More About SpaceX’s Oil Rigs

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This is a screenshot from a SpaceX event, but when Phobos and Deimos are deployed in the Gulf of Mexico, it may look similar to this at night.

In a previous piece by my colleague and friend Johnna Crider, CleanTechnica covered SpaceX’s plan to convert oil rigs into floating launch platforms. There’s a lot more detail there, but in a nutshell SpaceX bought two used oil rigs that were available near its Boca Chica launch facility. The plan is to convert them into floating launch and landing facilities for SpaceX’s Starship and its booster, Super Heavy.

In this piece, I’m going to expand on Johnna’s work by giving more details about the rigs themselves and what we might expect as SpaceX repurposes and then deploys them in the Gulf of Mexico.

The ENSCO 8500 Series

ENSCO started building its 8500 series rigs in 2005. Between then and 2012, seven copies were built. The model numbering for these rigs is a little different from other products consumers are familiar with. All seven of the rigs are the “8500 series,” but they each get a sequential number, starting with 8500 and ending with 8506. SpaceX purchased 8500 and 8501.

Valaris, an oil producer, purchased the 8500 series rigs as ENSCO built them, but its website now only shows rigs 8503, 8505, and 8506. The other rigs were sold or leased to other drilling companies, possibly as part of Valaris’ restructuring last year. Shortly before restructuring, Valaris sold SpaceX the two rigs for $3.5 million each shortly before bankruptcy.

The ENSCO 8500 series are semi-submersible rigs. What this means is that they don’t sit on the bottom of the ocean like a drilling platform (which sits atop a tower) or a “jack up” (which has extendable legs to sit on the sea floor). They differ from drilling ships in that they sit on pontoons that are pushed under the water, below the waves, which gives them greater stability. They’re often anchored to the sea floor with a cable to keep them in roughly the same place and stay coupled to the wellhead, but in some cases they stay put with thrusters or a combination of the two.

The chains, cables, or ropes securing the rig to the anchor point or points are computer controlled. They are able to be spooled in or out, and can stabilize the floating platform against even the nastiest conditions. According to the National Ocean Industries Association, all platforms built since the late 1980s are designed to withstand category 5 hurricanes, but are still evacuated as storms approach to protect life and prevent injury. The last time many rigs were damaged was in 2005, but most of the damaged rigs predated requirements to be able to withstand the storms.

Tug boats are usually needed to move the rigs around when relocation is needed. The platform can be raised or lowered by pumping water in or out of the pontoons to adjust buoyancy. Setting the platform lower gives more stability, and raising it is usually necessary to reduce water drag and move it more easily.

The rigs’ main decks are 240 feet by 255 feet. Normally, there’s a big tower in the middle for lowering drilling equipment into the “moon pool” and then lower into the ocean, but with the tower removed or relocated to the side, there’s a lot of room on the platform for the things SpaceX would likely do with them.

Where Are They Now?

Most media reports indicate that 8500 and 8501 are in the Port of Brownsville, a ways inland from the Boca Chica launch site. Using ship tracking websites and Google Maps, I was able to find 8500 there. You can see it for yourself on Google Maps here, or use your preferred mapping program to look at 25.9672636, -97.3599312. Several enthusiasts and SpaceX news sites went and got photos of 8500 recently, as seen in Johnna’s article.

8500 is now named Deimos, after one of the moons of Mars. NasaSpaceFlight got photographs of Deimos signage on the rig’s rails. Presumably 8501 is now named Phobos, after the other moon of Mars.

Finding 8501/Phobos was a little more tricky. After looking around, I found one ship tracking website that told me it was in Galveston, Texas. Google Maps confirms as much, but it’s possible that SpaceX has moved the rig since the last time Google got aerial imagery from the area.

Google Maps 3D imagery of the ENSCO 8501 in Galveston, Texas (center). Rig at left is the 8502, and other rigs of different types are parked nearby.

As of Gooogle Maps’ last sighting, 8501 is parked right next to 8502, another rig that is no longer owned by Valeris. It’s possible that SpaceX could purchase 8502 for further a third platform, but there’s no way to really know that at this point.

What Will SpaceX Do With Phobos & Deimos?

The obvious answer is that they’ll be used for launches and landings, but it’s a little more complicated than that.

Yes, it’s possible to find land suitable for space launches, as we’ve seen in Boca Chica and Florida, but SpaceX has much bigger plans than to just put a few satellites in space or occasionally launch exploratory missions. The company wants to build thousands of copies of Starship not only to go to Mars, but also to conduct earth-to-earth operations. If all goes according to plan, it will be possible to go from any large metro area on the planet to another in under an hour, but large metro areas don’t tend to have the space one would need to safely conduct launches and not bug the hell out of the whole city.

To do this safely and legally, it’s going to be necessary to launch from water a ways out into the ocean or a large lake, because that’s the only place people tend to avoid living and building.

In other words, Phobos and Deimos will be the first of many such platforms. There are only 7 8500 series, and of those only 2 more may possibly be for sale unless Valeris goes completely under in the future, so these will only be test platforms for SpaceX to learn the ropes. To build hundreds or thousands more, it will need to build or buy custom platforms from the ground up.

In some ways, Phobos and Deimos will be roughly equivalent to the Tesla Roadster (version 1). Tesla started by partnering with Lotus to build vehicles, but eventually designed its own cars from the ground up. By buying these two used platforms, it will save a lot of money learning the ropes and get a much better idea of what’s in store when building their own later, assuming that’s the route it will take. It may also make sense to work with existing rig builders to build plain platforms for SpaceX to customize.


There are a number of big challenges the company will face modifying these platforms for launches and landings.

First will be the modifications themselves. These rigs were built around the idea of drilling for oil, so all of that infrastructure will need to be torn out. That’s going to leave a big hole right through the middle of the top deck that will need to be filled. Next, they’ll need to relocate anything in the way of building the launch platform, and that could include the small buildings used to house crew and equipment. Finally, they’ll have to build structures for their needs. Presumably, all of this will occur in the Port of Brownsville and possibly in Galveston.

Next, they’ll need to tow the modified rigs out to sea. That’s pretty standard, but in doing so, they’re moving the rigs away from support and logistics. There are no natural gas mains, power lines, or roads in the Gulf of Mexico, so they’ll need to figure out how they’re going to get fuel out to the rigs that were designed to send fuel to land. This might be done with ships or done with pipelines.

Finally, they’re going to need to buy or rent helicopters and boats to move people and maybe rockets back and forth from land.

That leaves a lot of questions.

  • Will SpaceX build Starships at sea, or will they need to crane them up from a ship and onto the platforms? Or will they launch from land and take themselves to the platforms?
  • Where will the natural gas be purified for use in Raptor engines? Where will it be stored before launches?
  • Will there be space for multiple Starships to be stored on each platform?
  • Presumably Starlink will be used for communications, but what backup methods will be available? Will the sites have an emergency operations center and radio room of some kind?
  • Will the launch platforms be beyond line of sight from Boca Chica?

We will eventually know all this, but for now it’s neat to know where the platforms came from, where they are, and what they’re going to be used for.

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Jennifer Sensiba

Jennifer Sensiba is a long time efficient vehicle enthusiast, writer, and photographer. She grew up around a transmission shop, and has been experimenting with vehicle efficiency since she was 16 and drove a Pontiac Fiero. She likes to get off the beaten path in her "Bolt EAV" and any other EVs she can get behind the wheel or handlebars of with her wife and kids. You can find her on Twitter here, Facebook here, and YouTube here.

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