The reorganization, announced by NASA chief Bill Nelson on Tuesday, reflects an evolving relationship between private companies, such as SpaceX, that have increasingly commercialized rocket travel and the federal agency that had exercised a U.S. monopoly over spaceflight for decades.

Nelson said the shake-up was also spurred by recent proliferation of flights and commercial investment in low-Earth orbit even as NASA steps up its development of deep-space aspirations.

“Today is more than organizational change,” Nelson said at a press briefing. “It’s setting the stage for the next 20 years, its defining NASA’s future in a growing space economy.”

The move breaks up NASA’s Human Exploration and Operations Mission Directors, currently headed by Kathy Leuders, into two branches.

Leuders will keep her associate administrator title as head of the new Exploration Systems Development Mission Directorate, focusing on NASA’s most ambitious, long-term programs, such as plans to return astronauts to the moon under project Artemis, and eventual human exploration of Mars.

A key factor identified by the scientists is a regular “wobble” in the moon’s orbit first identified in the 18^th century – that takes 18.6 years to complete. The moon’s gravitational pull helps drive Earth’s tides.

In half of the lunar cycle, Earth’s regular daily tides are diminished, with high tides lower than usual and low tides higher than usual. In the cycle’s other half, the situation is reversed, with high tides higher and low tide lower.

The expected flooding will result from the combination of continuing sea level rise associated with climate change and the arrival of an amplification part of the lunar cycle in the mid-2030s, the researchers said.

“In the background, we have long-term sea level rise associated with global warming. It’s causing sea level to increase everywhere,” Ban Hamlington, NASA team leader and one of the study’s authors, told Reuters.

“The effect from the moon caused the tides to vary, so what we found is that this effect lines up with the underlying sea level rise, and that will cause flooding specifically in that time period from 2030 to 2040,” Hamlington said.