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I don't know why people are automatically assuming you could just do this with off the shelf starlink sats instead. There's a huge difference between an optical

I don't know why people are automatically assuming you could just do this with off the shelf starlink sats instead. There's a huge difference between an optical link in LEO that goes a couple 100 km, and the moon which is nearly 400,000 km away. The link has to be bidirectional and I don't see how existing starlink sats would have anything close to the optics or antennas required for that. Let's not turn enthusiasm for starlink into poo poo-ing all over any other plan for something in space. The ESA just wants concept studies on what might work. That's perfectly reasonable.

_Microft 5y ago
There are only two comments mentioning Starlink, one of which is mine. As the other one does not go into details, your comment seems to be talking about mine and seems to be based on a misunderstanding of what I wrote. Feel free to ask if there is still something unclear after reading it more closely.
- jasonwatkinspdx 5y ago
  If I wanted to reply to you directly I would have. I did not precisely because I was hoping to avoid defensiveness from any particular poster. That said the logical place to put your relay would be L1, which is still some 60,000 km from the moon. It's not at all clear that off the shelf Starlink sats would be capable of communicating that distance from their orbit over the moon. You'd also need the earth side of the relay, which also clearly cannot be the existing Starlink cluster. They'd be foolish to not consider a Starlink derived design or SpaceX as a vender, but I don't think this can be done as inexpensively and quickly as your comment suggests.
  - labster 5y ago
    Maybe Starlink with a single ground station? I know landing makes it so much more complicated, but those Starlinks can communicate back to the station on the lunar surface easily, and the station stays pointing towards Earth on the near side. SPOF though.
    - jasonwatkinspdx 5y ago
      That's an interesting idea imo. You'd need to solve the earth side of the link too. The current NASA et all network is massively oversubscribed.
  - _Microft 5y ago
    Throwing subpar ideas out of the window is part of the process, so no worries about my feelings. I'll just outline the thoughts that went into my other post if you are interested in critizing them. I had also briefly considered a relay at the closest Lagrange point but came to the same conclusion as you did. Namely that off-the-shelf Starlink satellites might not be able to communicate with it which just means: it's not the solution. So let us consider a (few) separate relay satellite(s) [*] after quickly dismissing lunar ground stations: a lunar relay ground station might have the advantage of always being in sight of Earth but has the considerable disadvantage of having to live through lunar nights. This is highly impractical and would incur considerable complexity by requiring e.g. a RTG power source instead of using solar power as sats would do. So on-shell non-Starlink satellite relays it is for now. If there is more than one relay, any orbit might be fine [**]. If it really had to be a single relay satellite for some reason, a polar lunar orbit might be a possible solution that does not suffer from regular communications blackouts. Another solution might be to relax the requirement of having a continuous connection between the single relay satellite and Earth and to accept to be offline for a fraction of the orbit (at an orbital height of ~500km above Moon('s equator) a satellite would disappear behind Moon for a bit over a quarter of its orbital period), so if approximately 73% availability is fine, this would also work. Higher inclinations improve this value. One more thing because this also seemed unclear: at no point are Earth's Starlink satellites involved. All moving of data between Earth and Moon happens between the dedicated relay satellite(s) and a ground station on Earth, as this is the setup that NASA used for its laser optical communications test that I linked to from my other posting. All in all, that means that (under the assumption that Starlink satellites can operate under the conditions around Moon (it lacks Earth's protective magnetic field!)), that a few dedicated and custom-made relay satellites would all that is needed to use (my opinion:) dirt-cheap run-of-the-mill Starlink satellites for a constellation around Moon. Any thoughts on this? [*] Maybe even a few of them as material is cheap but engineers are expensive. If you can build one thing, you can usually build a second/third/n-th of it for less per-unit costs than the previous (with diminishing savings between each). [**] As stated in another post, I would rather expect the constellation to be in higher than in lower orbits so that fewer satellites would be needed to cover the same area on ground. This means that lunar mascons should not be of concern and even if they were, the satellites would still have ion thrusters to compensate for that.
kiba 5y ago
I don't understand why we need concept studies? It's not like we're doing anything particularly new. It's just engineering.
- robertlagrant 5y ago
  Perhaps some vital ontology definitions, process mapping, and enterprise architecture will need to be done.
  - slownews45 5y ago
    The EU has 22+ languages and most studies and results have to be translated. EU Charter of fundamental rights (art. 22) and in the Treaty on European Union (art. 3(3) TEU). So the EU is a pretty good spot for translators. Britan is not part of the EU, but outside of the official stuff, English is used in a lot of practical areas for technical work.
  - morelisp 5y ago
    This is a deep cut I expect will go over the heads of a lot of non-EU residents (though "enterprise architecture" might still clue them in). I was shocked to find RDF-era ontology "research" - already rightly a joke in my US-based undergraduate AI courses in 2003 - going on en masse when I moved to the EU in 2011. I've gotten four job applications so far this year from people with MSc in whatever ontology trash their local university was doing.
    - nradov 5y ago
      Ontology research is still relevant in the healthcare field. We need better ways to assign codes to the discrete elements of patient records in order to deliver better care and allow for effective data analysis.
      - robertlagrant 5y ago
        Oh yes. SNOMED, ICD, etc etc. Can't have too many standards!
dougmwne 5y ago
I'm quite interested if orbiting satellites could handle the backhaul connection to Earth or if larger and more powerful ground stations or a Lagrange station would have a place. Clearly we communicate just fine with existing Mars and deep space probes, but the problem must change enormously when you want a 100 gigabit uninterruptible connection.
notahacker 5y ago
Even weirder to pooh-pooh government funded concept studies when SpaceX is literally the poster company for governments chucking money at private enterprises to come up with innovative new solutions to variants of space problems with already existent solutions (after a decade and three orders of magnitude more funding) Not only is the requirement highly unlike LEO satellites, but members of both consortiums have satellite tech of their own (which is arguably both more mature and more relevant to the requirements than Starlink) Just as well nobody decided it wasn't worth NASA wasting money evaluating the PayPal guy's ideas when off the shelf space tech existed, though...
slownews45 5y ago
Just to confirm you are aware that spaceX will likely have the largest deployed fleet of satellites with optical links? They will have not just studies, but hands on experience operating these things at scale in space to space communication. Europe loves to come out with these white papers and industry studies and collaborations. It's basically an exercise to hoover up govt funding. The commercial side is very weak in most cases. They've been pushing Galileo as taking over the market AND making a ton of money in the GPS space. No way. "Due to be fully operational by 2008, Galileo would have “a four-year monopoly on the improved technology before Americans can catch up,” making the 4 billion system a profit center for the EU." Arianspace is supposed to be launched Ariene 6 at half the price of SpaceX. "“Ariane 6 will have twice the mass and twice the volume of the Falcon 9, at less than twice the price,” Bonguet said. SpaceX is at $50M retail launch price, and cost like likely < $30M per launch internally. So this means Ariene 6 pricing is going to be in $25M range? It can get a bit tiring to hear these things. The one thing Europe is good at is putting attorneys and lawyers to take down US companies rather than actually competing with them.
- notahacker 5y ago
  You are aware that some of the bidding companies were operating satellite constellations when Elon was at school? Think their collective hands on experience of satellite telecoms might even exceed SpaceX's beta program! And if I was going to bat for the superiority of SpaceX (and US programs) to the European space industry, accuracy of projections and the proportion of revenue coming from government really, really isn't where I'd focus...
  - GoOnThenDoTell 5y ago
    Operating a few dozen sats decades ago is very different experience from operating a thousand at once today
    - notahacker 5y ago
      By the same token, operating mission critical satcoms for the entire global shipping fleet is quite different from running a beta program for 10k customers with an uncharacteristically frank admission they're not sure whether it'll scale up to work properly in urban areas...
7952 5y ago
Exactly. It is perfectly possible that a few larger satellites in higher orbits would be easier. And would still be close enough to provide relatively low moon to moon latency.

_Microft 5y ago

There are only two comments mentioning Starlink, one of which is mine. As the other one does not go into details, your comment seems to be talking about mine and seems to be based on a misunderstanding of what I wrote. Feel free to ask if there is still something unclear after reading it more closely.

jasonwatkinspdx 5y ago
If I wanted to reply to you directly I would have. I did not precisely because I was hoping to avoid defensiveness from any particular poster. That said the logical place to put your relay would be L1, which is still some 60,000 km from the moon. It's not at all clear that off the shelf Starlink sats would be capable of communicating that distance from their orbit over the moon. You'd also need the earth side of the relay, which also clearly cannot be the existing Starlink cluster. They'd be foolish to not consider a Starlink derived design or SpaceX as a vender, but I don't think this can be done as inexpensively and quickly as your comment suggests.
- labster 5y ago
  Maybe Starlink with a single ground station? I know landing makes it so much more complicated, but those Starlinks can communicate back to the station on the lunar surface easily, and the station stays pointing towards Earth on the near side. SPOF though.
  - jasonwatkinspdx 5y ago
    That's an interesting idea imo. You'd need to solve the earth side of the link too. The current NASA et all network is massively oversubscribed.
- _Microft 5y ago
  Throwing subpar ideas out of the window is part of the process, so no worries about my feelings. I'll just outline the thoughts that went into my other post if you are interested in critizing them. I had also briefly considered a relay at the closest Lagrange point but came to the same conclusion as you did. Namely that off-the-shelf Starlink satellites might not be able to communicate with it which just means: it's not the solution. So let us consider a (few) separate relay satellite(s) [*] after quickly dismissing lunar ground stations: a lunar relay ground station might have the advantage of always being in sight of Earth but has the considerable disadvantage of having to live through lunar nights. This is highly impractical and would incur considerable complexity by requiring e.g. a RTG power source instead of using solar power as sats would do. So on-shell non-Starlink satellite relays it is for now. If there is more than one relay, any orbit might be fine [**]. If it really had to be a single relay satellite for some reason, a polar lunar orbit might be a possible solution that does not suffer from regular communications blackouts. Another solution might be to relax the requirement of having a continuous connection between the single relay satellite and Earth and to accept to be offline for a fraction of the orbit (at an orbital height of ~500km above Moon('s equator) a satellite would disappear behind Moon for a bit over a quarter of its orbital period), so if approximately 73% availability is fine, this would also work. Higher inclinations improve this value. One more thing because this also seemed unclear: at no point are Earth's Starlink satellites involved. All moving of data between Earth and Moon happens between the dedicated relay satellite(s) and a ground station on Earth, as this is the setup that NASA used for its laser optical communications test that I linked to from my other posting. All in all, that means that (under the assumption that Starlink satellites can operate under the conditions around Moon (it lacks Earth's protective magnetic field!)), that a few dedicated and custom-made relay satellites would all that is needed to use (my opinion:) dirt-cheap run-of-the-mill Starlink satellites for a constellation around Moon. Any thoughts on this? [*] Maybe even a few of them as material is cheap but engineers are expensive. If you can build one thing, you can usually build a second/third/n-th of it for less per-unit costs than the previous (with diminishing savings between each). [**] As stated in another post, I would rather expect the constellation to be in higher than in lower orbits so that fewer satellites would be needed to cover the same area on ground. This means that lunar mascons should not be of concern and even if they were, the satellites would still have ion thrusters to compensate for that.

kiba 5y ago

I don't understand why we need concept studies? It's not like we're doing anything particularly new. It's just engineering.

robertlagrant 5y ago
Perhaps some vital ontology definitions, process mapping, and enterprise architecture will need to be done.
- slownews45 5y ago
  The EU has 22+ languages and most studies and results have to be translated. EU Charter of fundamental rights (art. 22) and in the Treaty on European Union (art. 3(3) TEU). So the EU is a pretty good spot for translators. Britan is not part of the EU, but outside of the official stuff, English is used in a lot of practical areas for technical work.
- morelisp 5y ago
  This is a deep cut I expect will go over the heads of a lot of non-EU residents (though "enterprise architecture" might still clue them in). I was shocked to find RDF-era ontology "research" - already rightly a joke in my US-based undergraduate AI courses in 2003 - going on en masse when I moved to the EU in 2011. I've gotten four job applications so far this year from people with MSc in whatever ontology trash their local university was doing.
  - nradov 5y ago
    Ontology research is still relevant in the healthcare field. We need better ways to assign codes to the discrete elements of patient records in order to deliver better care and allow for effective data analysis.
    - robertlagrant 5y ago
      Oh yes. SNOMED, ICD, etc etc. Can't have too many standards!

dougmwne 5y ago

I'm quite interested if orbiting satellites could handle the backhaul connection to Earth or if larger and more powerful ground stations or a Lagrange station would have a place. Clearly we communicate just fine with existing Mars and deep space probes, but the problem must change enormously when you want a 100 gigabit uninterruptible connection.

notahacker 5y ago

Even weirder to pooh-pooh government funded concept studies when SpaceX is literally the poster company for governments chucking money at private enterprises to come up with innovative new solutions to variants of space problems with already existent solutions (after a decade and three orders of magnitude more funding) Not only is the requirement highly unlike LEO satellites, but members of both consortiums have satellite tech of their own (which is arguably both more mature and more relevant to the requirements than Starlink) Just as well nobody decided it wasn't worth NASA wasting money evaluating the PayPal guy's ideas when off the shelf space tech existed, though...

slownews45 5y ago

Just to confirm you are aware that spaceX will likely have the largest deployed fleet of satellites with optical links? They will have not just studies, but hands on experience operating these things at scale in space to space communication. Europe loves to come out with these white papers and industry studies and collaborations. It's basically an exercise to hoover up govt funding. The commercial side is very weak in most cases. They've been pushing Galileo as taking over the market AND making a ton of money in the GPS space. No way. "Due to be fully operational by 2008, Galileo would have “a four-year monopoly on the improved technology before Americans can catch up,” making the 4 billion system a profit center for the EU." Arianspace is supposed to be launched Ariene 6 at half the price of SpaceX. "“Ariane 6 will have twice the mass and twice the volume of the Falcon 9, at less than twice the price,” Bonguet said. SpaceX is at $50M retail launch price, and cost like likely < $30M per launch internally. So this means Ariene 6 pricing is going to be in $25M range? It can get a bit tiring to hear these things. The one thing Europe is good at is putting attorneys and lawyers to take down US companies rather than actually competing with them.

notahacker 5y ago
You are aware that some of the bidding companies were operating satellite constellations when Elon was at school? Think their collective hands on experience of satellite telecoms might even exceed SpaceX's beta program! And if I was going to bat for the superiority of SpaceX (and US programs) to the European space industry, accuracy of projections and the proportion of revenue coming from government really, really isn't where I'd focus...
- GoOnThenDoTell 5y ago
  Operating a few dozen sats decades ago is very different experience from operating a thousand at once today
  - notahacker 5y ago
    By the same token, operating mission critical satcoms for the entire global shipping fleet is quite different from running a beta program for 10k customers with an uncharacteristically frank admission they're not sure whether it'll scale up to work properly in urban areas...

7952 5y ago

Exactly. It is perfectly possible that a few larger satellites in higher orbits would be easier. And would still be close enough to provide relatively low moon to moon latency.