Hi Karl,

very interesting first post here :-) You mention some things in a factual manner which I've never before heard, such as that the ISS is in a bad orbit. Can you provide some links to more information on this, please?

cheers, Ingo

You may soon get your wish Karl, providing that everything goes to plan and NASA's budget doesn't get cut or something we could see a centrifuge tested on the ISS in a few years time http://en.wikipedia.org/wiki/Nautilus-X#Current_status

I thought the problem with the tethers was that they generated quite a large electric potential by cutting through the Earth's magnetic field, and effectively melt?

Sounds like the dude was having a bad flashback to that time his tether broke in mid spacewalk.

Hmm. I've been pretty downbeat about the end of the Space Shuttle, because now NASA has nothing big to look forward to. The talking heads are all upbeat about future missions and "we're never going to stop exploring" and whatnot - but the big plan? Hitch rides on crappy Russian capsules and hope the private space industry can bootstrap fast so we can continue servicing the ISS. Oh, and talk, but not really do anything meaningful about future missions - maybe to the moon, maybe to an asteroid, maybe Mars... or maybe nothing. The fact is, there isn't really an actual plan in place. Just talk about what that plan might eventually be. And that's sad.

But this is an interesting perspective on the problem. Maybe the problem really is a total lack of vision and spirit on the part of the leaders at NASA... I guess that means it really is up to the private space industry to make the next generation of space exploration possible?

I find that sad... because private industry lacks something that NASA had: a collective, national pride in our indominatable spirit and our resolve to explore. Ultimately, private industry will be about how it brings profits back to Earth. The national space program was, at least in part, about how it could bring something less tangible, and less mercencary, back to Earth. But... I guess the national space program hasn't really been about that, either, for a while.

Er, Karl, are you an expert in space engineering? Or anything remotely similar? Because all else being equal, I'm probably going to take the word of an astronaut over that of a science fiction writer. There certainly is a NASA orthodoxy on things like this, and it may be that the NASA orthodoxy is wrong. But I'd still want to understand where NASA got its belief that space tethers are completely unreliable before I dismissed it so entirely.

The main sadness I had with the ending of the space shuttle was the lack of any coherent plan for what we are doing next. 30 years would seem like enough time to put together some sort of follow on.

I still blame Ronny Raygun for treating NASA as (and insisting they act as) a business, and putting CEOs in charge. Sure, they had engineering backgrounds, but were mainly bottom line men. Look at what was being done back then, other than the Shuttle launching satellites, the only other thing (that I remember) are the Voyager probes, which were launched years earlier. It wasn't until the Clinton era that NASA got back to sending probes out, with great success.

Then Bush jr. came along, and it was back to business. He announced ARES, but he was never the one to inspire anybody to pull it off, or figure out how to pay for it.

JS Bangs @6; I suggest you go back and read this thread: http://www.antipope.org/charlie/blog-static/2011/07/yes-but-what-are-your-credenti.html

One of the best motivations is if you are always afraid that someone you hate will surpass you. We don't have an antagonist to race against anymore. The one upmanship that came from trying to outdo our sworn enemy, the Soviet Union, is lacking in the current political climate; and, so our space program stagnated. Relegated to a Earth orbit delivery and maintenance service.

Don't get me wrong. As an American, I love what NASA has accomplished. But, they did it too well. They made it look effortless; so we forgot the drama and peril. Just as the airline industry caused us to forget the impossibility of 900,000 pounds of metal and people flitting over our heads; NASA became polo wearing researchers rather then the daring test pilots that we idolized.

We don't have an antagonist to race against anymore.

The twenty-eight teams competing for the Lunar X Prize do. Granted, robotic probes and not tinned primate but still, Moon + twenty-eight teams.

Hey, guys, thanks for the comments. A few replies: --I remember from the original design discussions about the ISS that its orbit is too low to do real zero-gravity work. It's a "microgravity" environment, if you check. I believe it's also too low to be useful as a staging area for interplanetary flight, which is why you've never seen it used to, eg. put together large interplanetary probes. --Tethers do generate electricity, which needs to be taken into account but isn't a show stopper. I used tether power around brown dwarfs to generate starship-launching energies in my novel Permanence (2002). --Tether experiments have broken. A lot. But more recently, they haven't. Practice, as they say, makes perfect. --Credentials? ME? Bwaahaahah! You should never just believe anything I say. Look it up, and call me on my stupidities. --For instance, according to Wikipedia, each Shuttle flight cost $1.5 billion. Also according to Wikipedia, Elon Musk funded SpaceX with $100 million. That's the development of a whole new rocket company for less than one tenth the cost of ONE Shuttle flight. And there were 135 Shuttle flights.

Tethers? Were you stringing him along?

I'm afrayed knot.

Getting ropable?

He needed more moral fibre.

(okay, I'm done).

I tend to associate that kind of tenseness and unwilling to talk about certain subjects with approaching the edges of classified areas: if I recall correctly, the NRO have done a few experiments with tethered spacecraft, and indeed the tethers broke.

@JohnW That's not a bug, it's a feature! And not all tethers in space break. Some of them get horribly tangled :)

It is, of course, possible that NASA breeds astronauts for allegiance to the party line and even the thought of questioning that doctrine threatens to make their heads explode. It is also possible that astronauts are asked lots of stupid questions by members of the public, that they get tired of it, and that this astronaut thought - for reasons we don't know - that this was a stupid question. Perhaps both are true.

Tehers break. Which is why you should never drive across suspension bridges.

^Tethers, that is. :s

The bridges only stay up because of suspension of disbelief.

Its been obvious for a couple of decades than NASA is going nowhere. They've also pissed away billions on aborted projects, latterly Constellation. The Martian language will be Mandarin.

Regardless of the technology, the basic idea of variable gravity testing on physiology is urgently needed. Nasa wouldn't/couldn't even do centrifuge tests on mice.

I've no idea how viable tethers are, but clearly we use tension technology in a lot of places without a problem - like suspension bridges. Redundancy is a feature. A space elevator or even a skyhook would be tether technology. If tethers are really off the table, wouldn't this astronaut have said so and suggested an alternative method? I mean, it can't be fun using zero-g toilets, so at least partial g must be something that astronauts would like to make their work and living arrangements more comfortable.

its orbit is too low to do real zero-gravity work. It's a "microgravity" environment, if you check.

I'd like your definition of "real zero-gravity" please and some examples of places where you feel it might be encountered.

We'll see where manned spaceflight goes after Nasa. I was recently encouraged to learn that Bigelow has lined up 6 nations as clients for his inflatable habs, so maybe there will be early destinations for the nascent private space industry to expand into.

While we are still struggling with the "why" of human space flight, reducing the costs by orders of magnitude using new technologies will advance its practicality.

"We don't have an antagonist to race against anymore. The one upmanship that came from trying to outdo our sworn enemy, the Soviet Union, is lacking in the current political climate; and, so our space program stagnated." And now everyone uses Soviet ships to go to the ISS... Alternative history : maybe the Soviet Union did not die and is going to nationalise the SSS (Soviet Space Station). With the devt problem in the US, the social and demographic problems etc ... it won't last 20years as it appears. You can begin to sew your great Lenin flags. Seriously, let's say you are in 1991 and some time traveler from now comes and says to you that in only twenty years there won't be any space shuttle (nor mars program either) and the American astronauts (cosmonauts !) goes to the ISS using Soviet technology. What would have you thought ? (sorry for my poor english, I'm French)

Karl

What sort of response do you get from non Nasa astronauts?

I'm watching Atlantis being towed home right now, and feeling a little melancholy, even though from my point of view NASA does a lot of things that are cooler and more scientifically useful than manned space flight.

I've watched a lot of NASA TV during this last mission, and it occurs to me that astronauts in orbit are not only required to follow the party line, they're scripted and choreographed and micromanaged to an extent that makes me wonder how they stay sane, let alone retain any independent thinking capability.

Now thats an interesting link.

In all honesty, I've been fascinated by the idea of small scale tethers ever since I read David Brin's story Tank Farm Dynamo back in Analog (and freely available here: http://www.orbit6.com/et/tankfarm.htm).

I always wondered why they never attempted to conduct proper experiments on the concepts. It looks like they did, but had issues coping when stuff went wrong, and with respect to the astronaut, it looks like when stuff goes wrong it really goes wrong.

I especially like the bit where the end of the cable attached to the shuttle continued arcing until the shuttle passed into night and the particle density finally dropped enough to stop it. Thats a heck of an arc.

This book has a fairly complete discussion of the subject, plus all the experiments done.

It's possible the astronaut was an unimaginative drone. It's also possible they were involved in a tether experiment on the shuttle which was a spectacular and potentially dangerous failure. I am for once not being sarcastic when I say these are both genuine possibilities. But tethers in space do, indeed, break.

I probable wouldn't have believed them. I was so indoctrinated through media to abhorrer the Communist. Ivan Drago vs Rocky. I couldn't have imagined a world where we would be friends. It also shows the absurdity of our continued boycott of Cuban goods when the rest of the world has seemed to moved on. It probably won't be till Castro passes that we start trade talks with them.

Don't apologize for your English. I dare say it is better then mine and I grew up in the US.

I probably wouldn't have believed them.

See what I mean :-)

Astronauts are selected for being extraordinary. By that I mean extra-ordinary, more ordinary than normal, if that were possible. There are 24 astronauts from Ohio, for example: http://www.nasa.gov/centers/glenn/about/bios/ohio_astronauts.html

This makes sense, as you say, the program selects for people who stick with the program for a very long time and are consistent performers. Which isn't a great recipe for exploration or discovery ask it's a risk minimization strategy.

Another factor may be the conservatism inherent in being the guys that have to test that stuff. Rocket cars, great in theory but I'd rather watch it on TV or read about it than be in the rocket car.

Rocket cars, great in theory but I'd rather watch it on TV or read about it than be in the rocket car.

Enjoy!

http://www.youtube.com/watch?v=4Y9XZU_sy1w

Hmmm... sorry but the recovering engineer inside comes back with. "But tethers DO break. And they also jam and a bunch of other stuff."

AND, if you've a rotating structure in orbit with a broken tether you've a really REALLY interesting multi-body dynamic problem to solve on a structure of non-trivial inertia.

He was probably more tense just thinking through the potential failure modes and how you'd even start to deal with recovery from a break than anything to do with NASA orthodoxy. While NASA is extraordinarily risk adverse, I'm not sure that going the opposite way helps.

Finally, "basic engineering" doesn't really exist in space yet. We're still learning what that really means.

Karl@12 and James@9, I wasn't asking for credentials, although given that Charlie just blogged about that I should probably have been clearer in my disavowal of credentialism. I just want to know what makes you so confident that you know better than NASA about what space tethers are good for. This doesn't require you to have a degree or a fancy job title, but it does require you to back up your assertions with something other than "obviously this is possible if you just try harder".

Two people above have mentioned solid reasons that NASA is skittish about space tethers. Please tell me why they're wrong.

I didn't think you were asking about credentials, in particular, I thought it was more of a "What the hell do you know?" kind of question. My apologies if that's rude.

Two people above have mentioned solid reasons that NASA is skittish about space tethers. Please tell me why they're wrong.

Well, it ignores the fact that new technologies and materials are bound to come along. Not bothering to look into something because it isn't currently feasible is just plain wrong.

So, following the space tether experiment link, a tether designed to conduct electricity worked rather better than expected and melted itself. This does not mean that "all tethers from now nigh unto the end of time shalt break!"

James - there's quite a significant difference between "looking into something" - which I'm fairly sure is going on, and trying to do it when human beings are putting their lives at risk.

I think it's a valid point to make.

We've had a couple of space based tether experiments which have, charitably, been nightmares.

Fine, but we're discussing a Science Fiction Writer talking to an Astronaut about a hypothetical scenario (which the job of SF writers) and being shot down with a blanket statement, end of discussion. Would you accept that?

Also, why is it necessary that lives be put at risk? It's certainly possible to experiment with unmanned craft and tethers (assuming there was desire and funds to do it, of course). After all the Shuttle is the only US spacecraft to not have unmanned tests before its first launch.

Myself @39 After all the Shuttle is the only US spacecraft to not have unmanned tests before its first launch.

My point being, in case it's not obvious, that NASA has a 50 year history of launching unmanned vehicles/probes fairly successfully without putting a crew at risk. Not that I have anything against manned spaceflight.

Would you accept that?

Me, I'd dig my heels in and argue, I'm like that :)

But then I'm usually on the Astronaut's side of these discussions. It's REALLY easy to come up with ideas that "aren't rocket science" but are actually really hard to implement and explaining over and over again to people why X or Y isn't easy can get repetitive.

Sure you don't have to risk lives, but I've seen the tether proposal several times where the FIRST time it would be used is actually in a crewed spacecraft. Bob Zubrin does this in The Case for Mars with some awfully poorly thought out suggestions on how you'd use a tether.

The astronaut was being a bit of an arse about his reply. But I think Karl was making a poorly thought out suggestion himself of something that, yes, would be uber-cool, but actually isn't all that practical at the moment, or in the near future.

Great post sir. I must say I like your attitude better than Mr. Stross’s, who is something of a leftist curmudgeon and a space pessimist, I’m sorry to say.

Space exploration should be the unifying myth of our civilization, but for some reason it hasn’t quite worked out that way. It would be easy to give in to despair, but Bruce Bigelow, Peter Diamandis, Burt Rutan and others in the private space industry are reviving the bold, can-do spirit that today's NASA so sadly lacks. For me, nothing demonstrates the truth of the rightist criticisms of government bureaucracy like the space program. NASA’s manned spaceflight program is a total disaster, and I’m happy to see them getting out of that business. In times of war, perhaps the government can be effective in mobilizing efforts on the scale of the Apollo and Manhattan projects, but in peace time government really just gets in the way of progress. This is why I’m hoping for a new space race, because it seems obvious to me that strife and struggle are the source of real progress, not peace and contentment!

This is too true, and it is in large part the reason that I sneer at space enthusiasts. The way NASA acts, and they way they do things, I just don't trust them to be honest with themselves or the public as to why they do things the way they do them. Perhaps tethers do break, but we know for a fact that the Shuttle was a total waste of time and money that got in the way of real research.

Instead of putting a rocket into space, a tried and true technology, and then dropping a capsule back to Earth when you're done up there, you put an enormous space plane on giant booster rockets. This massive weight inefficiency is compensated by the giant space plane being able to glide back to Earth instead of parachute down.

In the meantime, the Russians are merrily popping things into space at a rate of several times what NASA can manage, and with a safety record that's just as good, if not better.

NASA is a bloated monstrosity of an agency that's been coasting on the success of the moon landing for over forty years. Had they put forward better and less wasteful programs in recent decades perhaps people wouldn't have lost quite as much faith in science.

In LEO, earth's gravity is present. Over time, an unbalanced object will orient itself with its most massive aspect towards the earth's gravity. True zero g, LaGrange points

I'd like your definition of "real zero-gravity" please and some examples of places where you feel it might be encountered.

I'm not trying to be argumentative, honest, and I agree with what you're saying @41.

I just think that cutting off a discussion like that isn't productive, it's better to explain why an idea won't work, and move onto better ones. (There I go again, stating what's obvious--or should be.)

Nasa is risk averse. But then again they have had two shuttles blow up on them

Scifi writers are not good sources for practical space engineering. They live more in the world of the possible or might-be-possible, not the practical. I would not ride in a rocket built by any of them that is for sure.

Astronauts are also generally not engineers

And I also want to hear what a "true zero G environment" it.

Some thought tethers were discredited when electric current fried a tether in February 1996. http://www-istp.gsfc.nasa.gov/Education/wtether.html

However, they learned from that experience.

A number of tethers have been launched, some of them successful. http://en.wikipedia.org/wiki/Space_tether_missions

Kirk Sorensen has a number of tether essays at his Selenian Boondocks blog: http://selenianboondocks.com/author/kfsorensen/page/2/ During Sorensen's time at NASA I believe he helped fund the tether development done at Tennessee Tech. So not everyone at NASA is down on tethers. I suspect that it's a personal bias of that astronaut.

Without gravity, tethers seem to whip around. But they make electricity. So a Ion rocket using the power would pull and steady the line ??
The Space Shuttle was suppose to be the size of a DC-3 and take of on its own from runways. Evertime NSAS got close to a design their budget was cut.
The only thing the GOP wanted to spend money on was on the Military. Nixon hated the Apollo program because of it and NASA's association with JFK and cut it short. Then trashed Apollo's rockets, so the cut down Shuttle and Military rockets were the only way to space.
There was a battle to save a Apollo rocket just to use it as a museum piece. For what it's worth the Apollo people were the best of the best. Dick Nix canned them.

@35: How about Gemini 11? 1966? Tethered to the Agena it had previously docked with, they undocked and spun the two of them up. Not, mind you, very fast, but still....it worked.

Engineering. Things break. You fix them.

Tethers can work and will work.

But the larger point missed in all this is...we have no idea what micro or zero-gee does to the human body. Where do the bad effects end? Right now the data set says, at zero-gee, despite all measures taken, the debilitating effects continue. They just continue at a slower rate.

Can one LIVE at 0.16 gee? (Luna's surface.) Do the effects stop at that point, with a little bit of gravity? If they don't, how is one to get folks to stay on the lunar surface for any length of time?

Does it stop at 1/3rd gee -- Mars? Or do the effects only stop at, say one gee?

After more than fifty years of human spaceflight, NO ONE KNOWS.

If NASA had been about space exploration and settlement -- which it never was -- this would have been one of the very first questions ever answered.

As for the ISS...it's not the orbit altitude that makes it sucky for a lunar return; it's that its at 57 degrees inclination. The Moon's down at about 23 degrees...

Regarding the ISS orbit: There is an argument that the ISS's orbit should have been inclined about 28.5 degrees, because a) reduces the plane change burn needed to go to most destinations in the solar system (especially the moon), and b) allows the US to get an ~6% increase in up-mass to the ISS.

The current inclination of ~51 degrees was chosen to allow Russian participation without substantial up-mass penalties.

Regarding 'Astronauts are also generally not engineers': A quick look at NASA's astronaut page seems to call this assertion into question.

Regarding Apollo, US National Pride, and the Cold War Politics of the Space Program: There are some very good and accessible books written on this topic, and people should read them, rather than making simplistic 'blame your favorite scapegoat' assertions.

Engineering. Things break. You fix them.

Interesting, when I was taught to be an engineer most of the focus was on avoiding designing things that break because a lot of stuff can break in highly entertainingly unfixable ways.

I'm reminded that NASA has an orthodoxy about space suits. Hard-shell suits were used by divers and aviators, and worked, but for sundry good reasons in the early days of NASA including weight and storage volume, they never made it to space. While modern suits often have a rigid torso, arms and legs are still the flexible bladders with cunning arrangements for constant volume joints.

Oh, NASA has done research, but one factor, not so obvious, is that the astronauts are used to the movement constraints imposed by the suits they have been using since the 1960s. Some of the arm movements needed to reach from there to here are very different.

And NASA takes the view that astronauts are the people with the experience. It's not crazy, but maybe it's a barrier to a radical change.

In thirty years, you'd think they could have developed a good mechanical hand, with a control mechanism inside the suit arm, and bypassed all the many problems of making a working glove. There's all sorts of applications for the tech, not just in space. It could be very thoroughly tested before it was ever taken into space.

And maybe it scares the astronauts because it suggests you don't need men in space, just machines.

Also if Astronaut is a step on the career path to senior management in NASA, is that biasing the selection process? The military test pilots who provided the crews of the pre-shuttle era went through a different sort of selection process. Even just picking professional pilots means that you're picking people who have to face a "real" world, which will cheerfully ignore all the paperwork while it tries to kill you. Those test pilots knew that there would be things happening that they couldn't predict.

There's been a lot of detailed development, but fifty years after Gagarin, manned spaceflight is still dominated by the basic R-7 booster design he rode into orbit. It's as if the Battle of Britain, and the whole of WW2, and the Korean War, had been fought with biplanes. Better engines, better materials, but still biplanes.

In LEO, earth's gravity is present. Over time, an unbalanced object will orient itself with its most massive aspect towards the earth's gravity. True zero g, LaGrange points

I'd like your definition of "real zero-gravity" please and some examples of places where you feel it might be encountered.

This is due to tidal forces, if you are in a higher orbit, tidal forces are much weaker(inverse square law and all that).

In LEO, earth's gravity is present. Over time, an unbalanced object will orient itself with its most massive aspect towards the earth's gravity. True zero g, LaGrange points

I'd like your definition of "real zero-gravity" please and some examples of places where you feel it might be encountered.

This is due to tidal forces, if you are in a higher orbit, tidal forces are much weaker(inverse square law and all that).

Let me argue against both points.

a) Tethers don't break if you do it right.

b) A tethered space station doesn't work.

Why?

You can't dock without first wasting fuel to stop it. It is rather easy to dock with the center of a rotating space station (see Space Odyssey 2001) - but try the same with the rim and you're screwed by basic mechanics. Because the rim would be where you'd have to dock on a space station tethered to a counterweight.

So, you'd at the very least have to have an airlock extending all the way to the center of gravity of the station to allow docking. Dunno if that makes a lot of sense though and it's of course immediately much more complicated than just putting two modules into space.

And how do you know whether something can break or not?

You experiment. You undertake controlled trials of structures and joints and materials and such like, and you see how real, physical, material objects actually work, as opposed to the theoretical designs that seem OK, but that may not have covered all the possibilities.

And when they do break, you fix them. Eventually, yes, you get to the phase where all the problems should be known, but in the mean time, you try to develop a flexible attitude, one where when things do break (and they always do), you have the best possible chance of recovering from them.

Houston, we have a problem. What are our options?

Well, to be fair to my former profession, that's how you used to do it, but much less so these days. Space just makes things harder because the significant barrier to entry to testing things in space means you tend to over-engineer and spend a LOT of time figuring out how to deal with stuff ahead of time.

Even then, yes, you'd want to test more things ahead of doing them. The loss of the British Beagle lander springs to mind where they'd woefully under-engineered and under tested what it was they were intending to do.

Other times, you get caught out by stuff that ought to work but something crept up to bite the designers in the backside.

Frankly, I'm waiting for Space-X to have a bad day around that sometime in the near future.

Regarding mechanical hands: People have been working on this for years. Building something that can adequately replace the human hand is hard. Building a control interface for your mechanical hand is even harder.

It was a much easier task to develop a working space glove instead.

R-7 and biplane silliness: The R-7 is an excellent example of an evolutionary design. The demand and insistence on revolutionary designs in a fixed budget profile is what doomed most of the US efforts for a shuttle successor. (It was a major problem for the shuttle design effort as well.) If you need to fit a budget profile, stick to an evolutionary design.

I think this thread is in severe need of an intervention from Charlie.

Wow, you guys are like a bunch of pitbulls running after a plush toy. Here's the thing: it's not about tethers. You can use a beam instead, and girder technology is not exactly new. You don't have to experiment with live people, and you never dock with the system while it's rotating--you spin it up and down as appropriate. If there were a fundamental problem with tethers, that would not in any way obviate the argument I was making, which was that a variable-gravity station was be necessary and practical. --And does anybody out there really think that we should NOT be experimenting with rotating systems in zero gravity to see what their dynamics are?

By the way, my only real stake in this argument is that I have giant rotating towns made of wood and rope in my world of Virga; they use jet engines to spin them up and you dock at the axis and take an elevator or a yin-yang staircase down to the "street." And of course, all of that is just sooooo possible...

Let's also not forget that space travel has always been about international politics, from Sputnik on forward. I don't particularly credit Bush 1 or 2 for their "visions," because they weren't doable, they were just distractions.

Right now, we're one satellite war away from rendering space travel impossible for the forseeable future, courtesy the Kessler Limit and runaway space debris. And the great powers are already building the weapons for that war.

While we're posturing away about space being humanity's Manifest Destiny and similar, can I point out that a little environmentalism in Near Earth Space is now required to keep space travel alive for anyone?

Like light foam that ought not to harm the Shuttle's heat shield?

The only way to find mistakes is to make them ... in a system that is otherwise stable and/or redundant enough to fail gracefully. Apollo 13 was, Columbia wasn't. Three Mile Island was, Fukushima Daiichi wasn't.

As someone that does work on space tethers, or at least likes to think he does, we have learned a lot from TSS-1 and TSS-1R (they generated more current than they should have, as noted above), have developed tethers that will survive multiple impacts from debris, and generally learned that ISS decides that there shall not be tethers anywhere for any reason b/c they're paranoid.

I'm not saying you can make systems that can't make mistakes, but where the failure modes are complete vehicle/station/crew loss, you should try a tad harder.

Apollo 13 would have had a different outcome, if the CM had been attached to Apollo 8, for example, and they hadn't had Aquarius for a lifeboat. They were lucky.

The trick is learning the right lessons from failures and problems. The foam issue, like the O ring issue before it, was a classic example of people making decisions on poor data.

Allen Steele's Coyote series starts with rebels against the dictatorship after the launch. Not everybody is a rebel.

From when are you counting the Soviet safety record?

For tides, it's actually an inverse cube law, and the effect of the tide is proportional to the distance from the center of the free-falling object. So for all practical purposes, anything in a capsule that is free-falling is in zero-gee, unless the orbit is extremely low and the 'capsule' is quite large. Even Beowulf Shaeffer had to get quite close to the neutron star before tidal forces became noticeable.

I never could understand why the foam cuuld not have cutting wires and cast in pull lines. Then the foam could be sliced up and pulled down.

There is the variation to the glass half full, glass half empty joke; to an engineering professional the glass is the wrong size.

While I confess that not all engineering fields have the same problems (my field is, well for the next few weeks, redundancies and all that, is land vehicles where failure means you walk home), your basic engineering principles still apply.

• Here is what I want
• Here are the problems
• Overcome the problems to give me what I want

Okay once you get into space your come across problems you just don't get on the ground; microporosity in metals is a MUCH greater problem in orbit then it is down here at sea level for example, but that still doesn't remove the core principle.

If a tether breaks, you work out why and design it so it doesn't or you engineer a solution that does the same task sans tether.

(then you give the solution to people like me and I spend 3 months cursing your name as I try and get the farcial 3D models and engineering data pack updated :P )

Oh... and did someone say plush toy?? :)

"The only way to find mistakes is to make them ... in a system that is otherwise stable and/or redundant enough to fail gracefully. Apollo 13 was, Columbia wasn't. Three Mile Island was, Fukushima Daiichi wasn't."

Perhaps you have some incorrect information or assumptions about Fukushima Daiichi. Things are not nearly so bad as your statement implies. The only casualties (3 plant workers) were the direct result of the earthquake and tsunami. No effects on health or significant contamination cases have been reported in the general population. Your point still holds, but Chernobyl would have been the better example, I think.

NASA died with the VentureStar project

Building mechanical hands with the full movement capability of the human hand is hard, but we've been doing it for some years - http://www.shadowrobot.com/hand/ - NASA even bought one.

Measuring the human hand movements well enough to drive the robot hand is really hard, though.

We don't have an antagonist to race against anymore.

The Chinese?

Glem Murie @ 43 NASA is useless and blaoted BECAUSE the US guvmint made it that way. They did not want independant thinking, they wanted "yes-SIR" people in charge - and they got it. Now, they wonder why it does not work. It's a failure of management. Believe me, as a Brit, we get to recognoise that failure-mode only too often .... See also @ 48

Hey, less of that "crappy Russian capsules" stuff. Apart from Soyuz-1 and Soyuz-11, it just works and keeps on working. Only four deaths in the whole program (Soyuz-1 and Soyuz-11), and none in the last 40 years.

Remind me never to travel on an orbiter whose name begins with C...

And ground landings too - none of that wussy 'let's use water 'cos it doesn't jolt so much'.

ISTR that the ISS orbit was chosen on the grounds that "this is about as high as the Shuffle Shuttle can get, rather than on any sort of "sensible engineering grounds".

Apparently, plans to replace the dear old Soyuz capsule with a vaguely Shuttle-esque vehicle called the Kliper are at an advanced stage:

http://mat-rodina.blogspot.com/2009/11/russian-space-tech-surges-forward.html

(NB, that link seems to be to some sort of Russian nationalist blog - go figure :-/)

The Shuttle could be launched with a reduced payoad to achieve higher orbits such as the Hubble repair missions at 560km altitude; when ISS construction was going on the Shuttles carried tens of tonnes of modules and components in their payload bays and couldn't have reached such high orbits. They also boosted the partially-built ISS on occasion, not something an underpowered Soyuz passenger capsule could do.

I'm not sure what the orbital limits are for Soyuz launches; I recall the Apollo-Soyuz rendezvous mission back in the 70s was a first for both vehicles as it was the lowest the Apollo CM/SM had ever flown in orbit and simultaneously the highest-ever orbit for the Soyuz capsule. The Soviet/Russian station MIR orbited at about the same height as the ISS does today, 350km or so.

I'd like your definition of "real zero-gravity" please and some examples of places where you feel it might be encountered.

Real zro gravity would seem to require there to be no gravitational attraction between the space craft and any other body (ideally, and not from itself but that's hard to manage using matter).

It should be easy enough to calculate when the field strength drops to zero. We know that it drops off as the inverse square of distance so all we need to do is get far enough from every object with mass.

gravity ~= 1/r^2 or r ~= (1/gravity)^1/2

solve for r.

r ~= (1/0)^1/2

See, there's your problem: that 1/0. It's going to take a fair while for a chemical rocket to travel 1/0 kilometers.

At this point I would like to invoke my commonwealth rights to harvest organs from anyone whose discussion of gravity in space turns out to ignore the presence of the sun. Not that anyone has but this is usually the point where someone does.

I personally feel that the Chinese don't have the same gravitas as the Soviet Union used to. They seemed to have found a magic balance of communism and capitalism. Plus, we depend so much on their inexpensive goods and them buying our Treasury notes we seem to overlook just about anything.

Hacking? "No problem you wacky Chinese."

Human rights abuses? whines "Come on guys...... seriously.... just quit it...."

New Iphone comes out? We're lining up around the block. ( Here I point out my own hypocrisy. Damn if I don't love my electronics)

Maybe North Korea if they had the wherewithal or Iran. I don't think America could let either country show them up.

Dave, it seems to me that the real issue with researching the engineering constraints of tethers is that NASA seem to have started out with two flagship experiments on the Shuttle -- vastly expensive and dangerous failure modes for a man-rated craft with a crew of seven. The right place to start would be to thoroughly explore some small models on orbit using cubesats to get the basic deployment stuff right, then scale up from there using small, cheap, unmanned test missions in low orbit (so that atmospheric drag will remove the tether before it becomes a navigation hazard).

In other words, play like it's 1959 again, only using cast-offs or flying as ballast on Ariane 5ECA or Falcon Heavy or other big commercial flights that need some dead weight to balance the payload of big comsats.

A quick Wikipedia suggests that the then current R-7 variants could have boosted somewhere between 6.6 and 7.7 tonnes to LEO, and shows some some R-7 variants as capable of boosting 4.5t to 800km or so.

I'll counter your comment about the "under-powered Soyuz" by suggesting that Soyuz was no more designed for boosting a 200t space station to higher orbit that Soyuz was, or the Shuffle should have been. Having that much spare inpulse in orbit is yet another design flaw in a purely orbital craft!

The Progress unmanned cargo vehicle is also used occasionally to boost the ISS but it's not got a man-rated re-entry capsule attached so the Progress service module can carry more fuel for its motors to perform the boost operation.

As for manoeuvering in orbit, the ISS track is optimised for the less-capable Soyuz launches; the Shuttle had to use its cross-range capabilities to make rendezvous since the Soyuz/R-7 isn't really capable of large changes in delta-V to match a less-oblique orbital path.

The Shuttle was a multi-purpose vehicle, not just a spam-in-a-can people transporter. As such it was quite successful in doing stuff like the Hubble repair missions, carrying cargo and modules to the ISS and back again, acting as a workshop and backhoe for ISS construction and repairs, ISS personnel transfers, science laboratory work etc. and all in shirt-sleeve conditions and with a real (if somewhat exotic) toilet on board to boot.

I'm not sure that any sort of expendable cargo-launch system plus spam-in-a-can to orbital rendezvous could have achieved what the Shuttle achieved; for example I suspect that without the Shuttle or someting similar the Hubble project would have died an ignominious death shortly after launch rather than being the roaring success it has turned out to be over the past 25 years.

NASA and failure and National falure(s).

1] Try looking up BLACK ARROW (weep) 2] Try reading THIS book and really try to stop yourself from beating your head against the wall at the monumental crassness of British "management" ....

Hmmm... sorry but the recovering engineer inside comes back with. "But tethers DO break. And they also jam and a bunch of other stuff."

AND, if you've a rotating structure in orbit with a broken tether you've a really REALLY interesting multi-body dynamic problem to solve on a structure of non-trivial inertia.

Right. Remember those kooky old ideas about using - of all the wacky ideas - rockets to get into space. Thank God that the engineers had the good sense to abandon this approach early on and . . . oh. Wait.

Now do you see the problem with that line of thinking?

Finally, "basic engineering" doesn't really exist in space yet. We're still learning what that really means.

And this is what should have been happening (and hopefully will in the future) all along. It may be a not-nice fact of life, but in the real world, engineering works by incremental improvements. You tend more often than not to Break Stuff along the way when you're figuring out improvements. And when you're in space, breaking stuff is Very Expensive.

That last seems to be what you and a lot of other people seem to be having problems with. Unfortunately, the rules for design don't change. And if you're really serious about a long-term presence in space (human or otherwise), you will - sooner or later - have to confront these obstacles. Spending a piddly few hundred million and then announcing that the idea simply won't work is nothing more than a feeble attempt to buck the facts of life.

I get this sense a lot of times that when people say doing stuff in space is expensive, they then proceed to behave as if it isn't. As if there mere acknowledgment that it is is enough to deal with that issue :-(

Myself, I think that this is an excellent reason for governments to be funding this stuff[1]. No private agency is going to be able to do this sort of basic research with an eye towards ROI. Sort of like that whole business with the intertubes.

[1]Ideally, several governments working together. If it's going to cost $150 billion to come up with a good tether design, another $150 billion for some sort of universal snap-on join, etc., you might as well have Japan, China, France, the U.S., and everyone else who has to nickels to rub together all working as a team and contributing their shekels.

Please try again with that link, AW.

Here you are: survive multiple impacts from debris

I think that an awful lot of people simply do not want to know what really happens in the long term (longer than Krikalev's stay) to humans in lower gravities. They don't even want to know what happens to food animals or to vegetable growth. They're afraid it would spoil their dreams.

@ Karl

Although I don't dispute the use of the word "useless" with regard to the actual resulting application of the shuttle, it is far from a useless design. I feel like a lot of people around the 'tubes have been blast the shuttle without understanding it's development history. I think it's important to highlight the shuttle's failings in a post-cold war space era while using terms like "useless." If I remember correctly a large extent of the shuttle's design is to enable significant down mass capability, that to date, no other vehicle comes close to achieving. The ability to retrieve satellites on orbit was seen as a driving factor in the design. Also, I believe it was design so that it wouldn't have to de-orbit over the USSR, which added more constraints to the design process.

All this is to say, I think it very important to understand and discuss the rationale motivating the engineering decisions if you are to use such a sweeping blanket statement.

It was years ago in Analog that I saw this discussed. The basic problem is tidal effects: put two objects a metre apart in orbit, and they're going to slowly drift apart. It's not the only thing. The author suggested ways of cancelling out these effects.

Since the sun is gravitationally bound within the galaxy and that is bound within the Local Group it is going to be a little tricky to find true zero-G.

However what we actually want is flat space, so various of the Lagrange points would do and also the late Dr Forward would have been happy to sell you the design for a neutronium ceiling that is only mere engineering details away from realisation,

-- Andrew

So... you spin your tethered station down whenever something docks, and up again afterwards? And your reaction mass for this spindown/up has to come from the entity that's docking, and must be accelerated and decelerated during the spinup/down process...

... and you think this is not a sizeable problem?

Spinning up and down doesn't need reaction mass! A large flywheel can eat and release angular momentum as required, with only friction and heat losses. Same deal as regenerative braking on trains (and electric cars).

Or you might use the earth's magnetic field and tethers with current as a motive force to spin up the structure. The tethers no longer will be flexible cables for this to work.

So... you spin your tethered station down whenever something docks, and up again afterwards? And your reaction mass for this spindown/up has to come *from* the entity that's docking, and must be accelerated and decelerated during the spinup/down process... ... and you think this is not a sizeable problem?

Er, why can't you have a central ring that have n tethers clipped to it, with n>=2?

This isn't rocket science.

If NASA is bloated and useless, what does that make other countries' space programs?

Health care: this is something America can easily improve because there are many good international examples which are far superior; follow any of them and they will improve

Space exploration/research: this is something the US cannot easily improve as they already have the top program in the world

If NASA is bloated and useless, what does that make other countries' space programs?

Smaller?

We're about to find out if the more private model is going to work in the US. We'll know in about a decade.

If NASA is bloated and useless, what does that make other countries' space programs?

The Soviets, on about a quarter the budget, nearly got to the Moon with a cosmonaut. If Apollo 11 hadn't pipped them to the post they'd probably have made it in 1971 or 1972 -- they'd nearly ironed the bugs out of the N1 engine management system when the program was cancelled due to Neil Armstrong planting that flag and Brezhnev not wanting the embarrassment of coming in second (or worse, a speculacular and lethal public failure).

As it is, they ran a very solid space station program and built and flew a better Space Shuttle before the financial crunch of 1988-90 killed progress stone dead. Let's not forget that the core of the ISS are the modules that were built for Mir 2 -- for the first couple of years, before NASA began shipping up the large US modules, the ISS was de-facto a Russian space station.

The ESA is doing excellent work -- an astronomer of my acquaintance who works on space telescopes points out that if Congress kills the JWST then ESA will be the planet's main space astronomy power for a generation -- again, on a smaller budget.

Japan managed an asteroid sample return mission before the USA. And China's getting ready to launch its first space station.

All on lower budgets than NASA. Much lower.

My take on the matter is that if the USA canned its space agency tomorrow, it would set the rest of the world back maybe five years, if that -- mostly because the US cancellation of funding for joint projects would derail or delay everyone else's work.

The Russian launch vehicles and capsules seem to be rather reliable, actually.

AS I understand it, NASA is in part so bloated because of the Apollo mission. They felt that they could accomplish anything, and that bred a culture of managerial arrogance that lasted until the Challenger explosion.

Nowdays, they seem to play the military plane game, which involves spreading contractors to as many congressional districts as possible, then lowball cost estimates and hope that Congress will pay anyway, once something's halfway built. We're seeing that particular set of crows coming home to roost in droves, as both military jets (JSF) and space programs get killed off for massive cost over-runs, and drones (and unmanned missions) take their place.

Now, if the US Congress could just find its ass with both hands, that would be a landmark in the history of exploration (sorry, I've been listening to the debt limit news. It's hard to avoid).

ISTM that a lot of the bloat came from very bad choices in mission requirements. That's basically what sunk the shuttle: it had to do everything from acting as a first stage for launching geosynch and interplanetary satellites, to on-orbit repairs, to polar military surveillance missions (and then the USAF pulled out of the program, leaving the shuttle holding the bag for missions it would never fly). That's not very different from what happened to the JSF: it turns out that the supersonic jet missions it was designed for isn't terribly relevant to current military requirements (we have interceptors and fighter/bombers that do what we need), and they tried to make it handle tactical missions with the VTOL capability and damn near broke the plane completely.

Now if NASA had just left the satellite launch to Delta and Atlas-Centaur and their follow-ons and the polar missions to the X-37 and suchhlike, and if Congress had quit trying to design the shuttle by committee of technological ignoramuses, we might have gotten a vehicle that concentrated on reusability and reducing the cost of manned flight to LEO. That would in turn have reduced the cost of the ISS and probably shortened its schedule, and maybe it wouldn't have become the white elephant we ended up with. It's thoughts like this that make me approve of the Everett-Wheeler Many Histories Theory: I'd like to believe that someone somewhere did it right.

The ability to retrieve satellites on orbit was seen as a driving factor in the design. Also, I believe it was design so that it wouldn't have to de-orbit over the USSR, which added more constraints to the design process.

Capabilities which were, in fact, never used in combination, but which fundamentally compromised the design.

So: the shuttle was used, but not as intended -- and arguably was unfit for [eventual] purpose.

The real tragedy was that it was effectively a prototype; if they'd build two and flown 30-40 missions during the early 1980s, while working on a Version 2 model for the 1990s, it'd have been a rather different story.

Agreed, Bruce, on the JSF and the shuttle, although I've been noticing things like the littoral combat ships (did they really build ships with aluminum hulls and steel frames? Isn't that an automatic fail in naval architecture?) and a few other boondoggles that are annoying me.

Still, the culture of lowballing bids seems to be hammering NASA these days. They've got a widening credibility gap, and it's frustrating to watch. Couple that with presidents who seem to think that pitching a grand Mars (Bush 1) or Moon (Bush 2) mission/boondoggle is a great way to distract people, and it's a real mess.

By law they must use lowball bids. NASA did not like the company making the Hubble Mirror they were order to use, thanks to orders from the highest level. After a time they ordered a new one from the company that was their usual supplier. They could not get it used. And nobody knows what happened to it. For how NASA really must work people should read THE HUBBLE WARS, by Eric Chaission.

Nearly all satellite missions by the US were actually lofted by Atlas, Centaur and latterly the Deltas over the period the Shuttle was in operation. The Shuttle launched very few Earth-orbital platforms (absent the Getaway Specials) and no interplanetary probes at all as far as I recall. There were a couple of DoD launches but details are, not suprisingly, scarce on their payloads.

In contrast the Shuttle carried the Italian-built cargo modules up AND DOWN from the ISS twelve times; the last flight was one-way, adding the modified Leonardo module as a permanent part of the station. All the other cargo vehicles servicing the ISS are single-use, burned up in the atmosphere when they are finished with despite their eye-watering construction costs. The Shuttle was the only sample-return system for any science projects on the ISS; there are bodges on the drawing boards to try and fix this now the Shuttle has been withdrawn from service but there's nothing ready for use at the moment since all that's left is spam-in-a-can with incredibly tight mass and volume constraints and obvious safety risks if the samples are toxic or otherwise hazardous.

The Shuttle launched very few Earth-orbital platforms (absent the Getaway Specials) and no interplanetary probes at all as far as I recall.

Well, Galilieo and Magellan were both lifted by Atlantis, both 1989.

Unfortunately, WikiPedia's let me down; no specific list of satellites taken up on the Shuttle. So here's a list, via Google: http://rammb.cira.colostate.edu/dev/hillger/Shuttle-related.htm

As I understand it, there's a difference between having to accept the lowest bid and deliberately underestimating true costs within the agency. That's the accusation I heard on the JWST (probably the space shuttle as well, come right down to it). Ultimately, the problem seems to be a culture that assumes that one's bosses can't stomach the truth, and have to be cornered into doing "the right thing." That's dysfunctional.

Yep, there were a couple of interplanetary probes which I forgot about but I think you'll find that most of the list of satellites on the Colorado State site lofted by the Shuttle are what I called "Getaway Specials", small university or group-built (the OSCARs, for example are Orbital Satellite Carrying Amateur Radio) satellites lifted as ballast on missions flown for other purposes, not the main reason for the launch itself.

There are a few biggies on that list, of course, such as the TDRS and other satellites which were the principal mission cargo. There's also the LDEF, Long Duration Exposure Facility which was launched in 1984 and brought back to Earth in 1990, a mission an expendable booster system and spam-in-a-can couldn't practically achieve.

With 20-20 hindsight the Shuttle wasn't an optimal design; I think an unmanned cargo spaceplane plus a separate manned capsule (although that would not be spam-in-a-can) would have been better but at the time they were planning to bend metal on the thing the US had little experience of launching multiple missions near-simultaneously and making rendezvous in orbit. They were still in Apollo mode, throw everything for the mission up in one stack rather than hoping they could bring everything together in orbit afterwards. They know how to do things better today.

That old "sunk cost" fallacy works almost every time. Even financial training doesn't help, because it plays on the deep psychology of loss avoidance, and bosses will sink your career for such failures. Hence the institutional tendency to spread the blame and no one taking responsibility.

Late to the party--it looks like most points of the post have been answered.

(Disclosure: I worked at NASA-JSC 1986-1996 doing a number of things, ending as a flight controller the final 3 years)

In Commander X;'s defense, I was there when the TSS missions failed spectacularly. The technology has been proven since, but first impressions are the most lasting. The Shuttle trailing a big snarl of yarn across the night sky was a pretty embarrassing image. I think the astronaut might have been there too, at least as a candidate, and was reliving a trauma.

I can't speak to other deviations from the official NASA line. What I can say is that NASA has mostly lived in a political environment that was, after about 1970, indifferent at best and hostile at worst. It led to a "circle the wagons" mentality on speaking to outsiders, especially if loose talk could filter upward. Remember also President GWB installing a 24-year-old college dropout as official science mouthpiece for awhile.

I'm sure the astronaut has his own dreams, but he's a semi-public figure, so, yeah.

Considering how the 1970s played out, it's not too surprising that the Shuttle developed as it did, and NASA had to make a devil's bargain with the DoD and the NSA as well--lofting Lacross, Keyhole, etc. spy satellites. Some Star Wars crap too, I reckon. I saw in Aviation Week a design for a telescoping, folded-over neutral particle beam weapon that was supposed to fit in the Shuttle payload bay, but I think it was just High Frontier fap material.

For those who still dream, there is an organization that is trying to get humanity out there in a big way: The Living Universe Foundation.

It had a hiatus for a number of years but has been restarted with a completely revamped plan. It's purpose is to create communities and businesses with a built in cultural imperative to go to space. This is not just enthusiasts indulging in an interesting hobby. It is to be a lifestyle.

Please go to the following links and decide for yourselves if you want to participate:

tmp2.wikia.com www.luf.org

luf-team on yahoogroups.com is an email discussion list.

We are looking for doers. Please look and decide for yourselves if you want to be part of it.

NASA has tested tethers in space, and not only during space walks. Their live experience is that they do indeed break, in ways their engineering were not expecting. The astronaut probably knew this. Did you?

http://www-istp.gsfc.nasa.gov/Education/wtether.html