The way SpaceX is trying to recover the booster is like catching a bullet in your teeth. They have only a second or two of usable thrust, since the Merlin engines don't have enough throttle range to land at a nice gentle pace. But what if they developed a "Merlin DT" (Deep Throttle[TM]) and used that for the center engine? Even if the Merlin-DT was less efficient, it's only one of nine, so you could optimize it quite easily over the whole flight profile.

If you had that one center engine with enough throttle range to burn at very low thrust for 10 or 12 seconds, that would be ideal for landing.

I know, I know.... that's just what you guys need right now, another new engine design... But maybe you could find a way to add a tweak to allow greater throttle range, even at the expense of some efficiency. You only need the deep-throttle thrust for a few seconds at the end of the flight, and only on one engine, so it would be worth having a separate engine class devoted tho this use.

""The DC-X, short for Delta Clipper ... was an unmanned prototype of a reusable single-stage-to-orbit launch vehicle built by McDonnell Douglas in conjunction with the United States Department of Defense's Strategic Defense Initiative Organization (SDIO) from 1991 to 1993. Starting 1994 until 1995, testing continued through funding of the US civil space agency NASA.[1] In 1996, the DC-X technology was completely transferred to NASA, which upgraded the design for improved performance to create the DC-XA."" [wikipedia]

The DC-X was a prototype intended to develop a SSTO vehicle.

Yes, that's why it's nickname is the "Senate Launch System". ;-)

The tragedy is, most of the people working at those jobs are really smart, highly skilled professionals who could do a lot of good for the amount of money we'll spend on them. Instead, we're going to waste both the money and their talents on a project that will at best enable an asteroid mission before it gets mothballed.

No, you said they were first to "operate on the principle that it was practical," which allows both of you to be right on this point. Surely the folks at McDonnell were operating on the principle that it was practical, they just couldn't find a way to make it work, because single-stage-to-orbit is really f-ing hard, perhaps not even possible with chemical rockets. It was the shuttle era, and they were trying to make what everyone wanted the shuttle to be, a SSTO "space plane" just like Buck Rogers.

Elon had the insight that Von Braun's Saturn V was pretty close to an ideal design for its time, and upgrading it to modern technology would provide enough extra payload capacity to make reusability possible. You didn't need a new kind of vehicle, just an evolution of the tried and true, with legs.

In the near term, major players like ULA and Arianespace will stay afloat on long term contracts already in the pipeline, and political inertia will keep them going after that. But the best news for them is that SpaceX simply can't make rockets fast enough to meet the demand. On the down side, once they figure out how to reuse them, they'll start to decouple their launch capacity from their production capacity. And they're not the only ones. There are several dozen other companies offering launch services in the next few years. Most are still in development, but many have already built and tested engines and other components.

There are basically 4 or 5 launch providers on the open market (depending on how you count, more if you include India, Iran, NK, etc). That number is likely to double or triple in the next five years or so. And they will serve a wide range of needs. Several are focusing on small payloads in the few-hundred Kg range, while some others offer heavy-duty versions of the Spaceship One/White Knight configuration, emphasizing the convenience of launching from high altitude: "Any orbit, anytime!" is the slogan of one of them (Stratolaunch, I think). And there are others focused on various niches of the market.

Point is, the space market is going to get a lot busier in the next few years, and the dinosaurs like ULA are going to be in a heap of trouble if they don't start adapting right quick. They are not stupid. They can see this too, which is why we see this shiny new concept from Arianespace and the recent Vulcan announcement from ULA. They know if they want to still have a meal ticket in 10 years, they'd better stay in the game.

Question is, can they pull it off, or is their inherent bureaucratic structure impervious to change because it's joined at the hip with the political establishment? Only time will tell.

Agree. And assuming the Falcon Heavy flies as planned, there isn't much justification for SLS either. For the price of a single launch, you could fly at least 2 or 3 Falcon Heavies, and end up putting more mass on orbit. Since we're pretty experienced with rendezvous and docking, there's less need for such high throw-weight, even for large, complex missions.

And eventually, SpaceX will come out with their new super-heavy (based on the Raptor engine) which will outclass SLS anyway, as they announced back in 2012. I reckon SLS will fly a few times (at most) and then be retired.

If you just want to see how it works, scroll down to the video at the end. They don't really explain it very well in the text.

Actually, there is a fairly simple solution that can be done in a couple of decades, and has the bonus side effect of producing megatons of food in some of the more impoverished regions of the world. The trick is to convert semi-arid and arid grasslands into productive grazing lands for herbivores by using Managed Intensive Rotational Grazing which is described in detail (with stunning before/after photos) by Allan Savory in this TED Talk.

In a nutshell: MIRG simulates the "mobbing, mowing, and moving" behavior of large herds of herbivores in nature, where herds "mob together" for protection from predators, and move constantly to find fresh pasture. Following in their wake is a swath of "disturbed" pasture, which has just been aerated by hoof prints and fed with a rich load of fertilizer. This spurs a blaze of regrowth in the grasses, which replaces root mass which had earlier been shed (many plants shed root mass when cropped, to preserve the root-shoot ratio). Thus, every time herbivores graze a piece of land, they sequester a large amount of carbon into the soil, and actually increase the health and the depth of the topsoil.

Obviously, there's quite a bit more to this story, including earthworks to harvest and retain water, permaculture design to optimize ecosystem health and productivity, etc. But hopefully this will be enough to get the gears turning...

There's nothing wrong with open space, and nothing in permaculture argues against it. Grasslands are ideal for grazing livestock of various kinds... anything from chickens to rabbits, cows to kangaroos... And with Managed Intensive Rotational Grazing (MIRG) you can use these open spaces to sequester carbon and create new topsoil.

If you set it up right, it really takes very little input, a few hours a week to a few hours a day, depending on how intensive you want to get. If you just want to feed your family, a few hours a week. If you want to earn $50k per year per acre, it's more like a full time job.

Just to emphasize this point: With the amount of land you're talking about, you could easily feed a large family, in abundance, indefinitely, for free.

I would look at alternatives to having a "lawn" in the first place. In almost any climate, there are a lot more productive ways to use your land than raising an eternal crop of stuff you just cut and throw away. Put that surface area to work, harvesting solar energy in some way, even if it's nothing more than composting your grass clippings to feed a backyard garden.

Also, look into "integrative" housing design, which means a more holistic approach based on first principles, rather than tweaking the status-quo with than latest gizmos. For example, if you spend enough on insulation, you might not need a heater in winter, and end up with a lower total capital cost. Or by including a water feature, combined with appropriate shading and ventilation, you could reduce your summer A/C bills by 90 percent, and thus save a bundle on the A/C capacity to install. There are lots of people preaching this sort of thing, but the most prominent voice among them is probably Amory Lovins of the Rocky Mountain Institute.

As for your lawn look into permaculture. There's a ton of stuff on YouTube about this, and numerous blogs, groups, etc... Basically, you can set up your yard to be a "food forest" that naturally produces food, year round, at no cost and with very little maintenance. Checking out this trend will be very worth your time.

Hm... not sure how that link got mangled... here's the right one: https://en.wikipedia.org/wiki/Tata_Motors

This.

When you consider that there are now over 1600 billionaires, how many of them are "using their powers for good" to the degree that Musk does? Sure there's the Gates Foundation, and other philanthropic efforts, there's the Tata Motors guy in India... some VC guys like Khosla... But out of 1600 people, what a tiny percentage of them even show up on the radar screen, let alone those who are doing "cool stuff" with their immense wealth and power.

If every billionaire used his wealth like Musk does, I wouldn't mind this staggering inequality so much. Sadly, Musk is more an exception than the rule.

$4.9 billion? That's nothing compared to the Koch brothers. They got more than twice that amount.

Yes and no... Yes, they are competing in the same market; No, they are not "joined at the hip" with the rest of them. Yes, they do business with many, but SpaceX is not yet "assimilated" into the BORG. And as a privately held company, it's much easier to resist that pull. Elon has been quite clear on this. He won't do a SpaceX IPO until he's certain the company is going to Mars, with or without him.

More to the point, I would argue that membership in the MIC would imply a disposition toward warfare befitting a military contractor. I don't see that coming from SpaceX anytime soon. They have their own agenda, and lunching satellites helps them pay for that agenda. I'd wager that if the Air Force put out a bid request for a new fleet of ICBMs, SpaceX would take a pass on that project.