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New Horizons Arrives At Ksc
edstrick
post Sep 28 2005, 06:59 AM
Post #16


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BruceMoomaw: "..Actually, the blood-chilling thing about "nucular" is how many non-Bushians pronounce it the same way ..."

The word is a pronunciation booby-trap. Much the same way I think poor Neil Armstrong got booby-trapped as he stepped onto the moon.

"That's one small step for <a> man...One giant (etc)

The first phrase builds up a cadance with the article "a" brutally interrupts. I've always thought that was an accidental built in booby-trap that nailed Neil with a vengence.
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Guest_BruceMoomaw_*
post Sep 28 2005, 07:31 AM
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Well, I certainly never had trouble with it -- unlike, say, "February" or "arboretum" (which my mother fouls up every time -- fortunately, it's not an everyday word). Far as I'm concerned, the ability to pronounce "nuclear" correctly is a sort of IQ test for politicians: no one who can't get it right should be allowed near a position of major national leadership.
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Guest_BruceMoomaw_*
post Sep 28 2005, 07:33 AM
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I forgot to mention that Eisenhower also fouled it up routinely, but this is hardly a shock. The immortal statement "Things are more like they are today than they have ever been before" has been attributed both to Ike and to Gerald Ford, either of whom was fully capable of it.
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spfrss
post Sep 28 2005, 08:36 AM
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QUOTE (BruceMoomaw @ Sep 27 2005, 10:31 AM)
As I understand it, the only possible show-stopper now is that they still need official permission from Bush to launch that much plutonium.  I'm sure he'll agree, once they've explained to him what Pluto is.
*


The problem I think is not the presidential approvation to launch NH, but the so-called
'ecologists' à la Bruce Gagnon.
I still remember the protesters who tried to stop the launch of Cassini, Galileo and Ulysses even by judicial means, fearing a launch accident or something.

live long and prosper

Mauro
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Guest_Richard Trigaux_*
post Sep 28 2005, 09:22 AM
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QUOTE (BruceMoomaw @ Sep 28 2005, 07:33 AM)
Far as I'm concerned, the ability to pronounce "nuclear" correctly is a sort of IQ test for politicians: no one who can't get it right should be allowed near a position of major national leadership.
*





QUOTE (BruceMoomaw @ Sep 28 2005, 07:33 AM)
I forgot to mention that Eisenhower also fouled it up routinely,
*



Ooops
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Guest_Richard Trigaux_*
post Sep 28 2005, 09:24 AM
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QUOTE (BruceMoomaw @ Sep 28 2005, 07:31 AM)
Far as I'm concerned, the ability to pronounce "nuclear" correctly is a sort of IQ test for politicians: no one who can't get it right should be allowed near a position of major national leadership.
*


Step 1: learn to pronounce it correctly

Step 2: learn that it is dangerous
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Guest_Richard Trigaux_*
post Sep 28 2005, 09:46 AM
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QUOTE (spfrss @ Sep 28 2005, 08:36 AM)
The problem I think is not the presidential approvation to launch NH, but the so-called
'ecologists'  à la Bruce Gagnon.
I still remember the protesters who tried to stop the launch of Cassini, Galileo and Ulysses even by judicial means, fearing a launch accident or something.

live long and prosper

Mauro
*


I fully support far exploration, including to far planets. And anyway 30kgs of plutonium in a space probe, it is still that in less on Earth. Good bye and thanks goodness.

But what I fear is not ecologists blocking the launch of Cassini; it is rather the following scenario:

the launch fails, the rocket explodes... Worse, it let the probe on a long elliptic orbit, letting some days of suspens before the RTG re-enters the atmosphere at 10km/s, dispersing worldwide a deadly dust of plutonium... Still worse, the RTG was hardened to sustain such events, and it falls on the ground... in one of "certain countries".

Remember that 7 microgram of plutonium 239 dust is enough to kill somebody (by lung cancer from breathing dust) and Pu 238 is still more active.

We cannot say it will never happen. It is simply a matter of statistics: the number of nuclear probes, multiplied by the fail rate of rockets...

If such a thing would happen, Mr Bush may definitively forbid the use of RTGs in space probes. And he would not be alone to think so.

Bye bye Pluto.


OK, this forum is not about ecology. But it is certainly not about burying our head in the sand: space exploration implies some dangers. And thus some responsabilities. Even at our level of simple supporters.

Should we abandon the exploration of far planets for this reason? The choice may be not ours.

Perhaps there are other less dangerous solutions. Not at hand, but searchable.
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djellison
post Sep 28 2005, 09:59 AM
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Please go and read the safety reports for the launch. To say that a launch failure would unleash a worlwide distribution of a deadly dust is highly missleading and far from the truth.

Doug
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Guest_Sunspot_*
post Sep 28 2005, 10:33 AM
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QUOTE (djellison @ Sep 28 2005, 10:59 AM)
Please go and read the safety reports for the launch.  To say that a launch failure would unleash a worlwide distribution of a deadly dust is highly missleading and far from the truth.

Doug
*


I remember the fuss over the launch of Cassini and how envirnomental campaigners "emabarked on a campaign of misinformation" to get NASA's attention. ...... and even Martin Sheen showed up lol
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djellison
post Sep 28 2005, 10:41 AM
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If the public were made as aware of the military payloads that contain radioactive material as they are of the civilian ones - all hell would break loose.

Doug
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RNeuhaus
post Sep 28 2005, 03:33 PM
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I will put anything nuclear information from NH spacecraft here to clear any doubts and any missleading about the nuclear worries:

Designed for Safety
More than 40 years have been invested in the engineering, analysis and testing of RTGs. As described below, safety features of an RTG include the use of a specific type of fuel material, a modular design and construction and the use of multiple physical barriers.

The plutonium dioxide fuel contained in RTGs is a specially formulated fire-resistant
ceramic that is manufactured as pellets to reduce the possibility of fuel dispersion in a
launch or reentry accident. This ceramic form resists dissolution in water and reacts little
with other chemicals. If fractured, the ceramic tends to break into relatively large
particles and chunks that pose fewer hazards than small, microscopic particles.

Multiple layers of protective materials, including iridium capsules and high-strength
graphite blocks, protect and contain the fuel and reduce the chance of release of the
plutonium dioxide. Iridium, a strong, ductile, corrosion-resistant metal with a very high
melting temperature, encases each fuel pellet. Impact shells made of lightweight and highly heat-resistant graphite provide additional protection.

Each RTG contains 18 heat source modules with four plutonium dioxide pellets in each
module. There are two plutonium dioxide pellets in each graphite impact shell, and two
graphite impact shells go into each heat source module. The figure below shows part
of a heat source stack within the RTG.


Risk Assessment and Launch Approval
Any mission that plans to use an RTG as a power source undergoes a safety analysis
carried out by the Department of Energy (DoE). The safety analysis report provides a
comprehensive assessment of the potential consequences of a broad range of possible
launch accidents. In addition to the DOE review, an ad hoc Interagency Nuclear Safety Review Panel (INSRP), which is supported by experts from government, industry and
academia, is established as part of a Presidential nuclear safety launch approval
process to evaluate the safety analysis report prepared by DOE. Based upon the INSRP
evaluation and recommendations by DOE and other Federal agencies, NASA may then
submit a request for nuclear safety launch approval to the White House Office of
Science and Technology Policy (OSTP). The OSTP Director (i.e., the President’s science
adviser) may make the nuclear safety launch decision or refer the matter to the President.
In either case, the launch cannot proceed until nuclear safety launch approval has been
granted.


RTGs can provide continuous power in regions of space where the use of solar power
is not feasible. Over the past 40 years, RTGs have been used safely and reliably on 25
missions, including six Apollo flights to the moon, two Pioneer spacecraft to Jupiter and
Saturn, two Mars Viking landers, two Voyager missions to the outer planets, the
Galileo mission to Jupiter, the Ulysses mission to the Sun’s poles, and the Cassini-
Huygens mission to Saturn.


Long reliability.

Rodolfo
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SigurRosFan
post Sep 28 2005, 04:06 PM
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But how many RTGs are actually on board?

Earlier ...

--- Half of the plutonium for New Horizons was on hand when DoE stopped work at the nuclear weapons plant in July 2004. A total of 36 of the 72 fuel units ordered had been left over from a spare RTG built earlier for NASA's Galileo and Cassini missions. When the lab shut down, it had 18 more units in the works. The 2006 launch will go ahead with as few as 61 fuel units.

Los Alamos scientists could convert plutonium bought from Russia into pellets packaged in hockey-puck-sized containers. Then the Argonne National Laboratory at Idaho Falls would put those RTG containers into the RTG.

An RTG with a full load of 72 fuel units can deliver 200 watts of electricity. With only half of its fuel, 36 fuel units, it could deliver about 100 watts. With a minimum of 61 fuel units, the RTG could provide 170 watts of electrical power. The electricity would be used to power seven science instruments and spacecraft systems aboard New Horizons. ---


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Guest_Richard Trigaux_*
post Sep 28 2005, 05:38 PM
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QUOTE (RNeuhaus @ Sep 28 2005, 03:33 PM)
The plutonium dioxide fuel contained in RTGs is a specially formulated fire-resistant
ceramic that is manufactured as pellets to reduce the possibility of fuel dispersion in a
launch or reentry accident. This ceramic form resists dissolution in water and reacts little
with other chemicals. If fractured, the ceramic tends to break into relatively large
particles and chunks that pose fewer hazards than small, microscopic particles.

Multiple layers of protective materials, including iridium capsules and high-strength
graphite blocks, protect and contain the fuel and reduce the chance of release of the
plutonium dioxide. Iridium, a strong, ductile, corrosion-resistant metal with a very high
melting temperature, encases each fuel pellet. Impact shells made of lightweight and highly heat-resistant graphite provide additional protection.

*


Thanks RNeuhaus for your informations.

So it seems that the maximum possible precautions were taken:
-plutonium ceramics cannot disperse in dust., even when broken or exposed to fire
-iridium-graphite casing can withstand the heat of any rocket explosion. (Irridium 2454°C graphite more than 3000°C)
-iridium casing will not rust if fallen in a ocean or place difficult to reach such as a rain-foret.

The policy being, of course, in such a case where a very large risk is involved, to envision the worse case as BEING TO HAPPEN and avoid any nasty effect even in this case. So I suppose that the worse possible accident was envisioned.
The worse case here is a re-entry at more than 11km/s, from a trajectory error in a gravitationnal assistance manoeuver using Earth. In this case the atmospheric braking flame is theoretically hot enough to melt irridium and the ceramics, which would form droplets and eventually dust. But I hope the guies are not dumb and they envisioned this case, where anyway the flame is only during a given time, so that it has other things to grind before reaching the plutonium.

Anyway if a RTG was to fall on the ground, it would be a maximum alert for the local police to avoid ignorant or malevolent people to take away the parts.
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helvick
post Sep 28 2005, 05:50 PM
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QUOTE (SigurRosFan @ Sep 28 2005, 05:06 PM)
But how many RTGs are actually on board?
.....
An RTG with a full load of 72 fuel units can deliver 200 watts of electricity. With only half of its fuel, 36 fuel units, it could deliver about 100 watts. With a minimum of 61 fuel units, the RTG could provide 170 watts of electrical power. The electricity would be used to power seven science instruments and spacecraft systems aboard New Horizons.  ---
*


Not sure but Alan Stern's message here on Feb 19th says:
QUOTE
The RTG and the necessary fuel are both in good shape. Previous problems resolved.
All needed fuel is now ready. We expect 190 W or a tad more at Pluto in mid-2015.
The s/c requires ~165W, so there is a healthy margin. The launch approval process
has begun, and will take the remainder of the year to complete.


These RTG's degrade at around 0.79% per annum so 190W at Pluto (mid 2015) works back to around 205W now and should still be >165Watts in 2031.

Alan commented later:
QUOTE
This depends on when we launch in the 2006 window or the backup 2007
window because the exit velocity varies with launch date. The basic answer
is that predicts show that we have sufficient power to run out to 2025, which
corresponds to ~50-60 AU if all goes well.


So basically, no worries, loadsa juice. Let's just all do our bit to make sure that we don't let woowoo panic merchants hamper the launch.

Actually I've just been re-reading the whole thred - it's well worth it.
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SigurRosFan
post Sep 28 2005, 06:22 PM
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Thanks a lot, Helvick!


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- blue_scape / Nico -
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