SpaceX has successfully completed its eighth mission of 2016. Its Falcon 9 rocket sent up the JCSAT-16 satellite and then the rocket’s booster safely landed back on Of Course I Still Love You, the droneship in the middle of the Atlantic ocean, in the very early hours of Sunday morning.

Japanese telecommunications company SKY Perfect JSAT Corporation commissioned Elon Musk’s aerospace company to outfit the Falcon 9 with the JCSAT-16 satellite that will operate from a Geostationary Transfer Orbit (GTO). “Given this mission’s GTO destination, the first-stage will be subject to extreme velocities and re-entry heating, making a successful landing challenging,” SpaceX explains in its mission notes.

This was not the first successful droneship landing or JCSAT satellite launch SpaceX has taken on, but each new rocket launch presents its own set of unique challenges. Sunday morning’s GTO mission — lift-off was at 1:26 a.m. — was considered very challenging due to the orbital height the Falcon 9 was expected to hit. The satellite reached a 36,000 kilometer (22,369.4 mile) apogee, or the highest point in orbit.

As Materials Engineer Michael Hammersley explained on the webcast, “a low earth orbit mission — which can return to either land or the drone ship — is easier than a GTO mission which can only land on a drone ship. That’s because a GTO mission requires a lot more speed than a low-earth mission, that means it requires more propellant.” The mathematics behind a GTO mission’s strategic propellant use is the reason why GTO missions are considered more difficult, but not for reasons commonly believed.

“Sort of perversely it’s really the fact that we don’t have much propellant left that allows us to reach the speeds required to reach [GTO],” Hammersley told viewer. “And if you don’t have much propellant left then you can’t do a long re-entry burn to minimize the re-entry forces on the vehicle, and you get much less of the control that comes with the long, single engine burn.” In that regard, it’s not so much landing on a droneship that makes the GTO mission difficult, but the fact that the Falcon 9 will not have the necessary amount of fuel to minimize its speed as it heads back toward Earth to land on a droneship.

Despite the difficulties present in a GTO mission, the Falcon 9 rocket successfully landed on the Of Course I Still Love You droneship, approximately nine minutes and 30 seconds after initial takeoff at 1:26 a.m.

Falcon 9 Rocket successful landing

SpaceX would go on to successfully launch the JCSAT-16 satellite to its GTO destination, thereby completing the mission. SpaceX has been riding high recently on a series of successful rocket launches, and the August 14, 2016 JCSAT-16 mission is another win for the private aerospace company.

JCSAT-16 Launch
Falcon 9 Launch Trajectory
Photos via SpaceX/Flickr