Astranis emerges from stealth with new satellite tech for connecting the world

Post by gedmark » Fri, Mar 02, 2018, 1:35 AM UTC

planteen wrote: post #23

gedmark wrote: post #3

Hi everyone, I’m one of the cofounders of Astranis (YC W16). Thanks for taking the time to read about what we’re doing and happy answer any questions.

Ok, I'll hit you with 3 questions: 1. What bandwidth capacity are you aiming for per spacecraft? 2. Are you using commercial or rad hard parts? 3. Is there a deployable antenna that makes the spacecraft larger than 3'x3'x3'?

Post by gedmark » Fri, Mar 02, 2018, 1:49 AM UTC

caio1982 wrote: post #4

gedmark wrote: post #3

Hi everyone, I’m one of the cofounders of Astranis (YC W16). Thanks for taking the time to read about what we’re doing and happy answer any questions.

With what rocket system do you plan to launch these sats? Which company will launch and which will assemble them (often these are different ones)?

Post by robkop » Fri, Mar 02, 2018, 2:00 AM UTC

colanderman wrote: post #32

consciouskernel wrote: post #17

There's a reason that no other company tries to use geosynchronous orbit. Stationary orbit is at a distance of 35800 km above sea level, which implies a one way latency of 110 ms based off the speed of light. Since any request from a user requires a total of 2 round way trips (one for request, one for response), the minimum latency for a request is 440 ms. Avg latency with fiber is something like 30-60 ms, so we can…

> any request from a user requires a total of 2 [sequential] round way trips (one for request, one for response) Please elaborate? This makes no sense to me. Certainly, this is not the case for terrestrial communication (request/response latency is only 2× the one-way latency).

Post by jandrese » Fri, Mar 02, 2018, 2:11 AM UTC

dfox wrote: post #27

jandrese wrote: post #13

Earlier quoted context omitted.

Audio streaming not including voice calls I assume, because those are absolutely latency sensitive. Are your terminals going to include TCP Performance Enhancing Proxies (PEPs)? The TCP three way handshake followed by the TLS handshake makes it kind of painful to browse on an unaccelerated network with a GEO hop. And this is before you get to the latency from the ground station to the website. The problem gets even w…

From my experience it is not so hard to build completely terrestrial links that have latency that is large enough such that TCP works (althought it should not), but TLS handshake will timeout. For GEO links you will get exactly this behavior by using BGAN terminal over Bluetooth DUN profile (BT adds enough latency for this to happen).

Post by planteen » Fri, Mar 02, 2018, 2:19 AM UTC

jandrese wrote: post #29

dfox wrote: post #28

Earlier quoted context omitted.

There is a difference between the CPE (what you use to get the service) and what SpaceX uses to sink your traffic into the global internet. And in fact there is exactly zero incentive for somebody other than SpaceX to run the ground stations. On the other hand it is completely possible that SpaceX's ground stations will use HW that is similar to their CPE box and thus they can build ridiculous amount of such ground s…

That would be an interesting model for the ground stations. Everybody else builds large and capable ground stations with big dishes. Iridium for example provides global phone and slow data coverage using only one public ground station, but also uses a completely different band to talk with the ground stations vs. the handhelds.