SpaceX launched a commercial satellite into space on Thursday with the boost of a partly used rocket, a feat that may open an era of cheaper space travel.

A Falcon 9 rocket from SpaceX ? formally Space Exploration Technologies Corporation, based in Hawthorne, Calif. ? lifted off from the Kennedy Space Center in Florida to deposit the payload, a telecommunications satellite that will service Latin America, in the proper orbit.

What was noteworthy was that the first stage, or booster, of the rocket had already flown once before. It could conceivably launch again, since it returned in one piece, landing on a floating platform in the Atlantic.

“It did this mission perfectly,” Mr. Musk said during a SpaceX broadcast of the launch. “It dropped off the second stage, came back and landed on the drone ship. Right in the bulls-eye.”

A commercial flight employing a reused rocket is a stride toward reducing the cost of sending payload to space, for business ventures like satellite companies in particular. For Elon Musk, the founder and chief executive of SpaceX, replicating this flight with reusable rockets on a regular basis would be a crucial step toward his dream of sending people to Mars .

“It means you can fly and refly an orbital class booster, which is the most expensive part of the rocket,” Mr. Musk said.

Until now, almost all rockets have been single use. Once the fuel is spent, a rocket stage plummets to Earth, a quick demise to a complex machine that cost tens of millions of dollars to build.

Mr. Musk has likened that to scrapping a 747 jet after one flight.

The booster for Thursday’s flight had been part of the rocket that carried cargo supplies to the International Space Station for NASA last April. As the rocket’s second stage and cargo capsule continued to orbit, the booster steered itself back and set down on the floating platform, which is playfully named “Of Course I Still Love You.”

After the platform returned to port in Jacksonville, Fla., the booster was refurbished, tested and deemed ready for another flight. SES, the company that owns and operates the satellite launched Thursday, was the first commercial customer for a Falcon 9 in 2013, and it signed up for the first flight with a recycled booster at a discount from the usual $62 million launch price. Neither SES nor SpaceX has publicly said how large the discount was.

Mr. Musk has suggested that rocket launches could eventually be much cheaper because the cost of rocket propellants is less than 1 percent of the full price for a launch. So if a rocket could simply be refueled like a jetliner for another flight, the cost of space travel could drop to a fraction of what it is now.

How that might play out in practice is still unclear. The same reasoning led NASA to develop space shuttles in the 1970s, but the savings never materialized because of the extensive refurbishment of the orbiters needed between flights. “We were pushing a lot of technology,” said Daniel Dumbacher, a former NASA official who is now a professor at Purdue University.

SpaceX, however, has a better chance. The Falcon 9 was designed from the start to be reusable. Its engines, for example, do not offer cutting-edge performance ? but that means they are simpler and more robust, and thus easier, faster and cheaper to get ready for the next flight.

“They’ve taken the right first steps,” Mr. Dumbacher said. “This is where you just have to get out and do it.”

Reusable rockets may soon become commonplace. Blue Origin, a rocket company started by Jeff Bezos, the founder of Amazon, is putting similar emphasis on rockets that can be flown many times, not just once. United Launch Alliance, a joint venture of Boeing and Lockheed Martin, is also looking to incorporate reusability in its next rocket, Vulcan. But instead of landing the entire first stage, the plan is for the engine compartment ? the most valuable part ? to eject and descend via parachute, to be plucked out of the air by a helicopter.

In the near term, reusable rockets could lower the cost of launching satellites and thus make space affordable to more companies for more uses. Currently, most satellites are used for telecommunications or for observations of the Earth.

For his Mars dreams, Mr. Musk envisions a gargantuan spaceship he calls the Interplanetary Transport System that would someday transport humans. That would be far too expensive to be thrown away, so SpaceX needs to solve the reusability problem.

Perhaps an even greater challenge is finding a way to finance the development of such a large rocket. Today, most of SpaceX’s revenue comes from launching satellites for commercial companies and from NASA contracts to take cargo and, soon, astronauts to the International Space Station.