antimatter rockets

On Jan 4, 8:15*am, BradGuth wrote:
On Jan 2, 11:58 pm, Sylvia Else wrote:

wrote:
www.engr.psu.edu/antimatter/Papers/NASA_anti.pdf

Doesn't paint an attractive picture for pure matter-antimatter rocket.

The possibility of anti-matter catalysed fusion rockets seems less of a
dream.

Sylvia.

Our William Mook has lot of such notions as wet dreams, although
Einstein most likely dreamed his brains out over most of his notions,
some of which actually came to past, and a few others we'll not bother
to mention because they'll only make Einstein look like some kind of a
moron if not a village idiot that took many of his ideas from the
blood, sweat and tears of others, and seldom if ever giving credit.

- Brad Guth

So, are you saying Einstein would have written his own paper and not
quoted one as I did? lol.

Your usage of words is very interesting - I'm beginning to think you
and some of the other posters who are critical of me are the same
person. One name for the provacateur. The other name for the black
propagandist. This is a little of both - usual for you Brad -

On Jan 3, 6:58*pm, Sylvia Else wrote:
wrote:
www.engr.psu.edu/antimatter/Papers/NASA_anti.pdf

Doesn't paint an attractive picture for pure matter-antimatter rocket.

The possibility of anti-matter catalysed fusion rockets seems less of a
dream.

Sylvia.

They're all dreams sweetie when it comes to anti-matter - as opposed
to the other stuff I've written elsewhere.

A shaped block of tungsten illuminated with an anti-matter beam would
form a dandy solid core rocket - very similar to NERVA with no nuclear
materials.

The melting point of tungsten is 3,695K
The boiling point of tungsten is 5,828K

Multiplying 3,500K by 14.3 kJ/kg-K obtains 50.5 MJ per kg of gas.
Solving for gas velocity obtains 10,005 m/sec which resolves to 1,019
sec Isp.

This appears to be the limit for a solid core rocket heating hydrogen.

1,019 sec Isp, requires 10 kg/sec to obtain 100 metric tons thrust.
This also requires 500 MW heat source which is provided by 2.8 ug per
second of antimatter.

With a 50:1 thrust to weight, this rocket masses 2 metric tons. With
a lift-off gee force of 1.35 gees vehicle mass is 74 metric tons.
With an ideal velocity of 9 km/sec and an exhaust speed of 10 km/sec
propellant fraction is 59.34% - this translates to 43.9 tonnes. With
6% tank weight, that's 2.7 tonnes for tankage and plumbing. Total
structure faction is 15% - or 11.1 tonnes

GLOW 74.0 tonnes
LH2 49.9 tonnes
Struct 11.1 tonnes
2.0 tonnes - engine
2.7 tonnes - tank
Payload 13.0 tonnes

A 5 engine system - configured like the Saturn V moonrocket - though
these are far smaller (1/15th) than the F1 - could loft 65 metric tons
into LEO.

That payload could of course be... the single stage rocket described
here... slightly less than LEO,

The second stage which would impart an additional 9 km/sec to the 13
tonne payload.

Which could take it to the moon, land it, and return it to Earth -
with recovery of all components.

Ditto for Mars.. with aerobraking at Mars.

13 metric tons is nearly the fullup weight of the Apollo LEM
or the size of the Manned Orbiting Laboratory (MOL)

http://ntrs.nasa.gov/archive/nasa/ca...1965076610.pdf

Sufficient payload to carry up to 7 passengers/crew on trips to the
Moon and Mars.

Higher exhaust speeds require higher temps. This requires gas and
plasma reactors.

Rather than worry about steady state gas and plasma masses we could
steal a trick from the nuclear pulse people, where anti-protons are
injected into a containment which then leaks them out into a small
tungsten block which is vaporized. The plasma/gamma pulse is
reflected off ablative walls - which propel the vehicle - pulse
fashion. The tungsten and ablative material is consumed as part of
the propellant mass. Up to 40 km/sec may be produced in this way..
thrust to weight suffers - dropping to 10:1 - but propellant mass
improves.

A 100 metric ton thrust engine masses 10 metric tons, and has an
exhaust speed of 40 km/sec. To achieve 9 km/sec ideal velocity
requires 20.15% propellant fraction. The same 1.35 gee lift off
thrust means again a 74 metric ton vehicle. 14.9 metric tons of
propellant. Another 8.1 tons of structure - gives us 41 metric tons
of payload.

Alternatively, taking the difference between 13 tonnes and 41 tonnes -
as propellant - adds 28 tonnes to the propellant mass. This increases
propellant fraction from 20.15% to 57.98% which increases ideal
velocity from 9 km/sec to 34.67 km/sec - which gives a single stage
vehicle Omni-planetary capability. That is, a single stage could take
off from Earth and fly to Mars, or the Moon, land and return to Earth.

Am I doing this right?

v = SQRT(3*k*T/m)

where k = boltzman constant = 1.38065e-23 J/K
m = molecular weight in amu -
amu = 1.66054e=27 kg
tungsten = 183.84 amu


So, to get a velocity of 40 km/sec requires a temperature of 12
million degrees. This requires that a kiloigram of tungsten absorb
813 MegaJoules of energy and requires about 10 ng of antimatter -
assuming 50% efficiency. A kilogram of tungsten solid forms a sphere
of tungsten 4.63 cm in diameter and 3 quadrillion anti-protons beamed
at it, or stored and released inside it.

A 100 metric ton thrust requires a mass flow rate of 24.55 kg per
second - nearly 25 'blasts' per second. 250 ng of antimatter per
second. 20.3 GW.

BTW - the power calculations of the rockets given earlier are off by a
factor of 9.82 - because I forgot that force should be in Newtons, not
kgs, so 1 kgf = 9.82 Newtons... So, the 1,000 sec Isp is 5 GW not 500
MW for 100 metric tons of force.

40 metric tons of propellant consist of 40,000 spheres which occupy
about 4 cubic meters. Say 8 cubic meters with sphere handling
equipment. Think of a coca cola vending machine.

A low velocity 'gun' that pneumatically blasts the spheres to the
center of the 'engine' at low velocity. And anti matter 'injector'
blasts the tungsten when it reaches the detonation point. It explodes
and the plasma wave bounces off the ablating parabolic liner - all in
less than a millisecond clearing it for another 'round'

The antimatter injector would be modified from the solid core rocket -
that used solid tungsten radiator heated to 3500 K to heat a working
fluid.

Sylvia Else wrote:
wrote:

www.engr.psu.edu/antimatter/Papers/NASA_anti.pdf


Doesn't paint an attractive picture for pure matter-antimatter rocket.

The possibility of anti-matter catalysed fusion rockets seems less of a
dream.

Anti-matter catalyzed fusion rockets? How would that work?
Maybe that was just a slip, did you mean anti-matter ignited
fusion rockets? If you send a few anti-protons in a pellet
of Plutonium, or some other fissile matter, you can start
a small chain reaction even without having the critical
mass for the fissile fuel. So you can ignite fusion fuel
with anti-matter. But how would you use anti-matter in a
fusion rocket?


Alain Fournier

Alain Fournier wrote:
Sylvia Else wrote:
wrote:

www.engr.psu.edu/antimatter/Papers/NASA_anti.pdf


Doesn't paint an attractive picture for pure matter-antimatter rocket.

The possibility of anti-matter catalysed fusion rockets seems less of
a dream.

Anti-matter catalyzed fusion rockets?

That was the expression used in the document, which briefly describes
two approaches.

Sylvia.

http://news.yahoo.com/s/space/200801...ntimatterfound

It looks like there may be pockets of anti-mater in the universe that
self-identify.

One of the interesting things about the interstellar environment is
that it looks more and more like it a competitive environment for
special resources exists.

I worked in SETI back in the 1980s and 90s - as a volunteer at OSU's
radio observatory and later as a graduate student. During that time I
had the great opportunity to attend the switchon ceremony of project
BETA and meet Carl Sagan and othres in the field.

A standard question at that time was would ETI be friend or foe?
Sagan was of the camp that they would be friend. He felt that
continuous technological advance would end all shortages and reward
cooperative behavior leaving ancient competitive instincts behind,
just as we are now learning that slavery and violence are bad, in the
future technology would put a powerful selective pressure on those
species that survived to be cooperative. By this reasoning he felt
that those that survived nuclear and more sophisticated technologies
would necessarily be friend, and the concept of foe would only make
sense to primitive cultures like ours.

I thought that arguing from our special condition today - the control
of nuclear weapons. It could be, even in our case, that the US or the
USSR or some future nation, could decide that anyone possessing a
nuclear capability other than themselves, would be at war with that
power - and would remove these weapons from that opposing power, and
maintain tight control of affairs through their willingness to use
nuclear weapons. That is, nuclear weapons would exacerbate
competitiveness in a way that would also allow us to survive. I didn't
see where Sagan got his belief that the situation I just described as
being unstable. To me it seems very stable.

No, the real issue was the environment people found themselves in.
Sure, the development of humanity sees a triumph of cooperation over
competition over the past 100,000 years as we spread across the
globe. A thin patina of cooperativeness is laid atop a deeper
propensity to fight and win one's position and hold it by force. This
might continue if technology makes holding resources and property
secondary or not important at all to maintaining wealth and power.

And to me this depends entirely on the space environment.

If by mining planets, asteroids,or even the sun itself, resource and
energy limitations that we encounter today are a thing of the past,
never to recur - then, that would be a more powerful indicator that
species generally would tend to be selected for cooperativeness.
After all if there is an infinite store house (the universe) of raw
materials, and we can get more of that store house in our pockets by
cooperating with others to get more too - then the universe itself is
creating the condition for cooperation.

However, if the universe has very special and rare resources that are
extraordinarily valuable to a technical species - and its use by one
denies its availability to another - then the universe itself is
creating conditions to reward selection for competition.

We don't know enough about the universe or technical species or what's
valuable to them, to answer this question.

And we don't want to get our answer at the end of an alien ray gun!!
lol.

So, its something I think about when I read the literature...

And the article above, seems to me to show that the universe may be
rewarding competition... by its very nature.

After all,if anti-matter is just abundant enough to undermine the
value of making anti=matter from scratch, and valuable enough to be
worth going out and getting it,and easily detected through its gamma
ray emissions - then one can imagine this being as valuable on an
interstellar scale, as oil is on the planetary scale.

Another possible rare and valuable resource might be time violating
regions that might exist around ANCIENT massive spinning black holes.
These might be the key to time travel, time signalling, instantaneous
communications and travel. The trouble with these schemes is that for
any given black hole, the bandwidth is severely limited. And a signal
sent to wish my departed grandmother happy birthday from the
future,takes up just as much bandwidth as a signal from the National
Weather Service to fix this or that levess in New Orleans before
Katrina hits. Obviously is such things exist are this valuable and
this rare and this limited - they'll be used sparingly, and be
valuable enough to compete over.

So, the presence of just enough anti-matter to be useful, but rare
enough so that everybody might not be able to have what they desire,
and the presence of massive ancient black holes at the center of our
galaxy, massive enough to be very valuable, but not enough bandwidth
for every fool thing every one might want to do.. are setting the
stage to reward competition in the future.

Now, Sagan may still be right. That there may be those to abandon
technology altogether because of the horrific nature of interstellar
war - could decimate worlds. But so could errant clouds of antimatter
drifting into worlds, or errant asteroids for that matter. Some
species may forego using certain high tech because they don't like the
way it directs them. Other species may say - good - more for us!
lol. And those competitive types may self-destruct. This combined
with a general decline in density even as numbers increase - may be an
answer to the question where are they?

Somewhere off-world is where Mook's antimatter is for real. However,
we can't even safely set a human DNA filled moonboot upon that
physically dark and nasty moon of ours.

It's so pathetic that we can't even establish a viable Clarke Station
within the moon's L1, much less of going for the cool location and
much less gamma worthy environment of Venus L2.

We're running ourselves out of fossil fuels and losing ground via most
biofuel and/or synfuel alternatives because, we still do not have a
spare/surplus cache of clean energy to work with.

Of our going off-world is currently a one-way ticket to ride, and damn
spendy at that.

Your whatever antimatter should be put on the back burner, with
instead 3He/fusion placed up front along with your cheap PV or
whatever's the clean and renewable alternative. We also need to 4X
our national power grid capacity and expand its coverage before WWIII
kicks our mostly infidel butts.

- Brad Guth


On Jan 16, 7:38 am, wrote:
http://news.yahoo.com/s/space/200801...fmysteriousant...

It looks like there may be pockets of anti-mater in the universe that
self-identify.

One of the interesting things about the interstellar environment is
that it looks more and more like it a competitive environment for
special resources exists.

I worked in SETI back in the 1980s and 90s - as a volunteer at OSU's
radio observatory and later as a graduate student. During that time I
had the great opportunity to attend the switchon ceremony of project
BETA and meet Carl Sagan and othres in the field.

A standard question at that time was would ETI be friend or foe?
Sagan was of the camp that they would be friend. He felt that
continuous technological advance would end all shortages and reward
cooperative behavior leaving ancient competitive instincts behind,
just as we are now learning that slavery and violence are bad, in the
future technology would put a powerful selective pressure on those
species that survived to be cooperative. By this reasoning he felt
that those that survived nuclear and more sophisticated technologies
would necessarily be friend, and the concept of foe would only make
sense to primitive cultures like ours.

I thought that arguing from our special condition today - the control
of nuclear weapons. It could be, even in our case, that the US or the
USSR or some future nation, could decide that anyone possessing a
nuclear capability other than themselves, would be at war with that
power - and would remove these weapons from that opposing power, and
maintain tight control of affairs through their willingness to use
nuclear weapons. That is, nuclear weapons would exacerbate
competitiveness in a way that would also allow us to survive. I didn't
see where Sagan got his belief that the situation I just described as
being unstable. To me it seems very stable.

No, the real issue was the environment people found themselves in.
Sure, the development of humanity sees a triumph of cooperation over
competition over the past 100,000 years as we spread across the
globe. A thin patina of cooperativeness is laid atop a deeper
propensity to fight and win one's position and hold it by force. This
might continue if technology makes holding resources and property
secondary or not important at all to maintaining wealth and power.

And to me this depends entirely on the space environment.

If by mining planets, asteroids,or even the sun itself, resource and
energy limitations that we encounter today are a thing of the past,
never to recur - then, that would be a more powerful indicator that
species generally would tend to be selected for cooperativeness.
After all if there is an infinite store house (the universe) of raw
materials, and we can get more of that store house in our pockets by
cooperating with others to get more too - then the universe itself is
creating the condition for cooperation.

However, if the universe has very special and rare resources that are
extraordinarily valuable to a technical species - and its use by one
denies its availability to another - then the universe itself is
creating conditions to reward selection for competition.

We don't know enough about the universe or technical species or what's
valuable to them, to answer this question.

And we don't want to get our answer at the end of an alien ray gun!!
lol.

So, its something I think about when I read the literature...

And the article above, seems to me to show that the universe may be
rewarding competition... by its very nature.

After all,if anti-matter is just abundant enough to undermine the
value of making anti=matter from scratch, and valuable enough to be
worth going out and getting it,and easily detected through its gamma
ray emissions - then one can imagine this being as valuable on an
interstellar scale, as oil is on the planetary scale.

Another possible rare and valuable resource might be time violating
regions that might exist around ANCIENT massive spinning black holes.
These might be the key to time travel, time signalling, instantaneous
communications and travel. The trouble with these schemes is that for
any given black hole, the bandwidth is severely limited. And a signal
sent to wish my departed grandmother happy birthday from the
future,takes up just as much bandwidth as a signal from the National
Weather Service to fix this or that levess in New Orleans before
Katrina hits. Obviously is such things exist are this valuable and
this rare and this limited - they'll be used sparingly, and be
valuable enough to compete over.

So, the presence of just enough anti-matter to be useful, but rare
enough so that everybody might not be able to have what they desire,
and the presence of massive ancient black holes at the center of our
galaxy, massive enough to be very valuable, but not enough bandwidth
for every fool thing every one might want to do.. are setting the
stage to reward competition in the future.

Now, Sagan may still be right. That there may be those to abandon
technology altogether because of the horrific nature of interstellar
war - could decimate worlds. But so could errant clouds of antimatter
drifting into worlds, or errant asteroids for that matter. Some
species may forego using certain high tech because they don't like the
way it directs them. Other species may say - good - more for us!
lol. And those competitive types may self-destruct. This combined
with a general decline in density even as numbers increase - may be an
answer to the question where are they?

If there is competition among ETIs - assuming ETIs occur at a rate
sufficient for them to meet - then, this would be a powerful reason
for them to be stealthy. This is yet another answer to Fermi's
Paradox.