Author Topic: SpaceX and DSN  (Read 5831 times)

Offline rockets4life97

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SpaceX and DSN
« on: 03/18/2018 12:12 pm »
The Deep Space Network needs updating and budget cuts are making ongoing maintenance difficult [1].

SpaceX will need deep space communications for future missions. Will SpaceX build its own dishes around the world? Would they be able to funnel money to DSN through a foundation? How will (or should) SpaceX accomplish this task?


[1] Welcome to the Center of the Universe, Longreads, March 2018.

Online docmordrid

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Re: SpaceX and DSN
« Reply #1 on: 03/18/2018 12:47 pm »
The speculations I've read centered around modding their StarLink birds for use around Mars, and (IIRC) using laser relay satellites stationed at Sun-Mars L1, L4 and L5.
« Last Edit: 03/18/2018 12:50 pm by docmordrid »
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Offline AncientU

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Re: SpaceX and DSN
« Reply #2 on: 03/18/2018 01:24 pm »
Or Sun-Earth L4/5.
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Online S.Paulissen

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Re: SpaceX and DSN
« Reply #3 on: 03/18/2018 01:39 pm »
The Deep Space Network needs updating and budget cuts are making ongoing maintenance difficult [1].

SpaceX will need deep space communications for future missions. Will SpaceX build its own dishes around the world? Would they be able to funnel money to DSN through a foundation? How will (or should) SpaceX accomplish this task?


[1] Welcome to the Center of the Universe, Longreads, March 2018.

It seems pretty obvious to me that they should build the infrastructure themselves and donate the built infrastructure for 1/5th the price* NASA procurement could generate the same capabilities.

*Wild guess, but likely conservative IMO.
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Offline AncientU

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Re: SpaceX and DSN
« Reply #4 on: 03/18/2018 01:45 pm »
The Deep Space Network needs updating and budget cuts are making ongoing maintenance difficult [1].

SpaceX will need deep space communications for future missions. Will SpaceX build its own dishes around the world? Would they be able to funnel money to DSN through a foundation? How will (or should) SpaceX accomplish this task?


[1] Welcome to the Center of the Universe, Longreads, March 2018.

It seems pretty obvious to me that they should build the infrastructure themselves and donate the built infrastructure for 1/5th the price* NASA procurement could generate the same capabilities.

*Wild guess, but likely conservative IMO.

The SpaceX needs will be for high bandwidth communications with Mars... this can only be enabled by laser comms with significant aperture telescope collectors.  They have indicated that they will build it, but why 'donate' it -- at whatever price?  They will need it to carry increasing amounts of traffic.  If NASA or anyone else needs to transfer data, buy a subscription like any other commercial customer.
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Online docmordrid

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Re: SpaceX and DSN
« Reply #5 on: 03/18/2018 01:58 pm »
I wonder if they'd implement NASA's Delay/Disruption Tolerant Network protocol?

https://www.nasa.gov/content/dtn

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Offline speedevil

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Re: SpaceX and DSN
« Reply #6 on: 03/18/2018 02:50 pm »
Starlink will have several thousand orbiting satellites sometime 'soon'. (before optimistic departure dates for Mars.)

These contain, according to the original application, and perhaps confirmed by hardware shown in the PAZ launch several 6" telescopes to do LASER comms.

A thousand may also be in a position to do a residual radio beam.

Naive calculations of sqrt(1000) lead to at least the possibility to get more or less nominal radio service out to near GEO with no additional hardware. Much beyond this is very questionable - though depending on design, and dedicating a few satellites, the moon might be doable. (here I'm assuming that the satellites can cooperatively beamform - this is at least a stretch).

LASER may work better.
The 6" telescopes designed for inter-sat comms, at ranges of perhaps a thousand kilometers have such a high bitrate that making reasonable assumptions, it is plausible at least you may get a kilobit signal clear to Mars, to a similar receiver.

However, scaling helps lots.
Launch 20 starlink bus satellites, with a 50cm class scope, not 15cm, make limited changes other than software and put some similar receiver on the other end, and you've gotten several megabits/s to Mars.

There is no particular reason to stick to 50cm other than you can likely put it on the Starlink satellite with minimal modifications as it is of a comparable mass to the original payload. (HIRISE was 68kg).

Going into the future, if you are planning on landing BFS on Mars, and take some satellites along with you, you can have several of these long-range mirror sats, all capable of talking directly to earth at a few megabits/s. (If you drop the satellites after a first aerobraking pass into near LMO, they need only circularise, and you may sacrifice no landing mass)

These may also be able to do double duty as reconnisance satellites, and can let normal Starlink access points work on Mars.

And - well - if you go a little up from 50cm, and make a more custom satellite (co-orbiting with a Starlink sat), you can get gigabits to Mars.



Offline abaddon

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Re: SpaceX and DSN
« Reply #7 on: 03/18/2018 04:22 pm »
It seems pretty obvious to me that they should build the infrastructure themselves and donate the built infrastructure for 1/5th the price* NASA procurement could generate the same capabilities.

*Wild guess, but likely conservative IMO.
Is this sarcasm?  I'm guessing not based on the last statement.

Assuming not, what in the world makes you think SpaceX has any idea how to build large Earth-based transmitters/receivers, let alone at a competitive price with manufacturers who specialize in that field?

The idea of space-based relays makes a little more sense, although my gut feeling is using Starlink laser comms designed for small LEO satellites at very short distances wouldn't work at all for planetary distances.  You'd want a specialized satellite that could link in with the LEO constellation but had purpose-designed and built communications linking to Mars.

That still doesn't obviate the ongoing need for a robust DSN, which is IMO often brushed over in this section...

Offline rockets4life97

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Re: SpaceX and DSN
« Reply #8 on: 03/18/2018 05:20 pm »
Let me make sure I understand the commentary above:

If you have satellites in orbit to relay the signal, there isn't a need for the large ground based antennas used by DSN?

Online docmordrid

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Re: SpaceX and DSN
« Reply #9 on: 03/18/2018 05:30 pm »
Let me make sure I understand the commentary above:

If you have satellites in orbit to relay the signal, there isn't a need for the large ground based antennas used by DSN?

Not if your Mars-end relay sats are transmitting to similar relay sats in Earth orbit. Those can then hook up to the StarLink birds.
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Offline Roy_H

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Re: SpaceX and DSN
« Reply #10 on: 03/18/2018 05:37 pm »
Let me make sure I understand the commentary above:

If you have satellites in orbit to relay the signal, there isn't a need for the large ground based antennas used by DSN?

That's the way I read it. And with laser communication to Mars, you don't have to worry about cloud cover. I would assume that the Mars relay satellite(s) would be in orbit somewhat above GEO and only require one or two satellites. Looking farther into the future I would expect 2 relay satellites in an orbit around the sun so communication would be uninterrupted when Earth and Mars were on opposite sides of the sun.
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Online philw1776

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Re: SpaceX and DSN
« Reply #11 on: 03/18/2018 07:28 pm »
Let me make sure I understand the commentary above:

If you have satellites in orbit to relay the signal, there isn't a need for the large ground based antennas used by DSN?

That's the way I read it. And with laser communication to Mars, you don't have to worry about cloud cover. I would assume that the Mars relay satellite(s) would be in orbit somewhat above GEO and only require one or two satellites. Looking farther into the future I would expect 2 relay satellites in an orbit around the sun so communication would be uninterrupted when Earth and Mars were on opposite sides of the sun.

Musk has said that very thing when talking about communicating with Mars when one of the Earth-Mars pair is near to behind the sun in relative position.  Relay satellites in solar orbit.  Obvious that he has been thinking about the issue and problems.  Why wouldn't SpaceX set up their own high bandwidth (laser) Mars comm system? Probably one of the easier tasks supporting Mars exploration given the company's expanding skill sets.
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Online guckyfan

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Re: SpaceX and DSN
« Reply #12 on: 03/18/2018 07:39 pm »
Of course this won't be a DSN. It will be a Mars specific setup. The DSN can still do its function of connecting to all the deep space probes elsewhere.

Offline speedevil

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Re: SpaceX and DSN
« Reply #13 on: 03/18/2018 08:47 pm »
Of course this won't be a DSN. It will be a Mars specific setup. The DSN can still do its function of connecting to all the deep space probes elsewhere.

Well...
Once you have an existing network of receivers around Earth, Mars, and possibly L4, a nice debugged LASER comms system that works to those receivers, deciding to put a copy of that onto your probe to Jupiter or Saturn, and accepting the bandwidth hit may be quite reasonable.
It's going to take upgrades to work to Uranus or beyond.

Offline ThereIWas3

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Re: SpaceX and DSN
« Reply #14 on: 03/18/2018 09:06 pm »
Putting the deep space relays on the Moon, linked by laser to the Earth-orbiting cloud, gives you a very stable platform on a body that rotates quite slowly compared to Earth, no pesky atmosphere, and plenty of surface to deploy solar collectors for power.  That, along with a major far-side radio telescope, are major activities that a permanent Moon base could support.
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Offline su27k

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Re: SpaceX and DSN
« Reply #15 on: 03/19/2018 02:22 am »
Previous discussion on this: https://forum.nasaspaceflight.com/index.php?topic=41240.0

It looks like one aspect need to be emphasized is DSN is not just for communication, but also for navigation.

Online docmordrid

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Re: SpaceX and DSN
« Reply #16 on: 03/19/2018 03:31 am »
>
It looks like one aspect need to be emphasized is DSN is not just for communication, but also for navigation.

With XNAV (X-ray pulsar navigation) being developed by NASA (NICER, SEXTANT), China (XPNAV 1) and ESA will that still be necessary in a few years?
 
Paper....(PDF)
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Offline Asteroza

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Re: SpaceX and DSN
« Reply #17 on: 03/19/2018 07:00 am »
The new TDRSS sat refresh was considering lasercomm telescopes (currently only one lasercomm per sat though) for a hybrid RF/lasercomm setup.

MIT study was suggesting next gen TDRSS be RF only, and use commercial services for optical, especially in light of lasercomm beyond earth.


Online guckyfan

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Re: SpaceX and DSN
« Reply #18 on: 03/19/2018 09:30 am »
Well...
Once you have an existing network of receivers around Earth, Mars, and possibly L4, a nice debugged LASER comms system that works to those receivers, deciding to put a copy of that onto your probe to Jupiter or Saturn, and accepting the bandwidth hit may be quite reasonable.
It's going to take upgrades to work to Uranus or beyond.

That assumes a new generation of deep space probes. Assuming they start developing them in a few years with new budgets they can fly in 10-20 years. But even only switching Mars to the new system should provide a lot of relief for the DSN. Much of the data stream comes from Mars.

Offline AncientU

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Re: SpaceX and DSN
« Reply #19 on: 03/19/2018 09:56 am »
Previous discussion on this: https://forum.nasaspaceflight.com/index.php?topic=41240.0

It looks like one aspect need to be emphasized is DSN is not just for communication, but also for navigation.

With laser sats in GSO, L4 or 5, and Mars, solar system navigation will be vastly more precise than with the DSN.
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