SpaceX just successfully landed the first stage of its Falcon 9 rocket on a drone ship in the Atlantic Ocean. It was the third time in a row the company has landed a rocket booster at sea, and the fourth time overall.

The landing occurred a few minutes before the second stage of the Falcon 9 delivered the THAICOM-8 satellite to space, where it will make its way to geostationary transfer orbit (GTO). GTO is a high-elliptical orbit that is popular for satellites, sitting more than 20,000 miles above the Earth. The 3,100-kilogram satellite will spend 15 years there, helping to improve television and data data signals across Southeast Asia.

After landing, SpaceX CEO Elon Musk said that there would be "some risk of tipping" as the rocket was brought back to port.

Falcon 9 second stage and THAICOM 8 spacecraft in nominal orbit and coast. First stage has landed on the droneship pic.twitter.com/NH52PHhpyE — SpaceX (@SpaceX) May 27, 2016

SpaceX started trying to land the first stage of its rockets back in January 2015, but the first successful landing didn't come until December. Since then, though, the company has had more luck. SpaceX has now successfully executed three drone ship landings in the past two months. A second ground attempt is scheduled for July.

The company was coy about its chances for a successful landing this time, saying that recovering the rocket booster would be "challenging." That's because, when SpaceX performs these high-orbit missions, the rocket reaches a much higher speed and needs to be loaded with much more fuel compared to missions to low Earth orbit. In turn, the Falcon 9 booster is left with less fuel to guide it to the drone ship, and it has to decelerate from a higher speed. That's why some previous attempts at landing Falcon 9 first stages in the ocean after GTO missions had failed.

To be fair, though, all the other sea landing attempts that occurred before April also failed. That first sea landing in April came during a mission to low Earth orbit, but it was apparently a turning point. SpaceX successfully landed another booster during its following attempt at the beginning of May, which was a mission to GTO.

Crush core is aluminum honeycomb for energy absorption in the telescoping actuator. Easy to replace (if Falcon makes it back to port). — Elon Musk (@elonmusk) May 27, 2016

SpaceX is attempting to make its rockets reusable because it could drastically reduce the cost of launching goods (and eventually, people) into space. Successfully landing the rocket boosters is obviously a huge first step — one that SpaceX has now performed four different times.

But for SpaceX to truly achieve its goal of reusability, the company is going to have to start re-flying the boosters that it has landed. In April, Musk said that he hoped launch the first rocket that landed at sea by May or June, but the plan appears to have changed. The company now plans to re-fly the rocket that was landed at the beginning of May, but there is no timeframe for that launch.

In the meantime, SpaceX is running out of space to store its rockets at the Kennedy Space Center. The hangar the company is using can hold up to five rocket boosters, and this newly-landed one will make four. Musk has said that SpaceX might transport some of the boosters to the company's test facility in McGregor, Texas. And, at some point in the near future, SpaceX says it plans to take the first rocket it landed back in December and put it on display at the company's headquarters in Hawthorne, California.

SpaceX's historic first landing on a barge