Racescort666

I can hear Alan Stern rustling up his Pluto lander paperwork.

I'm really excited for IVF to fly.

In KSP SRMs are kind of terrible. In real life, they have ISPs of 250-295*, come with thrust vectoring, and are probably less dangerous than any liquid you'd want to use as a monopropellant. They are used in munitions for good reason and John D Clark discusses it in Ignition. *The range is from a quick glance through the old Orbital ATK catalog but these numbers are far better than the 200-235 listed in Aerojet's monopropellant catalog.

Is there a TL;DR? *remembers that this is a scientific paper* *scrolls to conclusion* Interesting indeed.

I suppose this is relevant:

An off the shelf missile system? Maybe. Being a weapon, the Stinger missile doesn't have a ton of technical information publicly available but enough to get you close. https://en.wikipedia.org/wiki/FIM-92_Stinger Solid propellant specific impulse and the square-cube law really kill you on this but my guess is that a Stinger missile could just barely get something into lunar orbit. The warhead is 3 kg and total mass of the missile is 10.1 kg so assuming a dry/wet ratio of 0.65 of the remaining mass and an ISP of 266 s (from another small SRM), you get 1591 m/s of dV. A 2U cubesat has a max weight of 2.66 kg and you wouldn't need the tracking system of the Stinger (which I don't know the mass of) so I'd say you're right on the cusp of making a Stinger work. The whole Stinger system (launcher and all) weighs ~15kgm which would be around 2.5kgm under lunar gravity, light enough to handle 1 handed. A purpose built launcher would be a piece of cake for a 3U cubesat. More importantly, the moon's gravity field has been described as "lumpy" so putting something into orbit is one thing but getting it to stay there would be a serious challenge.

The short version is tradition but why those particular units were chosen in the first place is sometimes interesting as well. Fahrenheit was a very skilled tool maker and it's likely that his scale for temperature was chosen because he made more consistent thermometers at the time. Fast forward a few hundred years and it becomes very difficult to break that tradition. That's not to say that the US is staunchly opposed to the metric system (or rather SI). In fact, the US customary units are actually based on the metric system: https://www.nist.gov/sites/default/files/documents/pml/wmd/metric/1136a.pdf The funny thing is, many major industries in the US use strictly the metric system. Speaking from experience, the auto industry is almost exclusively metric with a handful of exceptions like specialty manufacturers (like smaller bus manufacturers). In fact, the American auto industry had started doing new design in the metric system in the 80s and customary units were phased out with old models. Even things like government regulations have been converted to metric when it comes to cars: distances in meters or millimeters, temperatures in C, speeds in km/h (although I would prefer m/s), etc. So the US isn't necessarily a curmudgeon, progress has been made, it's just much slower than the science and engineering community would like. Also, public perception is very different from what's happening in the industries.

You could probably copyright protect a choreographed set so sort of?

This is something we ask before testing too.

I'm glad that this mission is going well. I'll admit that I was a bit worried when they postponed their first maneuver but it pays to be patient and have backup maneuvers.

Is it bad that I kind of want this to be delayed so that the launch happens during the 12 Hours of Sebring? https://jalopnik.com/watch-a-424-million-military-satellite-launch-over-the-1793410864

My first thought was, "why don't you stack a DCSS on top of a Falcon Heavy? The mass works out." Falcon Heavy Payload to LEO: 63 800 kg Orion Spacecraft (Including SM): 25 848 kg Delta Cryogenic Second Stage (wet): 30 710 kg FH mass margin: 7 242 kg LEO dV: 2972 m/s <- but this is the killer, not enough dV. Plus, this would require an expendable FH.

Getting off topic

Welding seems like an obvious solution. The station doesn't need to be immediately habitable or at least there could be a build up over time. Also, there's a chance that adhesive seals could be used but that would be new technology that would have to be developed. Something that no one has mentioned yet with regard to rotating stations is CG management.

It covered this distance in 3-3.5 minutes

I'm surprised at how fast it's moving.

I suppose they could have separate burns but considering how many ties I've crashed into my own service modules in KSP, I suppose it makes sense that they jettison before burning to get away from the trunk.

I disagree, their marketing team isn't great and they're certainly very conservative but that doesn't make them less innovative. They have good business sense and they understand their place in the market so you'll mostly see DoD and other government (NASA) launches that require low risk. As a result, they are much less likely to implement the "wizz-bang" changes. Not that they don't come up with them, they just don't implement them.

I don't have a twitter account but someone should ask if they plan to fly IVF on Atlas before Vulcan. I guess this sort of answers it but ACES is essentially a new upper stage:

When I was at the Air Force Space and Missile museum at Cape Canaveral, the guy working there was telling us stories about working on the early Atlas program and how they had one launch where the missile never initiated it's pitch maneuver. They activated the flight termination and he said it looked like sparkly confetti up there in the sky. He said, "then we realized that it was directly above us and we should probably get inside before any of those pretty pieces come down because they're basically slivers of razor sharp stainless steel."

https://en.wikipedia.org/wiki/Components_of_jet_engines The air intake section might be the most relevant to your question. The phenomena at work is Bernoulli's principle which comes from the law of conservation of energy.

I assume that the trust/weight and thrust/cost records are largely down to advances in design techniques, manufacturing techniques, and materials advances. It's much easier to optimize with modern tools than it ever was in the past.

@kerbiloid @Xd the great regarding dark matter and dark anti-matter annihilation.

1-2kW https://www.ge.com/additive/additive-manufacturing/information/direct-metal-laser-melting-technology

This paper from ULA indicates that getting LH2 boiloff down to <2.5%/day on centaur is reasonable with minimal modification. Also, as @sevenperforce indicates, ACES will also have a significant affect on heating as it allows settled coast which further reduces boiloff.