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While these articles are not space news, I will include them here, because railguns play a big part in my Star Hero campaign. Besides, I have posted railgun-related links here before. I have cross-posted these links in the "In Other News" thread on the NGD.

 

US Navy's railgun project hasn't made a lot of progress

 

On the other hand,

 

China's railgun project may be ahead of schedule

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On 2/6/2019 at 1:54 PM, DShomshak said:

The Feb. 2, 2019 issue of The Economist has three space-related articles:

* A proposal that x-rays might be better than radio for interstellar communications. They spread out  more slowly, don't scatter as much, and there's a whole lot less natural x-ray sources to mask messages.

* A bit of rock brought back from the Moon by Apollo astronauts may originally have been a bit of the Earth. The two-gram grain from the Fra Mauro highlands is a bit of the slashed debris from the Late Heavy Bombardment impact that created the Mare Crisium. The zircon and quartz grains in the rock, however, are of a sort unlikely to have formed in Lunar conditions; they more plausibly formed on Earth. (The brief article doesn't say what features lead to this conclusion.) So, one LHB impact could have splashed the rock from Earth to the Moon (which at the time was only a third its current distance); then another impact put it on the Fra Mauro highlands; and now it's back to its planet of origin. This interests geologists, because the Earth has very little rock that is relatively unchanged from that long ago. (You can judge the rarity by geologists considering being through two massive impacts still "relatively unchanged.")

* And an article on Pentagon proposals for laser-armed satellites to shoot down missiles, in the latest iteration of "Star Wars" missile defense.  The article notes the vast expense of existing missile defense, the likelihood that it would fail against relatively small numbers of missiles, and a "detailed and scathing" analysis of boost-phase interception that the National Research Council produced in 2012. I simply remember a Scientific American article from the 1980s that concluded the laws of physics make any space-based missile defense system, well, considerably harder than advocates make it sound.

 

First item: interesting, but one difficulty is that both broadcast and reception must take place from orbit or the surface of an airless moon or asteroid, since X-rays don't make it through any appreciable atmosphere.  Not an insurmountable detail, but it is an extra step that isn't there for either radio-frequency or visible-light signals.  If you're sending interstellar signals, it's not clear to me how the economics would work pushing you either toward or away from X-rays.

 

Second item: Saw this, and if it works out correct that's a very interesting source of ancient Earth rocks.  I have the impression they have a lot more work needed to establish the terrestrial origin securely, though.

 

Third item:  This again?  Anyone who was paying attention back during the Reagan Administration remembers that building an effective, genuine ABM defense system is exceedingly difficult, whether you use responding missiles or directed-energy antimissile systems.  It's a nice big yummy contract to build a prototype, though, and the people pushing for such systems have the contract as their goal, not a real defense. 

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The only real way to win a nuclear war is to not start one.

 

On the railguns, it seems like they would take up an enormous amount of energy using modern technology. Can a, say, destroyer-class naval vessel produce enough to fire more than once? Would you need to fire more than once?

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At lot earlier in the thread was a suggestion that our dominance over other terrestrial lifeforms comes from our brain size.

Well there is an extensive review of our position on the Neanderthal going on in the academic community. Their tools may have actually been better so we can't claim we were smarter. They were stronger, so how come we are still here and they are gone? 

https://www.bbc.co.uk/news/science-environment-46988399

Might be luck.

 

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Could have been as simple as resistence to disease. Or maybe we were just a tiny bit better at exploiting resources. No way to know really. I'm, going with Aliens! myself.;)

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3 hours ago, L. Marcus said:

Social organization is my guess.

Indeed, one of the leading hypothesis is that we were more social and maybe were able to support each other when we came into conflict. 

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Ultima Thule: think coins, not spheres

 

The two bodies in the contact binary that New Horizons flew past back near New Year's ... seem not to be even approximately spherical.  Flat, relatively thin tablets seem to match the images taken once the spacecraft was past the object.

 

EDIT: There's a Whiskey Tango Foxtrot for you.

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On 2/6/2019 at 10:54 PM, DShomshak said:

* A bit of rock brought back from the Moon by Apollo astronauts may originally have been a bit of the Earth. 

I am pretty sure the current theory says the moon was formed from earth crust debris. So it is a giant Earth Rock :)

 

On 2/8/2019 at 9:02 PM, Cancer said:

First item: interesting, but one difficulty is that both broadcast and reception must take place from orbit or the surface of an airless moon or asteroid, since X-rays don't make it through any appreciable atmosphere.  Not an insurmountable detail, but it is an extra step that isn't there for either radio-frequency or visible-light signals.  If you're sending interstellar signals, it's not clear to me how the economics would work pushing you either toward or away from X-rays. 

Visible light is distorted even just looking out of your Atmosphere. So much so, putting observatories in space is highly beneficial.

And if you want to get a high bandwith, highly precision measuring is required.

And there is also the part where a relay sat is easier to move around then a planetary receiver.

 

So there are plenty of reasons to go for a satellite relay anyway.

 

On 2/8/2019 at 10:09 PM, Michael Hopcroft said:

On the railguns, it seems like they would take up an enormous amount of energy using modern technology. Can a, say, destroyer-class naval vessel produce enough to fire more than once? Would you need to fire more than once? 

Oh yes. And that is actually one of the biggest design challenge with them. You need enough power generation.

The first sea trials will be on transport ships that are not remotely battle worthy, so they can put a sufficient generator on too.

The Zumwalt class was designed to have the power generation to spare for stuff like a railgun, on a military platform.

And there is a decent argument that we might see a return of the cruiser and battleship for Railguns.

 

As for firing it more then once:
Of course you want to be able too!

Afaik our current research is mostly about making it possible to use the barrel equivalent more then once.

And even if you got the Capacitors to store the total energy for one shoot, they might loose power quicker then you can produce it. Or give you a unuseably long reload time.

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On ‎12‎/‎30‎/‎2018 at 1:31 PM, DShomshak said:

 

Every time a probe visits a new celestial object, we find something that makes scientists say, "WTF? We didn't expect that. And there's another batch of theories thrown into the Dumpster." (All said with big grins and occasional mad giggles.)

 

I would be surprised if Ultima Thule did not continue the tradition.

 

Dean Shomshak

 

Aaand I was right.

 

Dean Shomshak

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7 hours ago, Lucius said:

 

Ever get the feeling the Cosmos is trolling us?

 

Lucius Alexander

 

The palindromedary does

 

There is a quote, which I've seen attributed to multiple people: "Not only is the Universe stranger than we imagine, it is stranger than we can imagine."

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On 2/8/2019 at 12:02 PM, Cancer said:

 

First item: interesting, but one difficulty is that both broadcast and reception must take place from orbit or the surface of an airless moon or asteroid, since X-rays don't make it through any appreciable atmosphere.  Not an insurmountable detail, but it is an extra step that isn't there for either radio-frequency or visible-light signals.  If you're sending interstellar signals, it's not clear to me how the economics would work pushing you either toward or away from X-rays.

 

Second item: Saw this, and if it works out correct that's a very interesting source of ancient Earth rocks.  I have the impression they have a lot more work needed to establish the terrestrial origin securely, though.

 

Third item:  This again?  Anyone who was paying attention back during the Reagan Administration remembers that building an effective, genuine ABM defense system is exceedingly difficult, whether you use responding missiles or directed-energy antimissile systems.  It's a nice big yummy contract to build a prototype, though, and the people pushing for such systems have the contract as their goal, not a real defense. 

 

The Economist article notes the atmosphere difficulty. OTOH the felloow proposing this -- Hang Shuang, at the Nanjing University of Aeronautics and Astronautics -- has built a prototype x-ray transciever for "a particular, specialized purpose": Communication with spacecraft during the early stage of re-entry when a sheath of plasma around the vehicle blocks radio communication. The air is still thin enough for x-rays to penetrate. It's a two-step process: the spacecraft uses x-rays to communicate with a satellite in orbit, which relays messages to the ground by radio. I'm not sure how big a problem the radio blackout period is in practice, and I'm not sure I'd want to be on a spaceship with x-rays beamed at it, but it's an innovative proposal.

 

As for missile defense... heh. The article notes:

"America does not skimp on shooting missiles out of the sky. Its 2018 budget allocates #19.3bn to the task -- roughly equivalent to the entire defense budget of Canada or Turkey. Since 2001 it has splashed out over $130bn." For ground-based midcourse defense against as-yet hypothetical ICBMs from North Korea or Iran, it has spend $67bn (and rising), making it "the Pentagon's fourth-most expensive weapons system." Four interceptors supposedly have a 97% chance of stopping a single missile. Against 12 missiles, it is still 30% likely that one missile gets through. "The average revolver offers better odds for a game of Russian roulette." Still better than all 12 definitely landing on American cities, but still not great.

 

Dean Shomshak

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