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Comment Re:k.i.s.s. (Score 2) 143

I, too, was in the Naval Nuclear Propulsion Program. And while it does have a nearly-sterling operational and maintenance program, history has "conveniently" forgotten some of the program's mis-steps over the years.

- The USS SEAWOLF -- SSN 575, not the badass SSN-21 -- used a liquid sodium reactor that was plagued by reliability problems. After its first deployment, the reactor was replaced with a traditional PWR.

- The USS JACK -- SSN 605 -- was unique in that she had contra-rotating propellers. These were generally unreliable, although the linked wikipedia reference doesn't say much about them.

- The USS TULLIBEE -- SSN 597 -- had electric drive.

- The USS GLENARD P. LIPSCOMB -- SSN 685 -- was the second attempt at electric drive. But both of these boats ended up being heavier, slower, larger, and more expensive than their counterparts.

- There's another submarine, I can't remember which one, had some unique aspect of its turbines, which was not effective. It was SSN-6XX, but its nickname was building 6XX because it was in the repair yard so frequently.

In the grand scheme of things, the above hiccups are a miniscule portion of the overall fleet. The Zumwalt ship is one of three in the entire $22B class. So, I think the naval nuclear propulsion program has been blessed in that it has been able to experiment and occasionally "miss" with some new technologies without threatening the entire endeavor.

Comment Re:Comets (Score 2) 96

The "Big Ear" which discovered the Wow! signal had two feed horn antennae. What's tough to explain is why the other horn didn't pick up the signal. I suppose if the comet were small enough, other horn might not pick it up as it scanned by a few minutes later. Ehman says he re-scanned the area fifty times, after the initial signal. Maybe the comets had moved far enough apart by then?

Anyhow, the guy is looking for some additional funding so he can go build his own radiotelescope and test his hypothesis. I wish him luck, but not enough that I'm willing to donate to his cause.

Comment Re:My interest depends on cost (Score 1) 310

You're right, I could get a 5S for cheap. But my concern with that is that I would then be stuck with doggedly slow hardware in a year, at the tail end of what's supported.

My traditional business model (as evidenced by the fact that I'm still using the 4S) has been to buy the current model of Apple hardware (but never the Rev 1 of a product!) and ride it as long as possible. Although I haven't run the numbers, that seems a reasonable way to amortize the cost of Apple products while getting decent performance for 3/4 of the life of that product.

Comment My interest depends on cost (Score 2) 310

My 4S is getting very long in the tooth, and I am ready for an upgrade. It all comes down to cost.

A 64GB 6s today costs $750. If the 64GB 4" version costs $650 or less, I'm sold. If it's the same price as the 6s, I will probably grudgingly shell out the $750 for the 6s.

I, along with my family, am too tied in to the Apple ecosystem to jump ship now.

Comment Re:Seriously, am I the only one surprised? (Score 1) 53

NASA's annual budget is about $18.5 billion, but what they actually spend on satellites is a small fraction of that.

NRO's annual budget is estimated to be about $16 billion, according to Wikipedia. And their main mission is spy satellites.

And the Air Force spends about $3.7 billion annually in space-related R&D and execution.

So, NASA has a lot of well funded, US-based "competition" on the satellite front, although the budgets of its competitors is usually classified. I'm glad to hear that the US government is agile enough to share resources, when appropriate.

Comment Re:a year ago? (Score 5, Informative) 93

Iridium-192 sources like the one stolen are typically sold in the US at activities between 50 and 100 Ci. They're used to take "x-rays" of pipe welds to look for porosity, evenness, cracks, etc.

The actual seed source is about as big as a pencil eraser, maybe a little smaller. Thus, it would be hard to repurpose as a dirty bomb - it's a lump and all it would do is fly somewhere else in an explosion.

Radioactive sources are lost all the time. This website from the NRC keeps a log of all lost sources. While losing a source like this in Iraq is unfortunate, it's not uncommon.

Comment Re:Meh, I'll wait for confirmation (Score 2) 412

The news reports are saying it was between a magnitude 4.8 and 5.1 on the M scale (kinda like the Richter scale).

This is remarkably similar to the 2013 test, which was also magnitude 5.1. The USGS has a nice summary plot of the 3 previous tests. All else being equal (namely, the coupling between the test tunnel and the surrounding rock), it looks like this test was about as big of a "pop" as the 2013 test.

Comment Re:earth helium (Score 1) 267

Going to the moon is a really dumb way to get your He3.

A far easier way is to use a Tritium Producing Burnable Absorber Rod. (pdf link) Rather than putting UO2 in the fuel pellet, put lithium aluminate (LiAlO2) in there.

This has been going on at the Watts Bar Unit 1 nuclear power station since 2004. Sure, more tritium has leaked into the coolant than expected, but tritium is a pretty benign radioactivity source.

Harvest the tritium, which decays into He-3. Voila. Far easier than going to the moon. Sheesh.

Comment Re:Energy Conservation (Score 1) 557

Phase change drywall. Like this stuff, called "ThermalCore" from National Gypsum:

I don't know why it hasn't been commercialized yet (they've been stewing on it for years, and some places in Europe already have it), but it sure seems like a good way to make use of the latent heat of wax.

Comment Re:Mis-use=reviewer don't do their job (Score 1) 208

They're not crazy. This fantastic article from Nature in February 2014 shows how seemingly statistically certain events (e.g., p less than 0.01) can be thrown off by low probability events.


Frankly, I've always been a bit confused by the p value. It just seems more straightforward to provide your 95% confidence interval limits.

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