The 'vision thing' and Nasa's new path
It's that "vision thing", or the "grand picture". We like the big ideas to be simple, easy-to-understand concepts.
George W Bush's call to "go back to the Moon" was straightforward enough. The trouble was, Nasa found it very difficult to implement - and very expensive.
Some $9bn has already been spent on the Constellation programme and the first mission is still years away.
And so on Monday, the current president, Barack Obama, substituted a new vision.
He's killed Constellation with its two Ares rockets and Orion capsule, and replaced it with a whole new way of doing space [PDF 1Mb].
In future, Nasa will no longer lead the design and development of space vehicles. It will instead leave this to the private sector and become a customer for transport services.
The market will need to be stimulated, of course. So Nasa has been given a budget to run competitions. Winning companies will be offered fixed-price contracts, with rewards triggered only when they deliver on promises.
The hope is that Nasa - and by extension the US taxpayer - will get access to a broader range of space vehicles, faster and at a fraction of the cost.
The immediate reaction might be to gulp, but there is actually something inevitable about all of this.
Today, when we board a plane, we don't fly "Government Air"; we fly American Airlines or British Airways. We fly with commercial operators.
We take for granted the excellent safety records of the carriers and concern ourselves only with issues of price and quality of service.
This is the future of space transportation that Barack Obama and new Nasa chief Charlie Bolden want us all to embrace.
Already, there is a queue of entrepreneurs waiting to seize this opportunity. Next month we will probably see the maiden flight of Falcon 9, a private rocket developed by the PayPal founder Elon Musk.
The rocket and its Dragon capsule are intended in the first instance to carry just cargo to the International Space Station (ISS). But Musk has designed his vehicles in such a way that they could carry people, also.
He claims his astronaut carrier would be ready for service just two-and-a-half years from first contract, with a seat price of $20m. To put that in perspective, the Russians are currently charging $50m per seat for a Soyuz ride to the ISS, and that's a fraction of the price of the outgoing space shuttle.
As Peter Diamandis, the chairman and CEO of the X-Prize Foundation, observed on Monday:
"It's been the pattern of what the US capitalist system does well - the government starts something and industry takes it over and injects innovation, brings down the cost and increases reliability.
"We've seen this in every industry that's been transferred from government to the private sector. And, frankly, space needs it more than anybody else, otherwise we are going to lose the race. There's no question - China, India and other parts of the world will eat our lunch in space on a price-performance basis."
With the budget request on Monday came an announcement from Nasa that it will be giving an immediate $50m in seed money to the winners of its Commercial Crew Development (CCDev) competition.
This is a precursor to what will eventually be a $6bn commercial crew programme.
The largest award in going to Sierra Nevada Corporation which is working on a six-seat vehicle called Dream Chaser that would launch atop an Atlas rocket.
As you might expect from the themes most frequently pursued in this blog, I'm intrigued now by what impact this development is going to have in Europe.
How will it change - how should it change - the business of governmental space on this side of the Atlantic?
Europe has talked for years about having its own crew carrier capability but it's always been deemed to be too expensive.
Is there a mechanism here that would make an independent European space transportation system finally realisable and affordable?
You can be sure journalists will be asking that question of European Space Agency and member-state officials.
The next few months will be fascinating, to see how all of this develops.
It's clear already that elements in Congress will try to restore Constellation. Senators and representatives from states that have Nasa centres where Constellation plays big will need a lot of convincing that "new space" offers the same job security for their constituents as "old space".
Like many, they will have winced at the revelation that just to close Constellation down will cost the government an additional $2.5bn.
And coming back to that vision thing, I think we're all looking for a bit more detail on some of the long-term issues - how humans will once again go beyond the confines of Earth orbit.
That really does need a big rocket or some "game changing" approach. At the moment, the talk is merely about an aggressive R&D programme on heavy-lift technologies.
I did manage to get a question to Lori Garver, the second in command at Nasa. I asked her if she thought she'd ever see a human walk on the surface of the Moon again in her lifetime. She believes "new space" could see many people manage it:
"I absolutely believe that; I believe I could still do it myself as a matter of fact. What this does is open up more people to be going more places. We're going to be investing in those technologies that allow that to happen in the future for many more people, and to do a lot of different things [like] going to the asteroids and to Mars."