For Questions That Don't Merit Their Own Thread

[YNM]

54 minutes ago, K^2 said:

If there is no reason to jam, there is no reason to jam better. 

But isn't jam delicious ?

[monophonic]

1 hour ago, K^2 said:

A sonar system that only shows you false targets without showing you real ones seems properly disabled. But if you want to split hairs on terminology, I won't argue the point. Lets call it, "Creating decoys using hardware more commonly used for jamming."

Decoys are physical things, although they do belong under the broader concept of jamming. What you have been describing is better categorized into deceptive jamming techniques.

Have you considered how your technique behaves in non-trivial acoustic environments e.g. surface duct or bottom bounce conditions? And especially when some emitters are in a different region from others?

(a quick reference of sound paths for those who want one: http://www.oc.nps.edu/~bird/oc2930/acoustics/summary.html )

[Green Baron]

 

Spoiler

"We're jammin', jammin'
And I hope you like jammin', too."

-Marley

 

Edited October 15, 2018 by Green Baron

[kerbiloid]

12 hours ago, K^2 said:

Keeping in mind that majority of large moons are going to be in equatorial plane

Keeping in mind that almost all of them have appeared from a protomoonary disc which is the same as a protoplanetary one, and the same as a ring
and keeping there that a protoplanetary cloud is originally potato-shaped, and only later the dust forms a protoplanetary disc (while the gas spherically shrinks into a gas ball inside, a protostar)
looks enough likely that rings and disks are primary, while the planets and moons are secondary.

Though, of course if there are massive bodies orbiting in equatorial plane, the process of a ring equatorization runs many times faster.

Spoiler

1 hour ago, Green Baron said:

  Hide contents

"We're jammin', jammin'
And I hope you like jammin', too."

-Marley

Make jam not war.

 

 

Edited October 15, 2018 by kerbiloid

[kerbiloid]

_{(multiposting, deleted)}

Edited October 15, 2018 by kerbiloid

[Green Baron]

Spoiler

Make jam like war !

 

Edited October 15, 2018 by Green Baron

[Diche Bach]

13 hours ago, Spaceception said:

Ignoring money and ethics (Although, I don't really see it as unethical to use Nuclear in space considering there's no life)?

You're right about Orion giving you around ~10% light speed, but I don't ever remember seeing 20% (Except now that I remember, I do remember some Ben-10 episode talking about Orion getting that high, but I wouldn't call that a reliable source ). 20% may be possible for something akin to Daedalus, but not Orion. And Daedalus definitely isn't possible with current technology. If we were really serious, I suppose we could start the research for that, but it'd probably take decades.
The caveat for Orion is that you're only going to see about ~5% light speed if you want to slow down. So that's 90 years to the nearest star. Not horrible, but not really fast either.

With current technology, anything we build will be limited by nuclear fission. If we had fusion, our options would be pretty large, but alas.
In this list, you can see a lot of options. I believe you want your specific impulse in the (high) hundreds of thousands of seconds - or higher - to be viable for an interstellar drive http://www.projectrho.com/public_html/rocket/enginelist.php#werkaffre

If you want to coast to the nearest star using current technology to around ~5-10% light speed, a combination of laser sails and nuclear pulse propulsion, or (maybe?) nuclear salt water would be your best bet.

And here we begin with starshot. Ignoring the fact I don't know if its possible to have a postage stamp sized spacecraft that can last decades; the basic idea of using a massive laser array to push a solar sail is a good one, and has been around for decades (Scroll down http://www.projectrho.com/public_html/rocket/slowerlight.php). You could get pretty impressive velocities too, at least 0.1-0.2c (or ~40-20 years to the nearest star. Now we're talking). But the catch is that there's no laser on the other end, so you'd be limited by your maximum velocity to something manageable (<.1c) by your drive (AKA, Orion), until you can build a laser array on the other end to catch your ship. You could also slow down using the solar wind of the target star, but I don't think it'd slow you down a whole lot to be done alone.

Going back to a fusion drive in general (http://www.projectrho.com/public_html/rocket/realdesignsfusion.php), you might be able to get away with it if it's powered by a new generation nuclear fission reactor. However, I don't know how inefficient/ineffective that would be. Or if a design could match or exceed 5% the speed of light. Someone more knowledgeable will have to answer that.

Finally, using current technology to build a starship would be hard, and if crewed, dangerous. I'd bet that if we started on one today, it would be delayed by things we hadn't considered, and require technology later down the line. But I would also say we have most of the base technology already. So we're in an ok position to begin. I'd try to account for the wait calculation though

Thank you!

Damn . . . 0.5 c for an arrival trip to Trappist (39 light years distant) is 780 years!

Even Alpha Centauri and Proxima Centauri (~4.4 light years, which are probably pointless from an "habitable target" standpoint) are 88 years!

ADDIT: looking at that link at the projectrho site . . . came upon the design for the URSS Alabama . . .http://www.projectrho.com/public_html/rocket/slowerlight.php#id--Go_Fast--Starships

Quote

The URSS Alabama is a fictional Bussard Ramjet starship from Alan Steele's novel Coyote (2002). It was the first starship, build by the authoritarian conservative regime which took over after the fall of the United States. At its dedication ceremony, it is hijacked by the captain, and escapes the regime by travelling to 47 Ursae Majoris. The 46 light-year journey takes 230 years cruising at 0.2c, with the crew and colonists in biostasis.

Thas what I'm talkin' bout! 

ADDIT: and just to clarify: the "0.5 c for a rendezvous journey (i.e., not a "fly-by" but a "slow down to arrive and enter orbit at target system")" for an "Orion-style" external nuclear pulse propulsion design . . .this is a result of the tradeoff between mass and energy capacity? Bombs, blast absorption plates, shock absorbers, life support apparatus, etc., etc., all have "minimum mass" values established by existing materials science (and reality!). One could carry more bombs in order to try to go faster, but at the 0.1 c threshold one reaches the point where: existing bomb yields are insufficient and carrying more bombs to allow for longer period of acceleration/deceleration just doesn't work?

So . . . less massive materials, more powerful bombs (per bomb mass), else some means to "multiply" the propulsive force of each bomb (like e.g., an energy field projected along the surface of the blast absorption plate that was calibrated to have repulsive reaction to the polarity of the blast wave?) could all increase the total viable velocity?

Edited October 15, 2018 by Diche Bach

[Spaceception]

46 minutes ago, Diche Bach said:

Thank you!

Damn . . . 0.5 c for an arrival trip to Trappist (39 light years distant) is 780 years!

Even Alpha Centauri and Proxima Centauri (~4.4 light years, which are probably pointless from an "habitable target" standpoint) are 88 years!

ADDIT: looking at that link at the projectrho site . . . came upon the design for the URSS Alabama . . .http://www.projectrho.com/public_html/rocket/slowerlight.php#id--Go_Fast--Starships

Thas what I'm talkin' bout! 

ADDIT: and just to clarify: the "0.5 c for a rendezvous journey (i.e., not a "fly-by" but a "slow down to arrive and enter orbit at target system")" for an "Orion-style" external nuclear pulse propulsion design . . .this is a result of the tradeoff between mass and energy capacity? Bombs, blast absorption plates, shock absorbers, life support apparatus, etc., etc., all have "minimum mass" values established by existing materials science (and reality!). One could carry more bombs in order to try to go faster, but at the 0.1 c threshold one reaches the point where: existing bomb yields are insufficient and carrying more bombs to allow for longer period of acceleration/deceleration just doesn't work?

So . . . less massive materials, more powerful bombs (per bomb mass), else some means to "multiply" the propulsive force of each bomb (like e.g., an energy field projected along the surface of the blast absorption plate that was calibrated to have repulsive reaction to the polarity of the blast wave?) could all increase the total viable velocity?

Yeah And to make it clear, it's 0.05c, 0.5 c is half the speed of light

There's always Ross 128, well over a couple centuries away with current-ish tech, but still fairly close by (Less than a dozen light years).

Unfortunately, the Bussard Ramjet may be closer to the Daedalus side of things, because the scoop needs to be massive, and you're limited by pure Hydrogen fusion, not deuterium, He3, tritium, or any combination of those. And pure Hydrogen fusion is harder. You could use a reactor design we have, and have the hydrogen fusion for the drive, but then you absolutely need to stop the ship in other solar systems to refuel the reactor.
You're actually limited by about 0.12 c, because of the drag caused by the scoop, and low density of the interstellar medium. However, you'll essentially have a near-infinite supply of fuel, and you only need to stop in other solar systems to stock up a bit and repair your ship. On the plus side, I think there was an idea you could use the drag of the scoop to slow your ship down. But you don't have to cut your speed in half, because again, all your fuel is in the interstellar medium (You still have to get up to a certain speed using onboard fuel to make the scoop effective though). So that's less than 40 years to the nearest star, and less than a century to anywhere within 10 light years or so!

The 0.05 c limit is there I believe, because beyond that, you start getting diminishing returns. Yeah, they're nuclear bombs, and pretty powerful ones at that, but to reach higher speeds, you need pure fusion pulse propulsion, or something similar (Like Daedalus. Man, that's always cropping up). Otherwise, the tyranny of the rocket equation will finally creep up on the Orion, and your mass/fuel ratios will become worse and worse.

[Diche Bach]

yes . . . 0.05 c my bad  

HOPE is not a strategy!

[Spaceception]

1 minute ago, Diche Bach said:

yes . . . 0.05 c my bad  

HOPE is not a strategy!

HOPE?

[kerbiloid]

They call it a cost-effective strategy.

Do nothing and hope.

Edited October 15, 2018 by kerbiloid

[Diche Bach]

Implying that my "error" of writing 0.5 c in place of 0.05 c reflected a deep-seated subconscious HOPE! 

When I express approval of the URSS Alabama design it was more in terms of the narrative the author has created around the imagined space craft not so much to say "Ah! THIS is what I will use in MY imagining!"

Like I said: for the phase of the timeline I'm working on, I want to keep the "hardness" on the science fiction hardness scale as hard as possible. If that means 0.05 c and 780 years is what we gotta work with: well so be it! As the timeline progresses, it makes sense for more futuristic "speculative" techs to open up, but not early on.

My understanding was anything EXCEPT nuclear pulse propulsion (meaning external detonation of a bomb and "surfing" on the blast wave) is across a boundary we might call the "Speculative Technology Line." Obviously the laser sail idea CAN WORK, but only for quite limited payloads.

As far as I can tell, even the NPP conception _IS SPECULATIVE_, at least in the sense that: the actual design, cost and redundancy systems needed to make it actually function reliably are only projections, which cannot be established without advancing the project beyond the drawing board phase. It could be that: even though the system is completely viable in terms of existing physics, the necessary redundancies to make the system function reliably prohibit its functional utility even with unlimited funds and no social or legal constraints.

But that is why they call it science FICTION!

Even the HARDEST science fiction is still science fiction! 

Edited October 15, 2018 by Diche Bach

[Spaceception]

2 minutes ago, Diche Bach said:

Implying that my "error" of writing 0.5 c in place of 0.05 c reflected a deep-seated subconscious HOPE! 

When I express approval of the URSS Alabama design it was more in terms of the narrative the author has created around the imagined space craft not so much to say "Ah! THIS is what I will use in MY imagining!"

Like I said: for the phase of the timeline I'm working on, I want to keep the "hardness" on the science fiction hardness scale as hard as possible. If that means 0.05 c and 780 years is what we gotta work with: well so be it! As the timeline progresses, it makes sense for more futuristic "speculative" techs to open up, but not early on.

My understanding was anything EXCEPT nuclear pulse propulsion (meaning external detonation of a bomb and "surfing" on the blast wave) is across a boundary we might call the "Speculative Technology Line." Obviously the laser sail idea CAN WORK, but only for quite limited payloads.

As far as I can tell, even the NPP conception _IS SPECULATIVE_, at least in the sense that: the actual design, cost and redundancy systems needed to make it actually function reliably are only projections, which cannot be established without advancing the project beyond the drawing board phase. It could be that: even though the system is completely viable in terms of existing physics, the necessary redundancies to make the system function reliably prohibit its functional utility even with unlimited funds and no social or legal constraints.

Have fun designing a generation ship then

I actually have an idea where a fleet of Gardener ships goes star to star, putting colonists around them to expand humanity.

Each ship has multiple, massive cylinders. I think 9 in total? And 8 rotate. 1 is for mainly human habitation, and the other 7 are for various ecologies. Which are used as preservation, and vacation spots for the crew. So you've got a tropical beach, or a temperate forest, etc. And each one of those are designed for comfort rather than real utility (Although it does kinda double as a live DNA bank in case they want to quickly paraterraform). And the main human inhabited cylinder has somewhere between 5-25 million people, depending on how large I actually make it. Or it could be a larger fleet of ships, a handful have people, and others have ecologies (and some people). This is more far future though. But you could probably tell.

[Diche Bach]

Well . . . my training is in human biopsychology, so  . . . I feel a little less "uncomfortable" about engaging with some "speculative" biological tech.

As such, cyrogenic stasis is the method I intend to invoke: remember cost, human rights, and ethics are NOT constraints! 

Not that I have kept up with developments but . . . a few years back (perhaps ten years now?) a Russian research group managed to put a dog into complete cyrogenic stasis for a long period of time (48 hours or something). The dog was effectively DEAD. Its body temperature was near the freezing point of water, and it had zero vital signs. They achieved this by sedating it, draining most or all of its blood and replacing this with a special substance that would allow the tissues to allow the process.

I'm not sure what permanent or long-term neurological or other physiological deficits the poor dog suffered, but yeah . . . I'd say we are less than a century from having functioning cyrostasis. If enormous sums of money were thrown at it, maybe only 20 years.

ADDIT: actually that Russian dog story may well have been a hoax!

Even so, we know there are vertebrates who have natural adaptations which allow them to enter long-term dormancy, so cryostasis is "tenable" and the methods for achieving it are a matter of research, not a matter of "imaginary biology," imo.

https://en.wikipedia.org/wiki/Cryobiology#Vertebrates

Quote

 

For the wood frog (Rana sylvatica), in the winter, as much as 45% of its body may freeze and turn to ice. "Ice crystals form beneath the skin and become interspersed among the body's skeletal muscles. During the freeze, the frog's breathing, blood flow, and heartbeat cease. Freezing is made possible by specialized proteins and glucose, which prevent intracellular freezing and dehydration." ^[6][7] The wood frog can survive up to 11 days frozen at -4 °C.

Other vertebrates that survive at body temperatures below 0 °C include painted turtles (Chrysemys picta), gray tree frogs (Hyla versicolor), box turtles (Terrapene carolina - 48 hours at -2 °C), spring peeper(Pseudacris crucifer), garter snakes (Thamnophis sirtalis- 24 hours at -1.5 °C), the chorus frog (Pseudacris triseriata), Siberian salamander (Salamandrella keyserlingii - 24 hours at -15.3 °C),^[8] European common lizard (Lacerta vivipara) and Antarctic fish such as Pagothenia borchgrevinki.^[9][10] Antifreeze proteins cloned from such fish have been used to confer frost-resistance on transgenic plants.^{[citation needed]}

Hibernating Arctic ground squirrels may have abdominal temperatures as low as −2.9 °C (26.8 °F), maintaining subzero abdominal temperatures for more than three weeks at a time, although the temperatures at the head and neck remain at 0 °C or above.

 

Even bats and bears enter prolonged torpor, which, while not as dramatic as examples in the quote above, at least demonstrate that neurologically advanced vertebrates can get very "close" to something like a cryostasis and conceivably all the way there.

 

 

 

Edited October 15, 2018 by Diche Bach

[kerbiloid]

But -4° is not a real cryo, it's a cold. And they don't become solid, they stay liquid.

Btw a suggestion for cryo.
As any body is expendable and gets depleted after a century of usage, and as a half of brain consists of "lizard brain" or so (though, it's probably enough for many humans even without another half), why freeze the bodies for spaceflights?

Freeze the better part of brain, then on arrival  grow new bodies around them. So, 1 kg instead of 80.

(If also you can dry them, there will be just several hundred grams per passenger.)

_{So, "to brain" - the passenger packing, "to unbrain" - the unpacking.}

Btw. The bodies after the part of brain removing still could work as androids and operate with controls during the flight.

Edited October 15, 2018 by kerbiloid

[Spaceception]

9 minutes ago, Diche Bach said:

Well . . . my training is in human biopsychology, so  . . . I feel a little less "uncomfortable" about engaging with some "speculative" biological tech.

As such, cyrogenic stasis is the method I intend to invoke: remember cost, human rights, and ethics are NOT constraints! 

Not that I have kept up with developments but . . . a few years back (perhaps ten years now?) a Russian research group managed to put a dog into complete cyrogenic stasis for a long period of time (48 hours or something). The dog was effectively DEAD. Its body temperature was near the freezing point of water, and it had zero vital signs. They achieved this by sedating it, draining most or all of its blood and replacing this with a special substance that would allow the tissues to allow the process.

I'm not sure what permanent or long-term neurological or other physiological deficits the poor dog suffered, but yeah . . . I'd say we are less than a century from having functioning cyrostasis. If enormous sums of money were thrown at it, maybe only 20 years.

 

I think Cryonics approaches softer sci-fi, since we don't know if we can revive the person, alive and healthy. This could definitely change in the near future, but you'll need to think of some speculative discoveries that have to be made beforehand. Plus, you have to revive people every so often or the body will decay from being unable to regulate itself. So it may end up being a hybrid. Whereas with a straight generation ship, we have most of the base technology for it. You can just imagine doing a kind of copy+paste of ecosystems around the world, managed by automation in place of the balance of nature.

[tater]

 

[Diche Bach]

9 minutes ago, tater said:

 

Wow. Literally tear invoking.

Who could guess that the accreted space wreckage of a 4.5 billion year old celestial planet crash could be so beautiful to the improbable big-brained bipedal hominids that sprang up on the bigger half of the wreckage only some 23 million years ago . . .

[Green Baron]

14 minutes ago, Spaceception said:

... we don't know if we can revive the person, alive and healthy. This could definitely change in the near future ...

Sorry to hail in, we know perfectly that we can only freeze a body to be dead meat. If it will someday be possible to freeze and revive is pure hope. Medicine and physics say no.

Edited October 15, 2018 by Green Baron

[Diche Bach]

1 minute ago, Green Baron said:

Sorry to hail in, we know perfectly that we can only freeze a body to be dead meat. If it will someday be possible to freeze and revive is pure hope. Medicine and physics say no.

Too dismissive, and apparently not very well informed.

 

[Green Baron]

Well, if we can have a regular scientific article about the hows and the probabilities, then i will revoke ;-)

Youtube does not count.

Arcor is a hopes&dreams company/foundation/whatever. The papers cited are, well "Rejuvenation Research" ... hmm, is that serious or made in-house ?

:-)

Look at that list: https://www.ncbi.nlm.nih.gov/pubmed?term="Rejuvenation Res"[jour]

To me, it sounds pretty ... esoteric. Like ads for a new anti aging cream.

 

Hey, i am just trying to help you with the "hard scifi" condition ;-)

Edited October 15, 2018 by Green Baron

[tater]

18 minutes ago, Diche Bach said:

Wow. Literally tear invoking.

I know, right?

Stunning.

[Diche Bach]

3 minutes ago, Green Baron said:

Well, if we can have a regular scientific article about the hows and the probabilities, then i will revoke ;-)

Youtube does not count.

Arcor is a hopes&dreams company/foundation/whatever. The papers cited are, well "Rejuvenation Research" ... hmm, is that serious or made in-house ?

:-)

Haven't had access to a Uni search engine for several years now, so if you seriously want to contribute, why don't you go find it? 

Normally you come across as a nice guy, but for some reason today it seems someone liquided in your cheerios? 

"Youtube does not count?" Seriously? What does that even mean? Like, some garble on a password protected peer-reviewed journal publishers server is somehow inherently BETTER information than a Youtube video!? I guess that means NASA, etc., should all stop posting on Youtube cause it "DOESN'T COUNT!"

 

[Green Baron]

2 minutes ago, Diche Bach said:

Haven't had access to a Uni search engine for several years now, so if you seriously want to contribute, why don't you go find it? 

Normally you come across as a nice guy, but for some reason today it seems someone liquided in your cheerios? 

"Youtube does not count?" Seriously? What does that even mean? Like, some garble on a password protected peer-reviewed journal publishers server is somehow inherently BETTER information than a Youtube video!? I guess that means NASA, etc., should all stop posting on Youtube cause it "DOESN'T COUNT!"

 

Hey, i am only helping with the "hard scifi" condition you wanted ;-)

I don't mean anything personal ! Sorry if it sounded like ...

but i still don't accept youtube as a source

Edited October 15, 2018 by Green Baron

[tater]

Regarding cryonics, the only thing that matters is brain state (unless the goal is storing spare parts). Until someone demonstrates that a complex animal has been frozen, then unfrozen in a way that preserves mental state (first I typoed this "metal," and I could see youtube music videos posted as to someone's "metal state," lol), it's pretty much meaningless. If you could have your body revived some arbitrary period of time in the future, but with a reset in brain state, you might as well not bother, you're in fact dead.