Humans on Mars by 1970

[stevebowers]

http://frontiermultimedia.com/humans-on-...have-been/

Dyson's Orion and what could have been...

The magnificent Orion ship of the 1960s would have cruised the solar system with a crew of hundreds of scientists living and working in large and luxurious rooms. On the first tour there would be a two-year stop at Mars before reaching Saturn in 1970. It was all so close.

[John M. Dollan]

I have not heard of this, at least not in its full, grand glory! This is something that is very relevant to my own setting. I might hijack this for the ArcBuilder list to mull over!

[iancampbell]

Yes. Orion is one of those apparently crazy ideas that would probably work; setting off nuclear bombs for propulsion certainly sounds crazy.

I also think it worth mentioning that Orion being proceeded with would probably have set back microelectronics and various other sorts of miniaturisation by decades, due to less need for it.

One caution; be very careful about googling Orion. You'll probably get hundreds of hits for the multibillion-dollar boondoggle being presented by NASA under that name. Something like "nuclear pulse propulsion" might work better.

[Rynn]

Whilst Orion might have been technically feasible like most proposed manned space technology even if attempted I doubt it would have been economically possible to sustain. This sounds like a mundane way of thinking about it but it's paramount, we could have had a fully manned Moon colony from the 1970s onwards but the cost would have been astronomical and the ROI compared to other uses for those resources would have been appalling.

I'm not opposed to space colonisation ideology by any means but I'm skeptical that it should be (and to some extent could be) pursued before a time when the relevant society(s) have a massive economic surplus/potential surplus and not much else to justify allocating it to.

[iancampbell]

Rynn - IMHO that is the whole point. Orion would be incredibly efficient in terms of use of resources. Most of the cost of present-day space travel is due to the need to shave as much mass as possible off the vehicles and their equipment; this is in turn due to the fact that getting to space at all using chemical fuel and propellant (which aren't quite the same thing, but let's leave that) is marginal at best and necessitates multi-stage launchers - which means huge expense.

Orion-drive spacecraft would probably look fairly crude, because the necessity for shaving grams off the equipment just wouldn't be there. The difference is a little like the difference between an F1 car and a heavy goods lorry.

In addition, cheap space travel leaves open the possibility of obtaining resources that would help the world's economy immensely. To take one example, some of the asteroids are essentially made of billions of tons of high-grade steel.

[Rynn]

I'm unconvinced that Orion's R&D and construction would have been massively more cost-effective, nor that asteroid mining has a better ROI other Earth based mining or refining R&D. IMHO it will take a lot of advances in automation and in-situ resource allocation to make significant space industry a good investment but such technologies are likely to have a disruptive effect on Earth economics changing the initial parameters of the scenario.

[radtech497]

Rynn - IMHO that is the whole point. Orion would be incredibly efficient in terms of use of resources. Most of the cost of present-day space travel is due to the need to shave as much mass as possible off the vehicles and their equipment; this is in turn due to the fact that getting to space at all using chemical fuel and propellant (which aren't quite the same thing, but let's leave that) is marginal at best and necessitates multi-stage launchers - which means huge expense.

From this, I'm guessing that you envision launches of Orion from the Earth's surface. While feasible, this sort of activity tends to depress real estate values in the vicinity of the launch site and increases in global ambient fallout levels doesn't do much good for the environment. The nascent environmental movement likely would have joined with the existing anti-nuclear weapons movement to oppose Orion launches from the surface fairly soon after the first one (if not before).

Orion-drive spacecraft would probably look fairly crude, because the necessity for shaving grams off the equipment just wouldn't be there. The difference is a little like the difference between an F1 car and a heavy goods lorry.

The public outcry against launching Orion from the ground would lead to in-orbit launch requirements; these, in turn, would require that Orion's mass still be kept to a minimum, as the components would need to be lifted into orbit by a non-nuclear launch system. Perhaps the development of the Nova launcher might have proceeded in order to meet the payload requirements. Launching from orbit may, in turn, have prompted the development of orbital infrastructure to assemble and test Orion components. This, in turn, might have provided an impetus for developing orbit-capable aerospacecraft (the X-15 was, with some proposed modifications, just barely capable of reaching low Earth orbit).
Much of the infrastructure, if built in the 1960s-1970s timeframe, would require a human presence, and getting people into orbit in sufficient numbers would also motivate rocketplane development.

In addition, cheap space travel leaves open the possibility of obtaining resources that would help the world's economy immensely. To take one example, some of the asteroids are essentially made of billions of tons of high-grade steel.

Asteroid mining might follow the development of orbital infrastructure, but it would be many years after the construction of that infrastructure before it would become economical to do so.

Radtech
[/quote]

[iancampbell]

There is a point here that isn't often discussed with respect to space launches. That is: Getting a craft to orbital height and getting it into orbit are by no means the same thing; the former needs MUCH less energy to do it. Which leads to the possibility of getting an Orion ship off the ground (to around 300km, perhaps) and then lighting off the main drive. I rummaged around a bit and found this, which illustrates the concept:

http://www.youtube.com/watch?feature=pla...vsbVBy-shc

[radtech497]

There is a point here that isn't often discussed with respect to space launches. That is: Getting a craft to orbital height and getting it into orbit are by no means the same thing; the former needs MUCH less energy to do it. Which leads to the possibility of getting an Orion ship off the ground (to around 300km, perhaps) and then lighting off the main drive. I rummaged around a bit and found this, which illustrates the concept:

http://www.youtube.com/watch?feature=pla...vsbVBy-shc

Lighting the Orion stage before it attains orbit might introduce rather widespread EMP effects in the region beneath the exhaust cone, at least while the ship is essentially vertical with respect to the Earth's surface. See http://ed-thelen.org/EMP-ElectroMagneticPulse.html for an illustration of these effects. The page at http://nextbigfuture.com/2009/02/project...s-emp.html also has some interesting data on the subject (among other aspects of Orion).

Radtech497

[stevebowers]

As far as the use of Orion pulse craft in OA, the Cybiota use them - they aren't particularly bothered by EMP effects since they mostly use biotechology in their civilisation, such as it is.
http://www.orionsarm.com/eg-article/480d35f9a8ecd

Perhaps some of the lost and isolated colonies that were cut off by the Version War and other major events, like the Oracle War and the Gehenna event, were forced back to a 20th century level of technology; a quick and dirty way to get back into an interplanetary stage of development would be to use boom-boom ships into orbit.