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Yes, everyone should definitely refer to that much more in-depth thread. If there is something to be said about SSTOs, its been said already there. But whilst I do count myself as a SABRE/Reaction Engines fanboy, I have lost confidence in SKYLON. Its not that I dont think its both supercool and a huge leap forward in terms of spaceplane-enabling tech - they certainly could build a workable spaceplane if SABRE does what it says on the can - but its just that normal, comparatively simple rockets, are so much more well known, so much cheaper to make larger - and now they even come in reusable flavours, I just dont think the niche is big enough [YET] for an air-breathing infrastructure when you look at the tonnages of cargo involved and the fact that SKYLON would require an entirely new industry to come into existence. Maybe in 100 years when we have industry that requires, globally, the monthly shipment of thousands of tons to orbit and beyond, but not yet. It doesnt matter that SABRE can make a viable spaceplane, it matters if it can make one easier/cheaper to operate than a rocket. Which is not currently possible, IMO.

It does make large weight savings, but those weight savings dont save much money. And a SABRE spaceplane requires an enormous investment in terms of infrastructure (Current SKYLON plans cant use existing runways because of weight/pressure restrictions). It makes a lot more sense to spend a bit more on a larger rocket that to try and convert all of modern space travel to spaceplane basis. Technically the SABRE might give significant savings, but if a large rocket can do the same thing cheaper (and it is significant that rocketry is a mature science with a great deal of experience in the field) then it doesnt make any sense. Helium coolant loop (closed) transfers heat to liquid hydrogen which is burned as fuel. More hydrogen is needed for cooling than is needed for fuel so excess is burned in ramjet burners (which dont really provide much thrust, but provide significant fluid-dynamic drag reductions).

Is it just me, or do I read a different description/explanation of the M87* image on every site where it is mentioned?

SABRE performs very well in the Mach0-6 range, but for space applications its just too easy and simple to do that part with a regular rocket. I do think that SABRE represents an important advance in air-breathing propulsion though, its just that I expect it to have applications that involve more...well, more air breathing. And also, not for a while, we are not ready for hypersonic airliners.

If we call it "Test Earth" it might make us seem way more impressive to any visiting aliens.

So one of the most wholesome threads was closed on my favorite forum the other day. Sucks. But also, 2 pigeons have decided that they would like to be housemates in the apartment we just bought. I named them Sharon and John. They like to poop on the bannisters. Interestingly though, the building developers are going to hire a Hawker to bring his raptors around and chase them away. That'd be cool to see, although I dont necessarily wish Sharon & John any harm. But on the other hand, pigeon is delicious and I had to disinfect the kitchen from floor to ceiling. If anyone wants to ask me questions about these slightly negative things in my life, or would like to offer advice, understanding or support, or tell us about similar or even just tangentially related issues, that would be totally within the intended scope of my thread. I think this would be a good place for anyone else to post negative things in their life, if they would like to talk about it or just get it off their chest as well. Sometimes you just need to scream into the void, but sometimes its good to answer one too.

I balefully curse all those hundreds of men and women around the world who have ever deliberately and wilfully contributed to the design, manufacture or sale of any rotating tool or valve, such as a tap or a radiator control, that needs to be turned by hand and has been given a perfectly smooth, circular section with zero texture or geometry to grip, that relies solely on the friction between your hand and its polished, shiny surface. Triple bonus curse-points if the object is obstructed in any way or otherwise made hard to gain optimum purchase.

This is one of the few things that literally nobody knows. And weirdly, one of the most common things that people pretend to know. As far as I know, the properties of conciousness and "the self" is not even grazed by the totality of human knowledge, therefore literally anything could happen, no predictions can be made because we have no data. Nothing is ruled out, or ruled in. Could be a mystical soul-journey through the universe. Could be a permenant state of a 2001-style psychadelic acid trip. Could be permanent oblivion. You could wake up immediately in the body of a newborn, with total amnesia. The plot of "The OA" could be spot-on. Could be anything. My money is on oblivion, and not only does that not bother me, it baffles me that anyone would be bothered by it. *** I read a short story once that had a very nice explanation. Humanity (collective) is a juvenile god (singular). When you die, you are reincarnated as another person, at any time in history. Ever person that has ever lived, or will ever live, is the same person, reincarnated. A god must live countelss lives, acrue billions of "man-years" of experience, of all aspects of life and humanity, in order to mature. I think it started something along the lines of: <man dies, reaches heaven, meets god> "God, what is the meaning of life?" <GODSIGH> "You ask me this every time, you never remember...fine, you are a god, one day....etc."

@Vanamonde Come on mate, you removed people's responses who were at least trying to offer some support/understanding/advice/compassion? We're not allowed to do that here? That would be very jarring if so. Do I really need to specify that I am complaining about this? This falls right into what I call "A Bit Much".

Its somewhat dark, but since you express an interest in the practical reality, the Challenger and Columbia NASA accident reports (and related documentation) are extremely interesting and are quite easy to find with a bit of googling. (tip: enter "filetype:pdf", without quotes, as an extra search term to only return PDF documents) Here's one I found quickly, the CAIB, the Columbia Accident Investigation Board working scenario: http://govinfo.library.unt.edu/caib/news/working_scenario/pdf/sts107workingscenario.pdf Study of failures is, unarguably, equally as important as studying how to succeed, in many cases more knowledge can be gleaned from failure. There is of course, a near infinite amount more that can be said/expressed about this subject, but that is not the purpose of this comment. (RIP to all those who perished in these tragic accidents)

Easy. Cripy duck pancakes. @TheKorbinjer CHEATER!!

"What do you need?" "Can I show you something?" "Have you done this before?" "Im a human and we eat launch codes. Say, do you have any launch codes?" "Can you help me make sense of the ending to "Lost"?" "You guys party?"

Well, the parts between the stray protons is hard vacuum, but in essence you have the truth of it - space is actually full of stuff, especially in the middle of a galaxy like we are. But hoo boy, just wait until you read about quantum foam and related work on the structure of space-time itself. Its a Dyson Sphere

"Old"? What do you mean "old"?

They're made of people, but they dont act or respond like people, nor have the same morals/ethics, nor - if you can stomach the concept of a "value" to these things - do they have the same value as a person. A civilisation is to a person, what a person is to a cell. Maybe? Im flying by the seat of my pants here! A fairly generic pistol. We will? IMO that is a YUGE extrapolation, we dont have a single datapoint other than a curve of past progress, curves can only be extrapolated so far. (Im coming off as a bit of a warmonger here, I swear I dont have an alien bloodlust! ) (Joke'll be on you guys when it turns out the galaxy is all xenomorphs)

I didnt say it was the right strategy, only that it is one Although, it is a false equivalency, civilisations are not people. What if you walked into a room of outwardly peaceful people, but they all have spears and if you die your whole species dies. And you have a glock. A silly, imperfect analogy, but it looks different now doesnt it? There is an opposite strategy which is in the same vein which says that we must stop looking for intelligent life, must stop broadcasting our presence, in case the - or according to some, because its likely that - aliens subscribe to the first, more aggresive strategy. These strategies also speak to the Fermi paradox - everyone is either hiding or destroyed.

So....many....joke....opportunities.... *** If its intelligent life, it'd be best if we stayed the heck away for several centuries, we are not ready. *** Though there is one school of thought that suggests, without irony, anger, or xenophobia, that we should immediately exterminate any intelligent life that we find. I think the rationale is something along the lines of a logical framework based on a certain set of assumptions that suggests that a sparsely distributed galactic society is an incredibly dangerous place to live, kill or be killed. Even though a species seems outwardly peaceful, will this last for 10,000 years? 100,000? For a long-lived civilisation, culling even benign, peaceful aliens might be a prudent choice. And the insideous cycle - knowing this, the peace loving aliens must learn that to remain peace loving, they must exterminate visitors (thus justifying the warlike aliens approach and perpetuating the cycle) Also, my "stay the heck away" approach, is somewhat influenced by this idea.

A new Terminator Movie? With Linda Hamilton and Arnie? That ignores every other movie since Judgement Day? SIGN. ME. UP. *** In other news, we moved into our new flat! Which we own! Sortof! I have a [tiny] ManCave! DISHWASHER!! OH GOD WE'RE LIABLE FOR E-V-E-R-Y-T-H-I-N-G TipTopTip: If you ever buy a piece of flatpack furniture, like even one piece, invest in an electric screwdriver. Oh my god it saves SO much time (and also wrist pain).

yup For snow: These, though, did not work out: (B-36 experimental undercarriage)

Yudkowsky sounds like he's great fun at parties.

It costs energy to convert a solid to a liquid and this energy will not be available for thrust.

Heres a thought - Breastmilk is not vegan!

No. Air-Air refuelling makes this idea entirely obsolete, even if its impracticalities did not already.

https://en.wikipedia.org/wiki/RAS_syndrome