[HN Gopher] Lasers enable satellite internet backbone, might rem...
___________________________________________________________________
Lasers enable satellite internet backbone, might remove need for
deep-sea cables
Author : wglb
Score : 126 points
Date : 2023-06-26 13:57 UTC (9 hours ago)
(HTM) web link (techxplore.com)
(TXT) w3m dump (techxplore.com)
| SiempreViernes wrote:
| Great for countries that think they can control space, not so
| great for those without ASAT capabilities.
| deepspace wrote:
| FTA: "However, scaling up is not something Leuthold and his team
| will be concerning themselves with".
|
| As an engineer, the words "devil" and "details" come to mind.
| NoMoreNicksLeft wrote:
| Why is scaling always necessary? Can't we just do this same
| thing, but more of and bigger? I mean, that makes it easy-
| peasy.
| oneplane wrote:
| Because 'more and bigger' can be summed up as 'scaling'...
| grimgoldgo wrote:
| They transmit in near infrared in an environment that is full of
| particles, wouldn't this cause light pollution in a spectrum many
| animals would be impacted by?
|
| Also, doesn't this have the issue that anything passing through
| the beam cuts off internet? A bird, a kite, a malicious actor, a
| dust storm?
| ted_dunning wrote:
| There won't be any significant light pollution since the beams
| are so narrow.
|
| The problem of interference from clouds and precipitation is
| real, but the problem of physical occlusion probably isn't
| because the satellites move pretty fast. That would make it
| hard to persistently block the beam unless you have something
| as big as a storm cloud.
| throwway120385 wrote:
| This seems like a reasonable question, on its face. I have NIR
| illumination on my surveillance cameras and insects are VERY
| interested in it. Every night I get at least one bat hanging
| out by my camera. I'm fairly certain it's because the camera
| attracts insects.
| agnosticmantis wrote:
| Aren't lasers extremely susceptible to weather conditions? E.g.
| when it's raining/snowing/cloudy, can the base station
| communicate with a satellite via laser?
| looofooo wrote:
| No, it is 1550nm Laser.
| adrian_b wrote:
| The lasers are used only between the Starlink satellites, not
| in the uplinks or downlinks.
|
| While this experiment has demonstrated that it is possible to
| compensate for the turbulence of the air, there is no solution
| for the attenuation caused by bad weather.
|
| It might be possible to use lasers between a base station and
| satellites only if the base station is located at high altitude
| in a dry place, like those typically chosen for astronomical
| observatories, so that the links will be blocked by bad weather
| only infrequently.
|
| So I do not believe that there is even a remote chance of
| replacing most undersea cables.
| cycomanic wrote:
| I like the ETH result and it is an impressive feat (I know some
| people involved in that work). That said the article is a lot of
| rubbish. First there is the weird focus on lasers, all (relevant)
| Optical Communication uses lasers, including fibre comms. Then
| they make it sound like this is to replace fibre, again rubbish.
|
| The amount of data going through fibres is absolutely staggering,
| replacing this with intersatellite links is just not going to
| happen. First you still need fibre to connect your ground
| stations (and you need quite a bit of redundancy due to weather)
| and there are still a lot of unsolved problems (tracking and
| pointing for example). However there are many interesting
| applications of optical satellite links and quite a few players
| are investing in it, the big one is actually data connections for
| scientific space missions.
| Aeroi wrote:
| HFT bros jizzing in their pants
| cvs268 wrote:
| What pants? :-D
| ortusdux wrote:
| Current fiber optic cables transmit signals at 2/3rds the speed
| of light. Modeling has shown that starlink's laser backbone would
| allow it to beat deep-sea cables in some situations. This article
| estimates a NYSE -> FTSE reduction from 76ms to 43ms. I wouldn't
| be surprised to learn that there is a HFT bidding war going on.
|
| https://archmeregreenarch.org/1456/news/starlink-and-the-ris...
|
| There is a newer version of fiber optic cable that uses a hollow
| core. Testing has shown it transmits signals at nearly the speed
| of light. It is very difficult to produce at scale and will
| require a generational shift to deploy.
|
| https://www.nature.com/articles/s41467-020-19910-7
| posnet wrote:
| The question isn't whether satellite links can beat deep-sea
| cables, it's whether they can beat shortwave.
|
| https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-tr...
| moffkalast wrote:
| How can that scale when they need to increase trading volume?
| Radio has jack shit in terms of bandwidth.
| bhouston wrote:
| And HFT setups are also nearly colocated with the exchanges I
| understand -- as close as they can get physically, so adding
| a hop to space and back may be adding quite a bit of
| distance.
| heipei wrote:
| This would be about reducing latency between these two
| exchanges to enable arbitrage opportunities the way I
| understood it.
| ortusdux wrote:
| Exactly. IEX exchange is relatively new, and their big
| innovation is that they use long spools of fiberoptic
| wire to delay their user's connections, thus creating an
| even playing field.
|
| https://www.sec.gov/files/07feb18_hu_iex_becoming_an_exch
| ang...
|
| _" The reduction in trading costs (spreads) is broadly
| consistent with recent theories on how speed advantages
| may be used to exploit mechanical arbitrage
| opportunities. These theories suggest that market makers
| face adverse selection from fast traders even in the
| absence of traditional "fundamental" informed trading.
| For instance, Budish et al. (2015) defnes "quote sniping"
| as the mechanical arbitrage of taking "stale" quotes
| before market makers can cancel. In his Comment Letter on
| IEX's Exchange Application, Eric Budish argues that IEX's
| speed bump may be able to mitigate quote sniping as it
| allows IEX's pegged orders to avoid executing against
| market orders at stale prices.7 Moreover, cross-sectional
| di.erences in spreads in response to IEX's protected
| quote are consistent with recent theory suggesting that
| exchange speed is a double-edged sword for market makers
| (Menkveld and Zoican, 2016). On one hand, faster
| exchanges allow market makers to update their quotes
| faster, reducing spreads. On the other hand, higher
| exchange speed results in a higher probability of quote
| sniping. Hence, the results support this more nuanced
| view of the net e.ects of speed on trading costs. "_
| willis936 wrote:
| "Why is our market crashing" might actually have
| something to do with the price of tea in China soon.
| tikhonj wrote:
| It would be relevant for transmitting information from
| different exchanges (NYC = London = Tokyo... etc), not
| going from the trading firm's systems to the exchanges. At
| a high level, the firms would be making money by helping
| markets on different continents synchronize faster.
| [deleted]
| jdblair wrote:
| I think the use case is signalling between exchanges for
| millisecond advantages in arbitrage trades, not for trading
| on a single exchange.
|
| See https://spectrum.ieee.org/wall-street-tries-shortwave-
| radio-...
| ajsnigrutin wrote:
| Am I the only one who thinks HFT should be forbidden? Stocks
| and investments are a nice thing to have, since you can buy a
| share of a company you believe in, they get the money, do
| stuff, you get dividends and in the end can sell the stock
| after some time too.
|
| HFT changes these "beliefs in company" to "beliefs that the
| stock will go up", and the timeframe of those "beliefs" is
| sometimes in milliseconds. This turns classic "investment" into
| a computer game with a lot of real money.
| criddell wrote:
| > you can buy a share of a company you believe in, they get
| the money, do stuff
|
| I think that's only true for IPO shares which often aren't
| available to retail investors/gamblers like me.
| lend000 wrote:
| Where do you think all your liquidity comes from when you
| want to buy or sell some instrument? The difference in price
| isn't all that substantial if all you do is buy now, sell
| when cash is needed in retirement, but if you're that kind of
| general index investor, one could argue that your
| contribution to markets is actually negative (whereas HFT is
| helpful by making prices better and spreads tighter). Buying
| SPX makes no differentiation between bad and good companies
| in the index and allocates money based on current prices
| (which are mainly calculated by HFT's who did the legwork to
| get to the current point).
| anigbrowl wrote:
| No. It's garbage, trading is supposed to serve human needs
| and should take place on human timescales. If I had a magic
| wand I'd randomly fuzz the timing of trades to remove a lot
| of incentives for HFT and some other kinds of automated
| trading, which are not much more than banging on a known
| deficiency in a slot machine.
|
| Proponents argue that HFT and other such innovations provide
| liquidity to markets; my skeptical take is that this is a
| nice technical-sounding term for traders with cash to lowball
| falling asset prices.
| 542458 wrote:
| > since you can buy a share of a company you believe in
|
| I don't think this is generally true. Stock trading isn't
| charity, it's done to make a profit. Almost trading is done
| on the basis of second order effects, and has been for as
| long as there's been a stock market. Stocks aren't given
| value by the company being profitable, they're given value by
| what other people are willing to pay for them (okay, yes,
| dividends also factor in, but many companies don't pay
| dividends and people still assign value to those stocks).
| ajsnigrutin wrote:
| Well sure it's for profit, but what exactly do we (the
| society) get if we allow millisecond investments in our
| companies? Compared to classic, long-term investments.
| EMM_386 wrote:
| The common answer will be "liquidity".
|
| The honest answer is probably nothing.
| patmorgan23 wrote:
| Are HFTs taking trades that otherwise wouldn't have
| happened?
| jfengel wrote:
| Is liquidity even a real answer? The HFTs only work
| because the market would be made a moment later. A buyer
| and a seller already exist. If they didn't, it wouldn't
| be high-frequency trading. it would just be "trading".
|
| As far as I can tell, it neither benefits us, nor costs
| us. It siphons off a tiny fraction of money, too small to
| notice, but large enough in aggregate. Some parasite gets
| to survive, which is annoying if you look directly at it,
| but ignorable if you don't.
| CameronNemo wrote:
| If you have not already looked into it, the Long Term Stock
| Exchange (LTSE) is trying to buck this trend and cater to
| patient capital.
| elif wrote:
| HFT isn't even that harmful. What's harmful is brokerages
| that hold large portions of financial instruments who take
| advantage of customers' live buying and selling with delayed
| swaps, intentional front running, etc. This is how the stock
| market was bullied before HFT, options markets, trading bots,
| etc enabled 'everyone' to do skeezy arbitrage and not just
| market makers.
|
| The only meaningful way to limit the efficacy of these modern
| trading styles would be purposeful market friction through
| minimum holding times, circuit breakers, etc. You can't just
| legislate that people mustnt have low ping.. it's impossible
| to enforce. And those market friction mechanisms can create
| scary market conditions like backlogs, etc and guess what,
| enable market making brokerages to do internal swaps etc. in
| spite of the friction and essentially be the only ones able
| to bypass restrictions.
| bjelkeman-again wrote:
| Wouldn't a financial transaction tax be the friction
| required?
| https://en.wikipedia.org/wiki/Financial_transaction_tax
| strictnein wrote:
| > HFT isn't even that harmful. What's harmful is brokerages
| that hold large portions of financial instruments who take
| advantage of customers' live buying and selling with
| delayed swaps, intentional front running, etc
|
| HFT does very similar things, except it's even more opaque
| to those not doing it. Large financial firms and exchanges
| sell their order data to HFTs. If you're interested in a
| deeper dive on what they're doing, a book like Flash Boys
| will explain how there's a lot more going on than just a
| quicker network connection.
| DylanDmitri wrote:
| How about forcing public markets to bucket trades within
| say 2 second windows, executing best matches at the end of
| each period. Low friction and reduces value of millisecond
| latency advantages.
| phkahler wrote:
| >> The only meaningful way to limit the efficacy of these
| modern trading styles would be purposeful market friction
| through minimum holding times, circuit breakers, etc
|
| So I occasionally try to think of a reason to have a
| guaranteed delay due to signal propagation delay to/from
| Mars. Would there be a use for putting an automated
| exchange there? Maybe, but then whomever gates the orders
| could monitor and predict what will happen 40 minutes out
| or whatever. Need TLS from trader to exchange or something.
| govg wrote:
| You might be interested in IEX [0]. The idea behind that
| stock exchange was similar to your thought process -
| introduce a guaranteed delay / random offset so that HFTs
| can't exploit the markets the way they do others.
|
| [0] - https://en.wikipedia.org/wiki/IEX
| ajmurmann wrote:
| Eric Ries with his Long Term Stock Exchange for me really
| nailed this issue. HFT is the epitome of all the reasons why
| the LTSE is great.
| marcell wrote:
| What's the actual harm of HFT for the average person? I can
| set a $ limit on my orders, so I don't pay more than I want.
| Why should I care if some HFT guy scrapes 0.01% value off
| each trade?
| beirut_bootleg wrote:
| It scrapes that % every trade, every millisecond, thousands
| of times over. That adds up, and all that money has to come
| from somewhere.
| lend000 wrote:
| That's the price you pay for liquidity, and the
| alternative (paying a difference in price far more than
| 0.01%) makes everyone worse off except other people
| competing in the markets. The money HFT's make comes from
| other people trading the zero sum short term trading
| game, not you (assuming you are longer term investor or
| non-participant in the market), so why should you or
| others in your situation get worked up about it? It seems
| like either a demonization of that which people do not
| understand, a class warfare sort of vibe, or both.
| anigbrowl wrote:
| * * *
| willis936 wrote:
| What would that look like? If you rate limit stock exchanges
| to something like 1 update per minute then there will likely
| be the same amount of networking and computation going on to
| speculate on the next update and calculate optimal plays. It
| just moves it to behind closed doors where it is harder to
| know if shenanigans are going on.
|
| It would take a heavier hand to push against this problem.
| I'm all for it, I'm just not clever enough or knowledgeable
| enough to know what would be a good regulation that would fly
| in congress.
| patmorgan23 wrote:
| Small cost per trade (tax/fee)
|
| Minimum time between buying and selling the same ticker
|
| Mandatory network 'speed bump' of a few ms between the
| exchange and any trading parties
| Terr_ wrote:
| > What would that look like?
|
| One attempt is the exchange IEX [0] which introduced a ~350
| microsecond delay to everything simply by running incoming
| order data through a ~60km loop of fiber-optic cable.
|
| Perhaps not the most, er, _featureful_ solution, but it 's
| very easy to audit and argue that there are no biases or
| backdoors.
|
| [0] https://en.wikipedia.org/wiki/IEX
| vgatherps wrote:
| If everybody is exactly 350us slower, then it's still the
| same game.
|
| Iex also offers a variety of (dark) order types that can
| pull back without the 350us delay if iex believes the
| incoming flow will be toxic
| Terr_ wrote:
| > If everybody is exactly 350us slower, then it's still
| the same game.
|
| IANATrader, but I don't think that's entirely true. Yes,
| it won't stop Carol from getting information from
| somewhere and then running in front of Alice to the same
| exchange. [0]
|
| However even fixed-delays [1] can still create
| uncertainty about what price your order may actually
| execute at when it hits the server, which is something
| HFTs rely on more heavily than other traders, since their
| strategy depends on high-certainty that they will have a
| small positive margin on every trade.
|
| __
|
| [0] I find it geeky-amusing to write (i.e. IEX) or (ex:
| IEX) because it feels like the start of a mental tounge-
| twister.
|
| [1] Can't edit my original post anymore, but apparently
| there's another 350ms on the outbound path too.
| javajosh wrote:
| Limit trades to once per hour, then, and require a human to
| enter them.
| ajsnigrutin wrote:
| If you buy a stock, you must keep (hold) it for eg. 30 days
| (or 7, or 60, or whatever).
|
| Compute all you want, whenever you want, but instead of
| millisecond timings, optimize stuff for at least some time.
|
| Maybe even a tax on stock profits, which is really high and
| falls after some time of ownership of such stock (we have
| this in slovenia, but it's not really high in the first
| place, and time brackets go less than 5 years (25%), 5-10
| years (15%), 10-15 years (10%) , 15-20 years (5%), and zero
| tax after that.
| patmorgan23 wrote:
| Even if you said you have to hold it for 3 hours that
| would cut against the worst of the HFTs
| edgyquant wrote:
| There already is a penalty for not holding and a tax on
| wash trading (selling and rebuying within 30 days.)
| gnopgnip wrote:
| Raising the financial transaction tax to 0.1%, 1$ per $1000
| would eliminate the vast majority of unproductive and rent
| seeking HFT without negatively effecting liquidity. The US
| already has an FTT to fund the SEC, implementation should
| be straightforward. Currently the rate is very low, about
| 0.002%. Raising the rate would be minimally impactful for
| longer term investors and generate on the order of $50b a
| year for the government.
|
| Hong Kong has an FTT of 0.13% currently, it was 0.1% from
| 1993-2021 so you can compare HFT impacts on these markets.
| Or compare dozens of other countries with similar rates,
| Switzerland, Taiwan, France, Italy, Japan.
| paulsutter wrote:
| do you have a link, love to learn how it worked out in
| other places
| gnopgnip wrote:
| https://www.bnymellon.com/content/dam/bnymellon/documents
| /pd... has a good review of several countries laws
| robertlagrant wrote:
| What's rent-seeking HFT?
| lucubratory wrote:
| I'm not that person, but presumably it's that someone has
| purchased real estate in a geographically relevant
| location and constructed property on it/between it and
| the exchange which gives them an insurmountable latency
| advantage in HFT, and they are characterising the raking
| in of cash from that latency advantage as rent seeking.
| gnopgnip wrote:
| Rent-seeking is an "economic activity to gain wealth
| without any reciprocal contribution of productivity". Or
| put another way it means societies resources are put
| towards wealth transfer instead of productivity/wealth
| creation.
| karkari wrote:
| Is the $50b/year figure estimated after assuming the
| 'unproductive and rent seeking' HFT volume is eliminated?
| gnopgnip wrote:
| Yes, that estimate is with the greatly reduced HFT
| volume. And it may not be 100% accurate, HFT and trading
| in general could move to another market without these
| taxes and/or switch to a type of derivative with a
| lower/no tax. Like the UK, for swaps. But these other
| markets are smaller and not really a replacement. And
| these other markets may pass similar taxes in the future.
| Y_Y wrote:
| What about a flat "Tobin tax" charged on each transaction
| so that it becomes very expensive to do lots of small
| trades quickly and encourages doing bigger trades at lower
| frequency?
|
| https://en.m.wikipedia.org/wiki/Tobin_tax
| ortusdux wrote:
| A few congress people put forth a bill that would add a
| 0.1% tax on trades. This would be a rounding error for most
| traders, but a significant value for HFT.
|
| https://www.brookings.edu/opinions/congress-wants-to-tax-
| sto...
|
| I wonder what happened to it.
| [deleted]
| Loughla wrote:
| Honestly, I don't understand how they're legal, either. HFT
| just seems like the most naked of naked cash grabs in
| finance.
| tails4e wrote:
| I agree. HFT goes against the original ethos of a market open
| to all. Instead of trading on the merit of a given company,
| it simply reinforces the market is increasingly gamified and
| unfair. It's like futures, no ones cares about the commodity
| being traded, or that doing so can really hurt people and
| business that rely on that item, it's just another item to be
| gambled.
| pravus wrote:
| > HFT changes these "beliefs in company" to "beliefs that the
| stock will go up"
|
| No, this is the part most everyone gets wrong about HFT.
| These systems make money off of volume, not price. They don't
| care if the price is going up or down. All they care about is
| that they can capture a small price delta by facilitating a
| trade faster than someone else and they are willing to do so
| for smaller fractions of a cent which makes them more
| attractive to all market participants, including you and your
| retirement funds. Their concerns are orthogonal to investors
| and they compete with other HFT firms and market makers.
| Xcelerate wrote:
| I have a suspicion that at some point, an HFT group will
| obtain a brief but substantial lead in machine learning (a la
| RenTech, but on a shorter timeframe) that allows them to suck
| a decent amount of money out of the stock market before
| anyone else can respond or close the gap. We probably won't
| get any sort of regulation until after that happens.
| vgatherps wrote:
| Hft groups are about 15-20 years ahead of you on that
| cortesoft wrote:
| In a healthy market, HFTs serve as market makers, and allow
| normal traders to have faith that prices will be consistent
| at all exchanges. If there is enough competition, an HFT will
| have very low profit.
| [deleted]
| gorkish wrote:
| > require a generational shift to deploy.
|
| Photonic bandgap / Bragg fiber is being produced in quantity,
| and some subsea cables are using it.
|
| I'm pretty sure it's the satellite lasers that require the
| generational shift. One subsea cable has no bearing on any
| other; once the first is installed, you're up and running. not
| so with laser-connected swarms.
| ortusdux wrote:
| Starlink's laser connections have been active for a year now.
| cma wrote:
| What's the latency NY to Australia all over Starlink with
| laser interconnect now?
| modeless wrote:
| I don't know if Starlink is routing packets that way. I
| think it's more likely that they route packets to a
| ground station as soon as possible to save laser link
| capacity for customers that actually need it, like ones
| in the middle of the ocean. If you want your packets
| routed all the way around the Earth through space then
| you'd probably need a special contract with SpaceX.
| thesz wrote:
| [1] https://wccftech.com/starlink-turns-on-laser-
| satellites-for-...
|
| Judging from [1], lasers are used not for inter-satellite
| links, but for downstream or upstream links - from
| satellites to the ground.
|
| Intersatellite links require precise machinery, such as
| picometer-precise positioning systems [2].
|
| [2] https://www.pi-
| usa.us/fileadmin/user_upload/pi_us/files/prod...
|
| Also, there should be compensation for satellite rotation,
| initial targeting and tracking. At ~12km between satellites
| (~4000 on 550 km orbit), the (possible) target of laser
| signal receiver which, say, is one meter in diameter will
| be one third of an angular minute. It is not impossible to
| target that initially, but keep in mind that laser beam is
| very focused and its power drops significantly with the
| angular distance.
|
| I really do not know how to even target satellites'
| receivers initially, let alone compensate for rotation and
| track these targets afterwards.
| ortusdux wrote:
| From [1]:
|
| _" Space lasers allow Starlink satellites to connect
| directly to one another, eliminating the need for a local
| ground station and enabling Starlink. to deliver service
| to some of the most remote locations in the world - like
| Antarctica."_
| wmf wrote:
| Don't read WCCFTech; they don't know what they're talking
| about.
|
| AFAIK the satellites within an orbital plane are
| stationary relative to each other, so once the laser is
| aimed it should stay connected.
| cycomanic wrote:
| Photonic bandgap fibres are not used in submarine cables
| their loses are too high. There are recent antiresonant
| fibres (NANF) which can achieve lower losses than even SMF.
| However production capabilities are not ready yet to make the
| amount of fibre necessary for submarine. The startup (out of
| Southampton) that pioneered these was recently acquired by
| Microsoft.
|
| We probably see these fibres for links between the exchange
| and data centres first (although there it is difficult to
| beat RF links, as they are direct line of sight)
| [deleted]
| [deleted]
| HWR_14 wrote:
| Wouldn't they have to relay between many satellites due to line
| of sight? And wouldn't that eat up any decrease in time of
| flight for the signal itself?
| nine_k wrote:
| I suspect that retransmission with amplification only,
| without much processing, can be really fast. Modern
| electronics can routinely do sub-nanosecond latency.
| londons_explore wrote:
| Indeed. If the system is designed with latency in mind,
| then the receive to send latency can be as low as a few
| feet of distance equivalent.
| activiation wrote:
| HFTs are in the nanoseconds range, not milliseconds... They
| rent space AT the exchanges... They remove firewalls and such
| to shave even more time
| client4 wrote:
| Only within the DC, not between exchanges.
| [deleted]
| sleepybrett wrote:
| Used to work, in the early naughts, for a company that had a
| laser uplink in seattle from their office building to the westin.
| I sat in the office with the uplink for awhile, pointed out the
| window with a big gimble, you could watch it adjust for building
| sway.
|
| Uplink went to shit in heavy fog though...
| samtho wrote:
| This tech is really cool, but as they mentioned, they have not
| tested this with a moving satellite. Because any antenna would
| need to be localized on a satellite for transmission, you're
| going to be stuck with having to maintain (likely) expensive and
| precise motors who's job it will be to run in perpetuity.
| However, I would be confident that stepper motors of this grade
| will come down in price or will become more available.
|
| My primary concern comes down to reliably. Your ground station
| must now accurately target moving satellites, negotiate handoffs,
| and reroute when necessary. Architecturally, you will need to
| develop the ground station with at least three transponders: an A
| link, B link, and a redundant Z link. The A and B take turns
| localizing to their satellite where one is only allowed to move
| positions if the other is currently active. The backup Z link is
| on standby in case of failure or maintenance. The three would
| likely rotate roles periodically to keep time on each of the
| motors more evenly distributed amongst them. This system must
| work in harmony with all the satellites in its network. The
| satellite system has its own maintenance burden too, including
| orbital decay requiring you to periodically adjust its position
| until it runs out of propellant, and send more up when it's
| reached the end of its useful life. To me, this is a ton of
| moving parts.
|
| An undersea cable by contrast, will pretty much be maintenance
| free once laid only requiring infrequent repairs in the event of
| a wayward ship anchor. Yes, the data center components will need
| to upgraded periodically but you don't need to replace the
| transmission mode. There are no moving parts, no need To track
| objects hundreds of miles away, just sending light down a tube.
|
| Is this tech cool? Absolutely. Will it replace undersea cables?
| Probably not soon, but I can see this as a great solution to link
| remote islands where it does not make strategic sense to run a
| cable, or where it is difficult or uneconomical to run a
| terrestrial connection.
| colinsane wrote:
| > Because any antenna would need to be localized on a satellite
| for transmission, you're going to be stuck with having to
| maintain (likely) expensive and precise motors who's job it
| will be to run in perpetuity. However, I would be confident
| that stepper motors of this grade will come down in price or
| will become more available.
|
| the article says they direct the laser using a MEMS device. not
| dissimilar to the micromirror arrays used in DLPs for decades,
| i would assume. you've definitely got options that don't
| require stepper motors or any macroscopic moving parts here.
| hbogert wrote:
| are they trying to the feed the flat earthers?
| 1970-01-01 wrote:
| Last I checked, there is a 1% chance of a Carrington Event within
| the next decade. Leaving cables behind and trusting new wireless
| links before we have a "full DR" situation would be stupid.
| okasaki wrote:
| Neat, but won't it be slower?
| CorrectHorseBat wrote:
| It should be faster, the speed of light in optical fiber is
| only 2/3 of that in vacuum (and air). I'm more concerned about
| clouds and storms.
| Havoc wrote:
| I could see both being in use, but replacement seems unlikely to
| me.
|
| If nothing else I could see governments insisting on both just
| for strategic reasons. Both techs are vulnerable to being fk'd
| with so doubling up makes sense
| aj7 wrote:
| I suspect the tracking and switching infrastructure, the
| sophistication of free space lasers with their adaptive optics,
| and the inclusion of satellite receiver-transmitters with their
| own adaptive optics will not be competitive with laying a passive
| undersea cable for at least a decade.
| supriyo-biswas wrote:
| Does it bring any latency improvements for users?
| _R_ wrote:
| Hope to see it deployed in GEO, as this would significantly
| increase bandwidth and reduce costs in remote areas.
| huijzer wrote:
| Eliminate deep sea cables? How are they going to send the lasers
| in a curve from one base station to the next?
|
| Starlink is already working on a backhaul from satellite to
| satellite. Interestingly, they claim that they can speed up data
| transfers by 50% over long distances. Musk said that in a Tweet
| which I cannot find now. I looked a bit into it and the reason
| seems to be that light trough a cable can only reach 70% of the
| speed of light while lasers through the vacuum of space can reach
| the speed of light.
| toast0 wrote:
| Sending lasers in a curve should be easy if you use circular
| polarization. /s
|
| You would send to a satellite in view; my orbital dynamics are
| poor, but I think with the LEO orbits, you may need to relay in
| space for a cross ocean link, as it seems unlikely one satelite
| would have a view of both sides. But Telstar 1 and 2 were used
| for cross-Atlantic microwave relay with a single satellite in
| view at a time. Future Telstars were geostationary, because
| satellite tracking was a lot of work (and with only two
| satellites, service was intermittent as they were only in view
| for a portion of their orbits). I imagine satellite tracking
| for lasers is going to be very difficult as well.
| ackbar03 wrote:
| How hard can it be
| Tuna-Fish wrote:
| To be clear, Starlink is already doing this. Their
| satellites have laser links that connect them to each
| other.
| ceejayoz wrote:
| They've launched satellites with laser links, but I don't
| think they've got the satellite-to-satellite links active
| yet. https://www.starlink.com/technology says "testing"
| for that feature.
| Tuna-Fish wrote:
| The website is out of date.
|
| They are already providing service over open ocean out of
| reach of one hop to base station.
| dlisboa wrote:
| > How are they going to send the lasers in a curve from one
| base station to the next?
|
| All you need is a well-placed black hole in Earth's atmosphere.
| ceejayoz wrote:
| > Eliminate deep sea cables? How are they going to send the
| lasers in a curve from one base station to the next?
|
| Multiple satellites. The ISS can see about a thousand miles in
| each direction to the horizon, so you'd only need to bounce
| across a couple to cross the Atlantic.
| [deleted]
| Aaargh20318 wrote:
| > Eliminate deep sea cables? How are they going to send the
| lasers in a curve from one base station to the next?
|
| They use a special laser that gives the photons a bit of
| topspin.
| ryanwaggoner wrote:
| Sure, because we only need the internet on sunny days.
| teeray wrote:
| I genuinely hope one of these systems gets called "Tightbeam"
| CAP_NET_ADMIN wrote:
| > Although the laser system was not directly tested with an
| orbiting satellite, they accomplished high-data transmission over
| a free-space distance of 53km (33 miles).
|
| This is peanuts compared to under sea cables and issues you will
| find penetrating atmosphere and increasingly, space.
|
| We should keep under sea cables and work on additional
| connections to make our networks more resilient, both to natural
| phenomena, equipment failures and sabotage.
| pushfoo wrote:
| > more resilient, both to natural phenomena, equipment failures
| and sabotage.
|
| I think you're understating the risks from geomagnetic storms.
| In comparison to satellites, fiber optic cables seem like
| they'd be relatively unaffected even if the equipment attached
| to them needs replacement.
| zamfi wrote:
| Perhaps the ocean is protective to some degree, but beyond
| very short lengths undersea cables have powered repeaters
| that draw considerable current, and which would plausibly be
| destroyed if the base stations are too.
| adrian_b wrote:
| I would not say "very short lengths", because undersea
| cables without powered repeaters (only with optical
| amplifiers) are possible until a few hundred kilometer.
|
| But you are right that transoceanic cables need powered
| repeaters.
| CAP_NET_ADMIN wrote:
| Currently, you can cut internet connections to most countries
| with a small deep water sub. China, for example, was busy
| building one that can be used at 10k+ depth and has arms.
| giobox wrote:
| Its widely assumed China, Russia and the US have "kinetic
| kill" abilities on satellites in space too, its just
| capabilities are not as widely known. Projects Like the
| US/Boeing X-37 space drone etc, whose purposes still
| haven't really been revealed:
|
| > https://en.wikipedia.org/wiki/Boeing_X-37
|
| Russia has already demonstrated its satellite destroying
| tech:
|
| > https://www.cnbc.com/video/2021/11/16/russia-blows-up-
| satell...
| wcoenen wrote:
| Also, India. List of anti-satellite tests: https://www.re
| searchgate.net/publication/368223169/figure/tb...
| CAP_NET_ADMIN wrote:
| "Kinetic kill" is arguably easier to detect and harder to
| deny.
|
| I haven't said that we should only focus on sea cables, I
| said that we should do both so that the overall
| reliability and resiliency increases.
| kelnos wrote:
| Can those be deployed "anonymously" though? Publicly
| destroying another nation's satellite would be an act of
| war. Quietly and secretly cutting an undersea cable,
| while being able to plausibly deflect blame, is a bit
| safer.
| elzbardico wrote:
| The problem is that it is fairly difficult to do it
| cleanly without risking precipitating Kessler syndrome.
| https://en.wikipedia.org/wiki/Kessler_syndrome
|
| It is basically automatic MAD (Mutually Assured
| Destruction) out there in space.
| piyh wrote:
| Are solar storms an issue for LEO sats?
| irq-1 wrote:
| off topic: NASA is working on lasers in space.
|
| > The Deep Space Optical Communications (DSOC) package aboard
| NASA's Psyche mission utilizes photons -- the fundamental
| particle of visible light -- to transmit more data in a given
| amount of time. The DSOC goal is to increase spacecraft
| communications performance and efficiency by 10 to 100 times over
| conventional means, all without increasing the mission burden in
| mass, volume, power and/or spectrum.
|
| https://www.nasa.gov/directorates/spacetech/tdm/feature/Deep...
| JoshTko wrote:
| We should keep both, Solar flares, space junk, etc. can knock out
| satellites
| NelsonMinar wrote:
| The key thing here is it allows for very high bandwidth to go
| almost anywhere on earth, not just spots where it's easy to land
| a cable. Starlink's already demonstrated how great that is for
| consumer bandwidth (50Mbps); a multi-gigabit link terminated at a
| satellite is fantastic.
|
| The part that impresses me most is they're talking about LEO
| satellites. Those move fast! Starlink does this with a very
| impressive phased array antenna design. Conceptually tracking a
| moving satellite with a laser is as easy as rotating a mirror,
| not sure how hard it is in practice.
| nottorp wrote:
| > how great that is for consumer bandwidth (50Mbps)
|
| 50 Mbps is great consumer bandwidth where?
| littlecranky67 wrote:
| Almost everywhere in Germany.
| NelsonMinar wrote:
| Sadly, in most of the rural US. My other options are 12Mbps
| fixed wireless, 1-100Mbps cellular, or 3Mbps DSL which AT&T
| stopped selling in violation of various government contracts.
|
| Starlink in practice is 10-200Mbps. Here's their
| specifications:
| https://www.starlink.com/legal/documents/DOC-1138-34130-60
| UI_at_80x24 wrote:
| Rural Canada. On a lake shore. 30km from one of Canada's "Top
| 50" cities.
|
| Where I used to live, I had 2 options for internet access. A
| Wireless ISP that uses a parabolic antenna pointed at a
| water-tower about ~20km from my home; or a cell-phone based
| internet connection.
|
| The WISP allowed me on average 300kb/s transmissions. The
| Cell-Phone allowed me between 1.5Mb/s and 7Mb/s (to a max use
| of 5GB/month).
|
| So 50Mb/s is an incredible upgrade.
| bcrl wrote:
| Sounds like your WISP isn't investing in the new generation
| of massive MIMO radios made by companies like Cambium.
| NohatCoder wrote:
| An actual 50 Mbps link is perfectly good for most use cases,
| you can stream anything and it is not really a bottleneck in
| determining how quickly pages load. Large file transfers may
| still take appreciable time, but it is rarely a big issue.
|
| An advertised "50 Mbps" mobile connection is dog food if you
| are used to 50 Mbps fiber. You are lucky if you get 20 Mbps
| through, though it can be much less. Worst part is all the
| packet loss that cause inconsistent latency and speed.
| nine_k wrote:
| In most places where you can't economically get a fiber. That
| is, in most places outside dense urban cores. They are petty
| numerous in the US.
| lm28469 wrote:
| I'm on 50mbps and 99% of the time it's too fast for my needs.
| I've lived on 10mbps capped 4g for a month and I didn't
| notice any problems either
|
| Anything that allows video communication/streaming is "great"
| imho, it certainly is more than enough for most people.
| oceanplexian wrote:
| It also circumvents the biggest problem with fiber, politics.
| Starlink doesn't need permission to run a backbone across (or
| rather over) a country. This will be revolutionary for people
| in Africa, South America, and huge swaths of Asia/Australia
| where a few telecom monopolies have artificially jacked the
| price of transit.
| falcolas wrote:
| IIUC, it only circumvents politics due to existing treaties.
| Those old treaties are likely ripe for revision with the
| extensive commercialization and the increasing number of
| countries capable of launching payloads into space.
|
| https://en.wikipedia.org/wiki/Politics_of_outer_space
| thecosas wrote:
| It definitely helps mitigate the infrastructure buildout
| hurdles (which are not small), but they would still need to
| jump through any "I need to do business in this country"
| regulations, etc.
| looofooo wrote:
| https://en.m.wikipedia.org/wiki/Chappe_telegraph
|
| Might be cheaper to build an Tower with PV and battery every 30km
| than running lines.
|
| Cell-Tower in remote Locations etc.
| nine_k wrote:
| Congrats, you've reinvented microwave lines, widely deployed in
| exactly this manner.
| Tuna-Fish wrote:
| The big difference between open air laser and microwave links
| is that one of them doesn't require licensed spectrum. The
| costs of doing it will be much lower.
| nine_k wrote:
| Fair! And the existing MW re-translator towers can be
| upgraded / reused this way.
|
| Lasers have a downside though: optical and near IR light is
| much more readily absorbed by water vapor than microwaves.
| I wonder if a maser would be an acceptable solution, if
| cheaper versions of it existed.
| looofooo wrote:
| 1550nm water is super transparent.
| adrian_b wrote:
| Not at all.
|
| While 1550 nm falls between two absorption maxima of
| water, so it is not the worst choice, the absorption in
| water is still more than one hundred times higher than at
| e.g. 905 nm.
|
| Because of this, 1550 nm is absorbed through fog or
| clouds at least 3 to 5 times more than shorter
| wavelengths like 905 nm. Even the latter is absorbed a
| lot by water, while being much more dangerous for eyes
| than 1550 nm.
|
| There is no near infrared wavelength where the water
| absorption is negligible.
|
| See the graphs at:
|
| https://en.wikipedia.org/wiki/Electromagnetic_absorption_
| by_...
| looofooo wrote:
| Microwave is also slow compared to this.
| bcrl wrote:
| I'm sure regulators will start regulating the 1550nm
| spectrum once they realize they can start making money off
| free space optics.
| eqvinox wrote:
| This sure sounds useful, but "might remove need for deep-sea
| cables" is quite silly.
|
| Anything they do to cram bandwidth into their laser link can
| reasonably also be applied to fiber optical cables. Except the
| fiber optical cables come in bundles of 12 to 144 with absolutely
| no separation issues. Replicating that over open space (air or
| vacuum), if reasonably possible at all, will chug significant
| amounts of power in signal processing at the receive end.
|
| There are major benefits to free-space optics -
|
| - quicker to build
|
| - lower latency
|
| - in some cases, large coverage
|
| But deep-sea cables compete on bandwidth, and that's not
| something free-space optics can beat them on. Why diminish this
| research achievement by conflating it with that? :(
| NohatCoder wrote:
| On top of this I really doubt the claim about working in bad
| weather. Some weather will work, sure, maybe at reduced speeds.
| But if there is a proper cloud in the way, the near-visible
| 1550 nm light will be scattered completely.
| giantrobot wrote:
| I believe the idea is that the ground link is still radio but
| the interconnect between the satellites is a laser. While
| radio can be affected by weather, the "works in bad weather"
| is a long solved issue.
| dylan604 wrote:
| what is a proper cloud? it does not seem to be a term
| frequently used when discussing clouds:
| https://en.wikipedia.org/wiki/Cloud
| IshKebab wrote:
| Is this parody?
| dylan604 wrote:
| Not any more than saying a "proper cloud" will disrupt
| satellite transmissions is meant to be serious. Is it a
| cirrus cloud? Is it a cumulus? A cumulonimbus? Which
| cloud is going to do this blocking?
| staunton wrote:
| This really isn't that complicated. You can't do a link
| through pretty much any cloud where you would say "it's
| cloudy". If you're not sure, the link still works but a
| lot worse...
| nvahalik wrote:
| Not to mention stuff like Solar flares.
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