New Mars Forums

its probably important to note that it cant be built with todays technology........

I think the cost estimate is based on the cost of developing the technology and building it. Presumably the next SE after that would cost far less due to economies of scale etc

Its a bit like the pharamcuetical industry really.

Nick

UPDATE UPDATE UPDATE UPDATE UPDATE UPDATE UPDATE

Well the bad news is that we didnt get enough votes in, so the howstuffworks website wn the peoples voice award 

But, the judges voted it best website in the science category and it won. 

Lol, and their five word acceptance speach was:

"Mars or Bust; preferably Mars"

nick

Is that really what it says. Unsurprisingly i've never actually read it. So it was designed as a protection from the government, not criminals (which would fit in with the point about it having been about muskets). Also, when i read militia, i imagine anything from a privately organised, trained, local defence force, with a central weapons cache (armoury), up to say the national gaurd, as opposed to every man for himself holed up in his house, with his gun, doing as he damn pleases. ???

Ah yes, the classic seperate-the-argument-into-individual-sentences-thus-removing-all-context-and-allowing-you
-to-appear-to-relpy-to-an-argument-without-actually-making-a-point method. You may as well have picked me up on my grammar and spelling. Look, its easy.... i can do it too!

So you agree that gun-control laws do work

Sorry, ill stop now    let me show you how it is done. If you make claims in an argument you need to supply proof or evidence.

You claim to have seen the statistics from my government so i am sure you are very familiar with the following document.

http://www.homeoffice.gov.uk/rds/pdfs2/hosb103.pdf

Crime in England and Wales 2001/2002: Supplementary Volume is, as you know, the most up to date information available detailing gun crime in the UK. I could post the entire document but instead I have selected form this file some very interesting quotes that im sure you remember from last time you read it.

Let me refresh your memory....

"Overall, firearms (including air weapons) were used in 0.4 per cent of all recorded crimes. The proportion excluding air weapons was 0.18 per cent."

Naturally in the safe old US of A with your enlightened gun laws these stats will be far lower, wont they?

"There were 97 fatalities and 558 serious injuries resulting from crimes that involved firearms (including air
weapons) in 2001/02."

What? In the whole of England and Wales? With a population of over 50 million? Obviously, that side of the pond, there were far less than 250 fatalities last year.....

The report goes on to state that 53% of firearms offences involved robbery as opposed to 5% which involved burglary (i.e robbery in the home).So you would let everyone have a gun in there home just in case they are a victim of this 0.009% of total crime?

"However, firearms were reported to have been used in 4.5 per cent of all robberies in 2001/02, a much lower figure than in 1991 (11.7 per cent)."

But i though all the criminals had guns now?

"The highest proportion of robberies were committed in shops and on public highways [31% and 36% respectively], followed by other premises or open space."

I'm sure you would advocate letting people carry guns on the street to combat the latter, and maybe we should just let shop keepers keep guns at work to combat the former. But wait, if theyre not allowed to transport them to and from work each day [a bitter blow to you im sure] then theyd have to leave them in the shop. But...

"During 2001/02, 2,910 firearms were recorded by the police as being stolen"

Oh deary me! Gosh, all these criminals running round with our legally licensed guns, our money wont even be safe in the bank!

"However, the total number of firearm robberies in banks and building societies is considerably lower than in
1991 (250 compared to 1,395 in 1991)."

Now im just confused!

Anyway, please feel free to check me on the above quotes, i would hate to have quoted out of context. If you can read through thinly veiled sarcasm (sorry about that but gun-nuts do get me riled up) and relpy coherently i would love for you to find some similar statistics for America and prove to me that you live in a safer society.

nick

Of course it is easy to manufacture a crude firearms, just as it is easy to convert a kitchen knife to a weapon (ie just use it in a different way), making lethal weapons is easy and a curse of our own intelligence. However to actively manufacture firearms and distribute them to the population is foolhardy and invites the worst.

I live in the UK and pretty much the only people here with guns are the IRA, now the only places that they have been able to get guns are failed or failing states such as Libya and Columbia, and more recently they have taken advantage of the conflict in eastern europe (they actually import some from america too - but im not going to go down that road), on mars there will be no failed states or large scale conflict and so no need for the manufacture, and/or distribution of, personal weaponry.

I believe students in europe have already conducted experiments on tethered systems in freefall, using the ESA parabolic flight campaign.

This is one link a quick search pulled up.

http://esapub.esrin.esa.it/bulletin/bullet85/ocke85.htm

nick

My point was that the first mission to mars will want to involve minimal construction in space (keeping in line with the mars direct plan and assuming it is in the near future, <touch wood>, ie there is inadequate in-orbir infrastructure for this at the moment), thus a 60 meter diameter ship or two shuttle boosters connected via an elevator or any other rigid means is unrealistic.

nick

You are correct, a spinning ship would have significant 'wobble' issues, simply because of its small size (radius) and large rpm. The tether greatly reduces this affect by creating a (technically) large radius and a slower rpm.

Limited EVA would be possible on a tethered ship, but only by exiting the ship from 'top' ie the tethered end. This would probably be in order to access the other end of the tether via a small single person crawler which pulled you up the line (then down the other side) EVA would be possible (yet dangerous - but what isnt in a mars mission) down the sides the hab in an emergency (abseiling?) and would be greatly facilitated if the required induced g were lower than 1.

Mars - i very much doubt they would launch the ship if they werent sure the solar panels/dish would work just fine for the journey, the crew would also be able to handle the conditions without an EVA to 'get some air'  , otherwise they simply wouldnt be sent. Oops just re-read your post, think you were joking ???

I also imagine that equipment such as comms dish and possibly solar panels would be located at the centre of the tether in order to minimise problems with keeping them pointed at earth/sun. Also making them acessible on an EVA.

Heres a handy link someone here gave me for working out g equations

http://www.labcentrifuge.com/gforce5.html

nick

unfortunately this method cannot be used on the passage to mars as our ship would be too small. The size of the spinning habitat would be restricted and so any induced artificial gravity would vary to greatly over the length of the body of a person standing, thus inducing nausea. Put simply, gravity may be 1g at his feet, but it might be as low as 0.5g at his head.

One way to counter this is to simply only apply as much g as would be necessary to maintain muscle/bone mass. They are currently studying this at nasa and esa  Also a lower applied artificial g would drop of slower (it drops of exponentially) so the difference of g over an area would be less.

Also it should be noted that if you go for too high a induced g, there are problems of balance that might induce a wobble in the space craft (like a washing machine but less violent   ) which would disastorous in terms of applying your thrust in the right direction.

nick

Force would travel through the object at the speed of sound(in the respective solid). If you imagine the object being very long, when you push on it you will slightly compress it at the end the force is being applied, this compression will be transmitted along the material just like the compresive (transverse?) waves of sound through air, then will act to extend the material slightly at the end, thus the material will have moved.

Note: This might not be a very good explanation and i in no way intend to imply that any matter is transmitted down the beam/object, only energy.

cheers

nick