81–90 of 103 posts
If only we could produce anti matter. A tiny amount would provide a fuel source viable for deep space exploration.
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> nuclear is unfashionable at the moment It's more than that - this isn't just hippies, it's every major power on the planet. To fly Orion you have to put hundreds of nuclear explosives in orbit and pinky-swear that you're not going to use them to obliterate your enemies. Nobody is going to accept that. Orion's a fun paper rocket but will never be more. Engineers and they "yay nukes!" crowd will drag it out every cou…
Even worse: the EMP from an Orion launch would fry a lot of satellites. It's not a practical design for use anywhere near... anything. You could launch one from the far side of the Moon, but if you have that kind of space presence there are better engine designs. Some have been posted elsewhere in this thread.
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Even then, we can still send rovers more cost effectively than people! You can throw away the life support mechanisms, and so on, and get 550 tons of pure mars rover in your interplanetary transport. At ~800kg for a curiosity-level rover that gives about 600 rovers, instead of 100 people. What to do with your 600 curiosity rovers on Mars is left as an exercise...
The Curiosity rover has driven 9 miles in a little over four years on Mars. The Lunar Rover that came with Apollo 17 drove 22 miles in a little over 4 HOURS. As it turns out, humans are the best robots.
If it's simply mileage you want, Curiosity's RTG means it can just keep going for years. With an average speed of 30 meters/hr, I'm not seeing much reason to think that it wasn't capable of covering ~1000km over those 4 years (the LRV, on the other hand, could never exceed 92km, total, before the batteries ran out). But mileage simply wasn't the goal.
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> I'm talking about just flying the entire Orion ship to Earth, loaded with propellant bombs. Er… yes? > Sure, you can try to take it out during the journey, but that may be complicated by it being the highest g ship in existence for the Mars-Earth distance. That's not really a complication, it's still taking months to make the trip, and while it might be "the highest g ship in existence" that's linear acceleration,…
Er… yes? Sorry, I didn't understand why you were talking about bothering to do that and then crashing it into the atmosphere.
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> I'm talking about just flying the entire Orion ship to Earth, loaded with propellant bombs. Er… yes? > Sure, you can try to take it out during the journey, but that may be complicated by it being the highest g ship in existence for the Mars-Earth distance. That's not really a complication, it's still taking months to make the trip, and while it might be "the highest g ship in existence" that's linear acceleration,…
Since Orion doesn't need to accelerate constantly, it's in principle quite possible to turn it and fire bombs in the direction of any interceptor, and the thick pusher plate makes it actually pretty durable from some aspects. What happens when two Orion ships duel, I don't know, but shooting it down isn't quite as simple as for most other spacecraft.
If it's coasting along it's significantly increasing transit time and thus available window to consider and prepare counter-measures.
> it's in principle quite possible to turn it and fire bombs in the direction of any interceptor
Sure but that means less payload to deliver and even more time for the target to prepare counter-measures.
> and the thick pusher plate makes it actually pretty durable from some aspects.
No matter how thick your pusher plates are they're not going to stand up to the kind of kinetic impact involved.
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Er… yes? Sorry, I didn't understand why you were talking about bothering to do that and then crashing it into the atmosphere.
If you're crashing it into the atmosphere you're not delivering anything, the ship and its payload will just disintegrate, possibly bouncing back in the process. Even if the payload does detonate on impact, the only purpose an explosion at atmospheric boundaries would have would be EMP.
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If you read the book (by Freeman Dyson's son) or even the wikipedia page, you'd know the bombs were quite specialized. And it would certainly be possible to allow some verification (the trigger would not need inspection, that would probably be the really sensitive part, from a technology secrets point of view). [Edit: The bombs would be directed, throwing light weight molecules up against the pusher plate.] Also, the…
Any mechanism that can propel a starship to 0.13c is going to make your day unpleasant if it is pointed at things you have a particular fondness for. Favourite pets, cities, aircraft carriers, that sort of thing.
Now this is linear, so a car (2000kg)? = 200MT (4 times Tsar Bomba, global disaster).
A tiny spacecraft (5000kg maybe?)? = death of most of human race
A large spacecraft? = death of everything.
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Er… yes? Sorry, I didn't understand why you were talking about bothering to do that and then crashing it into the atmosphere.
If you're crashing it into the atmosphere you're not delivering anything, the ship and its payload will just disintegrate, possibly bouncing back in the process. Even if the payload does detonate on impact, the only purpose an explosion at atmospheric boundaries would have would be EMP.
If you want to argue that crashing into the atmosphere would be an inevitable result of the trip, okay, but I don't understand what else it would have to do with my initial comment.
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If you're crashing it into the atmosphere you're not delivering anything, the ship and its payload will just disintegrate, possibly bouncing back in the process. Even if the payload does detonate on impact, the only purpose an explosion at atmospheric boundaries would have would be EMP.
Galileo safely aerobraked into Jupiter at 47km/s. It takes one hell of a heat shield, but it can be done.
That's quite the understatement, the galileo probe was half heatshield by mass. And it took a 230g hit to the face.
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If you're crashing it into the atmosphere you're not delivering anything, the ship and its payload will just disintegrate, possibly bouncing back in the process. Even if the payload does detonate on impact, the only purpose an explosion at atmospheric boundaries would have would be EMP.
Indeed, I didn't understand why you thought I would suggest something pointless. I wasn't suggesting it. If you want to argue that crashing into the atmosphere would be an inevitable result of the trip, okay, but I don't understand what else it would have to do with my initial comment.
That's not what I'm arguing FFS, I'm saying that'd be the result of going with the fastest possible trip, which would still leave the target significant time to set up countermeasures.
Here's the rest of the paragraph of my original answer since you apparently stopped at the first period:
> If you want to actually deliver your payload in a useful manner you'll need twice that at the very least. 2+ months is a long lead time, and the engine you'll need will make the craft impossible to miss.
The point is that no matter how you slice it, "the difference between building on Mars and building it in orbit" is the target gets a warning several months in advance in the former case, a few minutes or seconds in the latter. One gives ample opportunity to set up and deploy countermeasures, the other not so much.