Charlie's Diary

SCUBA is mostly for hobbyists and collectors, not blue-collar sea workers. Underwater engineering is almost all done by people wearing drysuits, not wetsuits. They look different to the old canvas-and-brass diving suits of old but the technology is pretty much the same, with air and heated water being fed to the worker via hoses from the surface or from a support submersible. SCUBA imposes serious limits on operational endurance due to gas tank capacities and pressure problems and the depths users can work at are very restricted.

The hard-shell suits (such as the JIM suit) are even more specialised, allowing really deep operation for long periods with the operator not requiring many hours of decompression before they can get back to the surface.

As for the MIT spacesuit, well it looks good. I don't know if it's been tested in a vacuum chamber yet, never mind in orbit where it has to keep its occupant alive for 50 minutes of continuous radiative heat loss immediately followed by 50 minutes of 1300W/m2 of solar radiation, time after time. We know the existing NASA suits will do this, the MIT cosplay outfit? Maybe.

Yay! New Greg Egan book.

Robert Sneddon touched on this already, but I wonder how the suit could be heated and dissipate heat since it doesn't circulate a gas inside. I suppose there could be heating elements woven into the inner layer and similar fibres to conduct heat away, but the article doesn't mention it. I also wonder how such a system of fibres would be controlled to maintain a specific temperature range.

A New Greg Egan? What's it called? What an odd co-incidence, I was just thinking this morning, "It would be nice if C.S. would give some book titles (not his own)of some of his favs. I'm always looking to see where recomendations take me. I found Stoss through Corey Doctorow.

Jeff

Stephen @3: I seem to recall that in Jerry Pournelle's version (seen in The Mote in God's Eye) cooling was provided by the wearer's sweat evaporating into vacuum. This bio-suit doesn't look porous enough for that, though it looks as though you could put heating wires down the lines of non-extension. Or maybe just wear an overcoat.

The Deid Nurse- what a great name for a pub.

Great story! I read it yesterday (courtesy of a link from Cory Doctorow). No sympathy for the devil there!

Stephen @3: it's not in the MIT press release, but the original 60s studies of such suits went for cooling via sweat -- the suit is porous, and evaporative cooling was one way to go (with a shiny reflective oversuit to reflect excess sunlight). The beauty of evaporative cooling is that it's a homeostatic mechanism -- as long as your astronaut is fit and hydrated, they'll sweat in those parts of their body that need to cool down. For heating, they proposed using electrical elements.

I'm not sure how the biosuit proposes to do cooling, but I don't see anything in the design that precludes the use of flexible heat conductors and a refrigeration unit in the (inevitable) backpack.

There are certain obvious drawbacks with evaporative cooling (don't try this much inside 1AU of the sun, for example) but it's a nifty idea.

There's a very important technology between SCUBA and submersible-supplied gas - rebreathers, where the only gas you throw away is the O2 after it's been metabolized to CO2. You recycle the inert gases, and so can go much much longer on the tanks that one person can easily dive with.

In the last ten years, they've become affordable for the dedicated hobbyist, and are quite easy to maintain. The model I like is the Megalodon (just a customer) - on it, I can get several hours of bottom time to depths of several hundred feet (on mixed gasses).

There are several other benefits to rebreathers, chief of which is the ability to tune what you're breathing to your depth - your breathing gas is mixed as you use it, so you can always be breathing the optimal mix for your depth, breathing as much O2 as possible (to minimize the inert gas load in your tissues) while not breathing too rich a mix (to avoid oxygen toxicity).

On SCUBA, you have to preselect one mix per tank and you're stuck breathing the best mix for your bottom depth (indeed, a bit deeper so as to provide a margin of error) through your entire dive, unless you carry multiple tanks (and then you only have the same number of mixes as tanks).

I should mention, by the way, that the hard suits that deep hardhat divers work in (such as the Newt Suit are not drysuits. Drysuits are a variation on wetsuits, and are used with SCUBA or rebreathers - in essence, the primary difference is that where a wet suit allows a layer of water under the suit for insulation, a drysuit is not water permeable and is inflated with a seal around the neck and wrists (or sometimes fastening to a helmet and gloves to give total isolation, for longer or colder exposures, or work with hazmats).

Recreational divers do dive drysuits, primarily in areas too cold for wetsuits. In fact, I've been with classes of new open water divers training in flooded quarries in Pennsylvania who were taking their first breaths underwater in drysuits.

The one thing that gets me about the MIT suit is the gloves. Most of the photos show it with bare hands; and I'm not sure how well complex finger joints will stand up to the mechanical counterpressure thing.

Certainly suit gloves are one of the big problems now - they're bulky and clumsy and heavy and expensive.

I suspect gloves are one of those little detail items that are still under development. Although heating/cooling you could probably do on the cheap by cheating -- omit a built-in mechanism but provide a fold-away mitten with built in hand warmer/cooler, and possibly heavy gauntlets for doing hands-on work on cold/hot surfaces.

I remember reading Apollo write-ups that described how the gloves were sufficiently clumsy and ill-fitting that after ten hours on the surface breaking rocks and drilling into the regolith some of the astronauts got back into the LEM to find they had split fingernails and bruising/bleeding from the fingertips. (On later flights they paid attention to this ... a bit.)

There was a NY Times piece on NASA competitions that included a competition to design a new glove. The winner was a glove that used crossed stitching between each knuckle, which seems to follow the same idea as the MIT suit, of providing pressure along lines of constant length during movement - I think you have to watch the video from the article to actually see the glove itself.

The suit material wouldn't need to be all that porous, considering the vapour pressure deficit of a vacuum (near enough to infinite). Humans can get rid of an insane amount of heat by sweating, as long as the suit was a light colour I don't think that would be a problem. And if you're only losing heat by radiation, a light coloured outer shell might kill two birds with one stone.

Robert, I thought commercial divers mainly used drysuits where it was bluddy cold? They certainly used to use wetsuits in New Zealand, before drysuits were widely available. A drysuit is a bit nicer to pull on day in, day out, and all.

There is only one important question as regards the new spacesuit.

Is it flexible enough to allow ninjitsu moves?

@14:

Commercial divers tend to work at depth for hours on end. They get paid when they're decompressing after all and spending an hour at working depth and four hours staging up is a waste of time and money if they can spend four hours working and four hours staging. Beyond a certain point in time decompression tables limit out.

For extended endurance you need a drysuit to avoid hypothermia and loss of muscle efficiency. That's why a lot of divers also have heated-water undersuits fed by hoses from the surface. Sport divers who spend less than an hour in the water can manage the thermal losses using a wetsuit, but hot drinks afterwards are usually welcome.

Rebreathers -- the big worry I have with them is thay are complicated mechanisms, and if something goes wrong at depth then it's not fixable in-situ and the fault is probably going to kill you. SCUBA using "simple" gas tanks and regulators are less prone to failure, but obviously they don't have the same endurance for the bulk and mass carried.

The big users of rebreathers until now have been military divers, where the risks are balanced by the benefits (among others, less of a detectable bubble trail from expelled waste gases).

Jerry Pournelle told me that they had vacuum-chamber tested tight mechanical-pressure suits back in the 60's, but that internal NASA politics killed 'em. That's second-hand, of course.

Nightshade are doing a collection by yrs truly, too... distinguished company!

The Egan book seems interesting. I think his characters are pretty interesting, although his futures aren't always easy to relate to. Some of his ideas with regard to wetware implants, like those of Jon Walter Williams,Greg Bear, a variety of "sub-personality" psychologists and Plato (daemons), are very interesting. How does C.S deal with IA (Intelligence Augmentation) with implants? It must have been covered in Accelerando, or was it?

Jeff

What only the four minimum!! I went for 18 titles but then I do have a crushing amount of credit card debt I am in deep denial over. Just your average geeky American here.

She: "But, Doctor Asimov, why have you invited me up to this space station, all alone, with your wife out of town and all that?"

He: "Bwahahahaaaa ... it should be fairly obvious that crossing your legs is not an option."

@17:

I remember seeing a documentary here in the UK several years ago (part of the BBC Horizon series) that was dedicated to the topic of improved spacesuits. I think there was NASA footage of the mechanical pressure suit in a vacuum chamber on that. The problem they experienced was that they couldn't maintain the requisite pressure at critical points like the inside of the elbow or the back of the knee, and this lead to blood-blisters from the vacuum.

The other spacesuit technology that they featured was the hardsuit where the big problem was getting the complex joints at shoulder and hip working. You had to learn the right moves and commit them to muscle memory or it was easy to freeze up the joint.

Seems odd though that this kind of research appears to be restricted to small departments in MIT rather than being full blown NASA projects. After all, the suits they use today aren't that different from designs from decades ago.

I realize this is off topic, but I’m if I could make another blog-top-suggestion: The use of antidepressants in Great Britain. I’m currently listening to the BBC and there is a story on this topic. Anti-Ds and other mood-altering drugs are being prescribed more and more in G.B., as they are in the U.S. I’m sure you must have something to say, seeing how your background includes pharmacology. I deal with this issue in my writing, as have several of my favorite authors. It’s a huge part of our emergent social reality and I’m sure anything you have to say on the issue would be worth reading.

Jeff

Jeff 23 off-topic: Anti-Ds and other mood-altering drugs are being prescribed more and more in G.B., as they are in the U.S.

-- this is, generally speaking, a Bad Thing.

There are people who really need to be on meds because their brain chemistry is screwed. I know a manic-depressive who's that way.

But these cases of genuine need are rare.

There are legions who are on meds (or are put on meds) because they're just unhappy in one way or another, or because the powers-that-be can't or won't use millenially time-tested methods for dealing with unruly behavior, particularly among children, and reach for chemical substitutes to doing their duty.

Why it's considered taboo in some circles to give a kid a swat on the backside or stand him with his face to the wall in a corner, but perfectly OK to dose him (it's usually him) with powerful drugs... it's a mystery.

(Insert the Glyph of Irony here.)

And I've got news for the unhappy: the Buddhists are right -- to live is to suffer, and then you die, usually in terror and pain. You don't have an entitlement to a pain-free life, and your existence is going to end badly. Advice: learn to cope, and show a little dignity.

I read a convincing study some time ago which indicated that all forms of 'talk therapy' hurt more that they help, on average, and that the best way to deal with traumatic or unpleasant memories is the traditional stiff upper lip; try your best not to think about them.(*)

This will not always work, but it will work better than anything else, in most instances.

Freud's 'return of the repressed' is, like most of his theories, a complete crock.

Your memory isn't a write-once read-only media. It's continually modified. Memories are disassembled and rebuilt every time they're recalled; dwelling on them strengthens them. This is, of course, also an explanation for why false memories are so common and so easy to evoke.(**)

Repression works -- but it's hard and requires effort, which is enough to make it unpopular in an age that considers narcissism and self-indulgence to be virtues. It also requires getting over yourself; ditto.

(*) just as the best way to deal with physical fear, for example, is to refuse to acknowledge it to anyone around you, and as far as you can not to yourself either. Like any emotion, it builds on itself if you let it, and it's contagious.

(**) and it's also why, as anyone with legal training will tell you, eyewitness testimony is far less accurate than circumstantial evidence and forensic data. Interrogate witnesses separately and you'll always get substantial differences in their perceptions of an event; put them together in one room and let them talk about it, and they'll come out -- perfectly sincerely -- remembering things the way the strongest personality does.

Nothing is more common than for someone who was present at an event to start 'remembering' it the way the media do, often blatantly contradicting his recorded immediate recollections.

And in turn this explains why it took so long to come up with the scientific method, and why it's necessary to have such elaborate records and protocols to prevent even trained scientists from seeing what they very much want to see.

Mark@22 - don't forget other critical points such as groin and armpits!

The other issue is the need for urination which could be the ultimate limit rather than the life support system. I suspect that the next generation of suits will be as mentioned a hybrid of mechanical counter pressure and traditional gas bladder approach. One of the real bug bears for counter pressure suits is actually donning the things as anyone who has tried to but on a cold, stiff wet suit will attest to. One answer that I have seen put forward is the use of the two way shape memory metals (I don't think this has been achieved with plastics yet). The suit is donned with them in their 'relaxed' position and then they are contracted (usually by heating with a current passed through the metal) to achieve the required counterpressure. They also have the added advantage of being highly elastic.

Counterpressure suit filled with some sort of gel? Or even just water? I think that would work to maintain pressure at hollows like elbows and knees - it would also mean you could make the suit a little less tight-fitting, and it would be easier to put on; might also help insulation (as a wetsuit does). Of course, it's bloody messy to take off.

ajay@26 - As always ideas seem to occur simultaneously, the gel idea is something I have been considering for a while but not got around to researching properly. But yes it would seem a viable option. Gel 'pockets' contained in a highly flexible membrane at key locations. You would also need to consider heat transfer through this medium as some of the locations in questions (armpits and groin primarily) are important for heat regulation.

The other main issues, as stated, are allowing enough flexibility and 'feel' in gloves and also the connection to the helmet. Anyone who has worn a dry suit with a too tight neck seal will attest to how unpleasent this can be. Imagine Arnie in Total Recall when he smashes his faceplate in the opening scene.

Now we just need someone to develop a CO2 scrubber that doesn't need a consumable material and we're sorted, apart from you know development...........testing.........manufacture................

S.M. @ 24: I think we must have some very similar mindsets. Do you think that we might A, have a society/culture that is becomeing more like Accelerando in nature and this is causeing an increase in mental illness? If all our pollution (air, water, food...)can cause physical problems, I think our information pollution might cause physical/metal problems also. Like bad memes. I'm not sure what the answer is; I was trained in the mental healthcare field. I have seen lots of people helped by meds, but then I see the abuse also.

Jeff

If you haven't found your fourth book, then grab a Glen Cook title. Either "Passage at Arms" for SF or "A Cruel Wind" for a tragically underrated fantasy series. Passage at Arms is essentially a submarine novel in space, and it's very good. Cruel Wind contains the three core Dread Empire novels, which are... a postmodern Conan ? Kinda.