Who cares about current-model hand-held models?In this industry the normal lifetime of the devices is <4 years.I mean, when introducing 4G networks, did anyone care that existing 3G phones would have to keep using 3G?When SL is up, you'll need to get a phone that is SL compatible - as simple as that.The only question is whether it is possible for a vLEO constellation to directly service these hand-held devices, and I think the consensus was "yes". (Which is why the vLEO constellation is there to begin with)
The LEO constellation will do back-haul and maybe connect with non-hand-held terminals (e.g. car roof-top antennas, stationary stations)
I'd argue rad-hard (Si on sapphire etc) process technology is overkill regardless ... there are very few manufacturers, it lags several generations, etc.
As you say, I think rad-hard enclosures are a better approach. However, having said that, *some* level of protection is sensible (and is already in current commercial hardware; e.g. single bit ECC correction is pretty much mandatory on RAMs). [ I design high performance processors ]
They also routinely move payloads through van Allen Belts... so LEO isn't their only experience to date.Hopefully soon they will be flying routinely BEO and inform/solidify what defines state-of-the-art in comms and power processing.
I said this a few times, but I don't think it's far fetched to say that Starlink could be the most profitable single business venture on Earth... (well, technically, not on Earth, but you know what I mean ) Which is why they are so quiet about it.
The radiation environment isn't necessarily much better than deep space. In LEO, you also have to deal with part of the Van Allen Belts.Crews are more sensitive to GCR than silicon is, relative to the types of radiation received in LEO. You most certainly can extrapolate that experience to beyond LEO, concern-trolling aside.I'd say that SpaceX's experience in LEO shows their approach, if tweaked a little bit, would work just fine beyond LEO.
In the US, cellphone data is priced about 50x what broadband data is priced, per bit. I'd imagine there is a large ratio in other countries as well.
If Starlink ships all it's ground terminals so that they publish a WiFi network accessible by any Starlink customer, and if phones get fast at switching WiFi basestations mid-call, and if Starlink can patch their coverage by adding their own ground terminals along freeways and perhaps in downtown areas... then Starlink can capture some interesting fraction of the worldwide cell service market.
Quote from: speedevil on 01/20/2018 12:01 amRisk reduction.From SpaceX's POV.At a rate of 30 launches a year, splashing S2 costs some $600M/year, this is going to get worse as Starlink ramps.You are working to some date that you believe BFS (possibly with BFR) can take over the majority of F9 launches.Say this is 2021 (using BFS-SSTO launching maximum payloads of 10 tons, for the sake of argument).From a business case alone, from 2019-2021, you have $1B of S2 cost or so in F9 launches.If you can bring re-usability forward by S2R by one year, you have $600M or so extra to spend on BFS.If you consider that there is a 50% likelyhood that spending $100M now on S2R versus BFS will bring reuse forward a year (including probable BFS delays) that may be a very simple trade to make, as it may actually in many cases lead to BFS happening sooner.At some point 'distracting from the BFS effort' becomes 'providing more money for the BFS effort'.Yes, sign me up for that.But the decision they (apparently) made was to move forward faster.My point was that it was not a case of insufficient ooomph, if you'll pardon the phrasing...
Risk reduction.From SpaceX's POV.At a rate of 30 launches a year, splashing S2 costs some $600M/year, this is going to get worse as Starlink ramps.You are working to some date that you believe BFS (possibly with BFR) can take over the majority of F9 launches.Say this is 2021 (using BFS-SSTO launching maximum payloads of 10 tons, for the sake of argument).From a business case alone, from 2019-2021, you have $1B of S2 cost or so in F9 launches.If you can bring re-usability forward by S2R by one year, you have $600M or so extra to spend on BFS.If you consider that there is a 50% likelyhood that spending $100M now on S2R versus BFS will bring reuse forward a year (including probable BFS delays) that may be a very simple trade to make, as it may actually in many cases lead to BFS happening sooner.At some point 'distracting from the BFS effort' becomes 'providing more money for the BFS effort'.
...No, it was a case of insufficient materials science and the physics of reentry, and the inability to turn a stage into a reentry vehicle, without actually turning it into a reentry vehicle. ..
Quote from: IainMcClatchie on 01/19/2018 09:55 pmIn the US, cellphone data is priced about 50x what broadband data is priced, per bit. I'd imagine there is a large ratio in other countries as well.A very good point. But isn't that more an issue with regulation than technology?
Quote from: IainMcClatchie If Starlink ships all it's ground terminals so that they publish a WiFi network accessible by any Starlink customer, and if phones get fast at switching WiFi basestations mid-call, and if Starlink can patch their coverage by adding their own ground terminals along freeways and perhaps in downtown areas... then Starlink can capture some interesting fraction of the worldwide cell service market.And it only needs 3 "ifs" to work out as you predict to be correct.
All true, but this is a view of "how will SL look in the context of today's comm market."....What kind of comm market will grow around SL? How many industries will become dependent on it?What else can SL do once it has 10,000 satellites in orbit?
Quote from: john smith 19 on 01/21/2018 01:51 am...No, it was a case of insufficient materials science and the physics of reentry, and the inability to turn a stage into a reentry vehicle, without actually turning it into a reentry vehicle. ..Wrong, wrong, wrong, and not even wrong.There is and was no technical showstopper to upper stage reuse. It's a matter of proper use of resources.
A reusable upper stage for Falcon 9 wouldn't be able to serve the bread-and-butter GTO launches with sufficient performance, and generally it was decided that the huge amount of resources needed to make that work would be better spent on BFR.
...I don't think it's practical to project forward to more revenues that the existing global cellphone market (which is growing).Energy and food and now communications are sucking up a very large fraction of people's total spending. No matter how attractive a new product might be, it can't significantly grow one of these spending categories (or establish a new one) unless people either spend less on another category (e.g. spending on car depreciation drops as fewer cars service more people) or get more income from increased productivity. The trouble with the latter is that most productivity increases in the U.S. are going to a small fraction of the population who aren't a big enough communications market.
I thought this thread was about Starlink?
IOW the materials science is not good enough to do the job for the weight it would need......
Quote from: oldAtlas_Eguy on 01/21/2018 04:26 amI thought this thread was about Starlink?It's inevitable that "... but F9 US!" would crop up in almost any thread.
WRT the topic of this thread...People could do worse than study the Gravity Recovery & Climate Experirment. https://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_ExperimentThis probe lasted 15 years about the same target height as Starlink and was in the same mass range (487Kg). Likewise Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) ran about 5 years at 260Km and had a pair of ion thrusters while massing 1077Kg at launch. https://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_Ocean_Circulation_ExplorerBoth were long and thin, because aerodynamics (and the disturbances it causes to the internal payloads) were considered significant factors. I'd suggest both missions have valuable lessons to teach anyone wondering what shape these satellites should be and how long they could last.
Quote from: john smith 19 on 01/21/2018 06:53 pmWRT the topic of this thread...People could do worse than study the Gravity Recovery & Climate Experirment. https://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_ExperimentThis probe lasted 15 years about the same target height as Starlink and was in the same mass range (487Kg). Likewise Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) ran about 5 years at 260Km and had a pair of ion thrusters while massing 1077Kg at launch. https://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_Ocean_Circulation_ExplorerBoth were long and thin, because aerodynamics (and the disturbances it causes to the internal payloads) were considered significant factors. I'd suggest both missions have valuable lessons to teach anyone wondering what shape these satellites should be and how long they could last.We've already been told how long the sats would last (5-7years) and their basic shape/size. Not sure where you're going with this... (?)
What do the Van Allen Belts have to do with Starlink?The orbits for the Starlink constellation are around 1000km. (The VLEO thing isn't going to happen anytime soon.)
...We should be explicit on whether we're talking about the LEO or vLEO constellation.I thought the LEO constellation was significantly higher than 200-300 km... about twice that altitude IIRC. And yes - 5-7 years.The vLEO constellation will fly low and last fewer years, 2-3 IIRC.That's two IIRCs in quick succession... If I'm wrong, please jump in...
Quote from: gongora on 01/21/2018 10:18 pmWhat do the Van Allen Belts have to do with Starlink?The orbits for the Starlink constellation are around 1000km. (The VLEO thing isn't going to happen anytime soon.)For some value of "soon".If ChrisB had a nickel for every time someone said "won't happen in a decade", L2 would be free. StarLink is a commercial venture, and there is competition just around the corner. I don't think they'll be wasting much time once they get going.