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45 Years Ago We Landed Men on the Moon

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    #32
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    Maximus Alexander wrote: »
    That's a bit pessimistic. You could get humans into LEO in about 10 hours at those speeds and for a much lower cost.

    Of course current space elevator designs wouldn't be able to carry humans, but then we're not building one at present.
    No you can't.

    The humans will be 100Km up but only have 1,000mph orbital velocity out of the 18,000mph they need to avoid going splat sometime after they step off the elevator


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    #33
    Ping Chow Chi
    Registered Users Posts: 3,779 ✭✭✭Ping Chow Chi


    Why would the elevator be constricted to 10mps, would that be an engineering limit?

    I have to say that the more I look at the proposals, the more unfeasible it look, but still, good to dream and all that.


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    #34
    Maximus Alexander
    Registered Users Posts: 13,080 ✭✭✭✭Maximus Alexander


    Capt'n Midnight wrote: »
    No you can't.

    The humans will be 100Km up but only have 1,000mph orbital velocity out of the 18,000mph they need to avoid going splat sometime after they step off the elevator

    From what I've read it would cost about half to accelerate to orbital velocity at the altitude of LEO compared to launching from the surface. That's a pretty significant saving.


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    #35
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    Maximus Alexander wrote: »
    From what I've read it would cost about half to accelerate to orbital velocity at the altitude of LEO compared to launching from the surface. That's a pretty significant saving.
    There's a huge difference between being 100Km up and being 100Km up and travelling at 17,000 mph


    if you increase your speed up an elevator the downward force also increases so there is a limit on how much cargo and what speed it can travel compared to the strength of the cable and the size of counterweight

    elevators are great for slow cargo , not so good for perishables like humans.

    Sending cargo by ship is cheap
    But long distance aeroplane travel is cheaper for humans since you only have to supply life support for a seat for few hours instead of a full cabin for days.


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    #36
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    Maximus Alexander wrote: »
    From what I've read it would cost about half to accelerate to orbital velocity at the altitude of LEO compared to launching from the surface. That's a pretty significant saving.
    Use a chemical rocket to get to LEO and then use Hall Effect Thruster the rest of the way will save you something approaching half your launch mass.


    The only problem is that you are relying on solar panels so very slow acceleration. However, 40 years of use in space and there haven't been any failures yet so it's a very dependable technology.


    VASIMR is something similar except it only exists in theory and the claims for it don't add up.


    What are the maximum g's a human breathing perfluorocarbons could stand ? maybe 50g's ??

    50g's for 14 seconds would get you into orbit, you could hold your breath so wouldn't have to breath liquid during that time

    the distance at that acceleration would be 1,684Km ( 1,000 miles )

    that's a lot shorter than an elevator and one hell of a maglev ride through a vacuum tube



    of course most non-mammalian species develop from eggs so they could launch them at even higher g's

    ET might laugh at our ways of getting our fragile bodies into space


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    #37
    Maximus Alexander
    Registered Users Posts: 13,080 ✭✭✭✭Maximus Alexander


    None of that addresses the point I was making...


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    #38
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    Maximus Alexander wrote: »
    None of that addresses the point I was making...
    you're saying that accelerating to 17,000mph only takes half the energy when you are 100Km up ?

    https://en.wikipedia.org/wiki/Project_HARP
    On November 18, 1966 the Yuma gun fired a 180 kg Martlet 2 projectile at 3,600 m/s (12,000 ft/s) sending it into space briefly and setting an altitude record of 180 km (590,000 ft; 110 mi); that world record still stands as of 2013
    3.6Kms is only 1/3rd of orbital velocity

    also the first 1/4 or 1/3 or whatever of velocity is the easiest to get, solid rocket boosters are cheap , yes there are savings but it's big dumb booster territory

    even the first stage of the Saturn IV ran on kerosene/diesel rather than the lighter and more energetic hydrogen.

    and a space elevator that got you to 100km would still need to extend far beyond GEO to counter balance the weight


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    #39
    Rucking_Fetard
    Closed Accounts Posts: 1,260 ✭✭✭Rucking_Fetard


    What will it take to get us back to the Moon?


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    #40
    Hotblack Desiato
    Registered Users Posts: 34,100 ✭✭✭✭Hotblack Desiato


    What will it take to get us back to the moon?

    Money, lots thereof, just like last time - but also a reason to go there, which was tenuous enough the last time.

    39 years ago you could have bought a ticket on a Mach 2 scheduled airliner flight. These days you're lucky to do M0.8 in a cramped seat, but at least it's usually cheap...

    Concorde failed partially because the development costs were through the roof (partially recouped by Airbus recyling the technology though) but mainly because of the huge energy input compared to subsonic airliners. Similarly, short of a space elevator we're not going to get over the energy needed to overcome Earth's gravity well to LEO, never mind lunar injection.

    I wish I could be optimistic about the future of manned space flight, I grew up devouring books about Gemini, Apollo and Soyuz after all, but that was an unrealistic era brought about by disguised military expansionism, and cold war one-upmanship.

    Fingal County Council are certainly not competent to be making decisions about the most important piece of infrastructure on the island. They need to stick to badly designed cycle lanes and deciding on whether Mrs Murphy can have her kitchen extension.



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    #41
    Calina
    Registered Users Posts: 8,219 ✭✭✭Calina


    Hotblack Desiato wrote: »
    Concorde failed partially because the development costs were through the roof (partially recouped by Airbus recyling the technology though) but mainly because of the huge energy input compared to subsonic airliners.

    It wasn't helped by protectionist policies in America either.


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    #42
    nokia69
    Closed Accounts Posts: 2,050 ✭✭✭nokia69


    Hotblack Desiato wrote: »
    What will it take to get us back to the moon?

    Money, lots thereof, just like last time - but also a reason to go there, which was tenuous enough the last time.

    39 years ago you could have bought a ticket on a Mach 2 scheduled airliner flight. These days you're lucky to do M0.8 in a cramped seat, but at least it's usually cheap...

    Concorde failed partially because the development costs were through the roof (partially recouped by Airbus recyling the technology though) but mainly because of the huge energy input compared to subsonic airliners. Similarly, short of a space elevator we're not going to get over the energy needed to overcome Earth's gravity well to LEO, never mind lunar injection.

    I wish I could be optimistic about the future of manned space flight, I grew up devouring books about Gemini, Apollo and Soyuz after all, but that was an unrealistic era brought about by disguised military expansionism, and cold war one-upmanship.

    take a look at what spaceX are doing and you will be optimistic again

    once the BFR is flying a return to the Moon will be easy


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    #43
    Hotblack Desiato
    Registered Users Posts: 34,100 ✭✭✭✭Hotblack Desiato


    Do you really think we'll see humans on the moon again within, say, 20 years? I don't :(

    Fingal County Council are certainly not competent to be making decisions about the most important piece of infrastructure on the island. They need to stick to badly designed cycle lanes and deciding on whether Mrs Murphy can have her kitchen extension.



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    #44
    nokia69
    Closed Accounts Posts: 2,050 ✭✭✭nokia69


    Hotblack Desiato wrote: »
    Do you really think we'll see humans on the moon again within, say, 20 years? I don't :(

    of course, I think we will see it happen in less than 10

    spaceX have started work on their Mars rocket, this will make the saturn V look small, with a rocket that size getting people to the Moon is easy

    Musk has little or no interest in the Moon but if NASA or anyone else want to pay him to get there he will be happy to take the money


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    #45
    Manach
    Moderators, Society & Culture Moderators Posts: 9,674 Mod ✭✭✭✭Manach


    From history there are cases of a society turning its back on the cusp of a golden age of exploration. China had vast fleets in the Medieval period that mapped as far as the furtherest shores of Africa. Then, they stopped and turned inwards - in the belief that as the Middle Kingdom they could keep their levels of prosperity by ignoring the rest of the world. So from this, yes the moon will be reached again but by societies that have drive - ironically enough that would include to-day's China.


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    #46
    Hotblack Desiato
    Registered Users Posts: 34,100 ✭✭✭✭Hotblack Desiato


    nokia69 wrote: »
    Musk has little or no interest in the Moon but if NASA or anyone else want to pay him to get there he will be happy to take the money

    Well, that's your fail all wrapped up in one neat sentence.

    Fingal County Council are certainly not competent to be making decisions about the most important piece of infrastructure on the island. They need to stick to badly designed cycle lanes and deciding on whether Mrs Murphy can have her kitchen extension.



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    #47
    Hotblack Desiato
    Registered Users Posts: 34,100 ✭✭✭✭Hotblack Desiato


    Calina wrote: »
    It wasn't helped by protectionist policies in America either.

    That was only after the Americans were sure they couldn't build their own SST, there were no so-called 'environmental groups' objecting to the Boeing 2707.

    Fingal County Council are certainly not competent to be making decisions about the most important piece of infrastructure on the island. They need to stick to badly designed cycle lanes and deciding on whether Mrs Murphy can have her kitchen extension.



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    #48
    nokia69
    Closed Accounts Posts: 2,050 ✭✭✭nokia69


    Hotblack Desiato wrote: »
    Well, that's your fail all wrapped up in one neat sentence.

    watch it happen

    they already get paid to send supplies to the ISS, when the SLS gets cancelled NASA will just use the BFR because it will be a better rocket for a fraction of the price


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    #49
    Rucking_Fetard
    Closed Accounts Posts: 1,260 ✭✭✭Rucking_Fetard


    nokia69 wrote: »
    watch it happen

    they already get paid to send supplies to the ISS, when the SLS gets cancelled NASA will just use the BFR because it will be a better rocket for a fraction of the price
    NASA’s Space Launch System is officially all systems go for Mars and Moon landings


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    #50
    nokia69
    Closed Accounts Posts: 2,050 ✭✭✭nokia69


    yeah the SLS may fly a few times, but its going to be cancelled

    its launch costs will be to high


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    #51
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    Hotblack Desiato wrote: »
    That was only after the Americans were sure they couldn't build their own SST, there were no so-called 'environmental groups' objecting to the Boeing 2707.
    Mach 2 wasn't good enough , they wanted Mach 3 and that's a lot more expensive. Sonic booms from the XB-70 didn't help.

    But the big kicker was a simple Schoolboy error. If the plane can go Mach 3 you only need 1/3rd as many. This means development costs can't be spread out and that's why the B2 bomber and Space Shuttles cost billions each.
    Hotblack Desiato wrote: »
    39 years ago you could have bought a ticket on a Mach 2 scheduled airliner flight. These days you're lucky to do M0.8 in a cramped seat, but at least it's usually cheap..
    Actually if you add in the queues and circling the airport it's more likely to be Mach 0.4-0.5 unless you are on long haul.


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    #52
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    IIRC a lunar space elevator could be constructed with existing materials with a mass of 80 tonnes, excluding counter balance of course.

    Yes it would take ages to land stuff on the surface but to land stuff using rockets would mean having to use half the mass for fuel. And that translates to half the initial launch mass so it's a huge saving if you need to get a lot of stuff there.

    Then again the lunar tunnels might mean less material needed for habitats.


    But it would take as much energy to get to the Asteroids so should we be looking beyond the moon.


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    #53
    Rucking_Fetard
    Closed Accounts Posts: 1,260 ✭✭✭Rucking_Fetard


    Forget Mars. Here’s Where We Should Build Our First Off-World Colonies


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    #54
    Lapin
    Banned (with Prison Access) Posts: 18,184 ✭✭✭✭Lapin


    nokia69 wrote: »
    we will be back on the Moon very soon

    its closer than you think

    Whats the point in going back there ?


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    #55
    Maximus Alexander
    Registered Users Posts: 13,080 ✭✭✭✭Maximus Alexander


    Lapin wrote: »
    Whats the point in going back there ?

    Mainly for science, but there are lots of other reasons too.


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    #56
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    There are few volatiles on the moon

    http://blogs.esa.int/rosetta/2014/09/11/rosina-tastes-the-comets-gases/
    As expected, the main species in the comet’s coma are found to be water, carbon monoxide, and carbon dioxide, which are being released from below the surface layer of the nucleus, which VIRTIS has shown to be dark, porous, and probably dry.
    ...
    n addition, ROSINA has not only detected these main species already, but many of the expected minor ones, such as ammonia, methane, and methanol.

    Yes the moons of Mars are easier to get to though and may also have volatiles.


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    #57
    SpaceTime
    Closed Accounts Posts: 9,088 ✭✭✭SpaceTime


    Hmm.. I can think of a few reasons why Venus might be challenging as a place to live.


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    #58
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,830 Mod ✭✭✭✭Capt'n Midnight


    SpaceTime wrote: »
    Hmm.. I can think of a few reasons why Venus might be challenging as a place to live.
    Since it's at the bottom of a gravity well nearly as deep as Earth's it's more or less a one way trip too.

    Anyone care to guess the cost of putting a balloon carrying 300 tonnes of ascent rocket at 50Km altitude.

    There is also the slight problem of getting to the Balloon if you don't choose to live there.


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    #59
    Rucking_Fetard
    Closed Accounts Posts: 1,260 ✭✭✭Rucking_Fetard


    Capt'n Midnight wrote: »
    IIRC a lunar space elevator could be constructed with existing materials with a mass of 80 tonnes, excluding counter balance of course.

    Yes it would take ages to land stuff on the surface but to land stuff using rockets would mean having to use half the mass for fuel. And that translates to half the initial launch mass so it's a huge saving if you need to get a lot of stuff there.

    Then again the lunar tunnels might mean less material needed for habitats.


    But it would take as much energy to get to the Asteroids so should we be looking beyond the moon.
    New diamond nanothreads could be the key material for building a space elevator


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    #60
    Rucking_Fetard
    Closed Accounts Posts: 1,260 ✭✭✭Rucking_Fetard


    The Quest to Build an Elevator to Space


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