A bunch of tiny bomblets makes far less EMP than say, Starfish Prime
View attachment 600638
Bomblets were between 0.15kt and 5 kt, so varies from 0.115–0.5% of the total weapon yield of that, as Gamma radiation
That's really low on the Volts/Meter scale
There were a number of issues with using bomb even that tiny in quick succession, (one a minute IIRC) in orbital space and satellite technology was such that it took till the mid-70s to get to a point where the satellites could probably survive in such an environment. Don't get me wrong you essentially have large armored (and likely manned) "satellites" in an Orion-drive world rather than many smaller satellites because of the nature of the system but you also have likely dozens of Orion drive spacecraft flying all over the place in short order and the havoc was recognized early on. (Since there essentially WAS no space infrastructure at the time it didn't matter but as most of the people working on it were somewhat "space travel" oriented they went ahead and figured the issues anyway and tried to come up with solutions. The sad part was the folks they needed to talk to about solving some of the main issues, those developing chemical type orbital rockets, they weren't allowed to talk to)
Something to keep in mind is that at it's core the Orion drive is still a possible weapon which means the there is no way the Soviets are not going to have that capability as well and if we get the
"Star Fleet" the Air Force wanted then US and USSR "Space Boomers" will be a thing. (There's a short story about that in some book I read a blurb about I think at Atomic Rockets but can't find atm) So tensions will be much higher as will be suspicion so expect a lot more capable planetary missions but a lot more restrictive, (likely 'accompanied by "escorting" national WarOrion's to keep an eye on the expedition and the "other guys") and probably fewer and further apart than one would think given who has 'priority' for propulsion units.
This has taken a strange turn!
Strap in it gets wilder
Fairly tame: My notes for an alternate "origin" story for the Niven/Pournelle
"CoDominium" universe involves an "Icarus Falling" scenario where Nixon and Khrushchev agree the world must be saved but quite obviously it is a world where the US and USSR must remain the dominant powers. The rapid building and launching of several Orion Drive ships saves the world while a great effort is made to build an economical surface to orbit launch system. Pretty soon Orion Drives are assigned to CD Navy ship only and civilian ships use various fission and finally fusion drives to get around.
Wilder: Some background, Orion type drives are technically known as "Externally Pulsed Plasma Propulsion" systems. As has been noted before they are known to be the only plausible drive that could be built in a relatively short order and used against a major threat to Humanity on Earth. There remains an issue with launching them from the surface of the Earth though and a paper on EPPP
(HERE) that discuss an asteroid/comet defense concept called GABRIEL. It's a rather small Orion-Drive vehicle but being automated it has some advantages but one is NOT being easy to get off the Earth in a timely manner. So various methods are described that could be used to launch a GABRIEL interceptor.
1) The Atomic Verne Gun. Take a deep shaft, (salt mine, old mineral mine, or new construction) seal it and put a couple kiloton nuclear weapon at the bottom. Fill the shaft half way with a 'reaction mass', we'll use water and top it with a shaft filling cap on top of which is GABRIEL. If you need GABRIEL in orbit wait for the right moment and light off the nuke, which will vaporized the reaction mass and push the cap and payload out the end of the tube at a velocity able to bring GABRIEL to a point in space where it can use it's own drive to circularize its orbit and begin its mission. (Note if you've done this right then there is a secondary cap and braking system that will ensure none of the radioactive materials from the launch leave the launch tube.
2) Loft GABRIEL with more conventional chemical or solid boosters to a high altitude where it can then use its own drive to push itself into orbit. Problem though, any plausible system is going to leave GABRIEL low enough that contamination and pulse effects are going to be severe. Answer? Don't use atomic bombs for this portion of the flight AND off-load them to a "beamed" pulse unit system based on the ground. And change the "pulse units" from very low yield nuclear weapons to a category of explosives known as "Super High Explosives" which can reach near nuclear levels albeit very small, low yield nuclear levels. Sound too good to be true? Well it kind of is. While SHE as it is called is known and has been worked with it suffers from issues that make it useless for most military work such as spontaneously exploding after a few months in storage or decomposing within a year of manufacture into a toxic and volatile goo as a few examples. Which is not actually a problem if you use them soon after they are made. Such as in specially designed shells to be fired at the thrust-plate of a Orion Drive spacecraft which explode then just short of impact with the plate and acting like a standard pulse unit.
But you need to deliver these unit to the Orion while in flight and at a pretty high rate as well. Let me digress a moment … A 37mm rotary cannon on a light chassis? How cute... How about a 4,6, or 8 barrel version mounted on a solid land base but using modified 5" Naval guns?
This is the 'beamed' propulsion part of the concept.
3) Similar to the above but instead of SHE shells you use a very powerful laser array and the "oil" sprayers on the Orion Pusher Plate as a type of laser ablation pulsed propulsion system. Again the GABRIEL is launched to an altitude where the ground array can pick it up and track it and fire pulsed laser bursts which vaporize the 'oil' coating and provide the impulse shocks for propulsion.
Needless to say Orion Drives (Or EP3 as it's known today) has a lot of interesting permutations and side-effects that can be quite fascinating to explore.
Randy