Boeing swipes at Starlink as it finishes two internet slinging satellites Boeing has delivered a pair of O3b mPOWER satellites to telecom network provider SES – and had a dig at rival space broadband technologies along the way. The spacecraft are scheduled for launch into a Medium Earth Orbit (MEO) of about 5,000 miles (8,000km) next month. Once in orbit, the satellites "will provide low-latency, …
It’s the (fixed) size of the selected launcher divided by the size and mass of each satellite. Most (not all) launches contain two satellites sometimes of different owners - it’s a bit more cost-optimal to develop larger launchers and share, but does cause problems when one satellite owner has to wait due to a production hitch on the other
Apples and oranges though.
Lose one satellite and Starlink can compensate and/or launch more cheap boxes. If SES lose one they lose the entire "constellation" of 5000 beams and it is both difficult and expensive to replace it but, arguably, they are less likely to lose a satellite.
I would assume you'll need a much bigger dish for MEO too - so no roaming. It will be interesting to see what the beam footprints are and whether there's overlap to preserve "reasonable" signal strength across the entire coverage area eg Europe or whether it's designed for higher bandwidth, specific targets - Paris, Amsterdam, Skegness ...
They are launching in-orbit spares, so if they do loose a complete satellite (something that happens, but not often) then they can rejig the constellation to cover the gap.
You don't necessarily need a bigger dish on the ground terminal - depends on how they have closed the link budget. Most likely they put a bigger dish on the satellite with a huge gain; entirely feasible given modern antenna structure technology (look at the size of the antennas that the likes of Intelsat and Inmarsat are using on their current-generation GEO satellites).
I personally worked on an experimental terminal that used an antenna that was only about 60 mm high and weighed in at about 30 g. We used this to transmit terminal-to-terminal over GEO, passing IP packets back and forth, albeit at low data rates.
"Apples and oranges though."
Yep. Also worth mentioning the different target markets too. Boeing/SES are after government contracts where latency from MEO will likely be less of an issue than the consumer oriented target market and even lower latency of Starlinks LEO based kit.
I wonder why they felt the need to repeat "low-latency" quite so often? Starlink is up around 500kms, and that gives 30-50ms round-trip latency depending on a bunch of stuff. Assuming some of that is routing on the ground, and waving a finger vaguely in the air, I reckon that puts this service at, what, 3-400ms round-trip latency?
Which, OK, is way better than the 1100ms I "enjoyed" with our first satellite service many years ago (actually, that was hilarious, made Telnet sessions feel like a 110baud teletype), but definitely isn't low.
GJC
TLDR; No, LEO or MEO satellite are both rather low-latency, hedged around with the usual “it depends”.
How are you calculating 30-50ms round-trip latency? If all you are considering is radio time-of-flight, I reckon you have a decimal point in the wrong place. 1000km round-trip is 3ms, not 30ms. However, RTT processing delay in any 4G telecom system is going to be in the 10-20ms range, so you are sort of right…..but then that has nothing to do with MEO etc.
And then finally, if you are looking at global hops via inter-satellite links, then yes by definition that’s up to 15000km, and dozens of milliseconds....but that’s actually *faster* than undersea cable. Because signal-speed through cable is slower than light in a vacuum ( although also, the cable usually goes in the right direction, while ISL will typically have to triple-hop in a bit of a zig-zag).
I understand what you are doing, but you are mis-applying your measurement. You’re on my lawn: I’ve been responsible for the design and implementation of a major global satellite Internet system myself, plus more than one terrestrial telecoms system.
You measure 30-50ms on Starlink, and assuming that this is $BecauseSatellite. You assume that if the 30-50ms is radio flight-time to Starlink LEO, then a MEO must be multiples higher. Whereas actually, almost all of the 30-50ms latency you are seeing is digital processing delay in the satellite receivers, not radio flight-time. Therefore MEO satellites won’t necessarily be noticeably higher latency. Going from LEO to MEO is single-digit milliseconds, even given that satellite systems have two up-and-down trips per data round-trip. The main thing being doubled by satellite, is processing delay (four radio-receivers-worth), unless you are going to GEO, plus satellite radio-receivers are typically a few generations old in terms of technology.
I’m well aware of the slant distance issue. But you don’t connect to a low-azimuth satellite, because blocking by trees and buildings, therefore, unlikely to more than double the slant distance.
Satellite constellation design is complex, and depending on what you’re doing MEO can actually be lower-latency than LEO, if it can mean fewer inter-satellite-link hops due to the horizon.
One could do it the way Kosmos 2251 did...
More seriously: This is wel beyond range for a laser broom to be effective (and yes, we should be developing these), however it's an ideal task for an ion tug such as MEV1
You don't actually need much delta-V. Simply tweak the orbit to go highly elliptical (relatively easy to do) and the atmosphere will do the rest for you
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