It really was 40 years ago...

Preferrably a different planet. Or solar system.

Phil

 

That wasn't quite forty years ago.

 

You want to talk to Ginge about that.

 

Still totally impractical for the distances involved.
Ion drives still require a reaction mass, and interstellar travel would
require enormous quantities.

 

Lovely crease-free finish, though.

 

So we need a spaceship big enough for 4bn people with enough resources
to sustain them for *years* and enough fuel to propel the thing for
years. It would have to be as big as a planet! Oh...

And anyway, can you imagine how miserable it would be? I've never
been on a cruise, because I think that a week with a thousand people
in close proximity would be bad enough...*ugh*

I'm cool with that.

I'm cool with that, too.

 

I've seen that Arnie movie, I know it can be done, so there.

 

Have a look here:

http://www.marsroverblog.com/discuss-31715-alpha-centauri-probe.html

 

Exactly. That Lunar Lander, what an ugly beast. Why, a good shoe or
handbag guy could have cleaned that right up and appealed to the
shoe-buying public immediately.

 

Actually, I doubt it. The private companies whinge about what NASA
does but nothing's stopping them doing better. Bar thermodynamics.

 

Not released until November '69, it's true, but apparently written
sometime in 1968.

 

Maybe the teacher was a ukrmer.

 

You must have been a barrel of laughs in RE lessons.

 

Oh christ, I'd completely forgotten the ghastly experience of taking a
dump in the Chimay jazz loo, then stepping out of it with sticky
toilet paper stuck to my shoe.

Bleuch.

 

On Tue, 21 Jul 2009 13:10:47 +0200, Phil Launchbury

[...]

It's about par on saying that we could built a cross-Atlantic highway,
all it would take is *vast* amounts of cash.

I know of ion drives. They have high specific impulse but for relativistic
speeds you still need insane mass ratios. And insane amounts of power.
Ion engines are not magical solutions for low-mass ratio space travel.

Let's do some math: 10% of lightspeed is 29 979 245.8 m/s. Now, let's
assume
an ultra-lightweight starship of 10 000 kg. The kinetic energy of such a
starship is (clickety click wolfram alpha go!) 8.9875518x10^18 J.

This means that to accelerate to 10% of lightspeed using 100% efficient
ion engine you need a bit less than 9 exajoules. And then, 9 exajoules
to slow down. Of course, the ion engine will not be 100% efficient. Using
current technology we can build 70% efficient ion engines, so you really
need more like 18 exajoules of juice to accelerate and decelerate,
a cooling system capable of dealing with 8 exajoules of waste heat, oh,
and a power source capable of supplying 26 exajoules of energy throughout
its entire lifetime.

This is a ship-borne powerplant which is capable of producing 7200+
terawatt-hours throughout its entire life, without fuel replacement.
What "current day technology" is this?

Wikipedia says that the total energy usage of the world in 2005
was 500 exajoules, with 80-90% of it coming from the burning of fossil
fuels. If we had such a current day technology, we would use it.

Also, I really doubt you could make an ion-engine powered starship capable
of any significant acceleration and at the same time large enough to carry
passengers through interstellar space. It's the question of drive power
density. There are also the small unsolved issues of radiation shielding,
protection against relativistic dust, life support and technical
maintenance
systems capable of working reliably without any support from Earth for tens
of years etc.

The devil is in the details. In this case, the details are "how to
manufacture
nuclear-powered aircraft carrier when you have only built the Monitor
recently".
There's no know-how, no practical experience, no shipyards, we don't have
the
lift capacity to even start thinking about being capable of building such a
monstrosity and so on. You can't solve this by just throwing money at
things.

If a significant fraction of the world's economy would be dedicated to the
task,
there's a chance we could build a working starship in half a century or
so. Nuke-powered,
something akin to Project Orion or Daedalus. A small chance, IMO. And it
would disrupt
lots of things, including possible scientific advances in other avenues of
technology
which could provide cheaper space access.

Leslie

 

The very same loons will flock to see a film about the demolition of
Building 7, WTC, and come out saying, "Told you so, that's how it was
done, but they erred a bit in the detail."

 

Look, ffs, SF authors hammered this out decades ago.

Ramscoops, see?

 

They are (and often do), which is why during their training teachers are
warned to avoid sarcasm.

 

Aye, but how many people had heard those allegations before the film came
out?

--
| |What to do if you find yourself stuck in a crack|
| |in the ground beneath a giant boulder, which you|
| |can't move, with no hope of rescue. |
| Andrew Halliwell BSc |Consider how lucky you are that life has been |
| in |good to you so far... |
| Computer Science | -The BOOK, Hitch-hiker's guide to the galaxy.|

 

The what?! They had a special toilet for that, did they?