sevenperforce

Elon did specifically say that the Dragon V2 would be man-rated for LEO and lunar missions, but nothing outside of the Earth-moon system due to limited life support and space constraints.

I think the implication was that they were starving to death one by one.

Only a few days of power post-landing, since the trunk can't survive a landing. Then again, it won't be hard to add batteries or a fuel cell to the payload. The notion that this could be used for sample return, on the other hand, are quite ill-conceived. The Dragon V2 does not have nearly enough propellant for direct SSTO ascent from the Martian surface.

While wearing sunglasses, let's not forget.

Jupiter, ready or not, here we come!!! So next thing is to land on the sun right?

A binary planet is not unstable. Earth and the moon are essentially a binary planet.

Although the current definition uses an equation to determine a given object's likelihood of clearing its orbit. If Earth was a Jovian trojan, it would still be in the right zone and mass to fit the equation for clearing its orbit even though it wouldn't. So it would fit the definition for clearing an orbit but would not have cleared an orbit. Unless it was a double trojan, where the two objects are close in mass and 60 degrees separated in the same low-eccentricity orbit. Lissajou.

A blunt re-entry surface is ideal when you want high drag and low heating. An ICBM doesn't need high drag, and it only needs to survive long enough to get to the surface.

Think you missed a few points. Those aren't inlets for the engine; they are inlets for ram compression and exhaust reheat. Wrapping even a very simple exhaust shroud around an engine results in a pressure-induced flow that increases thrust by 15%; at speed it goes up to 50% augmentation if your engine can vary its mixture ratio, which the Merlin 1D can. Takeoff is emphatically not relying on lift; it's relying on thrust. Rolling takeoff is to build up airflow through the ducts to increase the vehicle T/W ratio to 1.5-1.8, enough to point the nose (relatively) straight up. As I mentioned, it has enough static thrust (1.4:1) to take off vertically, but horizontal takeoff helps reduce gravity drag and allows it to fly out of any airport that can take a LOX depot, which is good if you want to use it for suborbital flights. This is similar in overall shape and re-entry profile to Skylon, though with a less depressed flight trajectory, a better T/W ratio, and a smaller overall size. And sure, SSTOs aren't generally a brilliant idea. But that is kind of the point of this. SSTOs aren't built because there isn't a reason to build them. And here's an example to show why building them is in many ways the easy part.

I don't mind space fantasy or soft sci fi as long as they try to stay internally consistent and they don't try too hard. Or, rather, try hard and succeed. If you're going to depict something that breaks physics, either handwave it totally or come up with a good explanation; don't jack it up. There's a decent fanfic in the DBZ universe, of all places, that seems to do a pretty good job of handwaving in the right places and explaining everything else. They even had one whole chapter (late in the series) explaining the universe's rules in-universe, in interview form.

It would fly like a brick for sure, but the fuselage is a blended Sears-Haack/lifting body and most of the weight is toward the rear, so with a decent angle of attack it should be able to get a reasonable amount of lift. There would also probably be some degree of rocket-assisted braking during landing approach. In theory, you could even use SuperDracos to set it down vertically. It could, without payload. Way too much engine though. Drop four of them and you'd be in business...only 2 tonnes of payload, though, with a totally expendable rocket. This is more derived from the Falcon 9 FT second stage, actually. The fuel mass is only slightly greater than the F9FT second stage fuel supply. Which, if you think about it, suggests that the Falcon 9 second stage is ALSO just about capable of SSTO.

Specific impulse isn't nearly as important for SSTO designs as impulse density is...you can pretty much send the impulse density as high as you want as long as your engine T/W ratio is good enough. The Merlin 1D FT has T/W in spades, so why not build a really small SSTO powered by nothing more than a pair of Merlin 1Ds? Basic HTOL design. The pair of fixed air augmentation ducts should increase the specific impulse enough to effectively zero out gravity drag and aerodynamic drag and give the Merlin 1Ds an average specific impulse equal to the Merlin 1D vacuum specific impulse. Kerolox is fairly dense so the craft is small, but heavy at 128 tonnes in only a 22-meter-long ship. HTOL requires pretty heavy landing gear, which increases dry mass, but thanks to the small overall size the payload fraction remains close to 1:1 with a total mass to LEO of 6 tonnes. Use VTOL with lighter landing gear and the payload mass jumps, but you lose the ability to take off and land from any large runway. You want to keep that in case you use this as an antipodal hypersonic suborbital transport. Rolling takeoff is to gain airflow through the augmentation ducts, not build up speed for aerodynamic lift. Payload looks like it should be just about enough for a 7-crew ISS ferry.

For anyone who was interested, here's a hypothetical trinary system (blue giant, yellow dwarf, brown dwarf, terrestrial planet) with eternal day on the terrestrial planet.

All the better to help you stay away from them. Oops, corrected. Still military...that must have been what I was thinking.

My assumption when I watched it was that he used a high-intensity magnetic field or somesuch to wipe it. It's not too terribly unrealistic to think that would be possible; hardening against a bunch of teslas isn't easy. Then again, I'm probably inclined to automatically explain things to a degree that most script writers couldn't even begin to conceive, so.... The MI series has a great deal of sciencelessness in general. I find it very amusing that the American pilot who got shot down and the Serbian colonel who shot him down are now great friends. It would take a long time to absorb enough energy from sunlight to do that. Like...for an average adult male to double his body mass, that means adding about 100 kg. 100 kg x (300,000,000 m/s)^2 = 9e18 J, which is 400+ Tsar Bombas or about 8 months of average United States energy consumption. With direct conversion of solar energy into matter and a fully-insolated body surface area of 3 square meters, it would take 79 billion years to absorb that much energy. Maybe Banner is just already really really dense in his normal human state.

Just an aside, but if you're looking at property, check for buried pipelines. Liquid is fine. Liquid might be very unpleasant if things go south, but it will be fine in the end. Gas is not fine. For Kerbol's sake stay the frack away from gas lines.

Eight times more massive with twice the radius is merely 2 gees. Would probably be fractionally higher because it would necessarily end up denser than Earth. Ought to still be able to support plant life, in theory. Different atmospheric makeup for sure...going to retain a lot more gas so it will be unlikely to have an atmospheric pressure anywhere near earth's at the surface. Though that's not necessarily a problem.

Well aware. But that is factoring in all possible deaths due to increased cancer probability assuming that there is no minimum threshold for risk. If you only factor in average US deaths then I think you get like 31 years of NYC's energy consumption without a death. And the only US deaths were directly tied to nuclear weapons programs, not nuclear power generation.

Yeah, a binary system allows for temporary full illumination, but you need a third or fourth star to get permanent complete illumination. You would definitely need to have an eccentric orbit somewhere. But if you have a nice 1:1 or 2:1 resonance going on, then you should be able to ensure full coverage. Let our sun be the first star, let earth be the second star, let our moon be the third star, and let a test mass orbiting earth represent the target planet. Place the test mass in an eccentric orbit with the apogee at 3x the Earth-moon distance and the perigee at roughly 2/3rds the Earth-moon distance, such that it has an orbital period of two months. If the semimajor axis points toward the Sun, such that the apogee is the nearest approach to the Sun, then the moon will complete two orbits for every one orbit of the test mass, always lining up at opposition precisely when the test mass is at apogee and opposition. If the primary is large and distant enough, then the resonant orbits will be kept in alignment with the primary because their period is so much lower. This is easier if the two tighter orbits are retrograde. Plus, if the masses and luminosities of the stars are correct, average insolation should remain roughly constant...perhaps with slight global seasons. The sizes, positions, and apparent brightness of the suns would change over time but not dramatically. Another question on planet formation inspired by DBZ: what's the highest surface gravity a naturally-formed terrestrial world could have? Assume it must still have a breathable atmosphere.

High-density atmosphere for refraction...I like it. If any of you don't know, the idea originally came from Namek in the DBZ series, where it is supposedly always daytime everywhere on the planet, and the planet has three suns (though only one or two are ever simultaneously visible, of course). Consider a binary between a sun-like star and a brown dwarf, where the brown dwarf has a high-albedo ice/water giant and a small terrestrial planet in moderately eccentric orbits. The sun-like star forces the argument of periapse for the two planets, which are in resonance so that the ice giant is at its apsis on the far side of the brown dwarf whenever the terrestrial planet is at its periapse on the far side of the planet.

Numbers are based on published figures for deaths per trillion kilowatt-hours, normalized to the average annual energy consumption of New York City. I used worldwide numbers, not US-specific numbers, so that inflated coal. Worldwide coal deaths are inflated 10x by adding in China's horrible coal-related death rate. But factoring in Chernobyl and Fukushima inflates worldwide nuclear-power deaths 100x compared to the US rate.

It's good to put it into terms people can understand. Let's say you want to give New York City a year of energy. 36.2 billion kilowatt-hours. Start with solar power. That year of energy will kill 16 people. How about natural gas? That's a little scary: New York's energy consumption in a year would kill 145 people. Oil is far worse. Provide energy with oil and its derivatives, and you'll kill 1,303 people. Coal...well, coal is the worst. To provide New York City with a year of energy in coal will kill 3,620 people. And nuclear power? One year of energy for New York City on nuclear power will kill 3 people.

Well, to be fair, I always thought the implication was that superman flew in a circle until he exceeded lightspeed, thus traveling backward in time and giving the illusion that the Earth was spinning in the opposite direction.

Reminded of Oblivion, where Tom Cruise has a single-person craft which uses a pair of jet engines for flying around on the ground, then apparently transforms into an ion engine of some kind to fly into space later on. He apparently achieves orbit (though it's possible that his target, the alien TET craft, is just hovering in space on antigrav or something). The G.I. Joe movie is also guilty of a subtler (but more prolific) error in films everywhere: iconic architecture pr0n. If there is a chase scene through a familiar city, you can guarantee that it will take you past every single iconic building in that city, regardless of whether it makes sense at all. The G.I. Joe movie had a chase scene in Paris that drove past the Arc de Triomphe, followed by Notre Dame, followed by the Eiffel Tower, even though those three landmarks are all in cardinal opposite parts of the town. Action movies show a general disregard for conservation of momentum. Vehicle collisions (particularly between unequal vehicles, like trains vs cars or a large boat vs a jet ski) will not obey any sort of momentum conservation and will result in vehicles or parts flying off in vectors completely foreign to the original momenta. This is also the case with near-misses; a jet plane will pass inches from impact with an object but not affect it at all, even though the air wash (or, in some cases, the jet exhaust) would either send it flying or rip it to shreds. Many times American films will use any Asian language, even when the characters don't match (for example, Korean for Japanese characters, or Chinese for Vietnamese characters). The effects of blasts on individuals is vastly understated. They act as though a bomb can fling you half a city block but as long as you land on something soft, you'll be fine. No, the acceleration caused by the blast is what would have turned you to oatmeal, regardless of where you landed.

I think it's too complicated an explanation. People's attention spans aren't that long, and while I automatically know what is meant by "higher" and "lower" energy radiation, most people don't. I think the concepts should be simplified, using terms closer to everyday use. For example... "Radiation is a term scientists use to describe any form of moving energy. Heat moving between two objects is a form of radiation. Light is a form of radiation. Electricity is a form of radiation. Relativistic particles in nuclear colliders are a form of radiation. Even waves on the surface of the ocean can be considered radiation. Most of the time, radiation refers to light or things like light, so that's what we'll be talking about here. "Obviously, not all radiation is dangerous, or we would all drop dead instantly. Whether a particular kind of radiation is dangerous depends on a relatively familiar factor: temperature. 'Hot' radiation will burn you; 'cold' radiation will not. "Most radiation we are exposed to is low-temperature radiation...radiation so 'cold' that no amount of it will ever be able to hurt you. Radios, computers, cellphones, and televisions all operate using radiation with a temperature far, far lower than the human body, so they have no chance of causing harm. "Slightly warmer radiation includes microwave radiation, infrared radiation, artificial lights, and sunlight. These are closer to the temperature of the human body, so they can burn you...but only if you are exposed to quite a lot. Cooking food in the microwave or going outside on a sunny day is basically the same process: you're exposing an object (the food, in the first case, or yourself in the second case) to a LOT of slightly-warm light. Too much, and you'll burn. However, burns from microwave, infrared, or sunlight affect only the surface of your body and cannot cause long-term harm. "Very hot radiation includes high ultraviolet, x-ray, gamma ray, and nuclear radiation. Very hot radiation is hot enough to burn away portions of individual atoms, which can cause cancer and death. Very hot radiation, also known as 'ionizing radiation', is the only thing you should worry about. "Surprisingly, there are sources of this 'hot radiation' all around us...but not from technology. Rather, most sources of hot radiation already exist in nature. Radon in the soil, potassium in bananas, ultraviolet sunlight, and even the carbon in your body produces hot radiation. Thankfully, however, the levels of hot radiation produced from such natural sources are very low...so low that your body will recover well before any permanent damage is done. "Just like a very hot stove is only dangerous if you touch it, very hot radiation is only dangerous if you are exposed to a lot of it. This can happen if you are very close to a very bright source of hot radiation, like a nuclear reactor. But just like you can touch a hot stove with an oven mitt and not be burned, you can be 'shielded' from hot radiation pretty easily. Sunscreen shields you from hot radiation in sunlight, while the lead casings around nuclear reactors shield scientists and technicians from the hot radiation in them. "Most sources of hot radiation are too dim to cause any harm, and the ones bright enough to cause harm are always kept tucked away in a safe place. Accidents with 'hot radiation' do happen, of course, but these are rare. Although using 'hot radiation' as a source of energy does carry some danger, accidents are so rare that it causes far less harm than energy sources like coal and natural gas."