Lunar Gateway has simply been taken off the critical path for Artemis, They still plan to build it, because where would we be without giant international money sinks? Besides, now that it’s not time critical, vendors can get back to larding it up and dragging their feet to maximize profits in a cost-plus fashion.
The gateway will probably get built eventually, due to too many special interesfs wanting to feed off it. Whether it advances lunar exploration in any way is a more difficult question.
Because it’s better for rockets.
The power of parachutes and exposure to salt water are very harmful to rocket boosters. It is much better to just plant them, as this makes reuse cheaper and easier.
Imagine if, when your car ran out of gas, you threw it into the ocean. Then you took it out, took it apart, cleaned and dried all the pieces, and put everything back together again. It’s much easier to just drive to the station and refuel!
I’ve driven a few cars that made me want to do that.
Interesting reason for that.
Fun stuff.
Already been done, although they stopped in 2014:
I read a book years ago that said there were three sites in the U.S. that were considered for a long-range missile test range. The requirements were to launch from land, over water, but with enough land downrange to build tracking stations. The choices were:
Eastern Florida, launching southeast over the Bahamas
Southern California, launching south near Baja
Western Washington, launching northwest toward the Aleutian Islands
I’ve never been able to confirm that from another source, though. According to that book, the Florida location was chosen mostly for its weather, and it turned out to be a fortunate choice when we progressed to putting things into orbit.
To be a bit pedantic, the closer to the equator you are the better.
Fair point. My northern hemisphere bias is showing. 
Looks like space bought two deepwater semis drilling rigs
https://www.offshore-energy.biz/elon-musks-spacex-buys-two-valaris-rigs-to-build-rocket-launchpads/
Those would be have been at least 300 million apiece back when they were purchased and high end dynamic positioning, probably would have been bringing in 500K a day for 5 years at least, obviously not so much for the last few years being stacked.
Anyway , looks like spaceX is planning on sea landings for a long while yet.
It says launchpad, i am not sure if that is correct or just more landing pads.
Launch pads. The full-stack Starsip is too loud and energetic to launch from land. They want these things going up more than daily, and they’re more powerful than a Saturn V.
I read elsewhere that the original price was ~$500M each. $3.5M is a heck of a discount.
Yeah I’d have guessed 500 but I found an article with the original price. Those rigs would have made some good money, but now have been superseeded by drillships and are likely to be cold stacked forever.
3 million would be worth it just so as not to have to deal with it left at port.
Overall the deepwater drilling rig contractors have something like 30 billion dollars of collective debt and a lot have filed chapter 11, so there probably are quite a few opportunities to pick up more rigs if needed for cheap.
I’ve also heard of tentative plans to use Starship as a suborbital transport, launched/landed from rigs offshore of major coastal cities.
They’ve certainly spoken about that. It’s an interesting idea and would certainly require an offshore platform, but I suspect once (if) they reach that point they’ll have some custom solution that looks more like an airport than an oil rig (then again, SpaceX may refit these rigs to be a little cleaner looking). Also, initial use as transport will likely be Starship-only (no Superheavy booster). It has a pretty good suborbital range by itself and avoiding the booster eliminates a lot of cost and failure points. A Starship-only pad would be a lot simpler than one that supported Superheavy as well.
Yeah they can strip off all the derrick items drilling equipment, accommodations, tubular and riser storage areas ( that would have contained several million pounds of pipe) helideck, fluid and bulk storage >1.3 millon gallons and 30000 cu ft of solids) and handling, , pumping equipment and the subsea stuff you are left with a 255 x240 ft deck area with 8 dynamic position thrusters , a huge ammount of power generation and all the marine command and controll stuff with a huge deck load capability and pretty damn stable when balasted down.
Even with the conversion cost it’s a great deal.