The SpaceX Autonomous Spaceport Drone Ship

Last Friday, SpaceX made history after successfully landing their Falcon 9 rocket on a football field-sized floating platform in the middle of the Atlantic Ocean. A lot has been written about the Falcon 9 rocket and Dragon spacecraft, but there is a surprisingly scarce amount of information regarding the landing platform that made this aerospace-milestone possible.

Let’s take a closer look at what we know about this mysterious vessel named, “Of Course I Still Love You”.

Construction
First of all, this landing platform has an official vessel designation as an Autonomous Spaceport Drone Ship, or ASDS. The ASDS started out as a simple barge but was converted into one of the most sophisticated objects on the water.

marmac 304

The barge is a Marmac 304 built by McDonough Marine Services in Belle Chasse, Louisiana. Most of the barge is built using cold rolled steel with built-in internal ballast tanks that can be filled with water for added stability at sea. According to McDonough Marine, the deck plate is 9/16” steel. Steel I-beams and stringers provide a solid foundation and deck stiffness.

McDonough Marine has actually leased the Marmac 304 to SpaceX. Of course once SpaceX engineers got their hands on it, the Marmac 304 stopped being a barge and became an ASDS. SpaceX added steel blast walls, enhanced hull rigidity, added “wings” to port and starboard sides and installed a thruster propulsion system. With the added wings, the official dimensions are 300′ long x 170′ wide.

Propulsion
“Of Course I Still Love You” does not have typical power and steering systems. In fact, it has to be towed everywhere it goes. What it does have is four Thrustmaster diesel engines with hydraulic-powered 360° propeller drives. Each of the four corners of the hull has one of these high performance thrusters installed. These diesel hydraulic thrusters use GPS and on-board sensors in order to stay as stationary as possible. Even in high winds and rolling seas, much like the conditions last Friday, these thrusters keep the ASDS within 3-meters of position-accuracy.

For additional location precision, Thrustmaster added its Portable Dynamic Positioning System. This is a modular system of even more azimuth thrusters, power modules and controls.

Navigation
While the pre-determined coordinates of the ASDS’s GPS keeps it where it needs to be, there is also a technical crew standing by on a chase-ship in case manual adjustments are needed. In addition to the GPS, both the ASDS and the Falcon 9 rocket are equipped with sensors that “talk” to each other as the rocket nears the landing zone. Without these sensors, landing would be impossible. Think of it like trying to throw a dart into a dart-sized hole…from space.

The Landing Site
Getting to the actual landing site takes some time. As mentioned earlier, the ASDS has to be towed wherever it goes. For this launch, she was towed to the landing site by the “Elsbeth III” tugboat out of Port Canaveral, FL. “Elsbeth III” does about 4-6 knots while towing.

The exact landing site is still unknown to the public but the approximate location is reported to be around 30.5°N, 78.5°W.

So somewhere in this area:

Screen Shot 2016-04-10 at 7.01.44 PM

As you can see it’s way out there.

If you look closely, you’ll notice something interesting about this location. It may not be as arbitrary as you think. I didn’t notice anything special about it until I input the coordinates into Google Earth. Do you see it?

The landing site is almost an identical distance from Charleston, Savannah, Jacksonville, and Port Canaveral. I haven’t been able to dig up any information on how or why they chose the location of the landing site, but can’t be a coincidence. If for some reason they needed to get the ASDS back to shore in an emergency situation, they had the four largest port cities in the region to choose from. All four ports are 170-175 miles away from the landing site. Pretty cool.

The Future of Autonomous Spaceport Drone Ships
It will be interesting to see how often and for how long SpaceX utilizes these ASDS’s as landing platforms. Including the “Of Course I Still Love You”, they have three ASDS’s at their disposal. Even if SpaceX decides to move in the direction of more land-based landings in the future, you can bet we will be seeing more of these drone ships being used for many more applications in the marine industry going forward. There is always a trickle down affect. And if it’s good enough for SpaceX, it’s good enough for just about everyone else.

Launch Video
If you haven’t seen the video yet, I highly recommend watching it. The ocean landing starts around 27-minutes in.

And you thought the roars of Augusta were loud.

Until next time,
Jeff Kibler

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