DerekL1963

0.o Everyone I know who indulges in such things, and everything I see about them (in various media) emphasizes that they take safety very seriously. They know there's a risk, but they do everything within reason to mitigate those risks. The most risky forms of any given activity are generally reserved to the experienced and knowledgeable, and those that don't make that cut are actively discouraged from taking those risks. They are in fact selling safety - "this is a risky endeavour, but we've done everything possible to minimize, mitigate, and eliminate the risk". Nowhere in the civilized world does anyone routinely allow a n00b to participate in any activity as risky as human spaceflight. Note how in all the tourist flights to date, the n00b has undergone extensive training prior to the flight - "minimize, mitigate, and eliminate".

But it's also the central problem - nobody is going to fund, design, and build around a booster that may-or-may-not exist a decade hence. SLS also faces an additional hurdle, the only probes worth it's performance are high end flagship ("battlestar") missions - a class of probe that's largely been deprecated and are extraordinarily unlikely to be funded.

That leaves the payloads in limbo for an extended period. Doing it the other way around leaves the booster in limbo for an extended period. There aren't any easy answers really.

Yes, VA was meant to be manned , not just as part of a space station. One version (Almaz APOS) would have been used on the initial launch of a station, a different one (TKS) would have been used for re-supply and crew exchange. So the pairs would have been Soyuz/Progress, Almaz APOS/TKS, and Zarya (in various modes). Buran AFAIK never figured in any serious or significant operational planning.

25k per annum for Kilimanjaro, 35k for Antarctica. So, yes, "tens of thousands" but barely. (And why do you keep tossing around vague numbers when real numbers are so easily acquired?) Then... why do you keep bringing up people who pay far less? Why can't you cite people who have done so or a single event that costs that much? Don't bring up Everest or any other form of mountaineer. They may spend hundreds of thousands cumulatively over a period of years or decades on their sport but they do not do so for a single brief experience. In general they seem to average around $200k - and there's only about a thousand per annum. 200 million dollars per year sounds very impressive, but that'll only buy you three or four Falcon 9 launches at current prices. (Maybe four to six with a reused first stage if the rumours are correct.) That is "hundreds of thousands" for a single experience isn't nearly enough - current prices are in the millions (as in "tens of".) Not to mention that Everest is generally climbed as the culmination of years spent in the sport - not a one off experience. That's what folks seem to fail to grasp - flight costs per individual (currently roughly $20m/per) have to come down at least two orders of magnitude to start attract the cream of the most wealthy adventure tourists. Halve that and you start getting into triple digits per annum. Halve again and you start getting in four to five figures per annum. But to really pull in the numbers, you half to halve again on top of that. And do so with airliner levels of safety. People are getting wealthier, and the culture is shifting to experiences, but the two trend lines (cost of space flight coming down, and the number of people and the amount they're willing to pay) are still impossibly far apart. And there's no indication that's going to change any time soon. (Unless you've drunk from Musk's kool aid.)

Cut up for razor blades, mostly because their hulls and systems are worn slap out. 0.o ISS Modules are four meters + in diameter and generally eight to twelve meters in length. And most (Western) missile tubes are more like 10-11m in length... The tubes have MUCH less volume. The place most tourists will pay to look (near reefs and near the bottom) are places nobody is going to take a submarine of any size. Or, to put it another way, pretty much all of the assumptions behind this subthread are arrant nonsense.

I wouldn't push that analogy too far... because if you're trekking, you're going someplace and doing something - not sitting in a can, regardless of how wonderful the view is. Some people do, most don't. Not until they get much older and pine for their salad days. Myself, I served with some incredibly talented people (some of whom I'm still friends with after thirty years), and prize the experience greatly... But I miss being 22 much, much more than I do going to sea. Less than a third of a typical SSBN's displacement (the former missile compartment) is available. The rest is taken up by machinery and crew quarters vital to operating the ship. Hundreds? There were only two hundred odd ever built, and the bulk of those were Soviet - which no sane person would willingly ride. (They appear to have only four no longer in service, but not yet scrapped.) Of the rest, there's only seven remaining - but only six still have their reactors. Two (missing their missile compartments and virtually all their non-engineering equipment) in the US, and four (essentially intact) in the UK. None of them are now cruising hotels because they're hideously expensive to operate and require a highly trained crew.

I posted the info on Everest more as comparison-and-contrast than anything else. It's an interesting look at how many (or few) people will pay tens of thousands of dollars ($50k+) to take on a challenge with significant risk on failure, injury, and death.

Hundreds of thousands visit Nepal... [1] But only 35,000 visit Everest. 700-1000 of them attempt the summit, but only 350-500 make it. [2] Though the numbers vary sharply by year, it appears an average of six climbers per annum climb the mountain eternal. [3] (Caveat: Some of the peak numbers are due to mass casualties which makes figuring an average rather more difficult.) Less often mentioned is the number of Sherpas who die supporting those climbers. The actual number of deaths per annum is actually higher because the Sherpas aren't generally counted in the statistics as climbers are.

Gimbaling leads to cosine losses... passive stabilization helps avoid these losses. Passive stabilization also helps with overall vehicle stability which in turn makes aborts safer. Dr. Von Braun's words the matter: https://books.google.com/books?id=MiYDAAAAMBAJ&lpg=PA185&ots=Cw7tIvaYUk&dq=Since the flight path--usually into orbit--is predetermined%2C and thus ideally suited to programed changes in ga in setting%2C it might appear that there should be no need for fins.&pg=PA185#v=onepage&q&f=false Edit: Ninja'ed by Tullius...

Disclaimer: Yes, I've swapped meaning for experiences. I misspoke in my first post and limited "experiences" to "sitting around admiring the scenery of a given place". @tater's post clarified my thinking. Admiring the view is certainly something tourists do, but that doesn't generate much in the way of economic activity other than transport and lodging. That's what I'm trying to get across here, the tourism industry is, as tater makes clear, more than just sitting there admiring the view. Certainly, going to Hawaii isn't all about laying around on the sand, but first and foremost it's Hawaii. Secondarily, it's the other activities - pretty much none of which will be available on orbit. No reefs to snorkel, no waves to ride, no sugar plantations or nature preserves to visit, no... well, you get the picture. While going to space is certainly important because, after all, SPACE!!, it doesn't offer much of anything else in the way of experiences. And those experiences are a huge part of the cash flow and economic activity generated by tourism, and are the primary drivers for the balance. (That is for transport and lodging.) That is, the income from transport and lodging are driven by their usefulness in providing access to experiences. While Space (and zero-G) has a certain attractiveness in it's own right, the lack of secondary experiences and amenities reduces the potential market dramatically. The more limited the experience, the smaller the potential traffic flow. Not as many people are going to pay to sit in a cabin while admiring a view and eat MRE's as would pay to get out into that view and eat further upscale.

That's the theory, reality is much harsher. The tourism industry is built almost entirely around going desireable places - and space isn't a place in that sense. That part of the tourism industry dedicated to providing experiences is much, much smaller... And experiences is all "space tourism" offers for the foreseeable future (even with a drop in launch prices of a couple orders of magnitude). Not really, no. There's nothing (in the way if minerals and metals) that can be found in space that isn't abundantly available here on the surface. Even with such a drop, your capital costs are still going to be higher than the terrestrial equivalent because the equipment will have to operate in zero-G and vacuum.

The parachute is probably a parachute... It's pretty common for expensive payloads to be suspended from a parachute which is in turn suspended from the balloon itself. When the envelope pops (as it inevitably will), the payload begins to fall and the parachute automagically inflates without needing any fancy deployment equipment. This video shows the chute fairly clearly.

True. But they never flew in their intended role - manned as a replacement for Soyuz.

Which is useful for determining if there is anything "new", but not really useful for determining what exactly that new thing is or how it differs from old things. For that you need (drum roll) high resolution. More seriously, though the high resolution cameras get all the attention, they flew a variety of cameras with a variety of resolutions for various purposes. Low res mapping cameras for cartography. Medium res survey cameras to look for "new" stuff and to surveil targets for the high res cameras. High res cameras for really close up views of specific targets. This was especially important back in the days of film. Nowdays, bandwidth being what it is, they probably just use the narrow angle high res cameras for everything and stitch the images together when needed. They're still Shuttle (cargo bay) sized - you can't get high resolution out of any much smaller.

New replacement for Soyuz being the operative term... Their previous three (or four? I've lost count) replacements for Soyuz (stretching back into Soviet era) having failed to materialize for one reason or another.

Not quite true. Many of the things they made up out of individual weldments, we'd cast as one part or or machine out of single block nowadays. Processes and procedures have changed a lot over the past fifty years and 3D printing is just the tip of the iceberg even if it is the current flavor-of-the-month. That being said there's plenty of precision welders about, you don't need guys with battleship experience (because the heaviest part you'd find on a rocket are a bare fraction of the thickness of the heaviest parts of a battleship). No doubt there's plenty of guys at EB or NNews (submarine construction yards) who'd be willing to take a flyer at welding on a rocket. (That is, what welding hadn't been designed out (by casting or machining the part) or automated.)

Yes, and no... We went to the moon (that is Kennedy chose it as a goal) in large part because most of the puzzle pieces were already undergoing research and development (the LM being the notable exception). We went to the moon because we were pretty sure the Saturn V was possible.

And it would also make incorporating any "lessons learned" or variability due to mission more expensive and difficult. It's pretty much always so for changes of any significance, more difficult and expensive to modify than to make the changes during production.

Which part of "nobody builds flight ready spares" was too difficult to grasp? That's true for boths numbers and schedule. If the mission calls for four tanker modules, then there's going to be four tanker modules. Period. If there's another mission in the next window, they're going to be somewhere in the pipeline - not sitting around waiting to be used in this window. Yet you're blithely certain that losing a part of your Mars craft won't be a problem. This does not compute. 0.o Everything they need to potentially fix any problem? No way in a very hot place. EOR or heavy lift, you're still weight limited by your transfer stage, by how accurately your engineers calculated what spares you'll need, and by budget. (Trust me, from bitter experience I assure you that the engineers get it wrong sometimes - even for mature systems with decades of operational experience.) You also presume the vehicle is designed to be extensively maintained in flight. So far. But with only seventy odd launches so far, a loss in the next ten or fifteen would immediately move it from "very amazing" to "among the worst of currently operational vehicles". (Worse than the Shuttle!)

Measuring spacecraft position relative to a proof mass was first used by NAVSAT (Transit) to allow accurate orbit determination.

Oh? And where does that redundancy and capability come from? No program funds flight ready spares anymore. Certainly you have the theoretical capability to delay a flight for years to decades while the next flight's unit is hurried through the process, but at the end of the day that's not significantly different from a heavy lift architecture. What do you think would have happened to ISS if (say) Destiny had been lost in a launch accident?

The problem with such simple minded math is that it fails to significantly reflect reality. First, because it fails to address total programmatic risk. More launches, more rendezvous and prox ops, more interfaces that must be connected, all of these things increase the risk that something will go wrong. (Not to mention the schedule pressure and headaches.) Second, because it fails to address parasitic mass. The more chunks you break your final vehicle into, the higher the proportion of parasitic mass (stuff needed to get the chunks into position, but not required for the final vehicle) grows. Basically, the higher the proportion of parasitic mass, the higher your overhead costs. (That is, the "obvious" step of reducing costs per launch doesn't mean your costs go down in proportion to the launch cost reduction.) The latter can significantly alter your total costs... An Altas V 551 doesn't launch 20 tonnes of final payload mass - it launches (as a SWAG) around 15-18 tonnes of final payload mass and 2-5 tonnes of one-time-use support and delivery mass. Even using the optimistic end of the spectrum, you end up shelling out 2.5 billion dollars (an increase of almost 10%). And that doesn't take into account the increased costs of engineering and integrating a finely divided system, nor the increased operational costs, nor the engineering and hardware costs of the one-time-use support and delivery systems. (That's why so many orbital assembly schemes use independent reusable tugs and fuel depots, trading increased complexity and risk for reduced costs.)

The makers of the video do not grasp that a rocket motor is just a bit more than an impressive torch.

That too.