different answer.

Don't forget that the passengers of these cool spaceships need to survive the radiation produced by moving through the hydrogen atoms in nearly 300,000 km of space every second. The best shape is the Earth.

So you put some mass at the front of the ship to act as shielding. It's not such a problem.

Except that this 'mass shield' would impact enough hydrogen atoms to start irradiating like a nuclear pile. So it's 200 millenia, get there alive, or two decades, get there as a glow watch.

Originally Posted by Arch2008

Except that this 'mass shield' would impact enough hydrogen atoms to start irradiating like a nuclear pile. So it's 200 millenia, get there alive, or two decades, get there as a glow watch.

It's not complicated. You just figure out how much mass you need for the shield, then use that much mass. Radiation is easy to block. Yes, eventually that outer layers of the shield will start to get radioactive - but that just means that the shield needs to be thicker. This is a trivial problem to solve. Certainly a hell of a lot easier than moving the planet, anyway.

Originally Posted by Scifor Refugee

Originally Posted by Arch2008

Except that this 'mass shield' would impact enough hydrogen atoms to start irradiating like a nuclear pile. So it's 200 millenia, get there alive, or two decades, get there as a glow watch.

It's not complicated. You just figure out how much mass you need for the shield, then use that much mass. Radiation is easy to block. Yes, eventually that outer layers of the shield will start to get radioactive - but that just means that the shield needs to be thicker. This is a trivial problem to solve. Certainly a hell of a lot easier than moving the planet, anyway.

Won't a magnetic field between two poles at the front and rear of the ship deflect the Hydrogen nuclei (protons) around the ship? No radiation problems :wink:

Originally Posted by KALSTER

Won't a magnetic field between two poles at the front and rear of the ship deflect the Hydrogen nuclei (protons) around the ship? No radiation problems :wink:

That could probably work, but I suspect that the mass of the equipment needed to generate the field would be much higher than the mass of the shield...and you don't need to worry about the shield breaking.

Originally Posted by Scifor Refugee

(...)so if you magically dumpped all 4E32 joules from fusing the oceans into the earth as kinetic energy, you could accelerate to about 11600 meters/sec.

Isn't it almost exactly the escape velocity from the Sun? Am I getting paranoid or are the numbers intentionally meaningful?

Originally Posted by Scifor Refugee

Originally Posted by KALSTER

Won't a magnetic field between two poles at the front and rear of the ship deflect the Hydrogen nuclei (protons) around the ship? No radiation problems :wink:

That could probably work, but I suspect that the mass of the equipment needed to generate the field would be much higher than the mass of the shield...and you don't need to worry about the shield breaking.

Ah yes, I think Ophiolite made this point as well some time ago. The issue now though is the residual radiation from the constant bombardment by protons at those high speeds, which a field could simply and easily deflect around the ship. I am sure that some ways can be thought of to limit the added weight, maybe routing the wiring from the main engine through the length of the ship.

http://en.wikipedia.org/wiki/Edward_Mills_Purcell

Well I read a book where this gentleman says that the crew would die from the radiation, which could not be deflected (they are hydrogen atoms, not nuclei) or shielded. So, take your word for it, or believe the guy with the Nobel Prize. Hmm…let’s see, that’s a tough one.

(they are hydrogen atoms, not nuclei)

Oh. That sucks! Maybe a pilot lazer could plasmalize the hydrogen and then you could deflect it? :?

Originally Posted by Arch2008

http://en.wikipedia.org/wiki/Edward_Mills_Purcell

Well I read a book where this gentleman says that the crew would die from the radiation, which could not be deflected (they are hydrogen atoms, not nuclei) or shielded. So, take your word for it, or believe the guy with the Nobel Prize. Hmm…let’s see, that’s a tough one.

Why don't you post some actual numbers on how much radiation would be created and how much mass would be needed to shield from it? In any case, you don't even need to go close to the speed of light to beat your 200k+ year earth ship - even going at just 20% of light speed would get you to other stars in 20-25 years, and then you don’t need to worry about your magical radiation that, unlike all other forms of radiation, apparently can't be shielded against. If you send a ship with 100 people that takes 20 years to get to another star and then move the earth there 199975 years later, you're going to find that the system is already completely populated by the descendants of the first 100 to arrive. 200k+ years is waaaaaay too slow. And if things go wrong, everyone on earth dies. I love the way you think it's too challenging to shield the crew of a ship from radiation in space, so the solution is to move the earth. That's like saying that a row boat is too difficult to build, so we should build a nuclear submarine instead.

In point of fact, Ed Purcell says it can't be done.
Another gentleman named Doral Froman, who was a lead technician at Los Alamos, came up with the planet Earth as a spaceship idea. The Earth survives object impacts all the time.
Your shielded ship has to go about 25 trillion miles to get to Alpha Centauri. If it hits just one chunk of ice the size of a watermelon at 20% of the speed of light that would be the equivalent of a North Korean atom bomb hitting your shield. So just how much shielding are you talking about?