All they say about it is that "it's against the laws of physics to take a 360 degree photo. That just seems odd.
You're right, they should have said 4 pi steradians instead of 360 degrees. They didn't explain their point very well. I assume they meant that the body of the camera, or the support, or the photographer/cameraman always block some part of the total sphere of vision.
DRM isn't that much a concern with a display device like an HDTV. It's more related to the players, recorders, and other set top boxes you connect to your TV. Admittedly DRM is sort of built in to the HDMI connection you use to pipe the digital output to your set. I believe only display devices can accept in incoming HDMI signal. DRM is performed by the source of the HDMI.
Have you heard of the NASA Deep Space Network? Every sat and probe we launch becomes part of NASA's network in space. That's why when they had communications problems with the Mars Rover, they were able to send reset commands from a probe heading elsewhere.
Did you even read the Wikipedia article you linked to? The Deep Space Network is an earth based network of large radio dishes that listen to deep space probes. It's not located in deep space. It's almost always easier to talk to a distant probe with a huge dish on earth than to try and use the small dish on another probe.
The closest thing to what you're discussing is NASA's TDRS system. That relays signals from earth orbiting satellites to the ground.
The article said: "The stars are packed into a disk that is just 1 light-year across".
So I guess I should have used a radius of half a light year. My mistake, I confused diameter with radius. That would make the gravity at the edge of the disk four times greater and the tidal forces eight times larger. That's still pretty insignificant.
I don't know whether that size agrees with the 1000 km/s mentioned. I haven't verified that the articles figures are internally consistent.
What keeps them from ripping apart from tidal forces is interests me.
If you crunch the numbers you'll find that tidal forces one light year from a galactic black hole are no problem.
TFA says the mass of the black hole is 140 million suns, but at 63,000 AU the gravity is only 1/30 that which the earth feels from the sun. And tidal forces work as the inverse cube of the distance, so they are 1.7 million times weaker than the solar tides on earth.
At that sort of distance tidal forces are only a problem for large diffuse clouds of gas.
For that matter, since event horizon size scales linearly with mass, the tidal forces at the event horizon of a galactic black hole are much gentler that a stellar black hole's. It would probably rip a star apart, but I seem to recall it's survivable by small objects like ships and probes.
Hubble's law says the universe as a whole is expanding. However locally things can be approaching each other. On a cosmological scale the Andromeda galaxy is local to us, part of the Local Group actually.
So you see, at 2.9 million light years away the Andromeda galaxy is too close for Hubble's law to apply.
Well, all the engines don't fire all the way to orbit. The SRBs are sort of half a stage since they separate early in the process.
But I agree that all engines firing in parallel at launch is a good thing. If any of the SSMEs fail to start, the launch is scrubbed. That increases reliability over traditional staging. A second stage engine failing to ignite can be a real nasty surprise.
Admittedly, you pay a penalty in hauling more tankage and engine mass to orbit than a true second or third stage would. But trading off efficiency for reliability can be a good exchange.
As far as I can tell, the SSME has to be the most complicated rocket engine ever designed. Using the older and simplier J-2S should significantly reduce costs and improve reliability.
I'd agree. The SSME has the design constraint of operating from sea level pressure to vacuum. Thus it runs at a very high pressure, which complicates things. Rocket motors designed to operate at altitude can be made simpler and more reliable.
If its not on the first stage it doesn't need to be a SSME, and it probably shouldn't be.
Exactly. NASA press releases are written by public relations experts, not scientists. One suspects they play up the "confusion" of the real scientists, in order to make the missions sound more exciting to the general public. Headlines like "Nothing New Seen" or "Unexpected Finding Immediately Explained" just don't attract much attention.
Also, "baffled scientists" may be the PR way of saying that the scientists are still arguing over the exact explanation of what they seen. They may well have some egotistical plasma physicist telling them he can explain everything with plasma fluid dynamics. At the same time the other specialists are all arguing that their discipline best explains things. It's the nature of humans to try and fit everything into your own world view, but science means having to prove it.
I think Rutan wants to say clear of as much government interference and regulation as possible. It can be a killer for independent launch companies. Moving outside the US is not the answer, because the government tightly controls the transfer of rocketry technology even to friendly allies. Launching from Equador would involve too much red tape, if it could be done at all.
Consider that an ICBM is simply a sub-orbital rocket with a dangerous payload, and you begin to realize why governments are so touchy about the export of this technology.
One of the things that make the shuttle main engines so complex is their design criterion of working from sea level to orbit. That necessitates a very high pressure engine. Launching from high altitude makes engine design much easier. If you drop the use of liquid hydrogen, it gets easier still. Still, you will need something quite different from SS1's hybrid, and likely more complicated. But the complexity of a shuttle SSME isn't required for reaching orbit, plenty of simpler rocket engines have done that.
"I'm not certain, and I didn't google it, but I don't think any craft has achieved orbit from a piggyback launch. Has that ever happened?"
Google for Orbital's Pegasus rocket:
"First air-launched rocket to place satellites into orbit, using its carrier aircraft as an 'air breathing reusable first stage'"
Good point. An expendable single stage rocket wouldn't be that hard to do. And while it wouldn't have as large a payload fraction as a multistage design, that only makes it less efficient in terms of launch mass or fuel. The really important metrics are complexity, parts count, failure modes, and expense. Staging drives up all of those, which is why single stage is so attractive, even if it isn't "efficient".
Of course, whenever anyone says Single Stage to Orbit, they invariably mean reusable. That makes the problem a whole lot harder, and it remains to be seen whether it's possible at all.
The circulars you refer to are done with such frequency because they are cost effective. Now, you may throw them away, but at least 15 - 20% of the people who receive those mailings respond with a purchase of goods or services.
I've always wondered who really profits from those circulars. I've heard stories of small printing shops making little to no profit off printing them, and of small businesses convinced to advertise and getting no response. I suspect that it is the middleman that profits, as always, the ad agency that puts it all together. Or maybe the local business, printer and ad agency are all struggling to just barely get by. Because I don't think there is a whole lot of money to be made off that sort of thing.
But that completely ignores isotopes. There are naturally occurring isotopes of both hydrogen and helium that have three neutrons, thus do differ only by a proton. It's the proton count that determines what element it is, the number of neutrons really only decides it's stability.
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All they say about it is that "it's against the laws of physics to take a 360 degree photo. That just seems odd.
You're right, they should have said 4 pi steradians instead of 360 degrees. They didn't explain their point very well. I assume they meant that the body of the camera, or the support, or the photographer/cameraman always block some part of the total sphere of vision.
DRM isn't that much a concern with a display device like an HDTV. It's more related to the players, recorders, and other set top boxes you connect to your TV. Admittedly DRM is sort of built in to the HDMI connection you use to pipe the digital output to your set. I believe only display devices can accept in incoming HDMI signal. DRM is performed by the source of the HDMI.
Have you heard of the NASA Deep Space Network? Every sat and probe we launch becomes part of NASA's network in space. That's why when they had communications problems with the Mars Rover, they were able to send reset commands from a probe heading elsewhere.
Did you even read the Wikipedia article you linked to? The Deep Space Network is an earth based network of large radio dishes that listen to deep space probes. It's not located in deep space. It's almost always easier to talk to a distant probe with a huge dish on earth than to try and use the small dish on another probe.
The closest thing to what you're discussing is NASA's TDRS system. That relays signals from earth orbiting satellites to the ground.
The article said: "The stars are packed into a disk that is just 1 light-year across".
So I guess I should have used a radius of half a light year. My mistake, I confused diameter with radius. That would make the gravity at the edge of the disk four times greater and the tidal forces eight times larger. That's still pretty insignificant.
I don't know whether that size agrees with the 1000 km/s mentioned. I haven't verified that the articles figures are internally consistent.
What keeps them from ripping apart from tidal forces is interests me.
If you crunch the numbers you'll find that tidal forces one light year from a galactic black hole are no problem.
TFA says the mass of the black hole is 140 million suns, but at 63,000 AU the gravity is only 1/30 that which the earth feels from the sun. And tidal forces work as the inverse cube of the distance, so they are 1.7 million times weaker than the solar tides on earth.
At that sort of distance tidal forces are only a problem for large diffuse clouds of gas.
For that matter, since event horizon size scales linearly with mass, the tidal forces at the event horizon of a galactic black hole are much gentler that a stellar black hole's. It would probably rip a star apart, but I seem to recall it's survivable by small objects like ships and probes.
What implications does Hubbles law have for this?
Hubble's law says the universe as a whole is expanding. However locally things can be approaching each other. On a cosmological scale the Andromeda galaxy is local to us, part of the Local Group actually.
So you see, at 2.9 million light years away the Andromeda galaxy is too close for Hubble's law to apply.
Well, all the engines don't fire all the way to orbit. The SRBs are sort of half a stage since they separate early in the process.
But I agree that all engines firing in parallel at launch is a good thing. If any of the SSMEs fail to start, the launch is scrubbed. That increases reliability over traditional staging. A second stage engine failing to ignite can be a real nasty surprise.
Admittedly, you pay a penalty in hauling more tankage and engine mass to orbit than a true second or third stage would. But trading off efficiency for reliability can be a good exchange.
As far as I can tell, the SSME has to be the most complicated rocket engine ever designed. Using the older and simplier J-2S should significantly reduce costs and improve reliability.
I'd agree. The SSME has the design constraint of operating from sea level pressure to vacuum. Thus it runs at a very high pressure, which complicates things. Rocket motors designed to operate at altitude can be made simpler and more reliable.
If its not on the first stage it doesn't need to be a SSME, and it probably shouldn't be.
In Soviet Russia, Linux runs Lunar Penguin.
Wait... that actually makes sense. Nevermind.
Also, "baffled scientists" may be the PR way of saying that the scientists are still arguing over the exact explanation of what they seen. They may well have some egotistical plasma physicist telling them he can explain everything with plasma fluid dynamics. At the same time the other specialists are all arguing that their discipline best explains things. It's the nature of humans to try and fit everything into your own world view, but science means having to prove it.
Consider that an ICBM is simply a sub-orbital rocket with a dangerous payload, and you begin to realize why governments are so touchy about the export of this technology.
One of the things that make the shuttle main engines so complex is their design criterion of working from sea level to orbit. That necessitates a very high pressure engine. Launching from high altitude makes engine design much easier. If you drop the use of liquid hydrogen, it gets easier still. Still, you will need something quite different from SS1's hybrid, and likely more complicated. But the complexity of a shuttle SSME isn't required for reaching orbit, plenty of simpler rocket engines have done that.
"I'm not certain, and I didn't google it, but I don't think any craft has achieved orbit from a piggyback launch. Has that ever happened?" Google for Orbital's Pegasus rocket: "First air-launched rocket to place satellites into orbit, using its carrier aircraft as an 'air breathing reusable first stage'"
Good point. An expendable single stage rocket wouldn't be that hard to do. And while it wouldn't have as large a payload fraction as a multistage design, that only makes it less efficient in terms of launch mass or fuel. The really important metrics are complexity, parts count, failure modes, and expense. Staging drives up all of those, which is why single stage is so attractive, even if it isn't "efficient". Of course, whenever anyone says Single Stage to Orbit, they invariably mean reusable. That makes the problem a whole lot harder, and it remains to be seen whether it's possible at all.
I've always wondered who really profits from those circulars. I've heard stories of small printing shops making little to no profit off printing them, and of small businesses convinced to advertise and getting no response. I suspect that it is the middleman that profits, as always, the ad agency that puts it all together. Or maybe the local business, printer and ad agency are all struggling to just barely get by. Because I don't think there is a whole lot of money to be made off that sort of thing.
But that completely ignores isotopes. There are naturally occurring isotopes of both hydrogen and helium that have three neutrons, thus do differ only by a proton. It's the proton count that determines what element it is, the number of neutrons really only decides it's stability.