101–110 of 197 posts
Earlier quoted context omitted.
Super fast compute, but awful ping…
To put it into perspective: https://solarsystem.nasa.gov/moons/saturn-moons/titan/overvi... According to this (at the time of reading) a one way trip at the speed of light is ~75 minutes, so you will have approximately two and a half hours of ping. Ouch. Still, it raises an interesting question: how would a hypothetical Earth-Titan network protocol work?
Earlier quoted context omitted.
Super fast compute, but awful ping…
To put it into perspective: https://solarsystem.nasa.gov/moons/saturn-moons/titan/overvi... According to this (at the time of reading) a one way trip at the speed of light is ~75 minutes, so you will have approximately two and a half hours of ping. Ouch. Still, it raises an interesting question: how would a hypothetical Earth-Titan network protocol work?
Earlier quoted context omitted.
From a scientific standpoint, there's really no value in downlinking video as opposed to still images. It costs several multiples worth of scarce downlink bandwidth, for a tiny gain in what there is to see of the same rocks at slightly different angles. Same reason we didn't have New Horizons at Pluto or the various Mars rovers do any video.
Why is bandwidth so scare still? Satellites in geosynchronous orbit on earth can do terabit/sec of total capacity now. Obviously latency is going to be extremely high, but I can't really understand why data rates are still so low?
Latency is high, but the power you have to pump through an antenna / laser to get enough watts on the receiver goes up really fast with distance.
Here's a summary that touches on it if you'd like to learn more: http://www.qrg.northwestern.edu/projects/vss/docs/Communicat...
And here's a detailed derivation for voyager. https://space.stackexchange.com/questions/24338/how-to-calcu...
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I mean sure, eventually, over many down link cycles. But not real time.
Space travel just makes it utterly clear there is on such thing as real time. Computing is constantly running up against the speed of light.
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Naively, a round trip requires twice the delta-v, which means you need to launch with a lot more than twice the fuel. Maybe they could produce more fuel and oxidizer in situ, and maybe Earth is a more attractive target for aerocapture, and maybe gravity assists line up better one way or the other, but it's not a bad starting point to assume a round trip is far more expensive than a one-way trip. I'm not sure on what…
Yeah that was my thinking. And I didn't have a basis for thinking it could get there in the first place which is why I asked the initial question. I didn't realize just how high the delta v requirements were for Saturn.
It is an interesting question for sure, especially given that one of the stated goals for Starship (IIRC) is to enable exploration of the outer planets.
Earlier quoted context omitted.
From a scientific standpoint, there's really no value in downlinking video as opposed to still images. It costs several multiples worth of scarce downlink bandwidth, for a tiny gain in what there is to see of the same rocks at slightly different angles. Same reason we didn't have New Horizons at Pluto or the various Mars rovers do any video.
Why is bandwidth so scare still? Satellites in geosynchronous orbit on earth can do terabit/sec of total capacity now. Obviously latency is going to be extremely high, but I can't really understand why data rates are still so low?
Earlier quoted context omitted.
I'm confused by your comment. this is absolutely a NASA mission, subject to all the whims of congress that any other is. APL has long bid on missions and instrument proposals just like other institutions.
Its just a statement of fact. NASA likely wouldnt even have revisited this moon without the European probe taking pictures under the atmosphere It is nice that multiple public sector agencies worldwide are doing space travel now
Earlier quoted context omitted.
From a scientific standpoint, there's really no value in downlinking video as opposed to still images. It costs several multiples worth of scarce downlink bandwidth, for a tiny gain in what there is to see of the same rocks at slightly different angles. Same reason we didn't have New Horizons at Pluto or the various Mars rovers do any video.
Why is bandwidth so scare still? Satellites in geosynchronous orbit on earth can do terabit/sec of total capacity now. Obviously latency is going to be extremely high, but I can't really understand why data rates are still so low?
Earlier quoted context omitted.
From a scientific standpoint, there's really no value in downlinking video as opposed to still images. It costs several multiples worth of scarce downlink bandwidth, for a tiny gain in what there is to see of the same rocks at slightly different angles. Same reason we didn't have New Horizons at Pluto or the various Mars rovers do any video.
Why is bandwidth so scare still? Satellites in geosynchronous orbit on earth can do terabit/sec of total capacity now. Obviously latency is going to be extremely high, but I can't really understand why data rates are still so low?
That received signal strength is what determines channel capacity (C) which is the upper limit on the bit rate you can get.
see Friis and Shannon's channel capacity
[0] https://en.wikipedia.org/wiki/Friis_transmission_equation
[1] https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theore...
Earlier quoted context omitted.
Super fast compute, but awful ping…
To put it into perspective: https://solarsystem.nasa.gov/moons/saturn-moons/titan/overvi... According to this (at the time of reading) a one way trip at the speed of light is ~75 minutes, so you will have approximately two and a half hours of ping. Ouch. Still, it raises an interesting question: how would a hypothetical Earth-Titan network protocol work?
http://ipnsig.org/wp-content/uploads/2015/05/Whats-new-in-IO...