The next iteration of space flight has been hiding in plain sight for several months, docked at the Port of Brownsville on the southernmost tip of Texas.

It is there that two ultra-deepwater semi-submersible drilling rigs — the Valaris 8500 and 8501 — are undergoing a radical transformation into floating launchpads, according to a CNBC report, to support the Starship rockets currently in development by Elon Musk’s SpaceX.

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In a June 2020 tweet, Musk explained that SpaceX is “building floating, superheavy-class spaceports” for travel to Mars, the Moon and hypersonic travel around Earth.

The pair of rigs, now named Deimos and Phobos ostensibly in homage to the Martian moons, were sold in July 2020 by Houston-based Valaris to Lone Star Mineral Development for $3.5 million each.

Incorporated in June 2020, Lone Star Mineral Development is registered in the name of SpaceX CFO Bret Johnsen.

SpaceX’s purchase and work on the oil rigs was first identified by reporters for NASASpaceflight, a space-focused website.

In their former life, the rigs were named ENSCO 8500 and ENSCO 8501 and were the first of Ensco International’s seven ultra-deepwater semisubs to be constructed in Keppel FELS’ Pioneer Yard I in Singapore.

The rigs were commenced operation in 2008 and 2009, respectively.