Atomic ramjet for exploring Titan

On Apr 2, 7:31*pm, BradGuth wrote:
On Apr 1, 5:25*pm, wrote:



On Mar 30, 5:07*pm, BradGuth wrote:

On Mar 29, wrote:

You are a freaking lunatic! *You don't read a freaking thing with any
understanding *Who gives a damn if you freeze it or liquefy it? *You
won't get any usable beta rays from the center of anything thicker
than a micron - even if its pure radon. *A ball bigger than a micron
will absorb most of its energy inside the body of stuff and heat up..

Didn't you look at the cost of the stuff? *$4 per millicurie means 1
kg costs TRILLIONS of dollars. *What does that tell you about the
world's supply of Radon? *You'd need to build a special reactor - to
make whatever you needed. *You'd spend BILLIONS of dollars if you're
lucky. *Then what do you have? *NOTHING!

Radioactive decay is constant and in 20 days drops to nothing. *What
does that tell you? *Activity is LOW to start out with - LESS THAN
1/300th gee and drops to nothing thereafter. *WHAT DOES THAT TELL
YOU? * Beta rays have a mean free path of a micron before losing
essentially ALL THEIR ENERGY what does that tell you?

Sheez

You can't get more than 1 km/sec under even the most ideal
circumstances, the costs are absolutely horrendous and you can't use
the stuff for a return journey.

Radium has the half-life of 1650 years, as it continually gives of
Rn222. *How far are you planning on going?

Adding a good deal of Rn222 ion thrust, or if you'd like to use inert
xenon, mercury or lead ions, to a craft that just zipped itself past
our Selene/moon at 60 km/s seems kind of a good thing, especially if
that half-life supply of ions is good for 1650 years.

Extracting large amounts of radium from our Selene/moon shouldn't
hardly be any bother at all, as perhaps a unavoidable byproduct of
extracting He3. *Terrestrial radium is only spendy because of
systematic hording by the kinds of profit taking and dollar inflating
folks you so admire.

As I'd said before, using that arc-jet thruster could otherwise burn
damn near anything that can be directly zapped or laser vaporized.

btw, *we don't see your stuff (terrestrial or off-world) going
anywhere. *What does that tell us?

*~ BG

So, all you have to do is carry Radium around with you right?

HOW MUCH?

Figure that out and you will see that your performance is reduced.

You're not going anywhere dude. *You don't get it.

Power level is equivalent to thrust.

Power level is inversely proportional to the natural rate of decay of
an isotope.

So, something that decays over 1,602 years has far far far less power
than something that decays over a few days so has far far far less
thrust.

To make a nuclear rocket you need a nuclear reaction - fission or
fusion or some sort of exchange reaction that can be arbitrarily
powerful.

Check it out - we said a kg of radon 222 would generate something like
10 MW - and if you spread it in a thin film less than a micron thick,
you could get usable thrust out of it - at about 1/300th gee - if all
you pushed around was radon 222. *Add things like the film to hold it
in place and reflector and payload - and you're down to 1/600th gee -
and in the 20 days you have any sensible thrust, you'll add about 1 km/
sec to the delta vee.

There are 32 isotopes of Radium and only Radium 226 decays to Radon
222 and an alpha particle.

Now you come along and say hey hey hey, Radium produces Radon 222 -
well ONE of the 32 isotopes of Radium produces Radon 222. *So, lets
get that isotope and make Radium at just the rate it is decaying down
- that way we have a continuing supply since it has a half life of
1,602 years!! * Fine - HOW MUCH RADIUM DO YOU NEED TO PRODUCE RADON
222 AT THAT RATE?

Well, we showed before that with a half life of 3.8235 days - or
330,350.4 seconds - means a kg of Radon 222 will disintigrate at a
rate of 1.263e+21 atoms per second.
Radium 226 has a half life of of 1,602 years, that's 50,555,275,200
seconds - this means a kg of Radium 226 will disintigrate at a rate of
8.254e+15 atoms per second.

That means to maintain a constant supply of 1 kg of Radon 222 using
the method you suggest requires that we carry around 1.263e+21/8.254e
+15 = 153,036 kg of Radium 226, with no increase in the power of the
radium jet!

So, that means with thrust being equal, we've just reduced the
acceleration by a factor of 153,036 - and didn't increase delta vee
one iota! *Just the cost by a factor of 153,000!!!

By the way Brad, none of the isotopes are stable, they all decay from
other materials and are present in the environment. *So they are very
rare which means they're very expensive. *A single milli-curie of
Radon 222 is $4 - this means 1 kg of the stuff if you could get that
much (which you cannot) would cost several TRILLION DOLLARS!

For someone who ridicules me for costly impractical things - you take
the cake.

The other isotopes are given below

nuclide
symbol *Z(p) * *N(n)
isotopic mass (u)
* * * * half-life * * * nuclear
spin * *representative
isotopic
composition
(mole fraction) * * * * range of natural
variation
(mole fraction)
excitation energy

202Ra * 88 * * *114 * * 202.00989(7) * *2.6(21) ms [0.7(+33-3) ms] * * *0+
203Ra * 88 * * *115 * * 203.00927(9) * *4(3) ms * * * * (3/2-)
203mRa *220(90) keV * * 41(17) ms * * * (13/2+)
204Ra * 88 * * *116 * * 204.006500(17) *60(11) ms [59(+12-9) ms] * * * *0+
205Ra * 88 * * *117 * * 205.00627(9) * *220(40) ms [210(+60-40) ms] * * (3/2-)
205mRa *310(110)# keV * 180(50) ms [170(+60-40) ms] * * (13/2+)
206Ra * 88 * * *118 * * 206.003827(19) *0.24(2) s * * * 0+
207Ra * 88 * * *119 * * 207.00380(6) * *1.3(2) s * * * *(5/2-,3/2-)
207mRa *560(50) keV * * 57(8) ms * * * *(13/2+)
208Ra * 88 * * *120 * * 208.001840(17) *1.3(2) s * * * *0+
208mRa *1800(200) keV * 270 ns *(8+)
209Ra * 88 * * *121 * * 209.00199(5) * *4.6(2) s * * * *5/2-
210Ra * 88 * * *122 * * 210.000495(16) *3.7(2) s * * * *0+
210mRa *1800(200) keV * 2.24 µs * * * *(8+)
211Ra * 88 * * *123 * * 211.000898(28) *13(2) s * * * * 5/2(-)
212Ra * 88 * * *124 * * 211.999794(12) *13.0(2) s * * * 0+
212m1Ra * * * * 1958.4(5) keV * 10.9(4) µs * * (8)+
212m2Ra * * * * 2613.4(5) keV * 0.85(13) µs * *(11)-
213Ra * 88 * * *125 * * 213.000384(22) *2.74(6) min * * 1/2-
213mRa *1769(6) keV * * 2.1(1) ms * * * 17/2-#
214Ra * 88 * * *126 * * 214.000108(10) *2.46(3) s * * * 0+
215Ra * 88 * * *127 * * 215.002720(8) * 1.55(7) ms * * *(9/2+)#
215m1Ra * * * * 1877.8(5) keV * 7.1(2) µs * * *(25/2+)
215m2Ra * * * * 2246.9(5) keV * 1.39(7) µs * * (29/2-)
215m3Ra * * * * 3756.6(6)+X keV * * * * 0.555(10) µs * (43/2-)
216Ra * 88 * * *128 * * 216.003533(9) * 182(10) ns * * *0+
217Ra * 88 * * *129 * * 217.006320(9) * 1.63(17) µs * *(9/2+)
218Ra * 88 * * *130 * * 218.007140(12) *25.2(3) µs * * 0+
219Ra * 88 * * *131 * * 219.010085(9) * 10(3) ms * * * *(7/2)+
220Ra * 88 * * *132 * * 220.011028(10) *17.9(14) ms * * 0+
221Ra * 88 * * *133 * * 221.013917(5) * 28(2) s * * * * 5/2+
222Ra * 88 * * *134 * * 222.015375(5) * 38.0(5) s * * * 0+
223Ra * 88 * * *135 * * 223.0185022(27) * * * * 11.43(5) d * * *3/2+
224Ra * 88 * * *136 * * 224.0202118(24) * * * * 3.6319(23) d * *0+
225Ra * 88 * * *137 * * 225.023612(3) * 14.9(2) d * * * 1/2+
226Ra * 88 * * *138 * * 226.0254098(25) * * * * 1600(7) y * * * 0+
227Ra * 88 * * *139 * * 227.0291778(25) * * * * 42.2(5) min * * 3/2+
228Ra * 88 * * *140 * * 228.0310703(26) * * * * 5.75(3) y * * * 0+
229Ra * 88 * * *141 * * 229.034958(20) *4.0(2) min * * *5/2(+)
230Ra * 88 * * *142 * * 230.037056(13) *93(2) min * * * 0+
231Ra * 88 * * *143 * * 231.04122(32)# *103(3) s * * * *(5/2+)
231mRa *66.21(9) keV * *~53 µs * * * * (1/2+)
232Ra * 88 * * *144 * * 232.04364(30)# *250(50) s * * * 0+
233Ra * 88 * * *145 * * 233.04806(50)# *30(5) s * * * * 1/2+#
234Ra * 88 * * *146 * * 234.05070(53)# *30(10) s * * * *0+

Whatever, as per usual, your insurmountable mindset is noted.

I merely report reality - my mindset has nothing to do with it. What
you say can be done cannot be done because it is impossible to do in
the way you describe it. I have told you this time and time and time
again. You don't get it. You don't get it because you are
monumentally ****ing stupid, a moron, an idiot, someone too proud to
even take an interest in learning becaue to learn a thing you'd have
to admit you didn't know something in the first place, and this you
are uprepared to do - so you sail blithely on totally ignorant of
anything.

Why not a Nuclear/h2o2 thruster?

What the hell does that mean? What is the power level? That will
determine thrust. What is the exhaust speed? That will determine
propellant fraction to achieve a given final speed.


*http://www.astronautix.com/engines/rd0410.htm

This is not the sort of rocket you described originally. So, now
you're asking me to do another analysis. You have yet to admit you
were wrong in the first analysis. Admit you were wrong and never ever
bring it up again - and I will look into a radioisotope thermal rocket
for you - but without at least having the courteousy of acknowledging
where you are wrong - **** you. haha..

How hot can my radium reactor be made to get?

Jesus - 10 MW per kg - Put a kg of the gas in a ball 1/2 meter in
diameter. That's a ball 0.79 m2. Its radiating 10 MW - that's 12.8
MW/m2 - Stephan Boltzman says

T = (12.8 / 5.67e-8)^(1/4) = 3,868.6 K

Can you convert from Kelvins to Centigrade to Fahrenheit?


That's a different sort of rocket - that's a nuclear thermal rocket.
Temperature determines exhaust speed. Power determines thrust.
Simple thermodynamics relate the two if you are power limits. 10 MW
per kg AT THE OUTSET. IT drops to 1/16th that figure in 20 days.

Add 158 tons of Radium and lower the effective velocity and thrust to
weight by 153,000x - better to build a reactor and be done with it -
Less costly, more controllable, and more efficient, and more capable -
to use a nuclear reactor to power your nuclear thermal rocket.


*~ BG