SpaceX's DSN plans

[oldAtlas_Eguy]

NASA/SpaceX teleconfrence recently identified a new element of SpaceX near term plans. The development of its own Deep Space Network (DSN) capabilities.

http://forum.nasaspaceflight.com/index.php?topic=41231.0

That the SpaceX DSN would be operational after a couple (probably 2022 synod) of RD missions. No longer needing NASA's DSN to support SpaceX Mars missions. This capability of broadband communications with Mars has been scattered in other threads. But this I believe is the first indication that SpaceX actually has a plan for its own DSN. What we do not know at this time is what are the plans. Hopefully the IAC talk will also touch on this subject about how the Mars occupants will keep in touch with Earth. How the large communications data requirements of multiple near simultaneous Mars missions will be accomplished.

Speculation has been using orbital assets at Mars and Earth performing an optical Laser link and then a secondary RF link from Mars orbit to Mars assets in orbit and on the surface as well as an Earth orbit to Earth surface broadband link. Much of this is based on the "CommX" large constellation speculation as a communication model for implementation at Mars with the added Interplanetary links that connect into these broadband constellations at Mars and Earth.

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?

2) Orbital assets at Mars used for relays to Earth?

3) Will orbital assets be emplaced in Earth orbit?

4) How will the interplanetary broadband data requirements be met?

This thread will discuss the DSN aditional questions or speculations on the answers of questions related to the plans of a SpaceX developed DSN.

[philw1776]

Looking in the context of multiple RD missions leading to landing massive amounts of cargo on Mars before manned missions all in the next decade, I would be surprised if the architecture did not utilize higher BW optical for the links from Mars to Earth orbital optical receivers.  No need for big DSN radio antennas.  The problem of communicating when the Sun is in the way for a few weeks every 26 months would be addressed later before humans land.  Interesting options abound.

[guckyfan]

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?

I think none. Ground based assets would need dishes distributed all over earth. Like the NASA DSN. That's way too expensive.

2) Orbital assets at Mars used for relays to Earth?

I see a few sats, similar or identical to the planned small sats of the planned network in earth LEO.

3) Will orbital assets be emplaced in Earth orbit?

The planned 4000 satellite constellation. Maybe not the full number early on.

4) How will the interplanetary broadband data requirements be met?

Local satellites both in Mars and earth orbit. Laser communication between them for the interplanetary distance. Feeding into the local satellite network for ground contact.

[RonM]

5) How will SpaceX deal with communication blackouts during Mars solar conjunction.

It's one thing to not be able to communicate with robots for a couple of weeks, but it is another to lose communications with a colony.

[guckyfan]

5) How will SpaceX deal with communication blackouts during Mars solar conjunction.

Relay sats. The points easiest to reach from earth and to keep station in are Earth-Sun L4 and L5.

[whitelancer64]

5) How will SpaceX deal with communication blackouts during Mars solar conjunction.

It's one thing to not be able to communicate with robots for a couple of weeks, but it is another to lose communications with a colony.

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.

[ChrisC]

Just for anyone new to this, DSN = Deep Space Network.  OldAtlas_Eguy, edit into your first post above?

Also for anyone new to this, in case you haven't seen it yet, you have GOT to check out this live status of NASA's DSN system.  Click around, and don't miss the "more details" in the lower right. 

[guckyfan]

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.

Why do you favor Mars trailing over earth trailing? Earth trailing is much easier to reach.

[Robotbeat]

The interesting thing is that this is one of the only things we already have a good handle on when it come to Mars infrastructure, the other being orbital mapping.

The 2 week blackout is relatively easy to address, but it requires a fairly dedicated spacecraft at, say, ESL3 or 4. Probably could tolerate low bandwidth for a couple weeks, but some contact would be very useful.

The Mars relay network already in place will be upgraded to optical links with or without SpaceX before SpaceX's first crewed surface mission. SpaceX's own infrastructure will add to this, but it's interesting that they don't really need to add much more, besides the aforementioned relay sat.

My guess is a satellite or three around Mars and one for the blackout period would be more than sufficient.

[Lar]

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.

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.

[Robotbeat]

What WOULD be useful but isn't in place yet (other than experiments with existing relay sats) is a geolocation (areolocation) system. Doesn't have to be a full GPS-like constellation, but maybe something like the regional GNSS constellations by other nations. That'd help EDL and also make surface operations (especially robotic) much easier.

[oldAtlas_Eguy]

There is one aspect we are overlooking and that is the new emphasis by Musk and SpaceX on the Interplanetary aspects and not just Mars. Such would need a broadband DSN that can service interplanetary in general as well as Mars.

I see SpaceX's DSN effort as a broadband augmentation to the NASA DSN. Such that if everything is going normal no NASA DSN use is needed. But if a spacecraft looses contact the NASA DSN with its very powerful and sensitive receivers becomes a asset. This then allows the routine communication to be offloaded onto the SpaceX broadband DSN system which NASA could lease data bandwidth.

[DanielW]

There is one aspect we are overlooking and that is the new emphasis by Musk and SpaceX on the Interplanetary aspects and not just Mars. Such would need a broadband DSN that can service interplanetary in general as well as Mars.

I see SpaceX's DSN effort as a broadband augmentation to the NASA DSN. Such that if everything is going normal no NASA DSN use is needed. But if a spacecraft looses contact the NASA DSN with its very powerful and sensitive receivers becomes a asset. This then allows the routine communication to be offloaded onto the SpaceX broadband DSN system which NASA could lease data bandwidth.

I would not read too much into the interplanetary stuff. I read that as musk the overgrown child saying

"Sweet, The requirements for fast transit to Mars also fit the requirements for other destinations! How cool is that?"

I suspect that they will not go out of their way to enable other destinations specifically in the design unless it is really low hanging fruit that does not add cost or complexity.

[oldAtlas_Eguy]

There is one aspect we are overlooking and that is the new emphasis by Musk and SpaceX on the Interplanetary aspects and not just Mars. Such would need a broadband DSN that can service interplanetary in general as well as Mars.

I see SpaceX's DSN effort as a broadband augmentation to the NASA DSN. Such that if everything is going normal no NASA DSN use is needed. But if a spacecraft looses contact the NASA DSN with its very powerful and sensitive receivers becomes a asset. This then allows the routine communication to be offloaded onto the SpaceX broadband DSN system which NASA could lease data bandwidth.

I would not read too much into the interplanetary stuff. I read that as musk the overgrown child saying

"Sweet, The requirements for fast transit to Mars also fit the requirements for other destinations! How cool is that?"

I suspect that they will not go out of their way to enable other destinations specifically in the design unless it is really low hanging fruit that does not add cost or complexity.

In order to communicate to all those SpaceX spacecraft in transit they have to implement the general case of tracking and communicating with individual spacecraft. So to make it able to reach out further is a little more ERP (effective radiated power) and receiver gain. For optics a larger telescope. The more gain margin the better.

So yes interplanetary support is just another low hanging fruit not requiring different systems just more margins in required systems.

[guckyfan]

I doubt that SpaceX is planning to do anything like this. Their goal will remain Mars. If anyone wants to go elsewhere it is his responsibility to provide things like communications. In most cases they will fall back to the DSN.

[oldAtlas_Eguy]

I doubt that SpaceX is planning to do anything like this. Their goal will remain Mars. If anyone wants to go elsewhere it is his responsibility to provide things like communications. In most cases they will fall back to the DSN.

Probably. And even SpaceX for Mars would fall back to the NASA DSN for the non-normal communications cases. But for the normal high data rate case SpaceX would put in and use their own system because nothing exists to do that.

[ThereIWas3]

I don't know how many dishes the NASA DSN has but it is not a lot and they have to handle all of the still operating planetary missions.  If SpaceX builds its own dedicated Earth-Mars link system it can guarantee pretty much continuous coverage, with appropriate relays to handle the Sun plus planet rotations.

[ChrisC]

I don't know how many dishes the NASA DSN has

The answer is two clicks away, via a link I posted in a comment above.

Yes, they are busy, pretty much around the clock.  But it's getting quieter since just about all the New Horizons data from the Pluto flyby is finally down.  And a year or two from now it's going to get downright calm as Cassini and Juno both end their missions, resulting in ZERO missions at or even heading towards the outer giant planets.  Funding has consequences ...

[savuporo]

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?

For tracking and navigation, you need global continuous coverage, 3 dishes.

[guckyfan]

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?

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.