Every coin uses the Internet for coordination of its blockchain. It's ubiquitous, it's convenient.   But depending on this does has a major flaw for a currency. Your Internet may be limited due to location.. hard to get a hookup in the Congo even by phone dialup. Or maybe you just have a solar powered vending machine on a mountain trail far from a cell tower.  More importantly your Internet may be limited or blocked due to government control.. have you seen many blog posts from North Korean citizens? And perhaps most importantly your Internet (and therefore currency transactions) are monitored by governments (and not just yours), no matter how high your tech savvy level is.

So it's useful to have an alternative way to optionally, additionally, access a blockchain, making the currency usable without using the Internet. This second method doesn't have to be commonly used, it just has to be POSSIBLE.. we just need a "backup channel" to the blockchain for needed robustness. You need it to coordinate blocks and transactions globally and with low latency (though not much bandwidth), and be completely independent of the Internet.   What kind of communication system can do that?  There's really only one answer: Communication satellite constellations. Because it's so low bandwidth, you can use tiny cheap satellites. Guess what Vectorspacesys does?

The Nexus Earth site doesn't really explain the importance and appeal of this, but that's likely because they (quite properly) shouldn't hype a future feature that's planned but doesn't actually exist yet.