How To Get Back To the Moon In 4 Years -- This Time To Stay (scientificamerican.com)

Scientific American describes "a way to get to the Moon and to stay there permanently...to begin this process immediately and to achieve moon landings in less than four years." It starts by abandoning NASA's expensive Space Launch System and Orion capsule, and spending the money saved on private-industry efforts like Elon Musk's SpaceX and Robert Bigelow's Bigelow Aerospace. schwit1 quotes their report: Musk's rockets -- the Falcon and the soon-to-be-launched Falcon Heavy -- are built to take off and land. So far their landing capabilities have been used to ease them down on earth. But the same technology, with a few tweaks, gives them the ability to land payloads on the surface of the Moon. Including humans. What's more, SpaceX's upcoming seven-passenger Dragon 2 capsule has already demonstrated its ability to gentle itself down to earth's surface. In other words, with a few modifications and equipment additions, Falcon rockets and Dragon capsules could be made Moon-ready...

Major segments of the space community want every future landing to add to a permanent infrastructure in the sky. And that's within our grasp thanks to Robert Bigelow... Since the spring of 2016, Bigelow, a real estate developer and founder of the Budget Suites of America hotel chain, has had an inflatable habitat acting as a spare room at the International Space Station 220 miles above your head and mine. And Bigelow's been developing something far more ambitious -- an inflatable Moon Base, that would use three of his 330-cubic-meter B330 modules.
The article calls Jeff Bezos's Blue Origin rockets "a wild car" which could also land passengers and cargo on the moon and suggests NASA would be better off funding things like lunar-surface refueling stations, lunar construction equipment, and "devices to turn lunar ice into rocket fuel, drinkable water, and breathable oxygen."

Comments

Rockets are too expensive

[KeithCu]

With rockets it is still $100K - $1M per pound to get to the moon. We need a space elevator.

Re:Rockets are too expensive

[h33t l4x0r]

No we need a space escalator. Much more presidential.

Re:Rockets are too expensive

[Bruce Perens]

And a space elevator, of course, would only cost about a Trillion, and there's this little problem of it hitting something (we'd have to make Earth Orbit absolutely pristine and keep it that way) and there's a problem with the kinetic energy if it falls down. Sort of like having many atom bombs go off.

Maybe someday. But right now making rockets as cheap as they can be is a better idea. It's only $200K to fuel up a Falcon 9. We don't get the whole thing back in working order yet, but that would be a lot easier than making a space elevator.

Re:Rockets are too expensive

[KeithCu]

There are other detailed estimates for a space elevator that are around $10 billion. The people who throw around $1 trillion are trying to pick a number so big it prevents people from considering the feasibility. You definitely won't find any detailed breakdown that leads to something so insane.
Brad Edwards book covers all of the problem scenarios you laid out. He explains why it wouldn't be catastrophic if it did fall apart, and what needs to be done to prevent it. I agree we do need to make space more pristine, but we can clean things up, move the tether around, and repair it. It's all engineering work. This could have started in 1991, when carbon nanotubes were first discovered.

Re: Rockets are too expensive

[KeithCu]

You obviously have done very little reading about the space elevator, AC. It's not a building, it's a tether. How much would it cost to make 50 thousand miles of 3-foot, paper-thin steel? It's not strong enough, but it gives you some idea of costs more than what you are throwing around.

The key to making it cheap is the bootstrapping mechanism that Edwards described in his book. What you do is launch into orbit just a seed string, and the first climbers will be small and actually strengthen the ribbon.

Re: Rockets are too expensive

[lgw]

Half the energy to obit at GEO comes from lateral acceleration. A space elevator would be a giant pendulum. And not a nice freshman-physics harmonic oscillator, but a nasty chaotic system with multiple modes of vibration. The energy stored in the system would increase with every payload until it destroyed itself, because there's no way to shed that unwanted energy - minimal friction, trivial air resistance, and so on.

Re: Rockets are too expensive

[khallow]

The energy stored in the system would increase with every payload until it destroyed itself, because there's no way to shed that unwanted energy - minimal friction, trivial air resistance, and so on.

There are a couple of approaches for dealing with that. First,use an extremely efficient propulsion system like electric propulsion to shed said energy and provide the mundane control needed for the system.

Second, you can run payloads down the tether at the same time as your run them up the tether. That would keep the energy balance stable.

Re:Rockets are too expensive

[DrXym]

There are other detailed estimates [spaceelevatorwiki.com] for a space elevator that are around $10 billion. The people who throw around $1 trillion are trying to pick a number so big it prevents people from considering the feasibility. You definitely won't find any detailed breakdown that leads to something so insane.

And people saying $10 billion aren't being serious either. Not even remotely.

Re:Rockets are too expensive

[ShanghaiBill]

And a space elevator, of course, would only cost about a Trillion

Since the material to build it doesn't exist yet, estimates of the cost seem a bit premature.

and there's this little problem of it hitting something

Most designs are for many fibers in parallel. So in an impact you would lose one out of N. Other designs are for a wide ribbon. Nobody is proposing a cylindrical pillar.

there's a problem with the kinetic energy if it falls down.

Since it has a counterweight, why would it "fall down" rather than "float up"?

Sort of like having many atom bombs go off.

Except it is 25,000 miles long, so it wouldn't all go off at once. It would be like a ribbon falling into the atmosphere. It would burn up 60 km up, and unlike a nuke, there would be no radiation or EMP. Chelyabinsk killed zero people, and that happened over land. A space elevator would have its base at sea near the equator.

Re:Rockets are too expensive

[KeithCu]

The numbers come from this book: https://www.amazon.com/Space-E... Their research is more serious than your unsupported opinion.

Re:Rockets are too expensive

[silentcoder]

Indeed the Lunar Lander as it was built then could not have been done without the (recent) invention of Mylar. And they had to get creative at times - working under extreme limits on weight with an extremely precise set of requirements they had to meet. One of their biggest breakthroughs was tossing out the chairs. Have the crew stand upright - and that meant they could make the observation windows much smaller (since the pilot could stand directly in front of them as opposed to looking through them from a chair) - which cut the weight even more.

There is no doubt that a space elevator - if it's ever done - will require similar bouts of creative ingenuity which are utterly impossible to predict prior to the fact, it will be a case of engineers coming before a seemingly insurmountable conflict of requirements and getting creative to meet them all.

Re: Rockets are too expensive

[joh]

They only need fins because they have to steer a lot due to the inconsistencies of the atmosphere (wind and unknown pressure details). On the moon you need no fins, you can just aim a precise trajectory all the way down to the landing point.

Re: Rockets are too expensive

[Rei]

Are you under the impression that Dragon doesn't have an RCS?

Re:Rockets are too expensive

[Rei]

Quite true. The materials technology required is about two orders of magnitude away from actual materials technology, for starters. And among the countless other problems with space elevators, they're not actually all that efficient. Laser power beaming over those distances works out to single-digit transfer efficiencies, and microwave power beaming even less (microwave power beaming to space can be efficient, but only if the receiving antenna is huge). And no, you can't regularly hang things or run power wires up a space elevator - the mass of the cable has to be vanishingly small.

Active-suspended structures, such as Lofstrom loops, are a much better choice. Power transfer efficiency can be greater than 50% and current materials technology should be sufficient. They can also be designed to shoot payloads into any orbit (unlike space elevators), and work independent of the properties of the body in question, as well as having far greater throughput per unit mass. There's really no reason to choose a space elevator over a Lofstrom loop.

Re:Rockets are too expensive

[Rei]

I have read the book, and it's an absurd degree of wishful thinking. Just ignoring the huge number of things that they just gloss over or omit outright, the materials technology they're talking about is about two orders of magnitude away from what we actually have, and might even be physically impossible. Measurements of individual carbon nanotubes (let alone bundles, let alone bulk fibres) don't approach the strengths being talked about there. Colossal carbon tube does better on an individual tube basis, but again, we're nowhere even close to the materials tech required. And for what? For a massive, very low throughput, tiny safety margin, most-failure-modes-unaccounted-for, low-power-efficiency means of access to space? Colour me unimpressed.

If you want something better, I recommend looking into Lofstrom loops (launch loops). Current materials tech, high efficiency, high throughput per unit mass, no orbit restrictions, and works even on tidally locked bodies.

Re: Rockets are too expensive

[TheRaven64]

How much would it cost to make 50 thousand miles of 3-foot, paper-thin steel?

Assuming 'paper-thin' means 1mm thick, then that's around 75,000m^3 of steel, or about 680 Gg. At current steel prices, that's about $250-600m, depending on the kind of steel. The cost of getting that amount of steel to LEO (vastly cheaper than GEO, but assume that most of the mass doesn't have to go up to GEO) at current prices (assuming the cheapest possible launch) is just under $4tn.

The real question is why you care, because steel doesn't have anything like the tensile strength required to be a tether.

Re:Rockets are too expensive

[MachineShedFred]

The US Government spends $10B on post-it notes. If it only cost $10B to never launch rockets again, don't you think it would have been done by now?

NASA's 2011 budget was $18.4B. If they could have really done this for $10B, they could have done it in like 3 years while maintaining all the science probes and other operations.

Oh wait, the materials to get this done at any price, up to and including the GDP of the entire fucking planet, don't exist. I forgot.

Re:Rockets are too expensive

[MachineShedFred]

Yeah, the difference is that we've been making tunnels for a while now, and they still blow through the budget regularly and leave the taxpayers on the hook for massive overruns.

Budgets are based on guesses that are informed by work that has been done before. Nobody has even remotely come close to a space elevator, so writing a budget for it is an exercise in deep thought comedy, especially since the materials necessary for such a thing only exist in the imagination. You could spend $10B just trying to come up with three feet of a material that could work as the tether, much less making 50,000 miles of it. Or getting it into orbit. Or having the orbital anchor to attach it to already there. Or any of the numerous other issues I can think of without ever reading any book on the subject.

Re:Rockets are too expensive

[halltk1983]

Because he's proven to us that he has absolutely no interest in using the rich early on to finance projects for the masses, which is why the model 3 is only available to the super rich, significantly more expensive than the Model S.

Re: Rockets are too expensive

[Shatrat]

The Falcon has small thrusters as well, which is what it uses to make final adjustments at low velocity.

Re: Rockets are too expensive

[Type44Q]

The fins clearly provide stability and guidance at higher, atmospheric speeds but their usefulness is likely in proportion to their speed [through atmosphere]... In any case, you make a good point; perhaps the Moon's far-shallower gravity well would make that less of an issue. One thing's for sure, however: Musk's rockets are presumably designed to retrobrake and land nearly empty of fuel and free from top-heavy upper stages containing luna-bound cargo...

Re: Rockets are too expensive

[Type44Q]

Clearly this stuff will only begin to realize it's full potential when we figure out how to mass-produce monomolecular lengths of it.. and the only way to achieve that on a large scale will be to grow it as a crystal... perhaps the process can be accelerated with lasers (not a big fan of sharks... but if you've ever read Startide Rising, you already know that dolphins with lasers would be pretty fucking cool).

Re: Rockets are too expensive

[liquid_schwartz]

The tiny little ISS in low orbit cost in excess of 100 billion, and you're telling me you can build a 44 thousand mile tall geosynchronously orbiting building for 10 billion? 1 trillion would be cheap.

Just to be clear, for what's been piddled away since 9/11 we could have had *two* of these at the $1 trillion price tag. It's definitely possible.

Re: Rockets are too expensive

[hey!]

geosynchronous satellites: when the sun circulates over the north pole and it causes the satellite to exhibit the figure 8 orbit

geostationary : are fixed (fiction) stations , allegedly ground based

That is the most garbled explanation I've ever heard of geosynchronous orbits.

A geosynchronous orbit is one with a period that exactly matches the Earth's rate of rotation.

Geostationary orbits are a special case of geosynchronous orbits where the angle inclination of the orbit to the Earth's equator is zero.

So: a satellite in a geosynchronous orbit that is also geostationary appears to continually hover 22,236 miles above some point on the Earth's equator. If it is in a geosynchronous orbit that is not geostationary, it will appear from the earth to drift north and south of the celestial equator, tracing a figure 8 against the background stars over the course of one Earth rotation.

Of course in both cases the satellite would actually be following an elliptical (in fact almost perfectly circular) path around the Earth. The "stationary" or "figure 8" thing is simply a trick of perspective -- the way car in the next lane traveling at the same speed appears not to be moving.

Yeah, most of you knew all that. But insofar as there's an explanation here, it oughtn't be gibberish.

Re:Rockets are too expensive

[Rei]

1) It's about 7% of what NYC consumes, not 10%. NYC being only a tiny fraction of total US demand, which is in turn just a fraction of world demand. Global electricity production averages around 15 TW.

500MW is a moderate sized power plant. Not even a large one. It's nothing that impressive. Cost of such a plant is 500M-$1,5B, which is nothing by rocketry standards.

2) That's not 500MW to stand idle; that's 500MW to launch 175 tonnes per day. That's 68.5kWh per kilogram. $7 of electricity per kilogram. Oooh, what a terrible waste of power.

3) If that's too much, the larger version uses significantly less per kilogram.

Is there some reason to get so much mass out of this gravity well

Do you seriously have to ask what sort of market there would be for ~$800 tickets to orbit? I'm sorry, but we're not talking "for the wealthy", we're talking for everyone at those prices.

Not Happening Anytime Soon

[Anonymous Coward]

The cost of a manned moon base was and is astronomical. Moreover, there remain substantial unsolved problems, particularly with regard to moon dust which is razor sharp, microscopic and gets into everything, quickly degrading gaskets, lenses and other dust sensitive surfaces. Finally, there's nothing there valuable enough to justify the expense at this time.

Re:Not Happening Anytime Soon

[Rei]

That's the biggest concern I have. People tire of ongoing expenses. ISS seemed neat at first; now everyone hates it. Why would a moon base fare differently?

Long-term presences in space need to very quickly cut ties with earth, on order of greatest resource dependencies down to smallest resource dependencies. Aka, first things like oxygen, propellant, etc, then to industrial chemicals, of increasingly smaller quantities, with increasingly diversified manufacturing facilities, with very complex/low volume chemical feedstocks and manufacturing processes coming last. Cutting all ties is a process that would take centuries. But you can start with the low hanging fruit, bit by bit, and keep stockpiles of everything needed for maintenance that you can't produce locally.

Unfortunately, running counter to this is expansion. Because if you double the size of your operations, you also double your resource demands. So you need to improve resource independence at a faster rate than you grow.

Part of the problem with the moon is that it's just not a great place for ISRU. Volatiles are rare. We've never even sampled any moon that aren't depleted in volatiles, although there's some data to suggest that various volatiles might be scattered in permanently shaded areas (all of them, in the same place? That's a good question). Surface mineral diversity is limited - primarily light, non-volatile elements. Oxygen is at least widely abundant, but locked up tightly. And while the moon offers short transit times, it's surprisingly not that advantageous concerning delta-V. You can't aerocapture there, landing is fully powered (no parachute deceleration), and to get there you have to already be on such a high apogee orbit that it's not much more energy to go into a Mars transfer. Gravity is less and night is two days long. There are a couple "maybe" peaks of eternal light, but that doesn't mean that they're colocated with volatiles; the last I looked into it it looked like the closest suggested find of water was dozens of kilometers away from the nearest such peak, which would be quite the commute (and thus low throughput / high wear).

The moon is certainly the "cautious" option; emergency returns / resupplies are easy there, and communication fast. Its main value appears to be a testing ground for systems while minimizing risk. But it's not a very appealing place from a settlement perspective.

Of course, I prefer Venus to Mars, but that's neither here nor there ;) I'd like to see a parallel program for both, as the same sort of booster and transfer stage can be used for both, so it's only habitat / ascent stage development costs that are doubled. And once you get past the differences in feedstock sources, production industrial processes converge (Venus advantaged by the higher power availability and easier ability to get rid of heat - excepting in the case of cryogenics, where Mars holds the advantage)

No Dragon 2 Soft Landing Yet

[Bruce Perens]

Dragon 2 isn't built yet. The escape test was a boilerplate capsule more like a Dragon 1 than 2. Dragon 2 has not demonstrated a soft landing, because it's not built yet. That was the Falcon 9 first stage.

Also, you can't get Dragon 2 down to the Moon and back up on it's own. Not enough delta-V. You would need to have Dragon ride on top of something that can hold enough fuel. Like a larger version of the Apollo Service Module.

The Command/Service module was originally intended to land on the moon and return without the LEM, before NASA bought the LEM concept, and was overpowered for the mission it got. Dragon is larger and heavier, but a lunar landing one would probably look a lot like an Apollo Command and Service module, and legs.

And yeah, Orion: I'm Not on Board. Big expensive obsolete rocket with no mission that makes sense.

But good luck getting Elon Musk to focus on the practical and eminently desirable target of the Moon. He isn't interested. It's only Mars for Elon.

I try not to watch all of the Mars Colonial Transport speculation. Falcon 9 and Dragon are great, and they're here, and we could do so much with them.

Re: No Dragon 2 Soft Landing Yet

[lgw]

Venus is the only target that makes sense. Much easier in the long run than Mars or Luna, but the initial stake is high, as you have to get a fairly sizeable dirigible there to start things off. Once you do, though: proper gravity, proper pressure, reasonable temps, plenty of atmospheric rad shielding, plenty of oxygen, trace elements there for the scavenging so you don't need a "perfect" sealed colony that would never work. It's a great idea, really.

Re:No Dragon 2 Soft Landing Yet

[BarryHaworth]

But good luck getting Elon Musk to focus on the practical and eminently desirable target of the Moon. He isn't interested. It's only Mars for Elon.

The SpaceX launch manifest begs to differ. Elon Musk may have Mars as his ultimate goal and be developing the hardware to do it, but in the mean time he is busy launching communication satellites, Iridium satellites, space station resupply, military payloads - anything and everything that people will pay him to launch. If NASA were to foot the bill, he'd be more than happy to land on the Moon.

Or to put it another way, you don't need luck, just money.

Re:No Dragon 2 Soft Landing Yet

[khallow]

But good luck getting Elon Musk to focus on the practical and eminently desirable target of the Moon. He isn't interested. It's only Mars for Elon.

He's interested in paying customers. Maybe someone who is interested in lunar development should buy some Falcon 9 or Heavy launches and just make it happen?

Re: No Dragon 2 Soft Landing Yet

[Oswald McWeany]

People live in Kansas.

Yeah, and they fantasize about escaping Kansas and living in a land filled with flying monkeys, witches, and cities ran by con-men.

Re: No Dragon 2 Soft Landing Yet

[Rei]

What, exactly, is the purpose of hanging in the clouds of Venus ?

What, exactly is the purpose of hanging out in the near-vacuum of Mars?
What, exactly, is the purpose of life?

If you don't agree with the merits of the human race becoming a starfaring civilization centuries from now based on investments made today in getting the ball rolling today, I'm not going to debate that with you. But if you agree with that, then the whole point in expanding offworld is to develop into a multiplanetary species, where demand drives down launch costs and we learn, step by step, to make everything that we need in offworld environments and to become adept at the multi-month journeys between planets. At first, it's a sunk cost. With time, it's increasingly supported by trade. And after long periods of time, it brings the immense resources beyond our planet into our grasp.

If you want to talk about economics on Venus, here's a few for you.

* Power is immensely abundant. Many technologies that we employ are basically energy costs - to pick an example, isotope enrichment. So once the higher marginal capital cost for doing things on Venus becomes overtaken by the greater energy availability, Venus becomes the logical place to conduct such activities.

* Deuterium levels are ~240 times higher than on Earth. So depending on the level of enrichment you need and the means by which you return it, if you can return goods for somewhere in the "couple thousand to several tens of thousands of dollars per kilogram" range, it's profitable. Deuterium recovery can be rendered an inherent part of nighttime fuel cell power storage, since electrolysis has an excellent enrichment factor.

* Venus's lavas appear to be highly differentiated, and there's a great degree of chemical weathering and atmospheric processing, which can be another resource enrichment process. So concentrations of high value ores far greater than are found on Earth are not unrealistic. There are a couple dozen elements whose values are worth exporting at realistic launch costs several decades from now.

* Even simple rocks from offworld have great value (collectors, luxury goods, etc). It's not theoretical - people really do pay huge sums for offworld items. Their value will of course depend first the abundance of their export (if you export 100kg per year, you can sell for 10x more per kg than if you export 10000kg per year, which you can sell for 10x more per kg than if you export 1000000kg per year...). If you're selling in small quantities, the value could be in the millions of dollars per kilogram. Venus's surface atmosphere is dense enough that you can outright dredge loose rocks.

* The size of the market and sensitivity to export quantity also depends on their aesthetics (aka, moving more from the collectors market into the larger luxury goods market). This means minerals that are durable and aesthetically pleasing. What we've sampled so far of Venus's surface fits that bill - gabbro (sold as "black granite" - large crystalled, dark, hard rock, forms excellent slabs), anorthosite (rare on Earth, often associated with labradorite, which is an iridescent bluish-purple semiprecious to precious mineral), troctolite (rare, olivine (peridot)-rich relative of anorthosite and gabbro - looks like this when cut and polished), etc. It's one thing for your typical sheikh or dotcom millionaire to say "my yacht's countertop is made from the finest tuscan marble." It's another to say "my yacht's countertop is from freaking Venus." You're looking at a very large market in the 4 figure/kg range, a reasonable market in the 5 figure/kg range, and a small but decent market in the 6 figure/kg range.

* Venus's apparently high levels of repeated differentiation, in conditions very different from Earth, likely mean that some minerals, including gemstones, that are rare or no

What can SpaceX do with their hardware?

[Michael Woodhams]

I have considered before that the hardware SpaceX have or are building come quite close to supporting moon landing, and wondered how much of a gap there is and what it would take to bridge it. Unfortunately the article here is very light on detail and does not address my questions.

The Saturn V could put 140 tonnes into LEO. The Falcon Heavy will be able to put 55 tonnes into LEO. If you can split the Apollo hardware into three approximately equal bits, three FH launches could put them into orbit, then they rendezvous and head to the moon. You could probably use the existing second stage as a third stage to take the stuff from LEO to lunar orbit. (I couldn't quickly find the mass of a fuelled Falcon second stage, nor how much mass it could deliver to low lunar orbit.) You could use a Dragon in place of the Apollo command module. Whether you could use a second Dragon as the lunar lander is less clear.

Wikipedia (https://en.wikipedia.org/wiki/Delta-v_budget) says lunar surface to low lunar orbit requires 1.9km/s delta-v. If you wanted to land and takeoff with the same vehicle, that would be 3.8km/s. SpaceX are planning a 'Red Dragon' mission to land a Dragon capsule on Mars. Low Mars orbit to surface is 4.1km/s (assuming no aerobraking/parachuting) so Red Dragon should be able to land on the moon and return to orbit. However, Red Dragon is unmanned - I don't know whether you have space and mass budget to stuff some people and life support in there also.

The manned Dragon capsule has rockets allowing it to propulsively land - taking from terminal velocity falling through the atmosphere to zero velocity on a landing pad. I don't know how much delta-v this requires, but I expect much less than 3.8km/s.

(Falcon Heavy and manned Dragon capsule have been under development for some time and should fly this year. I don't know how advanced Red Dragon is, but they want to launch in 2020.)

Re:What can SpaceX do with their hardware?

[khallow]

It's easier to make a bigger rocket than to assemble stuff in LEO.

Then why is the US the only one to have ever made this "bigger rocket" (Saturn V and Shuttle). And currently doesn't make it?

Meanwhile we have a fair number of countries who have assembled things in orbit (US, Russia, China, all separately and the ISS group).

The problem here is that there's no rocket so big that you don't need to assemble things in orbit. You need to learn how to assemble things no matter how big your rocket is.

Meanwhile once you've learned how to assemble things in orbit, you don't need that expensive big launcher. You can put all your stuff up on the cheapest, high launch frequency launcher instead, greatly reducing the cost of such missions.

Too soon to say

[Eloking]

As much as I love Elon and his accomplishments, let's not forget that SpaceX reusable launch system's costs to refurbish and relaunch are not demonstrated...yet. Have they forgotten the the Space Shuttle Program already?

Good grief

[Anonymous Coward]

Abandon Ares. Abandon SLS...

SLS is up to 2.5 times the LEO capacity of a Falcon Heavy, which SpaceX has never actually launched. SLS is in a different class. SpaceX might launch a Heavy in 2017, but I personally doubt it; SpaceX has never hesitated to push back dates and they've done exactly that with each new development phase. That's not a knock; they've done well and should continue their pattern. But SLS goes up in 2018 and even that first launch will achieve greater lift capacity than anything SpaceX or its competitors are actually building, never mind the SLS scale out to 130,000kg.

A least Trump doesn't appear to want to kill off SLS. If anything he seems to want to accelerate the program into a manned phase. And I'm pretty sure he doesn't give a warm piss what Scientific American has to say about it, so it looks like this heavy lift system will finally survive US politics.

Re:Good grief

[khallow]

SLS is up to 2.5 times the LEO capacity of a Falcon Heavy, which SpaceX has never actually launched. SLS is in a different class. SpaceX might launch a Heavy in 2017, but I personally doubt it; SpaceX has never hesitated to push back dates and they've done exactly that with each new development phase. That's not a knock; they've done well and should continue their pattern. But SLS goes up in 2018 and even that first launch will achieve greater lift capacity than anything SpaceX or its competitors are actually building, never mind the SLS scale out to 130,000kg.

In other words, NASA might launch an SLS variant this decade, but they probably won't. Funny how your personal doubt fails to extend to NASA which is even more notorious than SpaceX for delaying launches and failing to deliver on a launch vehicle.

Re:Good grief

[Kjella]

SLS is up to 2.5 times the LEO capacity of a Falcon Heavy, which SpaceX has never actually launched. SLS is in a different class.

The block 2 version that's at least a decade away, yes. The one they plan to launch late next year is in pretty much the same class (70 vs 54 tons), by the time the 130 ton version is ready SpaceX should have a Raptor-based competitor to match. Maybe not ITS-size, that's a bit megalomania (300 ton reusable, 550 ton expendable) but even a "Raptor 9" would give NASA a run for the money. But yeah... I want to see the Falcon Heavy fly now too, it's been pushed back quite a few times.

"A wild car"

[Anonymous Coward]

I wonder what that could be?

A Jaguar? A Beetle? A Plymouth Barracuda?

No Idea on how valid the alternates are

[Crashmarik]

But it's hard to do worse than NASA's SLS

http://www.thespacereview.com/...

It has been estimated at a per launch cost of 5 billion a shot, and a cost per pound that makes the shuttle look like Amazon Prime.

Re:Not to be a wet blanket...

[crispytwo]

a moon base is uniquely suited to warehousing and building for bigger craft that head out further than earth's orbit.

examples:
1) going to Mars from the moon would be simpler, and cheaper.
2) mining on asteroids would be cheaper

Think of it as a lower cost half-way house. Doing the same thing from a space station is much more costly and complicated process. The moon has some raw materials that can be used to construct things like habitats, etc. A space station has nothing.

A habitat on the moon would be relatively cheap to build, and launching from it would be many times less than from earth, I think 36 times less. Ideally, you would only have to transport people to the moon, and everything else could be built and launched from the moon.

Re:Not to be a wet blanket...

[religionofpeas]

Ideally, you would only have to transport people to the moon, and everything else could be built and launched from the moon.

You're proposing an entire industrial base to be build on the moon, starting empty handed ? And you think this would be "relatively cheap" ?

Re:Not to be a wet blanket...

[khallow]

You're proposing an entire industrial base to be build on the moon, starting empty handed ?

Presumably, it'd start with a seed factory and build out from there. The cheapness oft he project depends on what inputs are required from Earth.

Re:Not to be a wet blanket...

[DrXym]

I don't really buy the argument that it would be cheaper to go to Mars from the Moon. Any manned Mars mission would likely to be assembled in stages in orbit of the Earth. Much cheaper and less risk than sending those same stages to the moon and assembling them there.

Re:and fairy dust and unicorns too!

[silentcoder]

You underestimate engineers. We went from "first flight" to the moon in less than 70 years. We went from "First rocket" that flew 30 feet to the moon landing in about 4 decades.It's JUST AS LIKELY that we'll go from "material with enough tensile strength invented" to "space elevator" in a few decades too.

STS has a problem

[joh]

It's not reusable and much too expensive to be flown more often than a few times. It never was anything than a gift to the companies that built the shuttle, so they could continue to supply tanks and solid boosters and hideously expensive engines. The point of it never was getting anything into space, but to keep the same old rivers of money flowing.

Re:and fairy dust and unicorns too!

[Anonymous Coward]

You underestimate engineers. We went from "first flight" to the moon in less than 70 years. We went from "First rocket" that flew 30 feet to the moon landing in about 4 decades.It's JUST AS LIKELY that we'll go from "material with enough tensile strength invented" to "space elevator" in a few decades too.

This is what I like to call the "extrapolation fallacy". People assume that if something is possible, anything is possible.

There are limits in the universe that put upper bounds on what's achievable. At the moment, we're not even sure that it's theoretically possible to create that "material with enough tensile strength". If it turns out it's not, then no amount of engineering will make it reality (disclaimer: I'm an engineer).

It's the same fallacy that people make when they imagine advanced alien races coming up with physics-breaking technologies (FTL, Dyson spheres, ring worlds, teleportation), or when they imagine life inside of stars (it's just too extreme inside there for stable systems to exist, let alone evolve).

Re:Not to be a wet blanket...

[4im]

I guess you misunderstood... it is not at all about sending stages to the Moon, to be assembled there, then launched. The point is to not have to launch great masses from Earth in the first place, but to build them on the Moon, from Moon materials, to fuel straight from there, and then launch. Or if it's not the Moon, then it will be asteroids.

Of course, this requires bootstrapping an industrial base from as small an invest as doable, i.e. sending robotic craft to start bringing in raw materials, and getting stuff done with them.

The trick is of course to figure out the details. Many ideas were already written up by Gerard K O'Neill back in 1976 - read "The High Frontier". Technology has since advanced, and there have been many proposals since. Private companies are digging into the problem, there are government invests.

The goal also is not to get to Mars, but to get mankind into Space, not just on a few short excursions, but for good. Moving heavy industry up there might also solve some problems down here (think energy, pollution).

Simple. Change the gravitational constant

[Thud457]

phhht, just let them throw away the money building the wall, then when he's out of office, just turn it up on its end. Presto, space elemavator!

Clarke wrote about it in SF

[Geoffrey.landis]

As noted, Clarke did not invent the concept of the space elevator, although he was one of the first two writers to highlight it in science fiction (with Charles Sheffield the other). The concept of the space elevator was invented independently several times, the first time Artsutanov (who only published in Russian), then by Isaacs et al, and then by Pearson.

http://www.isec.org/index.php/10-resources/18-the-history-of-the-space-elevator

Clarke didn't invent the concept of a geosynchronous satellite, either, although he was the first to point out that geosynchronous orbit was an excellent orbit for communications.

Nanotubes aren't as good as predicted

[Geoffrey.landis]

The numbers come from this book: https://www.amazon.com/Space-E...

Their research is more serious than your unsupported opinion.

Most of the space elevator research assumes that the problems of making long, perfect carbon nanotubes can be solved, that they be made in volume at very low cost, and that they will have an ultimate tensile strength equal to that calculated from theory of perfect carbon, and not one that is the actual measured tensile strength of nanotubes in the real world.

Unfortunately, carbon nanotubes not only have never been made with this theoretical strength, newer work makes it look like they cannot reach this theoretical strength. The pentagons of perfect nanotubes spontaneously convert into pentagons and heptagons under strain, which reduces the breaking stress.
https://www.newscientist.com/a...

Right now, the materials needed to make a low cost space elevator are still in the future. Later materials science may make us revise that estimate, but right now: it's still hard.