Steel

I have been to a mountain. However, my point is that Olypus Mons isn't mountainous, it's an enormous shield volcano that is almost devoid of any "mountainous" features. Ancient lava flows means that much of the surface is smooth and most of the notable features are craters. What is the purpose of climbing down the cliffs? If you want to get to the bottom, surely it's easier to land on the flat regions surrounding the volcano nearby and drive to the bottom of the cliffs, or alternatively land on the mountain and drive down the ramp-like sections on one of its sides (see image in spoiler, there are "ramps" on the east and west sides)? WARNING: LARGE IMAGES

One thing I picked up straight away. A suicide burn is where you start burning as you move towards the ground so you have 0 velocity just as you reach the ground (the sort of thing the Falcon 9 first stage does when it lands on the barge). I'm not really sure what you're trying to explain here (maybe an entry burn?), but whatever it is, it's not a suicide burn. My more general question is why the alpinists? Olympus Mons is a huge shield volcano with an incredibly gentle slope, (wikipedia states a 5 degree average gradient) and geography that is pretty far away from alpine. If you chose your path carefully, you could probably drive a rover for the entire mission without needing to hike at all.

I'll give you a hint: don't learn multiplication tables. In my opinion, memorising multiplication tables is archaic and has absolutely no place in learning good mental arithmetic skills. I have a physics degree and a masters in aerospace engineering and I haven't memorised these tables. What is a far better idea is to come up with a system that you can use to work out the answers to multiplication questions. For example, when I come across a mental multiplication I need to do, I usually start by multiplying by either 5 or 10 (which I know instantly, since 10 times a number is easy and 5 times a number is just half of 10 times) and then adding or subtracting numbers from there. An example: 6 x 8? I could do this in two ways: 1) 5 x 8 = 40 (that is the bit I can do easily, since 5 x 8 is just 10 x 8 (=80) /2), then I add 8 to get 48. 2) 6 x 10 = 60 (again, this is the easy bit), then subtract two lots of 6, (so 12) to get 48. (Bare in mind that there are other methods for mental arithmetic that may work better for other people, this is just what works well for me.) This (or any other another method that works for you) also gives the ability to work out multiplications that are not included on the tables. For example, most grade school multiplication tables go up to 12 x 12 =144. So what happens if you want to do 13 x 16 and you have only memorised up to 12 x 12? For me I just add 10 x 13 (130) and 5 x 13 (65, 130 + 65 = 195) and then add another 13 to get 208.

I never specifically mentioned ASD, all I said was that I'd discount people who had a disqualifying condition. If a doctor deems someone with ASD to be fine, then they're fine to fly in my eyes. Also, Neil Armstrong was never formally diagnosed with anything that would have disqualified him, but again, if he was alive today and I was the head of NASA, I would not let him fly if he had been diagnosed with a disqualifying condition.

There is a big difference between pioneering the first powered flights in single seat planes (at a time when there were no pilot regulations because there were no pilots) and flying 400 people from London to New York. If the Wright brothers had been alive today and I was an airline owner, I would not let the Wright brothers fly a passenger aircraft if they have a disqualifying condition, it doesn't matter who they are. Unfortunately, disqualifying conditions exist because doctors who have studied these condition for their entire careers think that they make someone who has them a higher risk to fly. An airline will always try to pick the pilots with lower risk. That is just how the world works I'm afraid. The only way around this is to prove that a condition should not mean automatic disqualification, but you'd need medically backed evidence for that.

The ones listed on the blog are 8kN of thrust each motor, so they're pretty much as big as you'd ever need. http://www.pro38.com/products/pro150/pro150.php

Ok, it sounds like the planet doesn't even try to adhere to the laws of physics, so I really wouldn't worry about tidal forces! After all, what does it add to the story?

*PLEASE DELETE*

The complication here is that what you're actually advocating is essentially "gluing" four of these off the shelf motors together to make one larger one. This is not exactly a well known procedure, and I'm not entirely sure how reliable the end product is going to be, after all, for a solid rocket you want a reasonable uniform and continuous burn surface and the seams between these motors would be a big question mark. Just because one motor will work does not automatically mean that four stuck together will. My other concern is thus: Are the manufacturing tolerances on these things high enough that you can use them in a cluster? Assuming stacking four motors to form one larger one is fine and works perfectly, you're still clustering four of these larger engines together to form a first stage. Are they manufactured consistently enough that you can say, with confidence, that one won't burn out half a second later than the others, or ramp up to full thrust slightly later, or make more/less thrust than the others? If there's no active guidance onboard then these things are absolutely critical.

The Ken Mattingly one is tough. However, the doctors couldn't risk him catching German measles in space (even if it was unlikely), because he might not have been able to perform his duties during the rendezvous with the LEM, which could have endangered the lives of the two astronauts in it.

For jobs where a small medical mishap could endanger the lives of many others (i.e pilots, astronauts e.t.c), I think it is right that doctors can stop people if they think it might be unsafe, however unfair it seems. The astronaut you mention is Deke Slayton, who was grounded (quite rightly) because he had an irregular heart rhythm. He spent years after he was grounded trying to get back into active service, so he cut out smoking and drastically reduced his alcohol and caffeine intake and his heart condition got a lot better, so he was allowed to fly again.

Not only that, but if you got caught and you had been flying passenger aircraft I'm sure there would be at least a civil lawsuit, maybe even a criminal trial.

Oh yeah, I'm 100% ok with the US having laws like that. I was just pointing out the fundamental differences between NASA and ESA. Anyway I'm from the UK, so apparently the EU isn't our problem any more anyway...

But as @Pawelk198604 said earlier, ESA is seperate from the EU (and besides, the European parliament is a bit of a joke to many countries anyway), so these votes you keep talking about them needing to get don't exist. ESA can't be operated in a Federal way because there is no government controlling how it is funded. All that ESA truly is is basically a piece of paper that says all these separate space agencies will cooperate towards common goals as long as everyone pays into the funding pool. Thus, to get everyone to keep paying, they've got to get back out at least what they put in.

The problem with ESA is that only a few countries get noticeable benefits from its budget (the ones with large aerospace industries, so UK, Germany, maybe Italy and that's about it) so only a few countries have an incentive to fund it. For instance, what incentive does Spain or Poland have to pay into the ESA budget if they know most of that money will end up in another country? And let's not even mention the whole political fall out because of Brexit. It's a much simpler situation across the Atlantic: NASA benefits the US, the US government funds NASA.

There is one more option: SpaceX continues to only hire US employees as per the law, the US federal law stays the same as it is now (because let's be honest, no politician who wants to keep their job is going to touch national security regulations) and non-US aerospace companies keep cooperating because it's in their best interests to do so. At the end of the day, the only people who lose out in this system are a few thousand non-US residents who are well-qualified and want a job in SpaceX, and there are plenty of other options for employment available for them.

Ok, so it would be possible to create a computer simulation of the event. However, because of how complicated this is, you would have do do a Monte Carlo style study, where you simulate it, change the input parameters, simulate again. This way you build up a picture of what the eruption would most likely look like. Unfortunately, because this is an incredibly complex physical event, this will take a supercomputer to calculate, and even with a supercomputer you looking at potentially years to complete the calculations and billions in costs. Of course, this can be done by a government if it funded a research program. The your suggestion about tunnels is interesting, but at this point in time it is unfeasable. It would represent the largest infrastructure project ever undertaken by human by maybe 100 times, including the longest, deepest tunnel ever built. Again this would cost billions, maybe even trillions due to the sheer size of this project and take decades to finish. Not impossible, but very unlikely. However, there is currently no scientific understanding on how (or even if) an event like this can be stopped. For all we know, drilling tunnels right up to the magma chamber might trigger the eruption earlier. The dome will never work I'm afraid. There is no way that you can make a dome strong enough to contain such an eruption unless you made entirely in a diamond reinforced carbon nano-tube lattice, and even that would likely not be enough. The eruption is simple so huge that the entire human race doesn't know any material that is even close to being strong enough to contain it.

I imagine it's to do with national security stuff. Plus if they don't hire people from other countries they don't have to go through the bureaucratic nightmare of sponsoring them thought the US visa system. Also Musk has been a US citizen since 2002.

All small launch vehicles have a high price/kg, that comes with the territory; you only get good $/kg when you want to launch tons at a time. For small sat launchers the total launch cost is all you really want to look at.

Are you talking planes or rockets?

The latter. There's so much to go wrong with things spinning at tens of thousands of RPM, and that's before you add in heat and vibrations to the mix. There's also so much to design in intricate detail if you want to make one from scratch. Just the topic of turbine blade geometry is something that people spend their entire careers researching.

What do you mean by that?

Oh yeah, it would be an immense achievement and a really interesting experimenter to see if it could actually be done. The other problem that you have, as @KerbMav pointed out, is that many primitive technologies are reliant on other living things (sticks from trees, fur/skin from animals) so you'd actually have to reinvent some primitive technologies in light of the fact that, for example, there are no sticks on Mars with which to make an axe, nor are there any trees to cut down to build furniture and equipment (a LOT of humanity's tools are wood based). The other Major thing is that you can't light a fire or the Moon/Mars, so how can you get metals from ore? In theory, yes. As long as you can synthesise/grow trees to make rubber for seals and things, and you have a sufficiently advanced workshop to make things like high quality canvas for a hab. The big thing is the electronics, silicon is tricky stuff, so making solid-state electronics would be difficult unless you had a full-scale silicon foundry.

Unless you're planning on recreating the entire history of human tool use in a vastly accelerated time period (i.e starting off with stone tools and gradually working your way up to precision CNC machines and silicon foundries for electronics) then no. All the technology we have now is entirely reliant on the technology that preceded it, and this goes all the way back to the beginning. Thus, if you take away everything, you have to start right back from the beginning and build up to get to today's technology.

I suspect that's the exhaust from the pre-burner that they're using as a vernier.