MagnaCool--Habitable Exoplanet!

[Ned]

Originally posted by Eli

But NASA has become very non aggressive regarding space exploration. The Chinese are the folks pushing the envelope these days.

Mercury style mission are not exactly pushing the envelope.

True, but their plans are very aggressive.

[KrazyHorse]

Originally posted by Krill
...Because it will **** up everything electronic on the ship?

[KrazyHorse]

Originally posted by Dr Strangelove
If this thing is 5 X the size of earth then wouldn't it's gravity be 5 X also? That doesn't sound like a fun place to visit. If it's that much bigger than earth wouldn't it's atmosphere be denser and therefore the surface temperature be much higher?

It depends on the radius of the planet.

GM/R^2

rewriting, 4piGdR^3/3R^2 = 4piGRd/3 (d the density)

or, we can write R = (3M/4pid)^1/3, so

(4pid/3)^2/3 * G * M^1/3

So, if planet X has mass 5 times that of the Earth, but both have equal mass densities, then planet X only has gravitational field (at surface) 5^1/3 = 1.7 times that of Earth's.

[KrazyHorse]

Originally posted by Ned


Funny. Every time I ask how fast can we go, or some such, I get the same kind of answer.

Most people thing 10% c is a necessary speed to get the travel time down to less than a thousand years, but no one seems to have any idea how to go even that fast with any technology, and others say if you go that fast, you won't last very long with all the space dust, etc.

Strange. I would have thought we would at least have had some idea how to get from here to there in less than a million years.

That's because you have absolutely no scientific training.

[Asmodean]

Originally posted by KrazyHorse


That's because you have absolutely no scientific training.

Which of course isn't a crime in and of itself. You, however, have plenty, so perhaps offer an explanation?

Asmodean

[KrazyHorse]

Okay. Even if we had a 100% efficient way to accelerate objects in space (which we don't) accelerating a 13 ton spacecraft to 10% of the speed of light would require an equivalent amount of energy as the electricity consumption of the entire Earth for 1 year.

[Asmodean]

*sigh*

We really need that hyperdrive.

Asmodean

[Ramo]

These are such silly threads...

[Provost Harrison]

Originally posted by KrazyHorse


It depends on the radius of the planet.

GM/R^2

rewriting, 4piGdR^3/3R^2 = 4piGRd/3 (d the density)

or, we can write R = (3M/4pid)^1/3, so

(4pid/3)^2/3 * G * M^1/3

So, if planet X has mass 5 times that of the Earth, but both have equal mass densities, then planet X only has gravitational field (at surface) 5^1/3 = 1.7 times that of Earth's.

Is there an echo in here?

[Seeker]

"Okay. Even if we had a 100% efficient way to accelerate objects in space (which we don't) accelerating a 13 ton spacecraft to 10% of the speed of light would require an equivalent amount of energy as the electricity consumption of the entire Earth for 1 year."

Aren't you ignoring time here? That sounds like a Big Scary Number unless you realize that we'd be accelerating over 50-100 years.

Facetiousness aside (if possible...?) are you referring to my 'discovery' of radar?

[Geronimo]

Originally posted by Geronimo


I imagine the problem is how high are the energy requirements to actively scan for those objects every moment of the entire trip? At those speed in order for the laser to have time to lock on and vaporise anything it would probably be necessary to illuminate a vast volume ahead of the ship to spot the objects. Surely passive detection won't be of much use in the cold dark of interstellar space.

Hrmm I take this back.

the energy requirements to give even a full second of reaction time 24/7 the whole trip there are a tiny negligible fraction of the total mission energy cost. Hardly an important consideration it seems

[Geronimo]

Originally posted by Seeker
"Okay. Even if we had a 100% efficient way to accelerate objects in space (which we don't) accelerating a 13 ton spacecraft to 10% of the speed of light would require an equivalent amount of energy as the electricity consumption of the entire Earth for 1 year."

Aren't you ignoring time here? That sounds like a Big Scary Number unless you realize that we'd be accelerating over 50-100 years.

Facetiousness aside (if possible...?) are you referring to my 'discovery' of radar?

Given that he refers to electricity consumption of the entire earth for 1 year I don't understand how he could have been ignoring time.

Spreading the requirement over 100 years certainly won't change the total mission requirement for fuel (either aboard the vessel or in some sort of 'ground based' system like a light sail).

In fact the more you spread it out the less benefit you get in terms of mission duration.

it seems to me we can't make the big scary number go away we can just trade it for other big scary numbers like mission duration.

The big scary number in the middle of it all is insane distance

[Seeker]

A power stations output in a single year is only a fraction of the earth's total power output...but that same station, over a thousand years (or whatever time length) can generate 'the earths total power output for year X'.

So if we accelerate slowly, yes we still have to use the 'earths total electrical output for a year' but only in bite-sized increments over time.

I'm not saying we can AVOID the power requirement I'm saying we can spread it out and make it manageable.

I mean, the power output for me to travel from LA to NY in 25-30 minutes would be astronomical, but if I walked....it would take forever, probably use about the same amount of energy, but it is feasible.

Basically we have to crawl instead of run.

What we really need to do is just test a few unmanned vehicles for a few decades in the I.M. to find out all these numbers we don't know like particle density, etc, and to see how fast we can reasonably go.

The big question: What is the top speed humans can travel relatively safely, assuming we gather fuel along the way, and that particle collision is taken care of using some means?

[Kuciwalker]

So if we accelerate slowly, yes we still have to use the 'earths total electrical output for a year' but only in bite-sized increments over time.

Not true...

[GePap]

I will be all kinds of amazed if by the time I die, assuming I meet the average life expectancy of an American male, humanity has created semi-permanent or permanent settlements on Mars.

I seriously doubt that by 2100 mankind will have sent ANY interstellar craft, and certainly nothing manned.