Quote from: savuporo on 10/16/2015 07:14 amQuote from: Semmel on 10/16/2015 06:57 amJust out of curiosity, why does the distance influence the data rate?You mean why does inverse square law affect link budget ?I dont know what you mean by link budget, but yeah. Double distance, 1/4th of the energy arrives. But the data is a modulated signal, either in wavelength (radio) or brightness (laser). Why does the distance i.e. power of the signal influence the rate at which one can make bright and dark segments in the stream? Is the signal so weak that you need to integrate the light on the detector longer just to get above the noise floor? I think I just answered my own question...
Quote from: Semmel on 10/16/2015 06:57 amJust out of curiosity, why does the distance influence the data rate?You mean why does inverse square law affect link budget ?
Just out of curiosity, why does the distance influence the data rate?
I am pretty sure that laser communication links use phase modulation, not on-off modulation.
What solution would SpaceX use to get past the Sun blocking the straight-line path between Earth and Mars?
Also, what is the minimum and maximum data latency that would be experienced on Mars? (I understand that a local backup of most the internet would be needed for instant access to many of the things we take for granted).
A relay at Earth- or Mars-Sun Lagrange point 3 or 4.
I would say that this is actually very speculative at this point. We don’t have a lot of effort going into that right now.Certainly I think that from a technical perspective this could get done. But can we develop the technology and roll it out with a lower-cost methodology so that we can beat the prices of existing providers like Comcast and Time Warner and other people? It’s not clear that the business case will work.
Looks like it isn't happening - for now.Quote from: Shotwell I would say that this is actually very speculative at this point. We don’t have a lot of effort going into that right now.Certainly I think that from a technical perspective this could get done. But can we develop the technology and roll it out with a lower-cost methodology so that we can beat the prices of existing providers like Comcast and Time Warner and other people? It’s not clear that the business case will work.http://spacenews.com/spacex-president-downplays-commitment-to-building-broadband-constellation/
Quote from: Robotbeat on 10/27/2015 02:07 amA relay at Earth- or Mars-Sun Lagrange point 3 or 4.That's L4 or L5; L3 is in line with sun on opposite side from planet, so doesn't help with problem.A pair of relay satellites at Earth/Sum L4 and L5 (at about 1AU from Earth each) would provide continuous coverage to Mars.
Keep in mind, swarms of non-synchronous satellites around Mars preclude a space elevator from ever being built there. Eventually their paths do meet.Ya can't have both!
The connection would be satellite type. They would use the same kind of satellite over Mars as the internet constellation over earth. Also dedicated satellites at Mars and Earth could do interplanetary connection and feed locally into the internet constellation for downlinking without need of a network of ground stations around earth. At least I think they could do it that way.
Who says it isn't happening?
The connection would be satellite type. They would use the same kind of satellite over Mars as the internet constellation over earth.