SpaceX Thinks Its Next Experimental Rocket Landing Is a Long Shot

— -- Every rocket landing attempt from SpaceX -- including a successful one on land in December -- is bringing the company one step closer to reducing the cost of space travel.

Elon Musk and his team are determined to nail a landing at sea. The company is attempting for the fourth time to land the Falcon 9 rocket on a ship in the open ocean. SpaceX said "a successful landing is not expected" due to the unique geostationary orbit needed for the satellite it will be delivering into space.

The SES-9 satellite will provide communications coverage for 20 countries in the Asia-Pacific region and will also help meet the demand for in-flight Wi-Fi for passengers traveling in the area.

The launch, which takes place tonight at 6:45 p.m. ET at Cape Canaveral in Florida, was initially set for Wednesday night, according to SpaceX.

Nailing the landing is huge for SpaceX and space travel as a whole because Musk has previously said he believes reusing rockets -- which cost as much as a commercial airplane -- could reduce the cost of traveling to space by a factor of one hundred.

While conventional rockets burn up as they reenter Earth's atmosphere, SpaceX designed the Falcon 9 to be able to withstand the heat and land vertically so the rocket can be used again on a future launch. Musk said the Falcon 9 that returned to Earth in December is free of damage and capable of firing again.

The company doesn't always have the option to land the Falcon 9 on solid ground, as was the case in December. Musk said drone ship landings are needed for "high velocity missions," which would allow payloads, such as satellites, to reach a higher orbit.

As SpaceX attempted a drone ship landing last month, Musk explained the landings are needed when it is "just not physically possible to return to launch site."

SpaceX almost had a perfect landing at sea in January; however, one of the four legs didn't lock completely, causing the rocket to tip over and explode as it touched down on the ship.