todofwar

I love thinking about it, but I hate working with it. The equations just never seemed related to anything real, and way too often explanations for physical phenomena boil down to "math says so" like electric dipole allowedness in transitions. Fortunately, density functional theory allows someone like me to skip the math and focus on important things like electronic structure. No idea about this stuff though. The experiment they describe doesn't seem to prove it either way? They shoot two entangled photons, one goes one way the other goes another, and supposedly the polarization of one reports on the polarization of the other, but only if they measure it after specified amount of time. How does this distinguish the two theories? Seems like this is just testing entanglement?

That's more a commentary on US inefficiency in general I think. Look at India and their Mars probe as another example.

I'll take a look, thanks! But before I dive too far down a rabbit hole, the main question I'm trying to answer is, would it take more or less fuel to reach GSO by traveling straight up from the equator? So, a space elevator without the elevator. Can't find an answer to this question, but this whole week has been a long stretch of google fails on my part so I might just be asking the question in the wrong way

I do love the Soyuz. Based on how little damage the boosters sometimes sustain, I wonder if they could survive with some strong parachutes, and have the core stage land Falcon 9 style.

But this isn't a jet engine, it's meant to operate where the atmosphere is so thin you can't use jet engines. General idea is it only needs to gently nudge itself to orbital speed over the course of several days. So low TWR is fine as long as it overcomes drag. Maybe if it starts going fast enough it can compress enough air to burn something, but I don't know for sure.

@p1t1o @peadar1987 How does centrifugal force play into that (yeah yeah, fictitious force, but we are in a rotating reference frame after all)?

Seems like the IAU is the space version of IUPAC, which chemists joke likes to change naming conventions every so often to justify its own existence.

So I always have trouble with this, and I can't ever find a good answer on the Google but maybe I just don't know where to look. Anyway, how do you calculate potential energy of something so high above earth that mgh doesn't cut it anymore? Like, the total energy required to get to geostationary by traveling straight up.

I was talking about a heat engine specifically, which has an inherent efficiency limit. Fuel cells are not bounded by the same limit, and I don't think PVs are either. Was just wondering if nuclear really is just a fancy way to boil water when all is said and done.

Well, this is a thread explicitly for nitpicking, I do appreciate the great lengths they went to make it realistic though. But I do think the Hermes goes into parking orbits on earth and mars. They mention the mav used at the end needed to be stripped because it was designed for LMO and they needed it to intercept Hermes while it was in a flyby. And they talk about the need for it to be serviced in earth orbit in between missions (that part might have been book only). Now, I do like that they used a real rocket for the final spot regardless of whether or not it's the actual rocket they would use. I'm actually surprised they didn't use SLS, since the movie was half an advertisement for NASA after all.

But kind of overkill I think. Unless it's a crew and supply launch I guess, but can't Soyuz get 6 astronauts to LEO?

So is fission/fusion just a way to get heat energy? No more efficient ways to harness it?

Last I'll say because this was supposed to be about Orion, but the reason we don't have those things goes far beyond government inefficiency. In fact, there are perfectly good reasons to not do those things, read every thread on manned space exploration and you see the compelling arguments for canceling the manned space programs entirely. Also, until recently space was not an industry ready for the private sector. If not for governments, we would not have a space program. Sometimes you need to create an industry first and after a while allow the private sector to take over. We are finally at that point, but without NASA pioneering the way it would never have happened. I won't argue it was perfect, when spending other people's money all kinds of regulation gets built in bit it was the only way.

Are you saying you'd rather have no space program? Just use rockets for satellites? No Juno, no Cassini, no mars rovers, nothing? NASA is damned if they do, damned if they don't it seems. They focus all their efforts on awesome science projects like the James Webb telescope and Curiosity, and people complain they're not sending people to Mars or back to the moon. They try and build a craft to get to the moon and maybe Mars and people complain it's just a jobs program. We all know there are inherent inefficiencies in government, but let me tell you scientists are very good at being on a budget and there will never be a profit in it, so unless you just want science to end up at the mercy of philanthropists you'll have to get used to the way NASA does things, and I think they do a damn good job.

Here we go again. Not everything comes down to pork. Plenty does, not everything. Without that "technical jobs" program we have no space program. But this is an argument that happens all the time and usually results in a locked thread.

I would disagree, most of the tech on the Moon will directly translate to a Mars colony. Efficient greenhouses, figuring out if low gravity is ok over twenty year time periods, radiation shielding, energy generation and building solar cells from ISRU, and getting a supply chain of raw materials going. There are a few key differences, but overall I'd say if we can colonize the moon about 90% of the tech will translate with little changes to Mars. And the moon has the benefit of being close by, so less risk for the initial colonists. They can come home in a worst case scenario with relative ease.

Also, if you use a more cylindrical shape, you can get much larger volume for large cargo at the same drag since drag will go up with the cylinder radius not the cylinder length. And you can probably link a few together. Maybe float a track that they accelerate on. Wait, now we have a train to orbit and that would be so awesome! Back to reality, I do wonder if the best design for this might not be a really long tube, almost like an eel flying at high speed. Of course, cargo would need to be carefully distributed.

It does offer the ability to get to orbit without the strain of rocket engines, so probably capable of really fast turn around. Also high isp, and you can even use the atmosphere to accelerate part of the way. How does lift work in the upper atmosphere? What if the airship deflated as it accelerated, relying more on lift less on buoyancy as it got to higher speeds? That way a constant output that overcame drag, with a reducing drag profile, could keep our accelerating to orbital speeds.

Back to the topic at hand, I have no idea if silicon Valley is accurate code wise, but I've always appreciated the fact that they emphasize how much work goes into making something, and how business interests play into it. And it's always a team effort, the main character is clearly a genius but he can't do it all and doesn't just code a whole product by himself in a montage. I swear you could make a similar show in a lab and have it work. And now I want a show starring Steve Carell as a professor with TJ Miller as a post doc, or maybe TJ as a new professor and Carell plays the older more established guy trying to help out.

I meant the very beginning. The ships enter as large flaming clouds. They send a hurricane chaser to find out what it is, and it gets swallowed by flames.

How does one go about getting clearance for something like this? Where I live bottle rockets can get you in trouble.

Haven't seen the second one, but in the first I thought it was still on fire while practically stationary

I always like thinking of chemical rockets as being the moral equivalent of ion engines that dump empty batteries as soon as they empty, and also throw them out the back fast enough to give even more umph.

I thought Independence Day was even worse. They include the fireball, but completely misunderstood why there is a fireball. Even when the ships are clearly too slow to compress air in front of them, they are covered in flames. My headcanon was that it was actually their shields coming into equilibrium with atmosphere that caused the flames around the ship, since they would probably have them cranked up to 11 to protect from radiation in space and need to reset for atmo as soon as they re-enter (can you really call it re-enter? was the Apollo lander's ascent stage really an SSTO?) and have no more need of heat shielding.

Futurama, somehow getting more things right than most sciencey movies and shows.