Bill Phil

Mini Mag is fission - just like Orion. However instead of chemical explosives to compress the fissile core, it's done with a Z-pinch. Now the idea would be to get just enough power from each pulse to recharge the capacitors, and to have backup capacitors just in case. You can use some fusion fuel in the fissile core to increase the neutron flux and thus the fission rate to get a higher yield per shot. This should increase ISP as well. I've been wondering if an "afterburner" is possible for Mini-Mag to increase thrust at the expense of specific impulse. Using the fusion boost, this could be a reasonable loss for more thrust for, say, fighting gravity during a lofted ascent.

We literally have no way of launching enough people to lower the growth rate, assuming we even had a place to send them. We'd have to build launch loops or orbital rings to get enough throughput. And of course that's assuming that Mars is even a good place to settle (it's not). The only habitable place in this solar system is Earth - followed by the ISS very, very far behind. Maybe even further behind is the upper atmosphere of Venus.

Not because there isn't enough energy, but because the pusher plate is actually very inefficient. It's basically a brute force attempt to harness nuclear energy for propulsion. Making the plate larger to catch more propellant/energy and making the shocks more efficient would improve performance. Indeed a larger Orion ship (probably taking advantage of thermonuclear pulse units as well) could likely get much higher specific impulse than just 12 thousand seconds, but at that point making large vehicles becomes less practical and it's better to use something more like Mini-Mag Orion or Medusa for that performance.

The best we could do now? With some development a lofted boosted fission Mini-Mag Orion is probably doable. Then getting anywhere in the Solar System is possible, even a Pluto sample return could be done. Personally I think delivering large scientific probes to every planet would be desirable, and potentially fleets of orbiters to the gas/ice giants. And of course landers/rovers for as many bodies as practical. Exploration of Titan seems like one of the more interesting ones - aircraft, ground vehicles, and "watercraft" are all possible. High detail gravity maps of every planet and their moons. And of course manned missions to Mars and maybe even Jupiter. The only issues will be the massive influx of charged particles in the magnetic field - though this may not be nearly as bad as a conventional Orion. Maybe a slight increase in the background radiation around Earth. However one advantage of the Mini-Mag Orion is that its performance is so high that this increase is not a problem. We have the "technology" to do this, but it requires significant RnD, and may take a good amount of time to actually develop. Still, it could be worth doing.

A good formulation is characteristic energy C3: C3 = V^2 - Vesc^2 Where C3 is characteristic energy, V is current velocity, and Vesc is the escape velocity at the current position. A positive C3 indicates a hyperbolic orbit, a C3 of zero indicates a parabolic orbit, and a negative C3 indicates a closed orbit (either elliptical or circular). One interesting aspect of this equation is that a relatively small difference between V and Vesc can create a large change in C3. For example, in LEO the escape velocity would be around 11 km/s. Adding just 300 m/s would give a C3 of about 6.7 km^2/s^2, or a velocity at infinity of 2.6 km/s. Mars missions require a C3 of roughly 12 km^2/s^2, so to go to Mars requires 530 m/s beyond escape velocity, or just 3.73 km/s of delta-V from LEO. Meanwhile a C3 of 80 is required to reach Jupiter directly, so about 14.2 km/s of velocity - 6.4 km/s of delta-V from LEO. But this leads to an excess velocity at infinity of 8.9 km/s. To leave the Earth system from the Moon's altitude requires about 1.44 km/s, a delta-V of roughly 440 m/s to escape. To reach a parabolic orbit, it would be preferable to simply burn at this altitude. But what if we want to go to Mars? A C3 of 12 would require 3.75 km/s, or about 2.75 km/s of delta-V. But what velocity would we have if we lowered our periapsis to LEO? So we have two delta-Vs, the braking burn and the final escape burn. Remember that the escape only needs 530 m/s past escape velocity. Braking burn: Assuming the Moon's altitude is a constant 384399 km, and LEO is at 6550 km: An orbit that goes between these two would have a semi-major axis of about 195000 km. Using the Vis-Viva equation the velocity after braking would be 186 m/s. So the initial delta-V is about 813 m/s. Escape burn: The velocity at periapsis will be approximately 10940 m/s - once again using the Vis-Viva equation. Only 624 m/s slower than the required velocity to reach a C3 = 12. The total delta-V would be about 1.44 km/s, more than half of which is for the braking burn. This is much less than the direct delta-V of 2.75 km/s. So it is cheaper for a suitably hyperbolic target trajectory. Indeed, for a direct transfer to Jupiter, it would be much more effective to "dive" - provided you were already at the Moon's orbit when you start. For KSP the required C3 is much smaller, and the benefit of "diving" is much less pronounced. So it's not all that useful unless you're around a large planet like Jool (which is similar in mass to Earth) or maybe Eve. Another factor is that you have to actually get to the Moon's orbit - the benefit of doing this is pretty much nonexistent unless we can use resources from space as propellant. Since you'd have to escape LEO to actually do it in the first place. Maybe using electric propulsion to create in space infrastructure and then just delivering the crew later could be beneficial?

I think it's very interesting to consider what's possible under our current understanding of physics. Settling the solar system is very possible, and the possible stories in the solar system as a setting have by no means been fully explored. Another interesting possibility is exploring the consequences of certain technologies and then involving them in a science fiction setting. For example: http://panoptesv.com/RPGs/Settings/VergeWorlds/VergeHistory.php This is written by a physicist - he knows how wormholes would work in theory. So he's applied that - and we get some interesting consequences. Assuming wormholes are possible and aren't too expensive and so on. In this setting wormholes are accelerated to relativistic velocities so the frame of the wormhole at the original location will experience the arrival at the target sooner. But this means that if the wormhole connection is cut, the time lag of the colony reconnecting to the original world could be huge. It also leads to interesting consequences for warfare in the setting.

Sure, and there are also 2.5x rescales that some players prefer over 6.4x. But overpowered parts might actually be good for a scaled down real solar system, considering that many planets are even further than Jool and Eeloo, and the delta-v requirements are also larger for them.

I think a scaled down RSS (to Kerbal Scale, or about Kerbal Scale) would be fun. Yes it would be inaccurate since velocities, times, and distances wouldn't be right, but it would still be fun to see real planets without having to rebalance KSP's tech. Mods already exist for this, of course. And I'd be just fine with it staying that way for KSP2.

Immortality can indeed be a selfish thing - but not necessarily so. "Leeching" off society wouldn't necessarily happen either. I would argue that humanity, as a social species, is not inherently selfish. We care very much about others - perhaps not caring for the entirety of the species but we certainly do care about others. I would also argue that hundreds of thousands of years of human history would seem to imply that we are not inherently selfish. Beyond that, there is not very much scientific research into "human nature" and of the research that exists, it's difficult to find an answer. From my own experiences humans are not inherently selfish. Some grow up in an environment that reinforces that trait, and others do not. Though if we were to invent immortality, I believe that society isn't ready for it. An immortal society must be fundamentally different from a mortal society. Though if such a technology were released it would be capitalized on.

Basically this (from Star Trek: TNG) Specifically the last part - "charting the unknown possibilities of existence."

Interesting. Looks neat. Maybe it’d be good for Halloween? A giant space pumpkin?

Slaughterhouse Five is all about the bombing of Dresden and the psychological effect of the bombing on a WWII vet. I only mention it cause aliens show up - but it’s debatable if these aliens are real or just a figment of the main character’s imagination.

Is that Orion TWR for the propulsion system alone or the entire vehicle?

Alright I put together a model in MATLAB. (I already had a similar one lying around, didn't take much to modify it) (Hopefully this works) Imgur album with plots: https://imgur.com/a/xMHwucs Assuming a cylindrical planet can be modeled as a line of discrete particles. Used an RK4 integrator with a step size of 60 seconds. Number of particles is 100. Each with about 1/100 the mass of Earth. Looks like it acts like mass concentrations around the poles.

Well, not necessarily. Around a finite cylinder the moon would still experience a gravitational force toward the cylinder even past the ends. In the case of our Moon, it's so far away from the Earth and the Earth is very small compared to that distance - so the real difference is likely insignificant to the Moon's orbit, or at most only perturbs it slightly.

Well the truth is we can’t treat real planets as spherical - they’re not. Terms like the J2 term are used to describe unequal mass and geometrical distributions as alterations to the point mass model. The J2 term specifically models a planet’s oblateness - which gives rise to precession of the ascending node. The ISS’s orbit precesses around 5 degrees a day (roughly 16 orbits) as a result. Precession around Jupiter or Saturn would be even more extreme. I suspect you could model the cylinder as a line of discrete points - perhaps the gravitational field could be calculated analytically using calculus though I can’t say for sure. Then integrating with a runge-kutta or symplectic integrator would let you see how that changes trajectories. Actually, I might do that myself...

Depends on the specific impulse and mass ratio, as well as the trajectory flown. For a decent variant a moon of Saturn and back isn't that far fetched, provided the payload isn't too massive or you're willing to sacrifice acceleration. For an antimatter vehicle, anywhere is possible - provided you have the mass ratio.

Actually I believe we do use relativistic corrections for certain trajectories provided the need is present. With low enough masses and velocities the differences are small enough to be ignored. A satellite will retain its orientation/rotation relative to the “fixed stars” (which aren’t fixed but we say they are when it’s convenient) or the frame of reference unless acted upon by a torque or other influence. I believe this is the case whether or not you use Newtonian physics or GR. Gravity can apply torque though to large enough objects.

Play Kerbal Space Program. Read papers about space exploration/travel. There are loads on NASA ntrs.

In recent memory? Probably my abscess tooth from last year. Man that thing hurt. Couldn’t sleep. Though the nerve was dead by the time I got the root canal procedure - so that didn’t hurt too much. Besides that my big toe once hurt so bad I thought I had broken it. I got lucky though, it wasn’t broken.

Yeah they're still developing it. Just can't do all the work they need to.

Hung out with friends over discord. Man I needed that.

Blue Origin is the prime contractor for one of the Artemis lander proposals (they will provide the descent stage and work with other contractors to integrate the ascent and transfer elements). But their current design is too heavy to throw to TLI/NRHO with the desired margins. The schedule also keeps slipping, as it always does.

Like hardware for Z-pinch and a magnetic nozzle. If it's advanced enough it can look like just about anything though. So it could be a normal propulsion system. It also seems to perform better than Orion generally - 16000 to 20000 seconds of specific impulse for the original Mini-Mag concepts compared to around 4 to 10000 for the original Orion concepts. Using boosted fission pulse units Mini-Mag Orion can likely have over 30000 seconds of specific impulse since it would have a higher burnup rate of the fission fuel. That means that, assuming a mass ratio of around 2.7, a Mini-Mag Orion could easily have 200 km/s of delta-v. Then it can easily get to just about any target in the solar system. Fast transfers to inner planets are possible, and 1 AU per month is about 62 km/s, so a fast transfer to Jupiter would be easy for Mini-Mag Orion (New Horizons arrived a little over a year after launch, so it's possible). If you use antimatter then you can make something way better. As for its appearance... it can look like a rocket. I think it needs radiators for its reactors though.