Can someone, anyone, please explain this veneration of the Chinese space program which thus far has demonstrated capabilities that are already well established using adaptation of existing licensed or stolen technology, and shows every sign of being done first for prestige and second for strategic benefit with no particular “game changing” plans of any degree of veracity? The Chinese are engaged in showing the world they are a superpower by doing what other superpowers do.
The [POST=“16486567”]SABRE engine and Skylon SSTO[/POST] are far from demonstrating technical feasibility and even if they are made workable are unlikely to be cost-effective to operate given the small amount of payload it could carry given the large amount of mass given over to tankage and lifting surfaces, which detracts one-to-one for payload to orbit. The only way the Skylon is actually a workable heavy lift vehicle is by assuming essentially magical material properties with regard to both strength and thermal resistance. There are workable SSTO concepts but all are vertical launch; the reason is that the paltry amount of benefit gained from lifting surfaces and air-breathing engines simply doesn’t compensate for the dead mass carried into orbit.
Additive manufacturing (AM or colloquially “3D printing”) offers some advantages but no more so in space than on Earth. Any large scale enterprise in space, and especially space habitation, is going to require the ability to manufacture finished products on a large scale, which AM does not do effectively. The real advantage of AM is being able to produce tightly integrated products that optimize the use of materials and reduce finished mass, e.g. printing circuits directly into the structure of a CubeSat. What is really needed for space habitation is a way to use materials found in space in a minimally proceed former, e.g. habitats built from fiber-reinforced ice matrix composites, or metals extracted by centrifugal separation and grown into pure crystal forms possible in microgravity.
The real game changing technology comes in two forms; propulsion technology that provides energy and propellant efficiency greater than that capable with chemical rockets (e.g. fission fragment, nuclear thermal, or nuclear fusion driving ionized plasma) and powerplant technology that allows high specific power throughput while being able to minimize or radiate away waste heat so that larger or habitable vehicles can operate at the distance of Jupiter or beyond where solar power is not remotely practical. Habitation and recycling technology, while challenging, is not a showstopper with a sufficiently large habitat or vessel such that closed cycle performance is not necessary, e.g. something on the scale of a large O’Neill cylinder.
However, there is a significant threshold of resource utilization that has to be achieved before this is practical, and the problem with crewed habitation is that you have to achieve the threshold before you can cost-effectively sustain a population. What this means is to achieve this requires either a massive (multi-trillion dollar) effort to hoist all necessary resources up from Earth until the point that there is a self-sufficient infrastructure in space, or developing an autonomous capability to build up the infrastructure (still in the hundreds of billions of dollars, but persistent and not requiring extraordinary measures to keep crew alive) in order to extract and process resources to build habitats or large interplanetary spacecraft.
Which is why if you want a permanent human presence in space and crewed exploration of planets beyond single missions of unsustainable cost, you should support robotic exploration and the development of autonomous space resource utilization capability. Like the lever, axle, and steam engine, these are the tools that will allow us to extend our very limited natural abilities in distance and strength to explore and inhabit interplanetary space.
“Hibernation” and other “generation ark” schemes for crewed interstellar exploration are demonstrably facile, requiring a degree of reliability and robustness beyond any proposed capability, and also having to bend thermodynamic principles to an absurd degree. Baring some kind of technomagical “warp drive” or somesuch, we’ll be exploring the stars by proxy, albeit not necessarily mechanical; Freeman Dyson’s Astrochicken concept, while a primitive imagining of such a system, is likely to better represent the future of interstellar exploration than anything imagined by Gene Roddenberry or George Lucas.
Stranger