h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

1 .The calculation of the lawson criterion determines the conditions required to achieve nuclear fusion. The conditions to fuse protons to each other are up to a thousand times more extreme then those required to fuse dueterium, and tritium, and the reaction proceeds
to slowly to be practical for artificial proton fusion reactors.

2. By the 1980s there were a wide variety of methods other then chemical rockets availible that could have been used to get to mars.
We were going to send men to mars until the U. S. congress refused to fund the Nerva project to completion in 1973. To learn more about the nerva project look it up up on the internet. In 1965 Congress
refused to fund the Orion nuclear pulse rocket (The Orion project)
, and peaceful nuclear weapon explosions should have bee specificly exempted from the 1963 test ban treaty. Also look up the Orion project, and learn about it.

Nuclear powered and nuclear propelled spaceflight is the
means to explore, and colonize the whole solar system economicly, and quickly . This nuclear spaceflight technology has been
availible for use since the 1950s.

Only radical liberal poltiticians , radical enviromentalists,
radial anti-nuclear activists, and other far left politicians
have prevented this from being done.

Like I said the problem is only one of politics. We have
already had all the technology , we need to do all the things mentioned above since the 1950s, including starflight at up
to .10 C by means of Orion nuclear fusion pulse rockets.

If you wish to discuss the Design of manned mars expeditions,
and the designs of manned interplanetary spaceships in general
, I would be happy to discuss this here.
Tim

Howdy, I am a 15 year old who is taking college courses in NJ. I am currently writing a paper for the Dupont Challenge, and I chose my topic as Bussard Ramjets, as they have always facsinated me ever since I read Larry Niven's Ringworld Trilogy. I have already acquired a considerable amount of information, and I would be most obliged if I could check this information with either or both of you. Thanks! You can drop me a line at [email protected] or my AIM name is Beumaster. Thanks!
-Dave

Dave,

Hi! Welcome to h2g2!

As regards br's, as I'm sure you can read for yourself, there's a degree of disagreement between myself and Tim (or 197681 as I like to call him), which I think is mainly based around the fact that

(a) Tim seems to actually want to BUILD one of these things within a human lifetime, in which case we've got some pretty strong technical problems to overcome and
(b) I seem to be a LOT more optimistic than him about the eventual level of our technology.

If you've any questions, pose them here - that way Tim and I can both see them, both respond to them, and everyone else gets the benefit of the interchange. OK?

H.

Thanks. My first question is whether or not space in our solar system is denser than space outside our solar system. I believe it is, and when I asked my fizix teacher he said I was correct. I would just like to see what you guys think. Because I read somewhere that a ramjet would have to travel at about .06c if it's scoop was rated at about 10 million tesla. I was wondering if that was from density of space in our out of the solar system? Unless I'm completely out of line, in which case I'm sorry. I just think that if we have all these bodies of gravity here, that would attract more matter. Any input would be most appreciated. I'll post more questions as I think of them, and maybe even a rough draft or finished product to show you guys how helpful you've been. Don't worry, I will cite you guys and this site. If I win, I'll be sure to give you guys special mention or something. Heh, I might even see Tim. The grand prize is a trip to Texas. Thanks.
-Dave

TIM! Bang Bang is futzy radioactive! You'd have to eject what, 5 bombs a second to get going? Granted, that sucker will move, but the crew would be dead, and the ship would be nothing more than a twisted piece of metal!

OK, fairly quick answer - yes, the hydrogen is denser in interplanetary space than it is in interstellar space, and is denser in an arm than in the interstices, and is denser in the galaxy than in intergalactic space.

The figure I've seen is one atom per cubic centimetre, but I don't know whether that refers to interplanetary, interstellar or intergalactic space - my money's on interstellar though.

Have you read "Tau Zero"? Because if you haven't, you should.

H.

I haven't, but I will now. Thanks. Book, essay, article? Who's the author?

You did read the article this conversation is attached to, yes? Section titled "Bussard Ramjets in Science Fiction"? Opening sentence of that section... "Tau Zero by Poul Anderson is the quintessential ramjet story."

It's usually in print - try your favourite online bookstore named after a huge South American river...

H.

Alright, I'm currently working on acquiring Tau Zero, should have it by about Wednesday. In the meantime, I have another question. The ramjet would actually have to carry some fuel with it in order to get it going at let's say .06c so the scoop would work. I suppose it could use it's fusion motor to do this, but it would have to have a sufficient fuel supply to do so. Ergo, it would have to have some sort of fuel pods. I was wondering how they would store the deuterium? Deuterium slush, as in Star Trek, or a giant ice ball, as the space ship Geographic did in "The Legacy of Heorot" and "Beowulf's Children" by Niven, Pournelle, and Barnes? I figure they'd get it from the Earth, seeing it as we have these huge bodies of water called oceans...

There's other ways of building up to ramming speed than carrying your fuel with you. You're probably better off asking Tim, actually, but he seems to be here quite sporadically, so I'll start you off with a suggestion I made further up the thread, namely:

Lasers. You build a thudding great laser on or around Mercury, focus it with something or other in one of the Moon's trojan points (L4? can't remember) and pump power into the ship remotely. That way you don't need to carry fuel, even for the accelerating part of the trip. You decelerate against the light off the destination star, assuming you've got a star as your destination, or there are other rather clever ways to decelerate without using much fuel. So, in the end, all you end up needing is what amount to maneouvering thrusters, and unless you want to do a LOT of maneovering, chemical rockets would do just fine. I must look up that power pumping method so I can tell you more about it....

H.

Thanks, I'll look into that as well. But now I'm pissed. Futzy Adobe is giving me issues about reading E-Books on my laptop and customer service won't help me because I somehow violated the user agreement that NOBODY ever reads and they now it and I'm about to kill something. God, that felt good. So, I don't know if I'll ever get Tau Zero, but I've managed to find some equations for a ramjet, and some diagrams. If you'd like, I could put in links to the site and you could check 'em out. Sorry it's taken so long to respond, I've been kinda busy.
-Dave

Manned mars missions with a D100 class spacecraft.

Here is an economical and practical plan for a
small 100 ton popup Interplanetary space vessel.

1. The 100 ton craft is launched into leo as the 2nd or
third stage of a Saturn 5 or Energia class chemical
propelled heavy lift rocket.

2. Here is the plan.
The Lift-off weight on the launch pad is 6,000,000
pounds. There are two 3/1 mass ratio stages that burn
H2 + O2 = H20. Both stages have a specific impulse of
450 seconds. The vehicle is made completely of Titanium
metal.

3. Stage 1 weighs 4,800,000 pounds.
It has 5 1,600,000 pound thrust engines that produce a
lift-off thrust of 8,000,000 pounds. The engines and
the fuel tanks weigh 800,000 pounds. Stage 1 has
4,000,000 pounds of H2 and O2 for fuel.

Stage 2 weighs 960,000 pounds.
It has 800,000 pounds of O2 and H2
for fuel. It has two 450,000 pound thrust
engines. The weight of the fuel tanks and
the engines is 160,000 pounds.



Stage 3 weighs 240,000 pounds. It has a 2/1 mass
ratio. It is propelled by a nuclear electric ion
ion drive. It uses 120,000 pounds of liquid hydrogen
as the ion propellant. This is 120 tons

This is stored in a 24,000 pound titanium tank.
The 120 ton ship is powered by a 20,000 pound nuclear fission
reactor that has a specific power A of 1000,watts per
pound of its weight. The total nuclear reactor power is
20 megawatts . The ion engine could be one large 10 meter
diameter model or up 100 smaller ion engines in a cluster.

This leaves about 66,000 pounds of weight availible
for a 15 to 20 ton crew module and and A possible
10-15 ton Mars Excursion module that could land people
on mars, or on another celestial body of the solar system.
A million pound ship could be made by linking about
4 of these 120 ion drive modules together if want a bigger ship
then 120 tons
Timothy J Mayes

By the kinetic energy formula 20 megawatts
of electric power will suffice to accelerate
1 gram of ion propellant mass per second
too an exchaust velocity of 200 kilometers per
second in an ion drive.

At a mass ratio of 2/1 the ion drive stage
can achieve a velocity of about 140 kilometers per
second if it uses all its ion propellant up.

By the rocket thrust equation this will
generate about 1320 pounds of thrust for the ion
drive. According to F=Ma this will accelerate
the ion drive ship at about 5.5 * 10 to the -3
Gs.

The ion drive ship will begin its journey after
being launched into leo by a chemical heavy
lift booster. It needs 3 km/sec in leo for a mars
mission. It would take about 7 days to reach this
velocity after the ion drive is turned on.

If we devide the 140 km/sec by 4 we can thus
achieve a round trip velocity of 35 kilometers
per second on a round trip interplanetary flight.
This is about 78,000 miles an hour.

Assuming a launch cost of 10,000 U S, dollars per
pound of weight it would cost 2,400,000 ,000 dollars for
a 120 ton ship and about 10,000,000,000 dollars
for a million pound ship.

Indeed. But we will never truly advance until we can eliminate Capitalism and Communism! And are all binded together into a planetary Gaia. Telepathic unification! Yeah!

So, the formula for calculating the acceleration is....
a = pi(r^2)*(that weird "p" looking symbol which means the density per unit value)*(some symbol that looks like "N" which means the efficiency of nuclear fusion, which is .753%)*c^2/M
Right?
-Dave

The Most efficient fusion reaction converts about
.7% of the mass into energy. That is why A fusion
rocket engine can generate a maximium exchaust
velocity of about .089 C ( 27,000 km/sec )

The best, and most practical fusion rocket fuel
is lithium 6 duteride. Lithium 6 and lithium 7
can be used to manufacture Tritium in nuclear
reactors. In an inertial confinement fusion system the
neutrons released by Dueterium + Dueterium fusion
will convert the the lithium 6 or lithium 7 into
tritium. The tritium will then undergo fusion with
the dueterium. Lithium can be mined from a wide variety
of celestial bodies in the universe.
Tim

There are several different methods of accelerating
a ramjet vessel up to ramjet take over velocity.
Here are some of them:
1. Nuclear electric ion or plasma drives.

2. Orion nuclear bomb powered pulse drives.

3. Deadalas class fusion microexplosion drives.

4. Antimatter rockets.
5. Ican class nuclear microexplosion pulse drives.
6. Solar sails

A ramjet spacecraft only requires a minimuim ramjet take
over velocity of about 30 kilometers per second, above solar
system escape velocity.

A ramship has two drives. These are the rocket propulsion
system of the vehicle, and the ramjet propulsion
part of the vehicle.

The maximium exchaust velocity that a given rocket fuel
can generate in a direct thrust rocket drive is =
the sqaure root of the fraction of the fuel's mass
that is converted into energy multiplied by the speed
of light in meters per second.
For the most energetic nuclear fusion reaction
for example: The Ve max = the sqaure root of
.0079 * the velocity of light
sqaure root of .79 * C = .089 C
where C = light velocity in meters per second.
For fission Ve max = the sqaure root of .001 *
C = .03 C

For H2 + O2 = H2O
Ve max = the sqaure root of .000,000,003 * C =
5 kilometers per second .

For matter antimatter annhilation Ve max =
the sqaure root of 1.0 * C = C (light velocity)
Tim

In one case I say sqaure root of .79 but
that is a typo. What I really mean is the sqaure root of
.0079 * C for the fusion maximium Ve (exchaust velocity)
Tim

The ramjet eqautions can all be found in a book called
" The Star flight hand book,A pioneers guide to
interstellar travel" by Eugene Mallove, and Gregory
Matloff copyright 1989 . There is also a lot of other
good, and accurate information in this book about star
flight topics.
TIm