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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."
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."
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.
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.
Bruce Perens.
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.
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.
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.
I'll never forget the last thing grandma said to me before she died: "What are you doing in here with that knife?!?"
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.
I'll never forget the last thing grandma said to me before she died: "What are you doing in here with that knife?!?"
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...
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
I'll never forget the last thing grandma said to me before she died: "What are you doing in here with that knife?!?"