New Mars Forums

Terrible! 

Palomar:-

"lovin' from the oven .."!  Ha-ha, excellent! 
How heavy was the husband??!!! 

Many thanks, Rik! 

The above is what's left of my August 12th post.
Having become used to Clark consistently deleting the evidence of his anti-social behaviour in the past, I edited my "Thank you" note by placing a quote of his exact words in my own post, where he couldn't get to it and delete it quietly at a later date.
-- I've only just realized, and I'm stunned to see, that the quote in question - Clark's vile and foul-mouthed attack on me personally - has been expunged from the record! :?

You'll note my own post consists of nothing obscene, profane, or insulting. But Clark's post was all of those things and more, and gave a vividly clear indication of his patently trollish style. It was nothing I said which did this; it was Clark's own words which damned him.

Why, after I prevented Clark covering his tracks in his usual devious way, has an official of New Mars done it for him?  :?:

If I posted the kind of stuff Clark has gotten away with here, I would fully expect to be banned from this site, or from any other respectable site in which I did likewise. But I accept the decision of the management not to ban Clark (as I undertook to do), even though I don't understand that decision.
-- But for the management to not only forgive a member his unforgivable and trollish tantrums, but then to assist him in covering his tracks, I find to be incomprehensible.  :!:

Anyone care to explain their motives? - preferably without trying to equate any past post of mine with Clark's disgraceful behaviour here. That would be the ultimate insult based on moral relativism.
-- I have contributed to New Mars for nearly four years and have enjoyed a cordial relationship with almost everyone. I have a very long fuse and I've certainly never complained formally or informally about any other member in all that time.

But now I make an exception.
-- And I'll offer a few unsolicited and, no doubt, unwelcome words of wisdom while I'm at it: If you continue to allow low-grade sociopaths to take out their psychological problems on other members, and then go about covering their tracks for them, this website will descend into chaos.
-- You cannot water down standards to this degree and expect to retain any long-term semblance of order and civility.

[P.S. Please do not delete this post. It is a legitimate call for a re-evaluation of standards, expressed openly and in civil language before all members of New Mars. Thank you.]

[tex:242091df20]C_2H_4[/tex:242091df20]
It works .. great! (Never would have thought of the "_" button!!!!!  Where do you pick up stuff like that?)
Thanks, Rik. 

How do you get x squared?

Rik:-

Hmmm. So TeX allows you to write chemical formulae, eh? That could be handy sometimes. I wondered what it was for.
I tried it but all I got was [tex:00b216f643]C2H4[/tex:00b216f643].
I can't get it to do superscripts or subscripts as you did. How does it work?  :?:

By the way, before Josh changed the set-up here, I was able to make links which were part of the text I was writing. e.g. I could write:-
"For a full report, read THIS ARTICLE" and, if you clicked on THIS ARTICLE, you'd get the link.
-- Now I can't figure out how to do that any more. (Actually, I did manage it once by a complex way of typing out all the URL stuff and deleting bits of it and typing in other bits, which took ages - can't remember how I did it now!) This new system we have seems user unfriendly and counter-intuitive to me.
-- Now I just end up saying, for example: "For a full report, click on the following:-
http://www.marssociety.org/",
... which is O.K., I suppose but not as neat.
I guess there's some little trick to it in this new system? Or was the old system just better? 

I noticed this article but wasn't too sure about the criterion for receiving astonaut's wings.
They seemed to be saying getting to 50 miles altitude is enough. But I thought 100 km was the required height, i.e. 62 miles .. ? 

Thanks for the feedback on that teacher, folks! 
It's good to know everyone feels the same way about that ignoramus. It's one thing to be ignorant of a new concept, as Cindy says, but to ridicule it from a position of ignorance, and at the same time humiliate an enthusiastic child in public over it ... Phewww!! .. I get so upset about things like that.  :evil:

Some teacher!

[Sorry. Harping again .. and off-topic again, too.
-- Though I do see Dragoneye's point of view that, in a more general sense, it is a relevant point because it highlights a problem we space advocates are up against every day.]

Thanks for that link to the Brad Edwards report on the Space Elevator, Flashgordon! 
-- As I would have expected, coming from him, it certainly gives a clear and exciting summary of the plans and the current state-of-play.
-- As a matter of fact, there's an eleven-year-old kid I know who thinks Space Elevators are great (yeah, yeah, so maybe I did influence him just a little!  ). And I've steered him toward that article today because, when he brought up the subject of Space Elevators at school recently, his teacher made a mockery of the concept in front of the whole class.

I don't understand teachers like that.  :!:   :?

Hi SpaceNut!
-- Forgive me if I'm wrong but I think I detect some confusion in your mind about the basic mechanics of Space Elevators (SEs).  :?:
    In the days before CNTs, people tried to design SEs as best they could using the materials available at the time. The stumbling block, of course, was always the lack of a material with a tensile strength great enough to support even just its own weight over a length of tens of thousands of kilometres, never mind that plus the weight of multi-tonne 'climbers'!  For this reason, it was found necessary to taper the cable - making it thicker and stronger the higher up you went, in order to support the weight of cable below. Working in our favour was the gradually lessening pull of gravity the higher you went, but nevertheless any cable they could devise at the time became exponentially wider as you approached Geosynchronous Earth Orbit (GEO).

At that stage, the shorter you could make the actual cable, the better chance you had of making the SE work because it resulted in a massive reduction in the necessary thickness of the cable at GEO. So, it was thought that building a self-supporting tower from the ground up would be a good idea - especially if that tower could be higher than anything ever conceived of by humanity before.
-- I recall seeing a website somewhere, in which they discussed the theoretical possibility of constructing a tower rather like the Eiffel Tower in Paris as far as the shape was concerned, but reaching an altitude of 50 kilometres!! (Some 6x higher than Mt. Everest.)

Whichever way they looked at the problem, though, the practicality of any solution they arrived at failed because of the lack of a material they dubbed 'unobtainium', from which to make the cable itself.
-- Now we have CNTs, the theoretical difficulties of building the SE have disappeared. We've obtained 'unobtainium'!    Now, it's just a matter of engineering.
-- As far as I'm aware (and this is something I'm prepared to be corrected on), CNTs are sufficiently strong not to require thickening towards GEO. As I mentioned in a previous post, I don't remember anyone at Liftport Group or HighLift Systems talking about tapering the cable.

Your quote:-

The way it works is this: GEO is at 36,000 km altitude, which is where you have to keep the centre-of-gravity (c.o.g.) of your satellite in order to maintain stability. From your satellite, you lower your CNT cable down toward your ground-station. Obviously, the act of doing this shifts your c.o.g. downward, too, which destabilizes your orbit. So, you have to either gradually shift your satellite slightly further away from Earth as you lower your cable, or keep the satellite where it is and simultaneously extend a length of cable outward. Either way, you can keep your c.o.g. precisely at GEO and maintain orbital stability.

Let's assume you're going to extend a cable both downward and upward, simultaneously, in order to keep your c.o.g. at the required height above Earth (36000 km). The length of cable you release upward will have to be greater than the length of cable you release downward, because the cable going downward is getting closer to Earth and therefore experiencing a stronger gravitational pull, while the outward-bound cable is getting farther away and experiencing less gravity. This is compensated for, to some extent, by centrifugal force, which causes more outward force on the outward-bound cable the higher it extends above GEO.
-- But the upshot is you need to release roughly twice as much cable upward as you do downward, to keep the c.o.g. at the geosynchronous orbit. This means you need about 100,000 km of cable - 36,000 km of it hanging down to the ground and 64,000 km of it hanging up and out into space!

In theory, the lower end of your cable needn't be attached to the ground-station at all. It could end just 1 metre above the ground and, as long as the c.o.g. of the whole system remains stable at an altitude of 36,000 km, the bottom of your cable will stay 1 metre above the ground!
-- But as soon as you try and attach a climber to the cable, the c.o.g. of the system is now disturbed and you're starting to pull the satellite downward out of its stable orbit.
-- That's why we have to attach the lower end of the cable to the ground and deliberately shift the c.o.g. of the system a little farther out, in order to use centrifugal force to put many tonnes of outward tension on the cable. This is easily achieved, once the lower end is secured, by simply releasing more cable outward from your satellite.
-- With your cable now taut, you can attach your climber and up you go!

Another advantage of balancing your c.o.g. by extending cable up and away from Earth at the same time as you're lowering the other end to the ground, is that you get yourself an interplanetary launching system into the bargain.
-- The outer end of your cable is whizzing around the world once every 24 hours at an altitude of 100,000 km above the ground. It's speed is roughly 28,000 km/hr. If you send an interplanetary spacecraft out to the end of the cable .. and let it go .. it will leave Earth's gravitational influence and head off into deep space, using Earth's rotation to propel it instead of rocket fuel!
-- Depending on the moment you choose to release it, you can send it off toward any planet you like.

Brilliant, isn't it?! 

Thanks for the background info., Cindy.

Hmmm. Well, I think I'll stay at least 200 km away from stray bits of the Sun's core .. just to be on the safe side! 

Bill:-

I understand your point. It all depends on the system and the costs.
In the case of passenger cars, it might be different. I envisage a multi-tonne multi-storey car with bedrooms and communal areas, including an observation deck - after all, it's a one week trip each way, and riding one of these cars to GEO will be a spectacular experience, enjoyed perhaps only rarely in a human lifetime.
-- Imagine passing through gravity equivalent to 0.5g, then Martian gravity of 0.38g, then Lunar gravity of 0.16g, on your way to zero-g at the GEO station! What a buzz!  And don't forget the incredible view of Earth receding beneath your feet, as seen from the observation deck!!

Returning these "Pullman cars" of the space-age to Earth in free-fall, using a heat-shield and parachutes, will not only be impracticable but undesirable, especially for older passengers.
-- By all means, employ reusable containers with disposable heat-shields for cargo, if you wish, or if it turns out to be better from a financial viewpoint, but for people it won't be as attractive, I think.

As for power transmission, a separate carbon nanotube power line may well be up to the job in transferring potential energy from the descending car to the ascending car. Who knows what electrical-conduction properties we may be able to induce in these amazing tubes? Perhaps we won't need a ground-based laser at all. We'll have to wait and see.
-- In any event, I think Space Elevators must surely make more sense than the "Roman Candle" routine we have to go through these days!  Just a few thoughts.