Spectrolab is owned by Boeing.
Even at a cost of $10k per kg it makes very little sense to use 50% less efficient solar panels to save a few thousand, especially when the superior technology is also far better tested in space. It makes sense to use an Android instead of a $100k RAD hardened processor if your entire CubeSAT barely costs that much. Since most satellites cost a minimum of a million each, very few can afford the risk to save money on parts (and if you're mass producing thousands of them you can get really cheap germanium panels).
You want the greatest possible power capability in the smallest and lightest package, and right now the way to do that is a triple or quadruple junction GaAs type PV cell with a concentrator lens in front of it. Efficiencies range from 32 to 40%, vs 22.5% efficiency for the very best monocrystalline Si PV cells.
These aren't geostationary - they're low earth orbit. This means several things:
- cheap to launch - and to deorbit.
- lots of erosion compared to GEO - LEO is like being in a mild sandblaster while occasionally being shot at by rifles and howitzers.
Taking those two alone into account, you either end up building for durability or for disposability.
When you're dealing with a fleet of 4000 and your speciality/the thing you want to practice is heavy lift to LEO/MEO, you are absolutely talking about a disposable fleet where you expect daily failures and replacements. Having mass production facilities at your fingertips can't hurt.
Which is why they'd likely go for the cheaper tech that they have very low cost access to, even if it costs about the same after launch costs. Also, it would be more profitable for the collective enterprises than outsourcing such a component to a third party. Think about it - spend the money with a competitor, or at the gas station. I know which I'd do.
So - despite obvious truths re GaAs, my money is on them using their own Si cells.
Do you see how small the difference is in absolute terms? That means that only a few hours of labor per solar cell or 100g of launched payload mean the difference between a 50x and 1x difference. Two GaAs panels ($100) will requires tens of grams less support structure than the three Si panels producing the same power ($3) so already the extra launch cost (at $5k per kg, assuming free payload support structure) for the Si panels is eating away at their benefit. Each solar cell will need hours of inspection and testing by people paid $25+/hr so even if each extra Si cell and support structure costs nothing to launch, the final cost once fully assembled, installed, and tested will be in the range of $1k-10k per solar cell.
Especially at the scale of disposable satellites, GaAs is likely to be cheaper, more efficient, and free more volume and mass in the satellite design. 4000 satellites worth of Si solar cells would be the equivalent of a few dozen decent sized residential installs so it would be a drop in the bucket for SolarCity. I don't think keeping such small scale business in-house is much of an advantage, especially when there are many other suppliers with lots of experience in using solar cells in space.
At 1100 km the debris population is relatively sparse. https://en.wikipedia.org/wiki/File:Spacedebris_upd_2011.jpg
Telecom satellites already require tons of specialised integrated circuits because general purpose CPUs are too complex and power hungry for the amount of bandwidth the satellites process. This SpaceX constellation will certainly have custom designed electronics, even if they don't use any rad hardened ICs.
That'd be a really bad idea. Linux is too complex to trust, and lacks WCET making it unsuitable for hard realtime.
There's open source options, but Linux isn't among them. I'd look at seL4 for this purpose.
Also, I think the Falcon 9 uses VxWorks for at least some of its realtime control:
Can anyone who works at SpaceX chime in?
> One of the areas they focus on is scheduler performance. They do not have hard realtime requirements, but do care about wakeup latencies, he said.
It sounds like their hard real time controls are on non-Linux OSs.
This means that existing companies that build telecom satellites need to do it a new way for these constellations of lots of small satellites.
They have a satellite division which has a bunch of people designing things, but they have not launched their own yet. They have also made known their intention of fielding a global internet service via a large constellation of satellites. This application would be a step toward that goal.
They are very clearly Sunpower C60 or similar, a high end mono-Si cell.
I am a bit skeptical about the economics too, but apparently it works for SpaceX.
Given SpaceX deadlines it's possible that they just ran out of time for this optimization.
How this will affect their choice of PV cells I don't know.
With 4000 satellites it's likely that their approach to each satellite will be smaller and much less redundancy:
If a traditional 5000 kg geostationary telecom satellite can be compared in analogy to a big, expensive, 4U, quad socket xeon server that has multiply redundant everything.
These small satellites might be much more like a facebook open compute blade server, 1+0 and redundant nothing, but much, much cheaper to build and with a software architecture tolerant of entire nodes failing and disappearing from the network.
Musk might not care if Tesla and SpaceX disappear if electric vehicle mobility and affordable transport to Mars is achieved. They are a means to an end.
He has said multiple times that he thought the likelihood of success for each of Tesla and SpaceX was less than 10 percent, but that was ok, because even in failure, they would 'move the ball forward' on sustainable energy and making humanity a multi-planetary species.
The other: vast networks of companies all dependent on each other. When any one of them gets in trouble, it all comes falling down like a house of cards. And the chance of none of them getting into trouble? (1 - 0.<failure rate>)^<# of businesses>. That gets very small, very fast.
Lesson: never ever make a decision for business <b> because you also own business <a>. Too many people going from millionaire status to personal bancrupcy, at just about the moment where they're too old to start fresh, yet too young to coast.
Shouldn't the lesson be, "don't allow any singular company to become a single point of failure?"
Yes, but that requires more detailed analysis.
This seems like a pretty foolish way to do that. Mobile data over ground-based cellular systems is rapidly becoming a commodity, and at least in the areas of the world where Teslas will be sold, it's essentially ubiquitous. Why in the world would it be worth setting up and maintaining a massive satellite network just to cover the .001% of driver miles spent far enough away from a tower?
It will be a very disruptive business if he can pull it off
Assuming that they can achieve the success rates they've been aiming for, demonstrating lowered risk and cost through their own deployments will provide about the best advertisement you could possibly imagine. Waiting for organic outside demand to fill the launch roster to the same point would take time that Musk clearly does not want to waste. It seems to be a Keynesian approach to the slightly Chicken/Egg problem of commercial space.
Edit: There are ≈80 missions listed on the link there, 200 launches for their own missions would provide ample opportunity to derisk their customers by reusing launch vehicles beyond their currently marketable mileage and proving their safety (I can imagine that one would want some pretty steep discounts for a rocket that's been used 5 times given current success rates).
Consistent small profit launches, then as the accident %'s decrease design an ultra low risk human module and start space tourism for real
Keynes' ideas have been adapted to a range of different forms, but are more about circumstances where the economy is in a deep recession and there is some restriction preventing the economy from utilising all its resources. Here debt financed spending may have demand-side benefits by stimulating yet more demand. This only works at the aggregate economy level, so Elon would have to launch a lot of satellites to benefit from it!
To be fair he's talking about tripling the number of satellites in service with his constellation alone. Within the industry spacex would become the primary supplier and the primary consumer of rocket launches.
I hadn't heard of Arrows learning by doing but that makes sense as well for this discussion.
Pay 40k a year and get unlimited SpaceX Internet, a Tesla w/ free charging, and a complimentary flight/weekend stay at Solar City Space Hotel.
In fact, that makes me seriously think about the ITS for earth orbit activities. Add a nice big docking port to connect it to a space station, and you've got yourself a relatively cheap reusable vehicle to fly a whole mess of people into LEO.
I mean the planes in the beginning could charge high rates for just flying someone in a circle, but today planes need to be fast, reliable, on time all while being cheap enough that most Americans can afford them.
One organisation that provides our transportation, internet (which itself is gaming, information, communication, business, etc.), energy, and basically every facet of our lives. Google and Facebook are already trying to get closer to that...
As the market matures, some of these businesses might be spun off.
These are stepping stones to the future, they are not the future.
OneWeb is trying to do the same thing and already has rights to the spectrum from the ITU. They are using Arianespace to launch and Airbus build their spacecraft. It's possible this whole application is a ploy to disrupt Arianespace since SpaceX is upset about not getting a massive launch contract.
Commercial satellite constellations do not have a great track record. Iridium and GlobalStar tried to do phone networks and both went bankrupt. GlobalStar was backed by Qualcomm and Iridium by Motorola. Though they both have complete, functioning constellations. Look at GSAT and IRDM to see how well they are doing post bankruptcy.
Teledesic tried to do the same thing in the 90s and was backed by Bill Gates. It didn't go anywhere.
SDR is quite interesting because it can track moving satellites, and do simultaneous multipath reconstruction of multiple terrestrial broadcast signals -- digital tlevision, FM/AM/satellite radio, shortwave, etc. No antenna pointing needed, as it's all done in software. After demodulating the carrier the video and audio content is streamed on a local web page available to computers/phones/tablets on the LAN. Existing TVs can be supported via an HDMI or analog (VGA/composite/3.5mm) stick w an RF remote.
Optional (or one-time software unlock?) on-board storage for multimedia time-shifting and distributed CDN caching (reducing bandwidth and latency by keeping commonly served duplicate files like js libraries locally). Having a local server also lets them do fun things in the future like transparent LZMA compression, optional ad/telemetry/malware blocking, data pre-caching, smart shared HTTP caching, etc.
The inclusion of on-board storage allows data to be sloshed around to best utilize the terrestrial spectrum (broadcast content) and satellite spectrum (multicast content). It's much like Tesla batteries allow energy to be sloshed around to best utilize distributed solar and the utility grid.
With proper RF front-end design, support for the diversity of global broadcast standards can added through OTA software updates via satellite. This simplifies hardware into a single "world" model with regional software variants.
Easy install, especially with the wireless version (mount on pole, erect, securely fasten, done). Broadcast signal reach and convenience (any device or TV) that beats the pants off of any OTA antenna out there. Convenient access to terrestrial broadcast content w time-shifting takes some of the load from streaming services, so it's a strategic move and not just a "gee wiz" feature they got cheap because of SDR.
At $200-300 for the equipment and $50/mo for internet, with a good multimedia time shifting UI, SpaceX would cream every rural data provider out there.
Anyway, just the idle dreams of an internet user living in a rural satellite "data desert"...
Phased array flat panel antennas cannot be purely software steered sufficiently to track a low earth orbit satellite from horizon to horizon. It's not good enough to just put a flat panel phased array facing straight up, you won't have enough gain aimed in the direction where the satellite actually is at any given moment. Assuming a CPE device that measures 1.5'x1.5' to 2'x2' in size, it will still need a motorized azimuth and elevation stepper motor system (or equivalent) to track a LEO satellite.
If you're trying to do multi-Mbps data to/from a satellite in bands >10GHz (and probably >18GHz), the path loss through the atmosphere and RF parameters mean that you want as much gain as possible... This is why the most economical solutions for high capacity two way satellite through geostationary transponder capacity involve 1.8 to 3.0 meter size dish antennas. Gain is important. Gain and enough signal over noise ratio that you can do higher order QAMs and not spend half your bitrate on FEC.
You could, I suppose, if the antenna system was cheap enough and large enough build a non moving, cone or pyramid shaped antenna covered in phase array segments that could maintain a high bandwidth connection in the >10GHz bands to a moving LEO satellite. But it would be pretty large.
edit: for those who are curious and want to see an example of a parabolic (steered) use for moving satellite comms:
there is also an israeli company which is a competitor to mitsubishi in this space. and a few others.
if you watch the weekly FCC filings for new satellite equipment licenses, there's a lot of MELCO antennas flying around on top of mid and large sized jet aircraft.
Mark my words, SpaceX is quietly working toward nothing less than a revolution in global data infrastructure, just as Tesla is working to accelerate a revolution in global energy infrastructure. Sneaking in some software, onboard storage, putting them on all Tesla cars, mesh networking the terrestrial base stations with MIMO links, etc.
Cars suddenly become a global peer-to-peer mesh sneakernet. It would be fun if Tesla distributed data via "pulses" between passing cars... (signed high resolution maps? deep learning connectomes? the latest Netflix original series? :D)
>Phased array flat panel antennas cannot be purely software steered sufficiently to track a low earth orbit satellite from horizon to horizon.
Righto. SpaceX plans to steer the beam down to 40° from the horizon. This also minimized path losses.
Drawing from the SpaceX filing: http://i.imgur.com/7zOZ7kr.png
>All Ku-band downlink spot beams on each SpaceX satellite are independently steerable over the full field of view of the Earth. However, user terminals at the customers’ premises communicate only with satellites at an elevation angle of at least 40 degrees. Consequently, as shown in Figure A.3.1-1 below, each satellite operating at an altitude of 1,150 km will provide service only up to 40.46 degrees away from boresight (nadir), covering an area of about 3.5 million square kilometers (1,060 km radius)
source: Figure A.3.1-1 on pp6 of the FCC technical information document, currently 404, via /u/SkywayCheerios
I mean, that's a really cool 40,000 ft view idea and all, but global data infrastructure is made up of things like the Hibernia Atlantic cable, its several dozen cousins of post-2000 transatlantic and transpacific cables with DWDM terminals on both ends, and cool things like 100, 200, 400Gbps per wavelength coherent QPSK/16QAM DWDM terminals. And major terrestrial traffic exchange points of existing Internet infrastructure where ISPs put $150,000 core routers (example: 60 Hudson, NAP of the Americas, Telehouse Docklands, Otemachi Building in Tokyo, One Wilshire, 350 E. Cermak, etc).
Satellite traffic is a pretty tiny drop in the bucket compared to terrestrial backbone infrastructure. It's a truly admirable goal to bring affordable broadband to really impossible to reach locations via satellite. On the other hand there are a lot of emerging terrestrial WISP technologies and PTP microwave technologies that can be used in rural areas to provide bandwidth without the need to pipe it up into space and back. It's a lot cheaper to establish a tower site on top of a mountain, even if you need to bulldoze a road to the top, and spend $30,000 on routers and PTP/PTMP radio gear.
In some of the areas of the rural western US where my network engineering job touches, there are WISPs which are rapidly eating into the customer base of people who are (rightfully so) dissatisfied with highly oversubscribed consumer grade VSAT satellite systems.
In the end there will be a combination of many things. The next generation of high capacity Ka-band geostationary satellites (ViaSat-2, etc) are a lot higher capacity. Services like o3b allow ISPs to buy a dedicated 1:1 high capacity pipe to places that can't be reached by PTP microwave and are uneconomical to reach by submarine or terrestrial fiber (example, all of o3b's new pacific island nation state customers). There's traditional geostationary c and ku band capacity from SES, Eutelsat, Intelsat, AsiaSat, russian companies, etc. And of course terrestrial fiber. You don't need a huge amount of money to run singlemode these days, assuming aerial wood poles and a mostly rural area, you need two guys, a bucket truck and about $10,000 worth of tools.
Could an OTA update (and repointing 90°) turn a satellite terminal into an auto/calibrating point-to-point MIMO link?
>global data infrastructure is made up of things like the Hibernia Atlantic cable
Surprisingly the stated primary goal of the SpaceX constellation is actually to compete with long-distance fiber backhauls. Their sell for satellite backhaul is that it's lower latency (no need to avoid continents, 50% faster speed of light, fewer hops) and works everywhere.
Giving global gigabit internet to rural areas and ~10% of urban customers (with the rest on fiber) is only a bonus. :)
Most of what we know about the plan comes from this video. Timestamp is to the start of the juicy bits. https://www.youtube.com/watch?v=AHeZHyOnsm4&t=2m10s
The entire data throughput capacity of a current generation, 5500 kilogram, geostationary Ka-band satellite that costs $185 million to build and launch is much, much less than the 80 channel x 100 Gbps per channel DWDM system you can run on two strands of 9/125 singlemode fiber. And vastly less than the 144, 288 or 864 strand count fiber cable you would see laid between two cities by a carrier-of-carriers operator like Zayo these days.
It is fabulous to see more competition for high priced monthly-leased transport kHz/MHz from geostationary satellite operators. O3b was an amazing thing (and still is). More competition is good. But it's a pipe dream to say that satellite backhaul will ever be preferable to fiber carrying N x 10GbE circuits or a 100GbE circuit...
I expect crosslinks and backhaul up/down will be multipath laser w adaptive optics, not RF. As you say the physics demands it.
At 1100 km altitude each satellite has vacuum line-of-site to any other satellite within 6000 km (ground track). By "skipping" satellites you gain extra bandwidth capacity and reduce latency. Easy to route around damage, with no single point of failure (unlike fiber in certain areas). Obviously this will all be optimized with network and timing analysis to hell and back, just like fiber.
LEO has advantages of lower distance traveled, dramatically lower attenuation, faster speed of light, fewer hops, no cable breaks to fix, and no actual cable to run (which the expensive part of fiber, after all). You just build the repeaters, and exploit the fact that the exosphere is really transparent.
Musk, a guy who knows his physics and math, predicts in that youtube video that they'll ultimately do "more than half" of all long distance traffic. He also acknowledges that they have to 'skate to where the puck will be' re: telecommunication technology or they'll end up dead like innumerable predecessors. It's an interesting watch.
The filing states they'll be using free space optics / lasers between satellites. The Ka/Ku links are only for the initial uplink and downlink.
> But it's a pipe dream to say that satellite backhaul will ever be preferable to fiber carrying N x 10GbE circuits or a 100GbE circuit...
It is not a pipe dream. Free space optics in... well space, have a 50% propagation latency advantage vs terrestrial fiber. This helps equalize things somewhat.
Then there's a huge bottleneck, if the links from the satellite constellation as a whole to the trunk earth stations (not the CPEs) are high capacity Ka-band, there's RF issues with capacity...
It's like if you have a network that's composed of a whole lot of 10GbE backbone links from router to router and your IP transit connection to upstream ISPs/the global v4/v6 routing table goes through one 1000BaseLX link.
That aside, I don't think there's a big market for even lower latency (apart from algo traders). It's bandwidth that matters. You can get stable <150ms round trip times Europe<->East Asia and much shorter times to the US already. Problems with servers on other continents are not due to high latency but low throughput. And as others have pointed out, I don't think a system of satellites can compete with enormous bandwidth a single sea cable can provide.
Does anyone know if there are actual numbers out that show how satellites could transfer even a fraction of what's already travelling below surface?
Rural areas will definitely profit. But while the goal is great (internet for all), it's probably not what pays the bill. Aren't FB/Google's ideas of planes/balloons cheaper?
The speed of light in a medium is slower than the speed of light in vacuum. Fiber commonly propagates at just 200e6 km/sec.
Latency is still important because it's a significant limitation of GEO satcom.
> Does anyone know if there are actual numbers out that show how satellites could transfer even a fraction of what's already travelling below surface?
I'm unaware of any fundamental physical limit that prevent optics in space from matching or exceeding the bandwidth of terrestrial fiber. In terms of engineering the main limit is likely keeping beams in precise alignment.
Yes, very close. The index of refraction of air is 1.0003, so the speed of light in air is c/1.0003 = 99.97% the speed of light in a vacuum.
The index of refraction in a doped silicon telecommunications fiber core is around 1.4475, so the speed of light is 1/1.4475 = 69.08% the speed of light in a vacuum.
>Otherwise it's probably just 10-20% which I guess would be slower after considering the extra distance?
Undersea fibers have to avoid these things called 'continents.' For long distance hops this makes satellite the fastest system that's physically possible. https://personalpages.manchester.ac.uk/staff/m.dodge/cyberge...
Regarding the sea cable length: the continent argument is what I was referring to before. I don't think it's valid as most data flows US<->Asia or US<->Europe. And in both cases the ways are nearly direct. Only Europe<->East Asia has a major detour but I don't know if that warrants a global satellite system. One could still put a cable through russia (actually wondering why that doesn't exist for algo traders, connecting HK and London directly).
My first job out of school in 1998 was writing test plans for the antenna pointing and tracking for the Teledesic CPE at Motorola. If I remember right, the initial plan was to have dual steerable dishes inside a pair of radomes—like a pair of Mickey Mouse ears. There was a vague future plan for phased-array antennas, but at the time it wasn't realistic to talk about getting them on roofs at a reasonable price point.
The bigger challenge was the optical intersatellite links; routing traffic between LEO satellites using lasers. The lasers had to track satellites in adjacent planes of the constellation that were traveling in the opposite direction.
It's interesting to see the same general idea for the large constellation come up every few years. If we had actually started building it in 1998, it would've been on a second or maybe even third generation by now.
I'm a little surprised that Apple hasn't given it a try with their billions sitting around. 4K FaceTime, or even just downloading movies or apps instantly would be a selling point for their other hardware.
Didn't Iridium get around that by having a single "seam" between adjacent oncoming planes which signals don't pass, but for all other adjacencies using crosslinks between planes?
The really curious part is how the satellite to ground trunk link will be accomplished, if they're going to try to build something like a modern version of the satellite-to-satellite links that Iridium satellites use, but at much higher capacities, draining traffic from multiple satellites through whichever one happens to be over a gateway earth station at a particular time. Or perhaps the satellites will be able to do that and also opportunistically connect to operator-owned earth stations when they are in LOS.
Also with 4000 satellites, you probably wouldn't have to track one all the way to the horizon.
Don't conflate SDR, phased arrays, and MIMO. They're separate things. The latter two can be implemented vi a variety of hardware. State of the art radars tend to use a lot of FPGA's for aperture synthesis, not SDR.
SDR also isn't quite the panacea you're presenting. You can't just slap some magic processor in something and then gain access to huge swaths of spectrum. Even highly advanced UWB phased array apertures are limited to around 10:1 bandwidth. Getting up to and past 1 gigasamples per second is difficult even using the prior mentioned pile of very expensive FPGAs.
You won't be able to pull in everything from ~100mhz signals to 18ghz signals all in one $300 pizza box on your roof. The spacex device will be much more narrowly targeted.
<script src="https://cdn.spacex.com/js/jQuery-1.8.3.min.js" />
I'm tethered to 3G, and for all purposes it's as fast as cellular internet I've used anywhere in the world.
It is a little more expensive than most locals really can afford, although they are all checking facebook multiple times per day.....
So I really don't understand this idea of "bring internet to the 3rd world" they have it already.
Besides, what's with the desperate attempt to slander this endeavor as some kind of misguided moral grandstanding? As far as I can tell, they're not doing this just to bring internet to 3rd world countries, they're doing it to bring better internet to the entire world.
Also, you aren't a real rich person until you've "helped the Africa".
Yes, very much. Now I've been moving around for 5 months my eyes are very much open to the reality.
People also thought I would be murdered on day 1, when in fact I have met many, many kind kind friendly people who have welcomed me into their home.
The culture of the West really does teach it's pupils they are the best, and everyone else is crap. The Media further enhances this idea.
I loved when I met a guy in a rural, poor part of Gambia - he said "Oh yeah, my brother lives in Australia. I was there for a few years. I came back here, I like it more".
Africa is not the hell-hole people think it is.
I live 5-miles outside of a town in Idaho with a state university, and a population of about 30,000 people. Between my house and town, I lose service for 80% of the drive. If I drive from here to the next major population center, I'll only have internet on the state highway for about 40% of the drive. If I make the same drive on back roads, I'll have internet for less than 10% of the drive.
The situation is much the same in much of the rural West.
Interesting note from the Organization section where it shows that Elon's trust owns 54% of outstanding SpaceX shares and over 70% of the voting shares.
I do wonder how this will affect potential customers who would launch communications satellites on SpaceX, but are worried about handing over something proprietary to a competitor.
In the long run though, success at scale with a system like this relies on the typically guaranteed losses. A certain percentage of rockets will fail, a certain percentage of satellites will fail, a robust system will be designed to accommodate this.
(Of course, and this is probably the topic of a totally different thread, the tolerance for this must change dramatically when there are people in there.)
I'm not saying I want more concentration, I'm just saying that the path to de-centralisation is not that clear cut (at there is a threshold were we have to talk about CO2 emissions).
Does someone know what orbit these are being launched into and how heavy they are?
For these satellites, you can find a description of their orbit and a guess at their mass at https://en.wikipedia.org/wiki/SpaceX_satellite_constellation
Keep in mind, this system is designed to give the Internet to everyone. The antennas will be small enough to conceal. Since the signals go up instead of across a border, censorship is not an issue.
That's very short-sighted. The connection terminates somewhere, so the whole path is either (you)-(satellite)-(local ground station)-(ISP in your country) or (you)-(satellite)-(another satellite)-(remote ground station)-(ISP in another country)
Censorship then can happen at:
- the satellite (unlikely, they probably just want to forward packets with minimal power/time use)
- ground stations (great firewall of china style)
- ISP (standard, existing filtering)
- any nation that wants to just shut down the access rather than censor it (wide band, high power noise, send straight to the satellites to kill all communication)
Also, the use of the equipment should be pretty easy to detect if you can afford a few plane trips (maybe even just vans), so nations that don't like the idea can just knock on your door and have a chat about it with you.
Rubber hose cryptography principles.
I imagine Musk could get even more than the already generous US government protection if he puts the base stations on US soil (I.e. all traffic in NSA reach)
Furthermore, nation-state censorship only has to make reaching censored services more difficult for the average person. They specifically throttle home internet connections but leave businesses alone.
I think I can glimpse what Musk long-term vision is for "connected cars..."
Satellite is pretty much perfect. One provider works globally (vs dozens of mobile proviers), coverage is near 100% everywhere, and mass broadcast signals (like firmware updates and SDC neural connectomes) can be cached locally on the satellite, conserving uplink bandwidth.
Edit: change Uber-like to distributed. Side comment, lots of Uber drivers buy cars. Uber even helps finance cars.
> Each satellite in the SpaceX System is designed for a useful lifetime of five to seven years. SpaceX intends to dispose of satellites through atmospheric reentry at end of life. As suggested by the Commission,50 SpaceX intends to comply with Section 4.6 and 4.7 of NASA Technical Standard 8719.14A with respect to this reentry process. In particular, SpaceX anticipates that its satellites will reenter the Earth’s atmosphere within approximately one year after completion of their mission – much sooner than the international standard of 25 years. After the mission is complete, the spacecraft (regardless of operational altitude) will be moved to a 1,075 km circular orbit in its operational inclination, then gradually lower perigee until the propellant is exhausted, achieving a perigee of at most 300 km. After all propellant is consumed, the spacecraft will be reoriented to maximize the vehicle’s total cross-sectional area, a configuration also stable in the direction of aerodynamic drag. Finally, the spacecraft will begin to passivate itself by de-spinning reaction wheels and drawing batteries down to a safe level and powering down. Over the following months, the denser atmosphere will gradually lower the satellite’s perigee until its eventual atmospheric demise.
Isn't that a relatively low lifetime for so many satellites? Doesn't that mean they'll need to make a lot of launches just to keep the fleet operational?
As someone stated above, this all hinges on first stage reuse proving to be viable. If a customer buys a flight and they recover and reuse the booster, it's almost a "free" flight for them.
But yeah, expect this number to grow fast as more people do stuff like that. It will be a problem eventually.
It would also kill Iridium (either the current generation of satellites, or the next generation which will be in generally the same orbital configuration) because it depends on low earth orbit, highly inclined polar orbit satellites. Iridium is incredibly important to maritime users and aircraft users, in addition to its massive US DoD use.
I'm sure SpaceX isn't the only player thinking of adding a lot of cheap satellites in orbit
So, yeah, I'm gonna assume people who're by every definition smarter than me aren't going to try this kind of 'meh' technology for their own Google Fiber like plans. Ground based RF networks make a lot more sense imho.
I'm not presuming I know better than a bunch of SpaceX engineers.
This has been mentioned before in the context of municipalities building/maintaining fiber infrastructure and subletting to ISPs.
How much microwave energy do you need to put on a watermelon to make it pop?
Source: I live in such a place.
Have you calculated the optimum?