Re: Nuclear
StrangerHereMyself,
Interstellar travel isn't happening for a very long time, short of some kind of breakthrough in fundamental physics.
At the moment it's still a struggle to get to the edge of our own solar system. Let alone the vast distances to get to another. Realistically we're going to need to be a lot more mobile within our own system before we can think about exploring others. So it's a problem that can be put off for now. So the question is, are light sails useful now? Nuclear material is quite expensive and also even RTGs are quite heavy - let alone a full reactor. And if you're talking nuclear pulse propulsion you're going for a whole new level of heavy - and the multiple small nuclear bombs are even more expensive.
Whereas light sails and solar power give an interesting, and relatively cheap (and light weight), way to explore the inner solar system with small probes. I wonder if we can get the sail made of solar panels embedded in cloth - or whether that makes it too heavy?
Now that it's getting cheaper to get to orbit - the economics of space exploration are changing. When launch costs were huge, it made sense to build one large, super-expensive spacecraft with multiple fail-safes. As lauch costs fall, it becomes viable to build lots of small, cheap, probes and launch several at the same time. You get less science from each, but you can make them cover a much wider area, so get much more general data. Sometimes you might find something so interesting that it warrants a single expensive probe to go and study just it, with as many sensors as you can cram in. But someiimesi multiple data-sets from many different places are going to help you to build a better picture.
Also if you mass produce lots of small probes, with maybe a few interchangeable instruments, your costs drop even further.
When it comes to sending our first probe to another solar system, maybe a light sail and big laser on some convenient asteroid might be a better bet. Since you can keep re-using that laser to send follow-up probes, or probes to other solar systems.
But at the moment we don't have the physics required for a warp drive or the materials / fuel for an intra-solar system drive.
Quick Google says that Project Orion required 800 small nuclear bombs to get to orbit. Another quick one gives the US 2kt nuclear artillery shells as costing about $4m a pop in late 1970s dollars. So using an online inflation calculator that's an average of 3.63% inflation per year since 1976 - so about $23m a pop. 800 x $10m (for mass production savings) = $8bn in fuel. Musk says a Falcon 9 uses about $300k fuel to get to orbit - although that's only carrying 23t payload - and Orion could be a couple of hundred, depending on spacecraft size. But that's still several orders of magnitude more expensive to fuel.
Biting the hand that feeds IT
