Lucky number 13.

SpaceX just performed its 13th rocket landing back on Earth after launching 10 communications satellites on their way to orbit on Sunday at 4:25 p.m. ET from California's Vandenberg Air Force Base.

The Falcon 9 rocket booster -- equipped with brand new titanium fins for landing -- touched down on a drone ship in the Pacific, making it the eighth such successful ship landing in the company's history, with the other 5 landings occurring back on a pad on solid ground in Florida.

This also marks the Elon Musk-founded company's second rocket launch and landing in 48 hours, and ninth launch this year. SpaceX also brought back a Falcon 9 booster to a drone ship in the Atlantic on Friday afternoon.

In total, SpaceX has tried to land its boosters 18 times.

SpaceX's entire business plan -- from continuing to launch smaller satellites for private companies to eventually sending people to Mars -- hinges upon reusability.

Instead of simply discarding rockets after one use, by bringing them back home, Musk hopes to refurbish and reuse them to save money on re-flights.

That reusability is already bearing itself out.

Perhaps the most astounding thing about all of it is how normal this feat has become.

SpaceX landed its first rocket in December 2015, and since then, the company has consistently brought home rocket stages from space. This landing marks the ninth in a row for the company.

The company has successfully relaunched previously flown Falcon 9 first stages on two different occasions, and both missions have seemingly gone without a hitch.

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SpaceX has also reused a Dragon capsule for a second flight to the International Space Station. That spacecraft is still on the station now, but it is expected to return to Earth for the second time in July.

Musk's company -- which he founded in 2002 -- has an ambitious couple months ahead of it. SpaceX is expected to launch its first test flight of the Falcon Heavy rocket (the company's most powerful rocket yet) at some point near the end of the summer.

SpaceX is also planning to send two people to orbit the moon and come back to Earth in 2018, with the first robotic trip to Mars planned for 2020.

（作者：新闻中心）