PakledHostage

Some religious groups probably wouldn't even flinch. Some like Sikhism (I am told) make allowances for the existence of alien creatures on other worlds. Others are too blinded by their faith for anything to phase them. I have met a few people who honestly believe that the world was made in 7 days, 6000 years or so ago, and that all the evidence to the contrary was put here by the devil. Pointing out to them that, if their belief is true, then the devil made more of the world than their deity did is met with incredulity. If they can hold that firmly to their faith, then nothing much is going to shake the foundations of their religion.

And arguably, that was why there was so much pressure to launch that day despite the air temperature being out of limits. IIRC, Reagan was making his state of the union address that same day or the next and NASA wanted to have Challenger and her "Teacher in space" crew member in orbit for the occasion... I agree though, that it was a story as big as Kennedy's assasination or maybe even 9-11 when it happened. I believe it was that public grief that had the biggest impact on the US space program.

Attempting to divert an asteroid or comet would require technology that pushes the limits of our capabilities. I don't think it is reasonable to characterize potential solutions as something that could be "mass produced and thrown at the problem". That said, I believe that the only realistic option currently at our disposal for diverting an object on short notice would be nuclear weapons. They have the advantage that we have a large stockplile of them and that they do not need to rendezvous with the object to work. They can be timed to detonate as they fly past. This saves large amounts of delta-V, which could make the difference between being able to use existing rocket designs or having to design and build entirely new launch vehicles.

I mentioned this post to my non-Kerbal colleagues... It is a bat s**t crazy idea, but my colleagues figure it would make a great sci-fi plot.

I reached orbit in that challenge. Since the challnges are basically the same, I'd like that entry to be considered for this challenge.

Your photo is more interesting because it is more colorful. I suspect that, at your latitude, you only ever get to see the ISS in the eastern and western skies near sunrise and sunset? I'm far enough north that we can see it in all parts of the sky over a wide range of times. In summer, we can see it pretty much any time of the night that it passes over. Looking around online, I was able to find some pretty spectacular photos of the ISS silhouetted in the disk of the full moon or the Sun. I imagine that those shots take some very specialised timing equipment, however.

I've gone out a couple of times to take photos of it going over. It doesn't look like much but I still think it is kind of neat. Here's one that I took of the ISS passing through Cassiopeia: And here's one of the ISS with HTV-4 in trail (the very faint line at the left end of the brighter line that is the ISS). That time was neat because I was able to see it go over on two successive orbits, and HTV-4 was a noticeably closer on the second pass than it had been on the first. HTV-4 also gave off a brief "flare" of brightness on both passes, although I wasn't able to catch it on film.

I admit we're discussing semantics, but I didn't interpret the title as literally as some here appear to have done. I am sure I am not the only one.

Not necessarily. Please see the passage from the article that I quoted on the previous page. It describes how the singularity may not actually exist. Black holes are often described as a singularity.

It feels a bit strange to be defending the media, but as Kerbin Dallas Multipass said, Nature isn't exactly mass media. The article is informative and seems to do a good job of describing the context of Stephen Hawking's quote. And as Idobox said, the catchy headline attracts the attention of those who might otherwise not have read the story, myself included.

I don't think the article intends to mislead or to have us believe that black holes are "some imaginary thing":

I am curious what some of you more qualified people here think about this article in Nature: Stephen Hawking: 'There are no black holes' Edit: The link to the abstract for the full paper on arXiv is: http://arxiv.org/abs/1401.5761

This question might be better asked in the Gameplay Questions and Tutorials sub-forum, but I'll take a stab at it. I am sure someone will correct whatever I get wrong (and what I get right, for that matter...) Ans: The Isp of engines in the game varies with atmospheric pressure, but the implementation is bass ackwards. In order to achieve the variable Isp, they've held engine thrust constant over the full range of atmospheric pressures and varied fuel burn instead. In reality, you would expect engine thrust to vary with back pressure (i.e. atmospheric pressure) acting on the nozzle while fuel flow rate would be roughly constant for any given throttle setting. I recall seeing a post once from one of the devs that they were going to fix this, but I don't think it has been done yet.

It is relevant and far from meaningless in this case though because the discussion was in reference to skylon flying itself with human passengers aboard. Certainly the technology exists for UAVs and spacecraft to fly themselves, and it makes a lot of sense for skylon to be unmanned and to utilise that technology. The concerns raised in this thread are valid, however, when discussing a fully autonomous aircraft or spacecraft with human passengers.

There's also this: the Titan Saturn System Mission. That proposed joint NASA/ESA mission would have put two robotic probes on Titan and an orbiter into the Saturn system. One of the two probes would have been a balloon, while the other would have been the Titan Mare Explorer "boat". Now I know that there are a lot of fans of manned space exploration around here, but there are others like me who would prefer to see money spent on robotic missions. For the cost of a few shuttle launches, this mission could have been on its way to a 2020 launch. Instead, it got cancelled in favor of the Europa Jupiter System Mission, which itself has been cancelled due to lack of funding. Very sad, because both the TSSM and EJSM would have returned some very valuable scientific data and would have captured the public's imagination.

I thought I'd hunt around for a video of the launch for anyone who's interested in catching the replay. I found a whole series of videos of the launch by a guy named Matthew Travis on YouTube. This one covers the launch itself:

With all due respect, I didn't realise that being a particle physicist made you an expert on aircraft structures engineering and regulatory compliance? It is my professional opinion as an aerospace engineer that these things do matter. Economic viability, safety and operational considerations must be taken into account in aircraft designs. Indeed they are and they have served to influence the evolution of commercial airliners into their current configurations and operating regimes. Attempts have been made with aircraft like the Concorde and Boeing Sonic Cruiser to break out of that niche, but after 50 years of jet airliners being in existence, we are still plodding along sub-sonically below ~42000 feet1. Any aircraft design that is intended to operate outside of that niche will have to deal with the problems that exist there, and those may render the design too unsafe, too impractical or too costly to be viable. 1Some business jets operate above that level, but for the people that can afford to fly in them, the convenience of uncongested airspace is probably worth the extra cost of certification, structural weight and operating restrictions.

@K^2: True enough, but there remains the issue of economic viability. Higher cruise altitudes require that the fuselage be designed for higher differential pressures, and must therefore be heavier. I don't recall what altitude the Boeing Sonic Cruiser would have operated at, but it doesn't stand out in my memory as being a particularly high altitude aircraft. Limited time of useful consciousness in the event of depressurization is already a concern at the upper operating limits of commerical airliners, and you don't have to go too much higher before pressure suits would be required. Obviously it is impractical to operate at those types of altitudes. The Concorde had (and many business jets currently have) the luxury of operating in uncongested airspace, but I think the OP was talking about a time when faster aircraft would be more common place. They too would have to be shoehorned into the same airway system that sub sonic transports currently follow, above the currently congested flight levels but in the same ~10 000 foot thick block of airspace that are already occupied by sub-sonic business jets today. The same challenges would eventually occur in those higher flight levels as do today.

I thought I also mentioned that it was a serious taboo? I realise that is a bit circular, but being shunned or even killed in punishment for violating a taboo is a threat to your survival. Among the Algonquin speaking natives that I mentioned, the expected behavior in times of starvation was to commit suicide or resign yourself to death. Those cultural norms evolved for a reason.

There have been documented cases of people resorting to cannibalism for survival throughout history... The Donner Party, the victims of Uruguayan Air Force Flight 571, etc. It is still a huge taboo, however. The Algonquin people of North America even had a legend associated with it. The Windigo was a mythical creature that ate human flesh and could possess people or take on human form. There are other problems with cannibalism too. IIRC, there was also a tribe in Papua New Guinnea that was dying out due to a prijon desease that was being transmitted due to their custom of honoring their dead by eating them.

The Boeing Sonic Cruiser proposal that I mentioned previously wasn't going to be much more than 100 km/h faster than conventional airliners, and the airlines already weren't interested in that design. Another thing that needs to be considered is how you integrate faster aircraft into the air traffic control system. Large regions of the globe (i.e. most of the oceans and arctic regions) are not covered by radar. Aircraft flying in these regions are slotted into tracks. Separation in the track system is maintained by specifying the speed that the aircraft must be flown at. It doesn't matter that your aircraft can cruise at Mach 0.87 if the guy in front of you can only do Mach 0.8. You can request an alternate altitude that doesn't have a slow poke1 in it, but that alternate altitude may be unfavorable for some other reason like wind direction/speed or turbulence. And while it is true that a lot of business jets are designed to fly faster than commercial airliners, they are also designed to fly higher to give them the freedom to do so. 1This is the source of the joke among Boeing pilots that the A340 is the only airplane certified for birdstrikes from behind...

Although there was a DC-8 that was intentionally flown to Mach 1.01 in a dive back in 1961, it would take a lot more than what you are describing to build an airliner that could do it safely and economically in every day operation. Boeing had proposed to build the Sonic Cruiser about 12 years ago or so, but the airlines weren't interested in the extra bit of speed and pushed Boeing to design a more conventional but more fuel efficient aircraft instead. The result was the 787.

According to the Leo online German-English dictionary, it means:

Sorry about the necro, but today's XKCD is somewhat relevant to this thread and I thought some of you may enjoy it:

Boring meeting... This is more interesting. I tried to pick out the supernova in that photo but it isn't quite bright enough. It is just to the left of Dubhe, near the path of the rocket, right? Is it visible in the photo?