Backup to GPS

I forgot to post about this when I saw it recently.   Given my view that satellite based global positioning is  an incredible thing that is greatly under-appreciated,  I just thought this was interesting:

SpaceX's Starlink satellites may be used for navigation and global positioning in addition to their core function of broadband Internet, a new research study suggests.

Engineering researchers external to SpaceX found a way to use the Starlink constellation signals for navigation similar to the capabilities provided by global positioning satellites (GPS), which are used in the United States and several other countries. The study represents the first time Starlink was used for navigation by researchers outside of SpaceX, the team members stated.

Researchers triangulated the signals from six Starlink satellites to fix upon a location on Earth with less than 27 feet (eight meters) of accuracy, the team reported in a statement. That's pretty comparable to the typical GPS capabilities of a smartphone, which typically pinpoints your spot on Earth to within 16 feet (4.9 m), depending on the conditions....

Kassas noted that Starlink's accuracy, using this methodology, will increase as more satellites in the fleet fly to orbit. SpaceX has about 1,700 working satellites today, the team stated, but the company hopes to launch more than 40,000 into orbit. (Recent launches have been delayed due to a liquid oxygen shortage induced by higher medical needs during the COVID-19 pandemic.)

The researchers suggested this method of using Starlink navigation could supplement traditional GPS navigation, the latter of which has vulnerabilities. Since GPS has been around for a generation (more than 30 years) and has a well-known signal, it is easy to use on smartphones or vehicles — but also more "vulnerable to attacks", the team stated.