August 31, 2019

Meanwhile, At Stromboli

Erupting volcanoes are mercurial and as such are not the most advisable of tourist destination.

Pyroclastic flows can really take you by surprise. .

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August 27, 2019

Chandrayaan2

Remember that post a few months ago about the glaciers on Mercury?
Well India sure did!

^{"I'm absolutely confident that that post had zero impact on India's space program"}

Shh!
Anyway, Chandrayaan2, India's second lunar probe, is set to land a rover near the lunar south pole on September 9. The main purpose of this mission is to do an extensive survey of the ice deposits which were confirmed by Chandrayaan1 via the straightforward method of shooting an impactor into Shackleton crater and noting that ice was blasted out of it.

Currently, the probe is surveying the possible landing sites in preparation for releasing the lander.

Unlike previous probes this one is intended to extensively study exactly what forms the ice is in so we may find out if there really are formations as unexpectedly spectacular as the glaciers on Mercury.

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August 26, 2019

Looking for Hohmann Transfer Tables

Some months ago, when I was otherwise obligated, I blundered into an online Hohmann orbit / travel time calculator for launch windows between all planets out to Jupiter (plus Ceres) out to IIRC 2050.

I can't find it now and suspect it may only be available from academic institutions, but I was wondering if anyone has a link to something similar.

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July 23, 2019

Here's Something Neat That You Don't see Everyday

Here we have a false color image of...something.
Guess what the 'greenish-yellow' stuff is.

Is it :
A: Impact related lava flows in Lunar Craters?
B: Sand dunes in windswept craters on Mars?
C: Stromatolite colonies in brine pools in Australia?

more...

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July 10, 2019

Some Correct Scale

Here is an excellent study of the interior of the Stanford Torus space habitat by Rick Guidice.

It's particularly notable as one of the few renditions to get the scale of the actual final design right.

The Stanford Torus was the final in a series of designs intended as minimum sized test beds for a self sustaining space habitat. The Stanford Torus's habitation tube was "only" 430 feet wide. That's still almost half again wider than a football field is long, and it would have been 3 and a half miles (5.6K) long, which is pretty impressive.

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March 10, 2019

Since That Last Post Was Depressing (UPDATED)

Here's something to give existential threat assessors hives, and the rest of us hope.

It's Ryan Weed, the CEO of Positron Dynamics who claims to have solved antimatter's production and containment issues. He's getting around the storage problem by the elegant method of avoiding it totally. They're generating positrons on the spot (using Krypton79 decaying to Kr78 ) and firing them into deuterium to catalyze fusion. The neutrons from the reaction transmutes the Kr78 back to Kr79 and the associated 'splody travels out the tailpipe and goes "woosh". Research is looking promising, but there are already some interesting spinoffs, which include a nuclear battery with a yield of as much as 100 watts a kilogram.

UPDATE:

Here's an animation of how their system is supposed to work.

Peter Thiel has invested in the company and their development has been promising enough that NASA gave them a big grant last March.
Time will tell.

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March 08, 2019

It Went Splash, Not Splat!

The most important part of a successful manned spacecraft is the ability to return It's crew safely.

Oh look!

^{"The plushy and the robot have not lodged complaints!"}

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February 09, 2019

Meanwhile, In the Kuiper Belt

N.A.S.A.s New Horizons probe has just had its best pictures of " _2014_MU69">Ultima Thule" processed. Now we've sent one of The Brickmuppet's Crack Team of Science Babes to bring us the latest on this Kuiper belt object. However, given what we've seen so far it's fairly clear that it is just a bog standard comet and pretty much uninteresting in any way.

"That last sentence is about as wrong as is grammatically possible."

Oh.

Well, it appears that Ultima Thule still had some surprises, one of which was only revealed when the spacecraft flew past it.

You see, according to the mission webpage, this is believed to be the best picture that New Horizons took of Ultima Thule...

There's a lot of oddness, including the fact that it appears to be a conjoined comet. Then New Horizons flew by the object aaand....

Yes.

It's flat.

It's surprisingly flat.

Why that should be is unclear to say the least, but it is interesting that one of the explanations for the weirdness of the recently departed Omuamua is that it was flat enough to be affected by solar pressure. Perhaps something causes objects on edge of interstellar space to flatten.

In any event, it's NEAT!

And, rarely does science give us such a straightforward and unambiguous lesson in the importance of perspective.

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January 15, 2019

The News is All About Hamburgers and Overpriced Razors So Here's Some Space Stuff

One of The Brickmuppet's Crack Team of Science Babes brings us the latest developments the search for extraterrestrial intelligence...

"My new favorite word is Technosignature."

The short video is a good quick overview of SETI issues. However, Mr. Cain also links to the referenced NASA report as well as the recent SETI conference minutes, which can provide hours of amusement.

In other SPACE news, while we wait for high resolution pictures from Ultima Thule NASA is providing some visual perspective on the matter.

The full presentations are here and here.

(We should see some high rez pictures in about two weeks or so.)

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December 31, 2018

New Horizons VS. Ultima Thule

Well, tonight (tomorrow actually) after the fireworks and the dropping of the ball, you should stick around because there will be an encore celebration around 12:15AM, when Clyde Tombaugh's atomic powered urn, better known as NASA's New Horizons probe, which not so long ago gave us spectacular views of Pluto is going to pass by(486958) 2014 MU69, a small but very strange transNeptunian object that has been given the unofficial temporary name Ultima Thule for marketing purposes.

The object in question, about 12 miles across, is a cause for a good bit of speculation as it doesn't seem to have much of a light curve, at all, which is...odd.

"But it's AWESOME, 'cause it's weird

and we're gonna discover something!"

Indeed.

Note though, that possible explanations include that the object is actually surrounded by a cloud of debris, in which case there's a decent chance that New Horizons will come to an end in a collision.

Because it is SO far away, the radio signals will take over 9 hours to get to NASA! Coverage of that is set to start around 09:45 Eastern Time(U.S.). There is a press conference scheduled for 11:30 Eastern to discuss the pictures, or what can be gleaned from the probes loss. There will be a lot of discussion of this online tonight and tomorrow morning with Launchpad Astronomy already 4 hours into their 24 hr livestream.

So tonight, after the celebrations, sit back, watch the coverage and throw back an egg nog for Clyde Tombaugh, the little probe that carries his remains, and the implacable spirit of mankind.

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November 09, 2018

A Spoiler Appears

The midterms aren't over!

It looks like all those missing ballots went to S.M.O.D. who will send his emissaries this weekend.

"Instead of tabloids and sketchyYouTube

sites, maybe check NASA?"

Well...

That wouldn't be click-baity at all would it?

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October 30, 2018

Thoughts on Proxima B

Shortly after the discovery that Proxima Centauri, the closest star to our sun has a planet in the habitable zone, NASA pointed out that Proxima is known to be a flare star and the planet is so close that it would probably be grilled, baked and flash fried.

Now, two years later, they've finished a study adding potential variables to see if anything could mitigate the effects of the flaring, and surprisingly, there some scenarios which allow for a habitable planet and a few with a sort of Earthlike biosphere. These are HIGHLY speculative numbers as we know almost nothing about the planet except its orbit and mass. They are interesting nonetheless...

The odds are still on it being a burned out cinder, but even for this planet, that is not a given.

Note that the second closest planet to our solar system, (Ross128b) is a better candidate, not only because it doesn't face the flare issue, but is even closer in mass and temperature to Earth. With such variables as discussed in the Proxima-B video, its odds might be better still.

"Schweet!."

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October 21, 2018

Follow-Up on that Hardware Hacking Story

A few weeks ago we noted that Bloomberg had broken a HUGE news story that involved China inserting small chips onto mother boards that were intended to allow back door access to ALL THE HARDWARE.

A week or so later we noted that sourcing was rather....thin, and that no rice grain sized chips had been produced.

Now it appears that Apple (who has vociferously denied it all along) is demanding a retraction and apology from Bloomberg.

As Pixy noted in the comments to our first post on the matter, one of the reporters involved has a rather chequered history with computer spying stories.

To Wit:

one of the reporters on the Bloomberg story -- Michael Riley -- had also done a story back in 2014 making bold claims that the NSA had exploited the Heartbleed bug, and multiple other reports ripped that story to shreds, with multiple people denying it and no one else confirming it.

That TECHDIRT story goes on to suggest that Bloomberg has whittled away their credibility on this and "set fire to the scraps".

For example people quoted in the original story are strongly contradicting it.

All of Bloomberg's sources on this are and remain anonymous. So as of now, the story seems to be a dumpster fire, that still hasn't produced any spy chips or any evidence whatsoever.

None of this is to suggest that its a good idea to be subcontracting our most vital components to overseas slaves whose masters hate our guts, or that this isn't an obvious and even likely threat. However, IF this story is in fact bunk, (as now seems likely) the "Cry Wolf Effect" will make it harder to prepare for such matters. Furthermore if this is bunk then those of us who reported it credulously will find it harder to be believed when it does come to pass.

If I were the CCP, that would suit me just fine.

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October 17, 2018

Project H.A.V.O.C.

While the acronym does accurately convey the idea, the High Altitude Venus Operational Concept acronym might need some tweaking for PR reasons.

In any event, the project is quite interesting and NASA's announcement Monday that it is seriously considering it for one of its upcoming manned missions is genuinely exiting. Conceived by N.A.S.A.'s Langley Research Center, H.A.V.O.C. has actually been around for a few years, Scott Lowther did an extensive write up on it in U.S. Spacecraft Projects #5 earlier this year.

The concept involves using a rocket to go to Venus, (which actually is easier to get to than Mars) which will drop a manned survey vehicle into the atmosphere.

So far so good, except that as we all know, Venus's surface temperature is that of molten lead, its pressure is higher than in the Marianas Trench and after CO2 and Nitrogen, the most common atmospheric gas is sulfuric acid. Also it's gravity is about the same as Earth and so would require a full sized ( Titan or bigger) acid proof rocket to get the crew back into orbit in the unlikely event they weren't baked, dissolved, and crushed.

This is why Venus has not been on N.A.S.A.'s shortlist for places to visit.

Fortunately there is an amazingly cutting edge technology that allows a manned survey of Venus.

The Blimp!

The High Altitude Venus Operational Concept takes advantage of the fact that temperatures 34 miles above the surface are around 80 degrees and the pressure is that of Boulder Colorado. However because the CO2 atmosphere is much denser than nitrogen, earth air is a lifting gas at that altitude.

"Dirigibles in space!"

So the idea is to inflate the "landing" party's ship on the way down and have it double as a 423 foot long airship, (Actually a manned, dirigible, rockoon) and then fly around the planet for a few weeks or months doing more detailed surveys than can be done from orbit and tele-operating probes on the surface. This also allows for detailed chemical analysis of the atmosphere, using sensors lowered on tethers into the dense lower atmosphere, much like a oceanographer uses Nansen bottles to sample the deep.

After completing the mission, the Blimp will launch a rocket from high altitude (Like a Pegasus) and transport the crew into space, where they'll rendezvous with their mother ship and return to Earth.

Assuming an acid proof blimp, Venus is actually much safer than Mars for the astronauts. The gravity is about the same as Earth, the thick atmosphere plus the planet's weak magnetic field would protect the crew from cosmic rays even better than earth does. Venus is much easier to get to and launch windows open much more often than they do for Mars. Two precursor missions, one manned but confined to orbit and one using a 1 quarter scale drone dirigible to test acid proofing and demonstrate that the inflation/deployment system works would precede the crewed Venus blimp sortie..

This is a very good idea for an icebreaker mission. It's more advanced than the moon or asteroid missions currently in the pipeline but still far quicker, easier (and probably safer) than the upcoming mission to Mars. Such a mission would be far shorter in duration than a Mars landing and would be a nice stepping stone on the way to those missions as well as expeditions to the asteroids Mercury, Ceres and Callisto. Flags and footprints albeit without flags or dirty feet (but with a blimp!).

So, today we've discussed rockets, space travel, a manned mission to the planet Venus and an airship, nay, a rockoon even! The only thing that would make this cooler is a swordfight.

Or floating cities...

The fact that air is a lifting gas means that large, long term settlements are theoretically possible, with all the advantages regarding radiation and gravity listed above. Even the sulfuric acid is not that big a problem as it is mostly below the altitudes proposed, where it is quite dilute. In fact, the temperatures while hotter than Death Valley are such that one could could probably do something one can do nowhere except Earth: step outside in a birthday suit and survive as long as one could hold one's breath (but run to the cold shower/eyewash station afterwards!). As an added bonus, unlike anywhere except Titan, due to the sheer density of the CO2, such cloud cities would also be far better protected against meteor strikes than any city on Earth.

A 2015 study at Rutgers (preliminary draft here) published the above artwork some time ago to illustrate what a (very hypothetical) more permanent research station might look like and news reports on Monday's announcement almost universally featured the below N.A.S.A. image of a large floating outpost acting as a tender to several H.A.V.O.C. type airships.

Both of these are very ambitious indeed and probably quite far term. For one thing, despite its advantages, Venus would seem to make little sense as a location for space cities, as they'd be far down a gravity well, there's no water except what one can crack from the sulphuric acid and no easy way to bring in supplies from asteroids. In an O'Neal cylinder or on the surface of a planet like Mars a major damage incident is survivable with space suits and repair teams, on Venus if you balloon deflates you're baked, dissolved, and crushed.

So unless the view of the clouds is SPECTACULAR and sufficiently so to somehow justify interplanetary tourism, there's little reason to believe that there would ever be any kind of permanent outpost on Venus.

I mean what could Venus produce that has real value and couldn't be gotten FAR easier somewhere, indeed anywhere else?

"PHOSPHOROUS!"

Oh right...

One of our Crack Team Of 2-D Science Babes reminds us of this paper (PDF) we perused recently that reviewed what scientists know about Venus's atmosphere. Here's an interesting excerpt...

Venera 13, Venera 14, Vega 1, and Vega 2 descent probes all carried X-ray fluorescence instruments. These instruments measured elemental composition of the cloud particles and found not only sulfur, but also phosphorus, chlorine and iron â€“ notably, as much phosphorus as sulphur in the lower clouds below 52 km [Andreichikov et al, Sov. Astron. Lett. 1986, 1987]. A chemical analysis by Krasnopolsky [PSS, 1985] con- cluded that the phosphorus could be in the form of phosphoric acid (H3PO4) aerosols, which would ac- count for the particulates observed by descent probes down to 33 km altitudes

Emphasis is mine.

Phosphorus, is not a trivial thing.

Phosphorus is absolutely vital to life and while theoretically common on earth is concentrated in useable forms mainly in living organisms and in phosphate rocks (mostly fossils of dead organisms). The amount of free phosphorous pretty much dictates the carrying capacity of the planet and it is a real concern for food production as phosphates are a finite resource. Furthermore, additional sources of phosphorus need to be found if humanity is going to expand into space. such deposits are presumed to exist, but on Earth they seem to have been concentrated by biological action leaving a bit of a chicken-egg problem finding it off planet. Even without off planet colonization phosphorous shortages represent a potential disaster for human food supplies. There is discussion of peak phosphorus here, here and here.

Even if the perils of peak phosphorus are overstated, it IS a finite resource and most off planet settlements are going to require off planet sources of phosphorus if they are to expand. Phosphorus could well end up being something akin to the dilithium, quanticum 40,or spice Melange of the real future. The only extraterrestrial places that I've read that it exists in other than trace amounts is the above mentioned cloud layer on Venus and the red clouds of Jupiter (bound in phosphene).

This moves the notion of a floating city on Venus from technically feasible to potentially practical and indeed desirable. See, if the Soviet probes were correct, then there is, in Venus's lower atmosphere, phosphorus (in gaseous form) in greater concentrations than the ubiquitous sulfur. You'd need to pump up atmosphere near the surface, filter out the undesirable stuff and if its phosphoric acid then you have to take out the water and oxygen (I'm sure uses can be found for those) I don't know what reagents might be necessary but this represents a steady supply of phosphorous.

But wait...there's more. Venus has more sunlight than earth, a zillion times as much CO2, and about 4 times as much atmospheric nitrogen as Earth. There's also water to be had from the phosphoric and sulphuric acid. And remember you're better protected from meteor strikes and cosmic rays than on Earth. A Venusian phosphorus-gas mine could grow all its own food.

Art from Technica Molodezhi TM - 9 1971 a Soviet Science Magazine

In the longer term, expanding upon such floating farms, Venus could be the breadbasket of the solar system. All that stuff that can be got so much easier on Luna, Mercury, Mars or The Belt? Well, the cloud cities of Venus ought to be able to just buy them. Of course you have solar power out the wazoo so it's at least conceivable that such an outpost might make something useful out of the carbon in the CO2. Note too that the referenced report also mentions the apparent presence of gaseous iron compounds in the lower atmosphere which might be industrially exploitable as well. Finally, Venus has, as mentioned, well more that three Earths worth of nitrogen in its atmosphere. If Venus sold Mars an atmosphere, there'd still be enough left over for thousands of O'Neal Cylinders. Venus has the potential to be not only self-sufficient but an exporter of food, fertilizer and air.

Of course for any of that that to eventually come to pass we need to confirm the Soviet probe data and do close surveys of the planet. N.A.S.A. seems to be planning just that in the next decade.

This is awesome. Even putting aside the longer term speculations; the fact that N.A.S.A. is looking at innovative missions like this is truly heartening.

With regard to the more ambitious proposals, I think we should begin a movement to have high pressure gaseous phosphoric acid referred to by the trade name "Tibanna".

Art by Ralph McQuarrie

UPDATE:

:Fixed some typos.

:Added 2 additional pictures

:While trying to hunt down a picture credit I discovered that there is an extensive disquisition on the topic of Venusian settlement and even terraforming from 2014 here.

UPDATE 2:
:Thanks to Pete Zaitcev in the comments there are some links to much earlier thoughts by John Goff on the matter regarding safe rocket recovery here and here as well as Venusian industrial chemistry here and here.

Crackerjack 2-D Science Babe is Rikka from Haganai

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September 12, 2018

The 21st Century is Here!

Robo-trousers to give elderly bionic strength designed by British scientists

Finally! Exactly the sort of human augmentation that science fiction has been promising us!

Beware of Penguins.

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July 15, 2018

News From the World of 'Splody!

One of the Brickmuppet's Crack Team of Science Babes brings us the delightful news that Lawrence Livermore National Laboratory has declassified about 300 more above ground nuclear test films.

Both the above and below are of the same test of the SADM, nuclear backpack bomb (positioned 110 feet underground).

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July 07, 2018

Prospecting Prospects

Issac Arthur's video this week is on the colonization of Ceres. This one is pretty neat. I had not realized that the gravity on Ceres was so low that spin habitats could be put on the surface and there would only be the equivalent to about a three degree list to port for the inhabitants.

The fact that sunlight is actually bright enough to grow plants and be marginal for solar power as far out as Jupiter is interesting as well.

I'm much more of the Dandridge Cole / Gerald O'Neal school of thought on space colonies. I'm skeptical of Mars settlement, especially when A Stanford Torus or O'Neal cylinder pretty much will have correct gravity. They can be anywhere, perhaps next to (or inside) mineral rich asteroids and potentially move if needed.

Art by Franz Blok

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1 What the hell is that accent? He's got more W's in odd places than Tweety Bird. Totally throws me out of the narration.

Posted by: Mauser at Sat Jul 7 13:54:52 2018 (Ix1l6)

1. With Niven & Pournelle, I always wondered why, after spending millions to get out of a gravity well, you would want to go down another.

2. Barring a cultural change far off my radar (which really isn't far) there are not going to be off-world colonies except as playgrounds of the hyper-rich. The entire notion is predicated on Malthusian/Ehrlich (so: false and insane) grounds of population growth. The populations of those that have the IQ & culture to live in space is in decline. The population that's still growing? I wouldn't trust them to close the airlock doors.

Posted by: Clayton Barnett at Sat Jul 7 15:56:55 2018 (ug1Mc)

What the hell is that accent?

Ohioan

He has a fairly epic speech impediment. Most of his videos mention this at the beginning and suggest one avails oneself of captioning. Note that in the last year he has improved dramatically, as the show is, it seems, good therapy for him.

He also used to have an Elmer Fudd pic at the beginning of each episode but I suspect there was a DMCA issue.

Note too that Mr. Arthur also did a couple of tours in Iraq.

Posted by: The Brickmuppet at Sat Jul 7 16:06:56 2018 (3bBAK)

4 I'd like to see a serious discussion of a habitat design modeled on the roller bearing. One ring nested inside another, with the two kept apart by magnets and vacuum. The inner ring would spin to produce centripetal acceleration, while the outer ring would not spin and would be sufficiently robust to contain the inner ring.

I don't have the math or engineering know-how to calculate the stresses or dimensions needed, but I suspect that such a design could be made arbitrarily large without needing exotic materials. Just make the outer ring more robust. As it's not experiencing any centrifugal tension itself (by virtue of not spinning) it can be optimized to whatever thickness is necessary to constrain the inner ring.

Start mass producing such nested-ring habitats (diameter 300 miles, length, 100 miles), and every group on Earth which wanted its own world, away from *those* people, could buy one and build its own little Utopia.

We'd need a Launch Loop to make access to orbit cheap enough to make the Lunar mining colony economical before we could start building the Rings, but none of that would require technological breakthroughs, or any scientific advances.

Well, unless the nested-ring geometry doesn't work as I expect it to.

Posted by: jabrwok at Sun Jul 8 06:04:11 2018 (wKZS0)

5 The spin gravity puts a strain on the habitats such that the maximum size with steel is a cylinder five miles by 20...Now that does have a safety factor built in.
You're right about the bearings though. That is going to be an issue in these combined gravity habitats.
Regarding the rock; Even the old Stanford Torus used slag brought up from the moon to provide a nonrotating radiation shield. The O'Neal Cylinder designs did as well, but most illustrations omitted the rad shield for clarity in exactly the same way this one doesn't.

http://brickmuppet.mee.nu/images/fig1202-radiation-shielding.jpg

Building them in Asteroids as I.Arthur suggests kills a couple of birds with one stone...er asteroid. The materials are in-situ, and the shielding is already there.

Posted by: The Brickmuppet at Sun Jul 8 07:49:21 2018 (Es+wK)

6 As I understand it, the strain induced by the spin is basically tension produced by centrifugal force. The geometry I'm visualizing has a spinning ring *inside* another, thicker, non-spinning ring, like the <a href="https://duckduckgo.com/?q=roller+bearing&t=h_&iax=images&ia=images">roller bearings</a> in a skateboard or a fidget spinner. The outer ring would act like a railroad for the "train" of the inner ring, and could be made arbitrarily thick so that it could handle the angular momentum produced by the spinning inner ring.

If it would work, then the whole system could be scaled up to arbitrarily large diameters, with no need for scrith or other unobtania.

Unfortunately I'm not an engineer, so I can't prove that it would work.

Posted by: jabrwok at Sun Jul 8 11:26:38 2018 (wKZS0)

7 A containing outer shell doesn't cancel the outward force, it just applies an additional force in the opposite direction. So now your inner shell material is being subjected to not just the tension from the centripetal force, but is also facing friction heating, compression, and drag from the outer shell. Your design would create more problems than it solves, and would result in a smaller habitat, not a larger one. (Also not an engineer, but that's pretty basic physics...)

Posted by: David at Sun Jul 8 13:37:35 2018 (JMkaQ)

8 <i>A containing outer shell doesn't cancel the outward force, it just applies an additional force in the opposite direction.</i>

Yes, thereby preventing the inner ring from tearing itself apart.

<i>but is also facing friction heating, compression, and drag from the outer shell.</i>

There would be no friction or drag if the rings were held apart with magnetic fields and had only vacuum between them. The "compression" is a non-issue as keeping the inner ring compressed is the entire point of the configuration.

Posted by: jabrwok at Sun Jul 8 18:53:43 2018 (wKZS0)

9 There would be no physical friction. The magnetic fields on the other hand...
Did you know that the moon's gravity is slowing the earth's rotation? It's a quarter million miles away, roughly. The outer ring and magnets would be a lot closer. So you'd need a fair bit of energy to be input constantly to counter that.

Another, more critical point. The outer ring is there to keep the inner ring from flying apart. Which means that, through the magnetic forces, the inner ring is transferring its centrifugal force outwards to the outer ring.
What keeps the outer ring from breaking up?

Posted by: Ubu at Mon Jul 9 09:38:46 2018 (SlLGE)

10 What keeps the outer ring from breaking up?

Thickness. The outer ring could be as robust as necessary to contain the centrifugal force being generated by the inner ring. Given that the outer ring would not be spinning, it's own mass would put no strain on its tensile strength.
As for the possible resistance produced by the interaction of the magnetic bearings, well, that's a possible obstacle. But again, I'm not an engineer, so I can't calculate whether that would be a problem or not, nor how difficult it would be to overcome. Possibly some electromagnets mixed in with the permanent magnets would be enough to overcome the hypothetical resistance.

To be honest, I was hoping there would be an engineer reading this thread, or that someone hereabouts would know one, who could run the numbers and provide a definitive answer.

Posted by: jabrwok at Mon Jul 9 14:35:48 2018 (BlRin)

11 I'm no engineer, but the other 'non-trivial' problem to borrow a word from SDB, is that you'd have to make certain the counter-forces need to spin it back up (or in the first place) would have to be very exactly balanced, and monitored in real time. I'm not sure how you could do that in a way that wouldn't set up a negative reinforcement cycle that got further and further out of control. Let's not even touch on where you're going to get non-electromagnets big and powerful enough to balance your giga-ton monstrosity. The moon's got a surprisingly high amount of iron, but that's not all it takes. And adjusting the position of a two-part "torus station" would be...tricky.

This reminds me of the flywheel discussion on Chizumatic. Which I'd link, but it's dead now, and I don't know the mirrors.

Posted by: Ubu at Mon Jul 9 17:05:48 2018 (SlLGE)

12 Ubu, Chizumatic is still up; denbeste.nu is down. Was this the link you were looking for?

Some of USS Clueless is still mirrored at sdb.dotclue.org.

Posted by: Rick C at Mon Jul 9 19:22:21 2018 (ITnFO)

13 Someday, we should reconnect with Steven's brother and see about transferring the domain registration, or at least renewing it and pointing it at the current server. I decided not to pursue it at the time.

-j

Posted by: J Greely at Mon Jul 9 22:23:15 2018 (tgyIO)

14 you'd have to make certain the counter-forces need to spin it back up (or in the first place) would have to be very exactly balanced, and monitored in real time.
My thoughts on spinning up the inner ring were along the lines of having mass-drivers on the outside of the Rim Walls. Push reaction masses along those mass-drivers in one direction and the inner ring spins in the other. You could use a LOT of reaction masses, or just some very dense one, or both. This would give you the advantage of allowing for the launch of interstellar space probes (the reaction masses) while bringing the inner ring up to the desired rate of spin. Or you could just use charged particles and take a long time to get the desires spin rate.

I agree that the magnetic bearings are a possible stumbling block. I keep hoping I'll run into an engineer who can address that concern. But I don't think it's an impossible obstacle.

Posted by: jabrwok at Tue Jul 10 08:54:51 2018 (BlRin)

15 Yep, that's the one, at 20060102. I really miss his stuff.

I can practically hear SDB complaining about derailing the thread....

Posted by: Ubu at Tue Jul 10 11:51:48 2018 (SlLGE)

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July 05, 2018

OK. Now Pele is Just Screwing With Us

Behold, a lava tornado.

via

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July 03, 2018

It's Important in These Trying Times to Maintain Some Perspective

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May 07, 2018

That's a Bad Thing to See on Your Commute

Via Volcano Cafe, which is doing a great job on covering the situation in Hawaii.

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