Quote from: savuporo on 09/23/2016 03:40 amQuote from: oldAtlas_Eguy on 09/22/2016 04:02 pm1) So what Earth ground assets are likely to be implemented? There is a effort at Boca Chica right now for moderate size dish emplacement. Is there likely a plan for even larger ones?For tracking and navigation, you need global continuous coverage, 3 dishes.The data can be fed into the planned internet sat constellation. No need for big ground stations anywhere. Just route them to where you need them and download with a pizza box sized device.
Quote from: oldAtlas_Eguy on 09/22/2016 04:02 pm1) So what Earth ground assets are likely to be implemented? There is a effort at Boca Chica right now for moderate size dish emplacement. Is there likely a plan for even larger ones?For tracking and navigation, you need global continuous coverage, 3 dishes.
1) So what Earth ground assets are likely to be implemented? There is a effort at Boca Chica right now for moderate size dish emplacement. Is there likely a plan for even larger ones?
Quote from: guckyfan on 09/22/2016 05:07 pmQuote from: whitelancer64 on 09/22/2016 04:33 pmI assume they would seriously consider a putting a relay satellite in a Mars-trailing orbit that would allow for comms relay around the sun during conjunction.Why do you favor Mars trailing over earth trailing? Earth trailing is much easier to reach.Even if the Earth local and Mars local ends are geosynch/areosynch, something has to deal with changing angles I think. If it's Earth trailing does that mean the Mars end has more angle change to deal with?Low orbit like CommsX would use makes this worse I think? If the planet/first sat links are radio at both ends, that means fewer moving parts I think, with rf beam steering. But how do you easily change laser beam angles without using moving parts? just musing out loud here.
Quote from: whitelancer64 on 09/22/2016 04:33 pmI assume they would seriously consider a putting a relay satellite in a Mars-trailing orbit that would allow for comms relay around the sun during conjunction.Why do you favor Mars trailing over earth trailing? Earth trailing is much easier to reach.
I assume they would seriously consider a putting a relay satellite in a Mars-trailing orbit that would allow for comms relay around the sun during conjunction.
I don't think you quite understand why Goldstone, Canberra and Madrid have 70m antennaes and what role do these things play in getting spacecraft going to where they need to be going.
Has laser communication been demonstrated at that distance yet?
How will optical communication systems cope with the generally (and sometimes *very*) dusty Martian atmosphere?
Quote from: Bob Shaw on 09/23/2016 09:16 amHow will optical communication systems cope with the generally (and sometimes *very*) dusty Martian atmosphere?At least I don't suggest laser communication from and to any planetary surface.My suggestion was for the interplanetary distance. With ground to orbit covered the way planned for the large array of small satellites.
Quote from: Lar on 09/22/2016 05:40 pmQuote from: guckyfan on 09/22/2016 05:07 pmQuote from: whitelancer64 on 09/22/2016 04:33 pmI assume they would seriously consider a putting a relay satellite in a Mars-trailing orbit that would allow for comms relay around the sun during conjunction.Why do you favor Mars trailing over earth trailing? Earth trailing is much easier to reach.Even if the Earth local and Mars local ends are geosynch/areosynch, something has to deal with changing angles I think. If it's Earth trailing does that mean the Mars end has more angle change to deal with?Low orbit like CommsX would use makes this worse I think? If the planet/first sat links are radio at both ends, that means fewer moving parts I think, with rf beam steering. But how do you easily change laser beam angles without using moving parts? just musing out loud here.Changing angles are required no matter if RF or optical... Earth rotation, eclipses, and orbital mechanics make moving parts and multiple lines of sight a feature of any system. GSO simplifies problem somewhat by mostly eliminating the eclipses. Both RF and Optical have high directionality requirements, RF to get the needed gain and laser on both ends to establish and maintain the link.
Quote from: savuporo on 09/23/2016 07:06 amI don't think you quite understand why Goldstone, Canberra and Madrid have 70m antennaes and what role do these things play in getting spacecraft going to where they need to be going.I don't think you quite understand how specific Mars communication with laser com sats from orbit to orbit will work.
Quote from: guckyfan on 09/23/2016 07:42 amQuote from: savuporo on 09/23/2016 07:06 amI don't think you quite understand why Goldstone, Canberra and Madrid have 70m antennaes and what role do these things play in getting spacecraft going to where they need to be going.I don't think you quite understand how specific Mars communication with laser com sats from orbit to orbit will work.I'm eager to learn though. I mean, how does a currently functioning laser relay network like European EDRS have any inputs to spacecraft navigation ?Specifically, without ground antennae and signal processing centers, how does one compute precise spacecraft velocity and location for example before and after mid-course trajectory correction maneuvers ?Did someone invent a replacement for Delta-DOR, which replaces DOR correlators , VLBI receivers and all the other equipment currently required for this ?
I was under the impression we are talking about high throughput data communications between earth and Mars.You are now talking about something else entirely. Something that I believe may need radio communication between spacecraft and the ground on earth with rather low throughput.
Quote from: savuporo on 09/23/2016 07:06 amI don't think you quite understand why Goldstone, Canberra and Madrid have 70m antennaes and what role do these things play in getting spacecraft going to where they need to be going.
Quote from: savuporo on 09/23/2016 04:20 pmQuote from: savuporo on 09/23/2016 07:06 amI don't think you quite understand why Goldstone, Canberra and Madrid have 70m antennaes and what role do these things play in getting spacecraft going to where they need to be going.So again, you have introduced an entirely new requirement into the discussion. My understanding remains that we are talking about a high speed data communications network between earth and Mars. You want to burden that with a totally different requirement. A sure way to increase cost and complexity while probably reducing capability.
So again, you have introduced an entirely new requirement into the discussion.
The NASA DSN is used track to spacecraft position and velocity for navigation. Unless SpaceX is planning to use something like the NASA test DSAC, the SpaceX DSN will also have to be able to track spacecraft for navigation.