Submitted by Corbulo2526 t3_z7exiu in space
swissiws t1_iy7iomz wrote
I think Starlink satellites could effectively replace GPS only satellites. There are orders of magnitude higher in quantity (and more satellites means higher precision). Also Space Force has priority above everyone else when it's about Starlink and SpaceX
BecomingCass t1_iy7qh2e wrote
Do Starlink satellites have atomic clocks onboard? That's necessary to work with existing GPS equipment, otherwise you'd need to replace a lot
swissiws t1_iy83jtv wrote
every satellites in the Stalink network self-destroys every 5 years by burning in the atmosphere. all of them will be replaced sooner or later and this means any kind of equipment could be added if needed
BecomingCass t1_iy84as5 wrote
There's a lot more to adding functionality to a satellite platform than just having a new one up there
Yes, they'll be replaced, but does the existing platform have space in the power or mass budget to add the needed equipment? If not, can changes be made to the base design without starting from scratch? Will DoD be on board with having a private company operate GPS satellites (Lockheed builds them, but the current GPS system is operated by the USSF)?
swissiws t1_iy8dvg2 wrote
Us European have our GPS satellites (Galileo) and it's mainly private money
sleepyzalophus t1_iy8g05q wrote
Galileo is great. It’s effective and relatively inexpensive. It unfortunately requires a lot more maintenance of uploading ephemeris data than GPS does. GPS gets daily ephemeris updates but can go as long as a week without it and still have okay accuracy. Galileo operates with multiple uploads per hour and if a satellite misses updates for a day, as happened in 2019, the whole constellation turns off. The two systems perform different roles so it’s a bit unfair to compare them directly. All of NATO uses GPS so Galileo doesn’t have as strict resiliency requirements; therefore, they can be made differently and cheaper. It’s an excellent system for what it does with its public/private signals though.
lendluke t1_iy8bp89 wrote
I thought the use of GPS requires devices to always know exactly where the satellites are to triangulate position. I would think using potentially thousands of starlink satellites would require extremely different software/hardware and possibly obsolete every current GPS enabled device.
sleepyzalophus t1_iy88zdj wrote
It’s unlikely GPS will be entirely replaced. Lots of platforms and equipment use the precise timing of its signals to do all of the functions they need. We already have requests for PNT in GEO and cis lunar space for accurate positioning on scientific, military, and commercial vehicles, which cannot be done from LEO. However, PNT data on Earth can be backed out of starlink signals as an unintended use of their service, but I believe that signal still requires GPS data from the aft antenna. There are at least two other programs actively developing PNT from proliferated LEO as well. The additional platforms providing PNT augment GPS signals to improve signal accuracy, minimize jamming effects, and provide redundancy to minimize adversarial ROI for attacking a GPS satellite.
Full replacement of GPS is possible, but won’t happen in this generation of satellites. My guess is we will have layers of PNT from mobile terrestrial ground beacons, proliferated LEO for resiliency, legacy MEO with the most accurate timing, and a persistent GEO layer for omni-present coverage to lower orbits and region-specific interests such as indo-pacom.
jonnyyen t1_iyaqmth wrote
And the GPS constellation is instrumented for a lot more than just positioning, navigation and timing. So full replacement will need the US government to have plans beyond a PNT replacement system, and likely that will still involve a heavy presence at MEO and continued presence at GEO.
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