Manned Spaceflight - the Next 30 Years
Discussion
Although we've literally barely scratched the surface of the moon, we're pretty sure there is water there, and there is certainly oxygen locked up in various minerals, along with aluminium, titanium etc. Digging deeper than the few inches we've managed so far may reveal higher concentrations of materials we are interested in, as could exploring areas away from the equatorial region where most landings have taken place ( due to it being easier in orbital dynamic terms to reach ). There is also the farside which has yet to be explored.
For deep space exploration it makes sense to build your spacecraft in orbit - launching from Earth is so expensive, so only components which can only be manufactured on Earth would need launching. Everything else should be made from raw materials mined on the moon and launched into space using a mass-driver ( think BIG railgun ) running on solar power generated using locally manufactured solar panels ( half the generated power can be used to electrolyse water to run fuel cells overnight ). Manufacturing of components can take place on the moon or in orbit, depending which is easier – large components would be easier to handle if made in microgravity.
Launching from Earth also requires that whatever you are launching can withstand the stresses incurred during launch. It makes little sense to build a spacecraft capable of withstanding launch stresses when its entire working life will be spent in microgravity – using efficient ion motors the accelerations produced are tiny ( despite what Hollywood believes ) and a spacecraft designed for this can be a lot lighter for its size if built in space rather than launched from Earth. Even spacecraft using chemical or nuclear/thermal rockets to provide higher accelerations would still be lighter if fabricated in orbit, as even these engines would have efficient acceleration levels much lower than experienced during launch from Earth.
Mars is an achievable destination, especially as we know the resources are present to manufacture the fuel required for the return journey, thus saving mass and reducing propellant requirements for the outbound journey. It is also the nearest world which offers the potential for a colony which could eventually become self-sustaining. It is also of massive scientific interest – and while the robotic rovers have provided invaluable data they can take years to carry out the same amount of work that a geologist on the ground could do in a couple of days.
However none of the above really address the primary motive behind most successful human endeavours, the motive which drove Europeans to explore the world, and which drives a lot of the current space industry – the chance to make a profit !
Apart from the military missions, the vast majority satellites are launched with the intention of making money for their owners through charging for weather data, earth resources data, or communications etc. The manned exploration of deep space is likely to only really take off when someone figures how to make money from it. At present that appears to be most achievable through mining asteroids for precious metals which are rare on Earth. While robot probes would be fine for finding these materials in the first place, the communication delays due to their distance make them difficult to control and less suited to use in a commercial mining venture.
So in conclusion. My answer to Eric’s original question is –
First return to the moon to setup mining facilities to produce cheap spacecraft components, then off to the asteroids to make money while also visiting Mars for science
For deep space exploration it makes sense to build your spacecraft in orbit - launching from Earth is so expensive, so only components which can only be manufactured on Earth would need launching. Everything else should be made from raw materials mined on the moon and launched into space using a mass-driver ( think BIG railgun ) running on solar power generated using locally manufactured solar panels ( half the generated power can be used to electrolyse water to run fuel cells overnight ). Manufacturing of components can take place on the moon or in orbit, depending which is easier – large components would be easier to handle if made in microgravity.
Launching from Earth also requires that whatever you are launching can withstand the stresses incurred during launch. It makes little sense to build a spacecraft capable of withstanding launch stresses when its entire working life will be spent in microgravity – using efficient ion motors the accelerations produced are tiny ( despite what Hollywood believes ) and a spacecraft designed for this can be a lot lighter for its size if built in space rather than launched from Earth. Even spacecraft using chemical or nuclear/thermal rockets to provide higher accelerations would still be lighter if fabricated in orbit, as even these engines would have efficient acceleration levels much lower than experienced during launch from Earth.
Mars is an achievable destination, especially as we know the resources are present to manufacture the fuel required for the return journey, thus saving mass and reducing propellant requirements for the outbound journey. It is also the nearest world which offers the potential for a colony which could eventually become self-sustaining. It is also of massive scientific interest – and while the robotic rovers have provided invaluable data they can take years to carry out the same amount of work that a geologist on the ground could do in a couple of days.
However none of the above really address the primary motive behind most successful human endeavours, the motive which drove Europeans to explore the world, and which drives a lot of the current space industry – the chance to make a profit !
Apart from the military missions, the vast majority satellites are launched with the intention of making money for their owners through charging for weather data, earth resources data, or communications etc. The manned exploration of deep space is likely to only really take off when someone figures how to make money from it. At present that appears to be most achievable through mining asteroids for precious metals which are rare on Earth. While robot probes would be fine for finding these materials in the first place, the communication delays due to their distance make them difficult to control and less suited to use in a commercial mining venture.
So in conclusion. My answer to Eric’s original question is –
First return to the moon to setup mining facilities to produce cheap spacecraft components, then off to the asteroids to make money while also visiting Mars for science
Simpo Two said:
There's another half page of replies for you to dispute. Don't forget those too 
I see you didn't reply or comment on interplanetary travel 101 that I thought may help you understand a little more why having a moon base is not really an answer to the problem.Rob made some great points below and based on facts which for me is far more interesting and highlights some of the realities and challenges behind the science of space flight. (my comments are probably a little harsh but heck if we don't get prodded how can we learn)
RobDickinson said:
Its actually more expensive ( in terms of delta vee) to land on the moon than it is to land on Mars...
edit - some science..
It takes 3000 m/s from LEO to transfer to the moon. It takes 4500 m/s to transfer to Mars even though Mars is so much farther than the Moon.
Once we get there? On the moon it's powered flight all the way down. About 700 m/s to enter lunar orbit, and about another 1700 m/s from lunar orbit to landing. While at Mars to land takes minimal fuel usage. It can be done straight from the transfer trajectory. Aim for the atmosphere, slow down to 400 m/s relative to surface for free, then deploy a chute and slow down further to about 80 m/s for free. That's how much dV you need to make a soft landing
But to do that soft landing you need heat shields and chutes, sky cranes etc... All that adds weight which the lunar lander can use for fuel/engines.
It took an Atlas V 541 (payload to LEO: 17 tons) to put a 900kg rover on Mars, and a Proton-K (payload to LEO: 19 tons) to put a 750kg rover on the moon. So pretty similar.
Any trip to the moons surface is purely to explore the moon. Not as a staging post. Not as an astronomy spot, much better putting that at L2 or something
edit - some science..
It takes 3000 m/s from LEO to transfer to the moon. It takes 4500 m/s to transfer to Mars even though Mars is so much farther than the Moon.
Once we get there? On the moon it's powered flight all the way down. About 700 m/s to enter lunar orbit, and about another 1700 m/s from lunar orbit to landing. While at Mars to land takes minimal fuel usage. It can be done straight from the transfer trajectory. Aim for the atmosphere, slow down to 400 m/s relative to surface for free, then deploy a chute and slow down further to about 80 m/s for free. That's how much dV you need to make a soft landing
But to do that soft landing you need heat shields and chutes, sky cranes etc... All that adds weight which the lunar lander can use for fuel/engines.
It took an Atlas V 541 (payload to LEO: 17 tons) to put a 900kg rover on Mars, and a Proton-K (payload to LEO: 19 tons) to put a 750kg rover on the moon. So pretty similar.
Any trip to the moons surface is purely to explore the moon. Not as a staging post. Not as an astronomy spot, much better putting that at L2 or something
Edited by RobDickinson on Monday 26th October 21:56
jmorgan said:
Mojocvh said:
jmorgan said:
Or find out the best way to survive, improve the technology. One day, something big will hit us.
What do you think drives Ellon Musk??Shuffles off to google to see who that is.
Did you get to read it yet Eric?
Toaster said:
Rob made some great points below and based on facts which for me is far more interesting and highlights some of the realities and challenges behind the science of space flight.
Yes he did. He took the time to explain to you why I was right. I just told you the conclusion because I knew it (though not all the numbers to prove it to you, and frankly why should I).ash73 said:
Leave it to the last second; Kerbal suicide burns are fun
Your numbers are interesting but you should be comparing Earth-orbit to Moon-orbit dV for the feasibility of refuelling.
Doesnt make a difference when you decellerate, only to the g forces, delta vee change is the same.Your numbers are interesting but you should be comparing Earth-orbit to Moon-orbit dV for the feasibility of refuelling.
And we launch from earth not LEO not sure what the point of thinking about orbital refuelling for using a moon as a base for further exploration.
Its pointless. you are just sitting needlessly in a gravity well , unless you are there long term and there are resources that make it work (water etc), we have got good at using water tho, and we would still need to send a lot of consumables wherever it was.
ash73 said:
And bear in mind we're talking about sending a *lot* more mass than the recent Mars rovers, not just the lander but the fuel required to get home; aero-braking on that scale would be a massive engineering challenge.
Which is why NASA are in the middle of testing large "ballute" aerobraking system and large parachutes that can be deployed at supersonic speeds. So far the ballute system seems to work well but the most recent parachute test ended up with a shredded chute. Simpo Two said:
Yes he did. He took the time to explain to you why I was right. I just told you the conclusion because I knew it (though not all the numbers to prove it to you, and frankly why should I).
Oh OK thats fine then, opinionated and lacks the ability to Justify a view I suspect thats the scientific way is it Getting back on track, Manned Spaceflight over the next 30 Years is still going to be the domain of the very few unless there is a huge change in technology and the current batch of 'new' space vehicles looks rather similar to those that have gone before and the costs are still huge. Robotic exploration is probably the best and most financially viable way we currently have.
It is an interesting period because for the first time, we do have parallel non-state run manned programmes. Obviously, these are all at early stages in their development and there is no guarantee that any or all of them will succeed. But it does at least provide an alternative path that is less reliant on the whim of the political mood.
And the other plus point is that it does look like the next 30 years will finally see us move away from low earth orbit only missions. What the destinations will be is still not quite clear, but at least it will be something different.
And the other plus point is that it does look like the next 30 years will finally see us move away from low earth orbit only missions. What the destinations will be is still not quite clear, but at least it will be something different.
Late to the party and a fun topic.
I would like to see us land somewhere with an aim to extract a commercially viable resource. Perhaps something which can be used for energy generation on Earth. Or rare metals for the increasing demand etc.
Once capitalism gets it's greedy paws on something, competition opens up, and the investment really starts to pile into it. Then more exotic exploration seems more likely.
That'll show those pesky Russians.
I would like to see us land somewhere with an aim to extract a commercially viable resource. Perhaps something which can be used for energy generation on Earth. Or rare metals for the increasing demand etc.
Once capitalism gets it's greedy paws on something, competition opens up, and the investment really starts to pile into it. Then more exotic exploration seems more likely.
That'll show those pesky Russians.
ash73 said:
CrutyRammers said:
The idea of a station somewhere further out to test long term living arrangements for mars trips sounds like it makes some sense, but in actuality I can't see much difference between being there and low earth orbit, apart from the expense of getting to it. Testing of radiation shielding etc is something we need to do but I don't know if we need to go into space in order to do that.
The key difference is learning to survive outside the Earth's protective shield. No humans have *ever* done that for more than a week. The ISS in LEO is shielded by the Earth's upper atmosphere and magnetic field.You could do some basic tests on Earth but the next step is to prove it works in the real environment before trekking off to Mars. Can we recreate cosmic rays in a lab? What about artificial gravity? And space suits? And solar power generation? And growing food in space? And crew psychological issues? We can't test all the maintenance activities required for a lengthy mission to Mars in a swimming pool.
For the radiation issue, I said I didn't know. I'd imagine a lot of it could be done on earth, then tested with smaller probes rather than hoisting an entire station up into high orbit.
I think after almost 60 years of launching things into space and sending items (manned and unmanned) through the various radiation belts that surround earth and experiencing radiation in interplanetary space, I would think we now have a pretty good understanding of the levels of radiation that are experienced.
All interplanetary probes and any craft that have to venture beyond the Van Allen zones are now radiation "hardened" to ensure they keep functioning. One of the prime goals of the Orion spacecraft test conducted last December was to give it a good soak in radiation to ensure its onboard electronics coped. They did with no problems.
All interplanetary probes and any craft that have to venture beyond the Van Allen zones are now radiation "hardened" to ensure they keep functioning. One of the prime goals of the Orion spacecraft test conducted last December was to give it a good soak in radiation to ensure its onboard electronics coped. They did with no problems.
Why do you not think they cannot be tested near earth or even on earth? We know the environment between earth and Mars quite well now. Dozens of craft have made that journey. Manned craft have been to the moon and back.
It's not an unknown environment.
We can replicate the radiation levels here on earth quite well I am sure - so protective materials can be tested here at much lower cost. We won't be testing the shielding methods on the first manned flight to Mars.
It's not an unknown environment.
We can replicate the radiation levels here on earth quite well I am sure - so protective materials can be tested here at much lower cost. We won't be testing the shielding methods on the first manned flight to Mars.
Eric Mc said:
Plenty of air and water on Mars. You just need to do a bit of simple chemistry to get at it (I've read The Martian - so I know).
Hanging around waiting for new technology is a bit like telling Charles Lindberg in 1927 not to bother trying to fly the Atlantic but to wait until Jumbo Jets get invented. The thing is, it's because of the exploits of people like Lindberg that Jumbo Jets got invented
So should we/they/you be concentrating on developing and using drones to go to Mars and deliver and build a habitable base there? The limiting factors are the systems for supporting humans. What do we want from Mars? If it's just resources, we can get them without even sending people there. Hanging around waiting for new technology is a bit like telling Charles Lindberg in 1927 not to bother trying to fly the Atlantic but to wait until Jumbo Jets get invented. The thing is, it's because of the exploits of people like Lindberg that Jumbo Jets got invented
Why do humans need to go at all. Everyone was inspired by the first moon missions but even those lost popularity after a while. I'm all for manned space exploration but do humans just need to go into space when the earth is no longer a suitable home.
The main problem is funding and governments are now unwilling to fund manned expeditions into space just because "it's there" or "because it's hard" there needs to be a real use for human space flight. The previous need was because of the Cold War. What's the need now?
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