New Mars Forums

OK - so assuming the laser is 100% efficient what would be the necessary output to lift say a penny.

I think one nice thing about the light propulsion idea is you could say send up small payloads and potentially construct stuff while in orbit.  Anyways, I'd like to see some numbers crunched(I suppose I should start the crunching).  I'll post what I get soon...

So what I picture is sending up small pieces of your solar sail at a time, put together the solar sail in orbit and then use a conventional rocket to get your crew into orbit and finally head for Alpha Centauri using the solar wind?

Hehe - yes the complications are giving me a headache too...  Anyways, just venting the imagination for what its worth.

Justin in Calgary

David vs Goliath

If getting to space, at low cost, is as difficult as it is for a young small boy to defeat a battlehardened giant warrior why don't we glimpse into history/legend (depends who you ask) and learn a thing or two from a boy called David.

I have been reading threads on a catapult idea for launching into space.  I like the idea though I believe that the paradox lies in the beam of the catapult - the only material that displays qualities which come close to having the strength per m^3 to withstand the insane initial acceleration of taking a sizable payload from 0 to 12 km/s in a rotation is the budding carbon-fiber technology.

Instead of a one time "catapult" into space why not "sling" into space.  Build a massive, vertical spinning, sling.  You could mount it in a large pit in the ground for better stability and instead of subjecting your "beam" to that crazy initial stress of the catapult, just gradually increase the rotational speed up to the point required to reach the necessesary departure velocity's and then like David let it go!  and whola - A giant is slain.

I want to hear from you more educated folks now... :-)  (I am only a humble student of engineering)

Justin

Rob - do you have the address of that website handy?

Ian, you unfortunatly belittle yourself with your arrogant comments. 

"Since we're talking about the distant future, isn't it interesting that basic supplies will be easier to send to the Moon than from Mars?"

Forgive me, this sentence doesn't make any sense.  please explain

"Oh, since you're an engineer, maybe you could answer this question for me.  Which has more of an effect on the mass of a rocket?  Earth's atmosphere or gravity."

Depends what you mean by 'effect'.  Atmosphere impedes velocity since the relative air density is much thicker than that in space where as in a gravitational field with no atmosphere huge velocities are attainable.

I think you mean that because the Moon also has gravity it will still require alot of energy.  Well compared to blasting off from earth, the answer is a fraction the energy (no atmosphere and much less gravity) though if you compare the energy to that required to throw up a basketball than yes it is significant.

Bottom line is I agree with you that it takes more energy to stop first at the moon.  We need to be careful that a single ambitious goal doesnt blind our vision to the whole picture.  Getting to Mars will not make your life complete.  Lets enjoy the ride...

Just because Mr. Zubrin so said his feelings doesn't make it true.  I am not saying it is the best idea to launch from the moon but it is something that should be considered and investigated.  His comparison to the small difference of cost of launching to the moon with launching to mars is a perfect example - that shows that the majority of the energy (and therefore fuel) is expended on the journey through our atmosphere - only to travel the huge distance to mars on near empty(or a flying box that detaches from a rocket).  Also you should account for the time factor.  It takes a fraction of the time to get to the moon then to mars so you could amass equipment there and then make low-energy blasts to mars rather than trying to make hole in ones from earth.  Remember that once a moon base is setup, a pitstop to mars would be only one of its few possibilities.  It would open up a new tourist industry and also the capability to launch spacecraft in a whole new way to other planets besides mars.  What would a spacecraft look like that didn't have to break the atmosphere?  How much freedom or possibilities would that add?  Just some ideas to consider.

well the problem with bunkering in is the threat that such places have on the rest of the country.  Where do you draw the line - I mean isolationism is fine, (I think of Ukrainians, omish etc) but if one is participating in society (using roads, infrastructure, getting pay checks) they also need to pay taxes and be responsible citizens (not commit horrendus crimes on their bunkered off territory).  I still think a balance is key.

I'm interested in your phrase 'cultural imperialist' - that has much connotation with it.  I would be interested to hear what caused this recent change.

Using the moon as a launch base is definetley not an idea to scrap as being suggested by some.  Launching from the moon would mean a completley different kind of spacecraft - one which needs a fraction of the fuel and therefore payload of those required to bust earths atmosphere.  What would happen is a specialization process:  A ship designed for a short journey to the moon from Earth (the heavy lifter) and then a much light craft to go moon to mars.  Hauling a cumbersome heavy lifter all the way to mars does not make alot of sense.

And besides how romantic is the idea of a moon base?

It is disheartening when we live in a time of so much potential and still linger onto past weaknesses which we cannot shake.  Hubble has made innumerable discoveries both with scientific implications and art extrordinare.  The last thing that was being considered in deciding to service the telescope is risk to human life.  If government is ready to sacrifice thousands of lives in meddling in other countries (be it war, special ops you name it) and then to pretend that the risk of several lives is too great simply disgraces logic.  Science is fundamentally what separates us from the animal world - shall we stop 'monkeying' around and finally step up to the task?