The Ion Interstellar Spaceship, from Hell to Sirius

Taking further note, that radon gas has been officially identified as
the primary cause of 21,000 lung cancer deaths per year in America
alone, and we're not even as nearly at risk as other more radium/radon
saturated areas around the planet, thereby we can safely extrapolate
our 21,000 deaths caused by radon to a global annual death via such
lung cancer impact rate of 462,000 per year, especially of
populations having to live on or worse yet below ground level, not to
mention having to work in poorly ventilated mines. In epidemic or
pandemic terms, even 462 global deaths/year from a recently discovered
toxin or nasty microbe should be extremely alarming, but oddly 462,000
deaths/year after year from the direct affects via radium/radon trauma
is not given so much as a mainstream hoot worth of consideration,
except of whatever's of less than 0.01% of the global population
apparently doesn't count as long as the fossil and yellowcake industry
gets to go on its marry way. Perhaps if Radon were given the same
attention as the drug-resistant MRSA Staphylococcus or of that hybrid
TB, as such we could see a positive trend towards nailing down these
preventable public exposures to Radon that's anything but DNA
friendly.

Of course our relentless fossil fuel drilling extractions, of mining
fossil solids and of various transporting, processing and the final
consumption that unavoidably deposits such raw elements as radium and
thus places a continuous supply of radon production into our surface
environment, via the mostly invisible soot of combustion that includes
CO2 and NOx that's laced with picoscopic but still lethal particles of
radium/radon isn't exactly helping, especially since little if any
efforts are made to extract hardly any of the radium prior to
combustion or even much less from the vest bulk of exhaust which
covers and unavoidably pollutes our entire global environment from sea
to sea and from top to bottom, as well as global dimming and boosting
those levels of CO2 and NOx.

So, it's all rather odd that the all-knowing folks like our William
Mook (aka willie.moo) seem as though entirely unconcerned as to these
artificially introduced toxins of radium/radon, that represents such a
well-known lung cancer causing element that's existing in nature as
well as getting so freely exposed and even pumped into our frail
environment, instead of such radium being easily identified, gathered
up and properly utilized in a perfectly safe and highly energy
efficient application on behalf of ion thrusters. Of course the same
argument of our policy of having ignored the "waste-not want-not"
aspects of 3He that's also continually going to waste, all because it
too hasn't been extracted from surface minerals or from fossil fuels
prior to their consumption and mostly unfiltered exhaust, that which
merely vents all such 3He into our polluted atmosphere. Another
undesirable element that's polluting our environment and killing us
off is good old mercury, of which this too could be utilized as a
inactive or passive resource of ions.

Is it just myself that cares about the future of humanity and of most
all other life on Earth, via salvaging our frail environment that's
getting itself industrially traumatized before our mostly "no child
left behind" dumbfounded nation of village idiots, while at the same
time doing perfectly good and nifty off-world things with radium/radon
and even mercury?
. - Brad Guth


On Apr 16, 1:00 pm, BradGuth wrote:
Rn222 atoms are another one of those pesky 'use it' or 'lose it' kind
of things. Seems whenever I do my best at uncovering the potential
worth of such matters, lo and behold shortly thereafter the Googol/
NOVA Usenet group server bites the dust. ("GOOGLE Server Error" I'm
terribly sorry about that)

In trying to accomplish my very own math without the help or supposed
good wisdom of the all-knowing likes of William Mook, whereas there
could be some unintentional errors or even somewhat dyslexic
consequences to my deductive but otherwise wishful mindset. So, with
your better math and expertise, perhaps contributing whatever comes to
your trained mind is what this topic of interstellar ion thrusting
needs.

If upon average there were merely 150e6 atoms of Rn222 per m3 of
air, seems to suggest that a good amount of Ra226 can't be all that
too far away. In places the intensity or occurrence of Ra226 that's
creating such atoms of Ra222 is of course much greater than 150e6/m3,
primarily because radon is a heavy gas is why it hugs the surface or
underground at much greater occurrence or population by a good hundred
fold = 1.5e10/m3, meaning that in many places the background raw
element of Radium(Ra226) is hard at work in the natural decay process,
as is naturally making enough Rn222 available for creating and
sustaining a good supply of commercial liquid radon (LRn222) for ion
thrust applications, into a very doable thing.

http://en.wikipedia.org/wiki/Radon
"At standard temperature and pressure, radon forms a monoatomic gas
with a density of 9.73 kg/m3, about 8 times the surface density of the
Earth's atmosphere, 1.217 kg/m3, and is one of the heaviest gases at
room temperature and the heaviest of the noble gases (excluding
ununoctium). At standard temperature and pressure radon is a colorless
gas, but when it is cooled below its freezing point (202 K ; -71 °C ;
-96 °F) it has a brilliant phosphorescence which turns yellow as the
temperature is lowered, and becomes orange-red at the temperatures air
liquefies (below 93 K ; -180 °C). Upon condensation, radon also glows
because of the intense radiation it produces."

"At standard temperature and pressure, radon forms a monoatomic gas
with a density of 9.73 kg/m3"

"Radon collects over samples of radium 226 at the rate of around 0.001
cm3/day per g of radium."

Therefore, per kg of Ra226 you'll get 1 cm3/day, and per tonne of
Ra226 you'll obtain a liter of Rn222 that's worth 9.73 mg, of which
doesn't sound like all that much until it's made to exit the ion
thruster a 0.5 c, or roughly 150,000 km/s = 219 TN.m or TJ
(teraJoules), or if you like 23.34e12 kgf.m of reactive force.

Taking this one down to the amount of available ion thrust as
formulated upon a continuous thrusting basis, as per fully utilizing
that amount of 9.73 mg in Rn222 that's being continually produced per
day from a given tonne of radium, that can then be made to produce
23.34e12 kgf.m, whereas if this reactive force were divided by 8.64e4
= 2.7014e8 kgf.s (same as 270.14 thousand tonnes of force per second),
of which can further suggest that we might not require nearly as much
Ra226 within the breeder reactor of what's creating LRn222, as you
might think.

Keeping in mind that a reactor core of merely one tonne of Radium
(Ra226) isn't even terribly volumetric, although a conventional
Thorium reactor as started up with a few rods of Pu238 would likely
have to go along for the ride, and as such it too creates a small
amount of Radium as the natural process of its decay. So, all and
all, there's hardly any shortage of those Rn222 atoms as becoming
nifty ions that our electrified thruster/laser cannons can toss out
the rear at the 0.5 'c' velocity of 150,000 km/s, eventually giving
us the potential 75,000 km/s worth of added trek velocity to our
interstellar craft or robotic probe(s).

Obviously the existing R&D as to this ion exit velocity is a good
thousand fold away from hitting the150,000 km/s mark. However, in a
laser cannon pumped format is where such highly energized ions of
Rn222 that can be so nicely and efficiently focused or aligned into
merging along with the laser beam formulated conduit, as such might
reach this goal, if not a little better.

This was another one of my 'use it' or 'lose it' mindset notions, as
to the likes of utilizing Radium and of the secondary Radon that's
already highly charged and going places as is. Seems a darn shame to
continually ignore or otherwise waste such a good thing.

If you can add a little something in the way of corrections or merely
being topic constructive and thus technically informative, have at
it.
. -BradGuth

Rn222 atoms are another one of those pesky 'use it' or 'lose it' kind
of things.

In trying to accomplish my very own math without the help or supposed
good wisdom of the all-knowing likes of William Mook, whereas there
could be some unintentional errors or even somewhat dyslexic
consequences to my deductive but otherwise wishful mindset. So, with
your better math and expertise, perhaps contributing whatever comes to
your trained mind is what this topic of interstellar ion thrusting
needs.

If upon average there were merely 150e6 atoms of Rn222 per m3 of
air, seems to suggest that a good amount of Ra226 can't be all that
too far away. In places the intensity or occurrence of Ra226 that's
creating such atoms of Ra222 is of course much greater than 150e6/m3,
primarily because radon is a heavy gas is why it hugs the surface or
underground at much greater occurrence or population by a good hundred
fold = 1.5e10/m3, meaning that in many places the background raw
element of Radium(Ra226) is hard at work in the natural decay process,
as is naturally making enough Rn222 available for creating and
sustaining a good supply of commercial liquid radon (LRn222) for ion
thrust applications, into a very doable thing.

http://en.wikipedia.org/wiki/Radon
"At standard temperature and pressure, radon forms a monoatomic gas
with a density of 9.73 kg/m3, about 8 times the surface density of the
Earth's atmosphere, 1.217 kg/m3, and is one of the heaviest gases at
room temperature and the heaviest of the noble gases (excluding
ununoctium). At standard temperature and pressure radon is a colorless
gas, but when it is cooled below its freezing point (202 K ; -71 °C ;
-96 °F) it has a brilliant phosphorescence which turns yellow as the
temperature is lowered, and becomes orange-red at the temperatures air
liquefies (below 93 K ; -180 °C). Upon condensation, radon also glows
because of the intense radiation it produces."

"At standard temperature and pressure, radon forms a monoatomic gas
with a density of 9.73 kg/m3"

"Radon collects over samples of radium 226 at the rate of around 0.001
cm3/day per g of radium."

Therefore, per kg of Ra226 you'll get 1 cm3/day, and per tonne of
Ra226 you'll obtain a liter of Rn222 that's worth 9.73 mg, of which
this doesn't sound like all that much until it's made to exit the ion
thruster a 0.5 c, or roughly 150,000 km/s = 219 TN.m or TJ
(teraJoules), or if you like 23.34e12 kgf.m of reactive force.

Taking this one down to the amount of available ion thrust as
formulated upon a continuous thrusting basis, as per fully utilizing
that amount of 9.73 mg in Rn222 that's being continually produced per
day from a given tonne of radium, that which can then be made to
produce 23.34e12 kgf.m, whereas if this reactive force were divided by
8.64e4 = 2.7014e8 kgf.s (same as 270.14 thousand tonnes of force per
second), of which can further suggest that we might not require nearly
as much Ra226 within the breeder reactor of what's creating LRn222, as
you might think.

Keeping in mind that a reactor core of merely one tonne of Radium
(Ra226) isn't even terribly volumetric demanding, although a
conventional Thorium reactor as started up with a few rods of Pu238
would likely have to go along for the ride, and as such it too creates
a small amount of Radium as the natural process of its decay. So, all
and all, there's hardly any shortage of those Rn222 atoms as becoming
nifty ions that our electrified thruster/laser cannons can toss out
the rear at the 0.5 'c' velocity of 150,000 km/s, eventually giving
us the potential 75,000 km/s worth of added trek velocity to our
interstellar craft or robotic probe(s).

Obviously the existing R&D as to this ion exit velocity is a good
thousand fold away from hitting the150,000 km/s mark. However, in a
laser cannon pumped format is where such highly energized ions of
Rn222 that can be so nicely and efficiently focused or aligned into
merging along with the laser beam formulated conduit, as such might
reach this goal, if not a little better.

Keep in mind that this concept was another one of my 'use it' or 'lose
it' mindset notions, as to the likes of utilizing the 1650 half life
of Radium and of the secondary Radon that's already highly charged and
going places as is. Seems a darn shame to continually ignore or
otherwise waste such a good thing.

If you can add a little something in the way of technical or math
corrections, or merely being topic constructive and thus technically
informative, have at it.
. - Brad Guth

For what it's worth, the "Ion Interstellar Spaceship" topic/rant is
not about another method of putting stuff into LEO, or even for
getting whatever to/from our moon's L1, not that some degree of
reactive thrust via ions couldn't be so accommodated without ever
hurting a terrestrial flea.

Much the same as 3He, Rn222 atoms are yet another one of those pesky
'use it' or 'lose it' kind of things. However, it seems whenever I do
my best at uncovering the potential worth of such matters, lo and
behold shortly thereafter the Google/NOVA Usenet group server bites
the dust ("GOOGLE Server Error") and for the most part I'm terribly
sorry about that, or that my topics attract the likes of those Semitic
Third Reich actions from all the pretend-atheists overreacting in
their usual brown-nosed clown like swarm of killer-bee intentions.

With passive xenon ions accelerated to the exit velocity of 48 km/s,
as based upon an acceleration charge of merely 1.58 KeV, by itself
seems to suggest that taking advantage of the existing 5.6 MeV charge
of the Rn222 ion is (if all other things being equal) going to yield
170,019 km/s, of which this is unlikely since the Rn222 ion has
considerably greater mass, plus the matter of 0.5'c' should become the
upper most threshold as to how fast of an ion exit velocity can be
artificially achieved without the use of antimatter or that of having
to create artificial black holes.

Unlike a frozen mass of xenon, Rn222 atoms are clearly another one of
those pesky 'use it' or 'lose it' kind of things, with less than a 4
day half-life doesn't exactly give whatever cache of LRn222/Rn222 a
good shelf life. But that doesn't mean or much less require that such
a supply of Rn222 should be continually ignored and otherwise freely
disposed of.

In trying to accomplish my very own math without the help or supposed
good wisdom of the all-knowing likes of William Mook, whereas there
could be some unintentional errors or even somewhat dyslexic
consequences to my less than perfect sense of deductive but otherwise
wishful mindset. So, along with your better math and expertise,
perhaps contributing whatever comes to your trained mind is what this
topic of interstellar ion thrusting needs.

If upon average there were merely 150e6 atoms of Rn222/m3 of air,
seems to suggest that a good amount of Ra226 can't be all that too far
away. In places the intensity or occurrence of Ra226 that's creating
such a continuous supply of Ra222 is of course much greater than 150e6/
m3, primarily because the element of radon represents itself as a
heavy gas is why it hugs the surface or keeps itself underground at
much greater occurrence or population by a good hundred fold = 1.5e10/
m3, meaning that in many places the background raw element of
Radium(Ra226) is hard at work in the natural decay process as is,
making enough Rn222 atoms available (as great as 1e12/m3) for creating
and sustaining a good supply of the commercial liquid stored radon
(LRn222) for ion thrust applications into a very technically doable
thing, especially if enough LRn222 could be made available for the
upper or 3rd stage on behalf of safely getting large amounts of
tonnage away from LEO.

http://en.wikipedia.org/wiki/Radon
"At standard temperature and pressure, radon forms a monoatomic gas
with a density of 9.73 kg/m3, about 8 times the surface density of the
Earth's atmosphere, 1.217 kg/m3, and is one of the heaviest gases at
room temperature and the heaviest of the noble gases (excluding
ununoctium). At standard temperature and pressure radon is a colorless
gas, but when it is cooled below its freezing point (202 K ; -71 °C ;
-96 °F) it has a brilliant phosphorescence which turns yellow as the
temperature is lowered, and becomes orange-red at the temperatures air
liquefies (below 93 K ; -180 °C). Upon condensation, radon also glows
because of the intense radiation it produces."

"At standard temperature and pressure, radon forms a monoatomic gas
with a density of 9.73 kg/m3"

"Radon collects over samples of radium 226 at the rate of around 0.001
cm3/day per g of radium."

Therefore, per kg of Ra226 you'll get 1 cm3/day, and per thousand kg
or per tonne of Ra226 you'll obtain a liter of Rn222 that's worth 9.73
mg, of which this doesn't sound like all that much until it's made to
exit the ion thruster a 0.5 c, or roughly 150,000 km/s = 219 TN.m or
218 TJ (teraJoules), or if you like 23.34e12 kgf.m of reactive force.

Taking this argument down to the amount of available ion thrust as
formulated upon delivering a continuous thrusting basis, as per fully
utilizing that amount of 9.73 mg in Rn222 that's being continually
reproduced while on the fly per day from a given tonne of radium, that
which can then be made to produce 23.34e12 kgf.m, whereas if this
reactive force were divided by 8.64e4 = 2.7014e8 kgf.s (same as 270.14
thousand tonnes of force per second), of which can further suggest
that we might not require nearly as much Ra226 within the breeder
reactor of what's creating LRn222 as you might think, even if our
interstellar spacecraft combined mass were that of 270,000 tonnes is
still suggesting one gee worth of continuous acceleration.

Keeping in mind that a reactor core of merely one tonne of Radium
(Ra226) isn't terribly volumetric demanding, although a conventional
Thorium reactor as started up with a few rods of Pu238 would likely
have to go along for the ride in order to pump out the required energy
for boosting the exit velocity of those hefty and very reactive Rn222
ions, and as such it too creates a small amount of Radium as the
natural process of thorium decay. So, all and all, there's hardly any
shortage of those Rn222 atoms as becoming ions that our electrified
thruster and ion pumped laser cannons can toss out the rear at the 0.5
'c' velocity of 150,000 km/s, eventually giving our headway of
SOA(speed of advance) the potential worth of 75,000 km/s in added trek
velocity to our interstellar craft or robotic probe(s).

Obviously the existing R&D as to this ion exit velocity is currently a
good thousand fold away from hitting the150,000 km/s mark. However,
in a laser cannon pumped format is where such highly energized ions of
Rn222 that can be so nicely and efficiently focused or aligned into
merging along with the laser beam formulated conduit, as such might
reach this goal, if not conceivably a little better.

Keep in mind that this concept was another one of my 'use it' or 'lose
it' mindset notions, as to the likes of our utilizing the 1650 year
half-life of Radium, and of our not wasting the secondary Radon that's
already highly charged and going places as is, because it all seems a
darn shame to continually ignore or otherwise waste such a good thing.

If you can add a little something in the way of technical or math
corrections, or merely being topic constructive and thus technically
informative, have at it.
. - Brad Guth


On Mar 25, 11:06 pm, BradGuth wrote:
On Feb 7, 10:40 am, BradGuth wrote:

What if instead of our going with whatever's small, extremely cheap,
fast and rad-hard robotic, what if going with larger is nearly always
better?

Perhaps this new and improved topic of "Building Spaceships" for
accommodating us frail humans on interstellar treks, and of those
multi generation habitat spacecraft being extensively ion thrusted,
along with the wizardly help of William Mook and those few of us
unafraid of whatever's out there, as such may be a little easier said
than done, not to mention folks having to deal with my dyslexic
encryption and frequent typos that can't always manage to keep those
numbers or terminology half straight.

Perhaps such a large scale ion thrusted spacecraft isn't quite as
insurmountable as we've been told, and it's not that a pair or quad
worth of substantial LRBs would not have to help get this rather
substantial package off the pad (in modules if need be, and assembled
at the moon's L1). However, upon launch and of once reaching the cool
upper most atmosphere is where the potential of ion thrusting could
start to contribute w/o Radon saturating Earth in the process, and
obviously from whatever LEO point onward is where the real potential
of ion thrust becomes impressive, especially since this method of
electro-rocket thrust can be sustained for as long as the given cache
of ions and electrical energy holds out. (with radium-radon there's a
failsafe worth of 1600+ years before reaching half-life, so there's
never a total lack of those Rn222 alpha/ions, and there's even some
electron energy derived from the Radium-Rn breeder reactor)

Given a sufficient cache of hefty ions and a sufficient onboard supply
of electron energy for artificially accelerating and redirecting those
ions into a narrow exit trajectory, and if this thrust is the direct
result of a given ion flow rate or mass of whatever ion particles per
second times the exit velocity squared, as then where's the
insurmountable problem, other than your not standing anywhere behind
those ion thrusters.

Radon just so happens to make for a very good cache of substantially
massive ions that are already quite active/reactive and supposedly
going places as is, at roughly 1.63e7 m/sec. Liquid Radon or LRn222
represents a nifty fluid cache of a easily stored concentration of
Radon gas (though because of its short half-life it's still very much
one of those use it or lose it substances, with possibly an extended
life within a near solid 0 K storage), of which I believe this cache
of Rn222 can be electrically induced or excited into exiting this ion
thruster at a velocity as great as 0.1'c' (perhaps an exit velocity of
0.5'c' is technically doable if we're talking about a radon pumped
laser cannon).

Similar to: http://en.wikipedia.org/wiki/Ion_eng....soton.ac.uk/4...
Our lord all-knowing (aka World FactBook) Mook says; "Check it out"
Here is how much thrust a rocket engine produces;
F = mdot * Ve
where mdot = mass flow rate, as kg/sec
Ve = exhaust speed m/sec
F = force (newtons) kg m/sec/sec

Here is how much power a rocket engine's jet produces
P = 1/2 * mdot * Ve^2
That is, the rate at which energy must be added to the exhaust jet is
the kinetic energy of the parts.
- - - -

Of course this is not about any Mook passive alpha particle directing
application, instead taking efficiency of the overall electrical and
ion tossing system into account (such as thermal energy losses) adds
to this existing amount of ion worth via applied electrical and
magnetic energy that'll focus and accelerate those ions. So, it is not
nearly as simple to express as one as Mook might suggest.

However, at the notion of our getting rid of this initial tonne worth
of our liquid cache of LRn222, at the ion mass flow rate of 1 kg/s,
whereas the kinetic power or energy worth of thrust supposedly
becomes:

If the 1 kg/s flow of Rn ions and the exit Ve were made as great as
10%'c' = 3e7 m/s

P = .5 * 9e14 = 4.5e14 kgf

At utilizing this ion exit velocity of 0.1'c' (3e7 m/s)
A metric tonne of LRn that'll essentially become just plain old Rn gas
of pure Rn222 ions, at using up one kg/s = 1000 seconds worth of
creating 4.5e14 kgf, of which this substance would push a 4.5e12 kg
(4.5 gigatonne) spacecraft at 100 gee in relationship to the gravity
at the surface of Earth.

At the more realistic ion exit velocity of 1% light speed is
0.01'c' (3e6 m/s)
A metric tonne of LRn that'll essentially become just plain old Rn gas
of pure Rn222 ions, at using one kg/s = 1000 seconds worth of 4.5e12
kgf, of which would push a 4.5e10 kg (45 megatonne) spacecraft at 100
gee in relationship to gravity at the surface of Earth.

Of course the 45 megatonne spacecraft isn't hardly any more likely
than human DNA or whatever spacecraft structurally surviving 100 gee.

So, to start off with we'd likely have ourselves a whole lot smaller
than 45 megatonne spacecraft, such as perhaps only as great as 4.5
megatonnes that'll exit away from Earth at perhaps as great as 10 gee,
then once 10r (63,730 km and just 1% Earth gravity) is reached,
whereas this is when the ion exit velocity could be safely punched up
from 0.001'c' to 0.01'c', and eventually the maximum of 0.1'c' could
be applied to as little as using a gram of Rn222 per second, because
at 0.1'c' or better exit velocity is where you really do not require
all that much mass flow per second.

0.1% light speed is 0.001'c' = 3e5 m/s

1 kg/sec at 3e5 m/s = .5 * 9e10 = 4.5e10 kgf

4.5e10 kgf would push a 4.5e6 tonne spacecraft along at 10 gee

Using a gram/sec:
4.5e7 kgf would push a 4.5e6 tonne spacecraft along at 0.1 gee

I believe that 1000 seconds of 10 gee acceleration is worth 78.4 km/s,
though of course we'd be past the 10r of Earth within the first 600
seconds, and thereby able to ion whiz past that 78.4 km/s mark like it
was standing still.

This next part is often where my math takes yet another nose dive, but
since I do not have the fly-by-rocket software and none others that
claim as always being all-knowing are seldom willing to share, is why
I'll just have to make do, especially since even the warm and fuzzy
likes of Mook always takes the lowest road possible in order diminish
and/or disqualify whatever isn't of his idea to start off with,
excluding just enough of the good stuff in order to foil any further
thought process.

The required energy for a given thousand seconds worth of accelerating
those Rn222 ions up to 3e5 m/s isn't exactly insignificant, demanding
perhaps at least 245.2 GW.h (8.826 e14 J) for accommodating all 16.7
minutes worth of ion thrust. However, due to the overall efficiency
of this energy transfer into accelerating those Rn ions is why it'll
more than likely demand somewhat greater energy for accomplishing this
task of tossing out the entire tonne worth those Rn222 alpha ions at
the rate of one kg/s, even if that's initially accomplished at this
minimal 0.001"c". However, since the existing Rn alpha particle
velocity is already self motivated at 1.6e7 m/s(.054'c'), perhaps
along with given another 5.6 MeV boost is where the required energy
can be limited as to whatever's necessary for accomplishing a good
exit focus or creating that laser cannon like beam, in which case the
required ion thruster energy could become relatively minimal for
accomplishing an impressive exit ion velocity of 3.26e7 m/s.

At times this spacecraft is going to require a hole lot more
electrical energy than any cache of Radium to Radon reactor could
manage at 32 kw/Ra tonne, or even 320 kw/breeder Ra tonne. However,
at a gross spacecraft mass of 4.5e6 tonnes, there's no problem with
incorporating an h2o2/aluminum fuel cell of 100 GW.h capacity, or
accommodating whatever Lithium nanotube ion battery storage, nuclear
reactors or fusion alternatives.

Once trekking off into interstellar space, and especially upon getting
this craft past our nearest interstellar L1, and of the other gravity
pulling us towards the likes of the relatively massive Sirius star/
solar system that we're already in blueshift as headed towards Sirius,
as this is when as little as a mdot microgram/sec of Rn222 at the exit
velocity of 0.2'c' would be more than sufficient ion thrust for
continually accelerating this 4.5e6 tonne spacecraft towards the
gravity pull of Sirius.

For a one microgram/sec of Rn222 mdot at 0.2'c' example:
P = .5e-9 * 3.6e15 = 1.5e6 kgf (1,500 tonnes/s of thrust, or in this
case 0.000333 gee)

The next problem gets down to the business of continually building up
another cache of LRn from the Ra-Rn breeder reactor while on the fly,
on behalf of that pesky matter of our having to ion retrothrust long
before overshooting the intended target. At 4.5e9 kg, stopping this
sucker that's by now going like a bat out of hell (possibly having
reached 0.1'c') is going to take some doings. Of course, there would
be generations of new and improved minds onboard in order to figure
most of this out before arriving into the Sirius star/solar system,
not to mention whatever could have been transmitted from Earth over
the past century.

BTW, at this point of topic argument sake, this mission to Sirius is a
one way ticket to ride, with absolutely no travel package guaranties
or ticket refunds allowed, because we may not be able to sufficiently
retrothrust in order to save any of those brave souls, and a purely
gravity-well trajectory turn-around or that of sufficiently
aerobraking is at best iffy, although a substantial solar wind
parachute as brake might eventually work. Also, recall the sheer size
of these required ion thrust nacelles, as being somewhat Star Trek
Enterprise like, and for all we know in need of those lithium crystals
or perhaps lithium nanotubes as part of their function (after all, any
good science fiction uses the regular laws of physics and the best
available science, and for all we know lithium could still be part of
it).
. - Brad Guth

I've top-posted for the ongoing benefit of others trying to decode my
dyslexic encrypted topic of accomplishing interstellar treks via ion
thrusting. Unfortunately, you'll have to filter out all of the usual
gauntlet worth of topic/author stalking and bashings as found within
the alt.astronomy and of a few other groups that think this is all too
funny.
. - Brad Guth

As per usual, the often out-of-context flow of technical information
from lord Mook that’s nearly always very interesting and seemingly of
doable stuff (99.9% or better as having been created by others), but
only as long as lord Mook is put in charge of everything, and for the
rest of us to merely ponder as to what are the odds of that ever
happening, seems rather astronomical to think that our NASA
replacement could ever become safely managed by such a bipolar wizard.

In spite of what’s being told about myself (mostly in a highly
negative light) I must be doing more than a little something right, as
why otherwise all the brown-nosed clownism of the mainstream status
quo, as clearly outfitted and/or orchestrated into such a Borg like
swarm of having devoted their full worth of damage-control, of which
this insider gauntlet of topic/author stalking and bashing even gives
our lord all-knowing Mook either their icy cold shoulder or some of
the very same warm and fuzzy flak that I get to deal with.

“Radioisotope rockets have been developed and built and studied
thoroughly. Not the direct use of the alpha particles however.”/Mook
http://en.wikipedia.org/wiki/Radioisotope_rocket

Ion thrusters typically require a good amount of applied electron
energy for accelerating those commonly passive ions of xenon gas,
however the already highly charged ions of radioactive isotopes are
quite another thing, that which may only need to be directed towards
the exit and past the final acceleration grids of each ion thruster,
whereas this should by rights result in a considerable thrust
improvement per joule of applied energy. If need be, the likes of
radium itself or perhaps mercury could be laser vaporized into ions,
although the Rn222 element seems of having a far better energy charge
of nearly 5.6 MeV to start off with, and since we’ll not be requiring
all that much in the way of these highly charged alpha ions is where
the natural decay process or breeder reactor as having that tonne of
radium which unavoidably gives off the 9.73 mg/day of radon gas seems
more than good enough to consider for this ‘waste not, want not’ task
of feeding our ion thrusters.

With the nuclear fly-by-rocket expertise of lord all-knowing Mook,
that runs most everything as though somewhat like a bipolar black hole
(meaning everything goes in and hardly if anything usable ever comes
out unless the all-knowing mindset of Mook implodes upon himself and
creates a new galaxy), except that our wizard Mook extensively runs
almost exclusively on his very own special superiority kind of bipolar
nayism, so that only that of his ulterior or bipolar mindset is what
matters, and perhaps otherwise by a few others contributing on behalf
of their using various other controlled nuclear detonation and/or of
the much safer fusion derived options, plus there’s always that of my
pesky notions for making use of those radioactive decay derived ions
(such as from a reactor core of Ra226--LRn222 or via any number of
alternatives) that'll result in becoming a long term supply of those
nearly effortlessly directed and otherwise easily focused ions, as
further accelerated by the least amount of applied electron energy, as
for causing such hefty and highly charged ions to go away from those
thrust emitters at terrific velocity is what seems entirely doable as
is. Unfortunately, if it's the least bit outside the box of
whatever's currently invested, as into those more conventional methods
of thrusting is why it's probably not ever going to happen, at least
not of any time soon.

Fly me not quite to the moon:
Of getting large amounts of tonnage to the moon’s L1 is not actually
about having to go fast, especially if given a lunar month per each
deployment would cut those fly-by-rocket demands per tonne
considerably, as each payload of whatever tonnage would coast ever so
gently into the moon’s L1 at perhaps 1 m/s.

Of course whenever having to go extremely fast, such as trekking off
to other worlds and of their moons (especially of those belonging to
another solar system), is perhaps only a third of the start to finish
task, because slowing down along with the advancing pull of the
destination gravity that’ll be making retro-thrusting somewhat less
effective is perhaps representing as much as the other 2/3 of the
package deal. The strong exception would always be for coasting
effortlessly into the moon's L1 at just one meter per second, whereas
such a gravity-null or gravity-soft destination wouldn't require all
that much reserve thrust for bringing a great deal of mass to a halt,
and if the orbital placement and timing of this kind of deployment
were accomplished exactly right, perhaps the moon L1 arrival could
become managed at as little as 0.1 m/s, along with only relatively
minor station-keeping adjustments for staying situated within this
interactive halo of such a nearby gravity nullified zone.
. - Brad Guth