PARIS — Satellite fleet operator SES on June 17 said it wants to reuse the first stage of the SpaceX Falcon 9 rocket that will launch the SES-9 satellite by September for a future, discounted SpaceX launch, and is awaiting the response of SpaceX.

In a presentation to investors in London, SES Chief Technical Officer Martin Halliwell said he remains convinced that Hawthorne, California-based SpaceX is on the verge of proving its reusability thesis, which is that recovering, refurbishing and reusing a Falcon 9 first stage will dramatically reduce launch costs.

Luxembourg-based SES, with Halliwell leading the charge, has been a major supporter of SpaceX and was the first established commercial fleet operator to use the vehicle for a mission to geostationary transfer orbit. The SES-8 satellite was successfully launched in December 2013.

SES has seven satellites under construction, five of which are contracted for SpaceX launches, starting with SES-9. SES said it has been given a guarantee by SpaceX that the launch will occur no later than September.

SES has agreed to allow SES-9 to be the first launch using an upgraded Falcon 9 main-stage Merlin 1D engine, whose performance is being increased to allow SpaceX to attempt first-stage recovery even on launches to geostationary transfer orbit, the destination of most telecommunications satellites.

Just as it secured an attractive SpaceX price for the SES-8 by being one of the first established customers, SES now wants a cut-rate price on a Falcon 9 with a previously used first stage.

“Our launch vehicle for SES-9 will be a recoverable vehicle,” Halliwell said. “We believe they will be able to recover it on this mission. We actually asked them: If we do recover it, can we use it again and get a good price discount? We’re still in discussions.”

Unlike previous presentations in which he mainly lamented the state of the launch-vehicle industry, Halliwell’s June 17 comments were laced with optimism that Europe’s next-generation Ariane 6 would be just as economical as today’s Falcon 9, and that Russia’s Angara rocket, to replace today’s Proton, also shows promise.

“So we said to him: Why don’t you put a net around the platform? You know what his answer was? ‘That’s not cool.’”

Halliwell said SES is such a strong believer in rocket reusability’s cost-reduction promise that the company suggested to SpaceX a way to improve the likelihood of recovering a Falcon 9 first stage.

“We asked Elon [Musk, SpaceX’s founder]: You almost landed on the platform. It landed, a leg broke, the rocket fell over and went into the sea and they couldn’t recover it,” Halliwell said. “So we said to him: Why don’t you put a net around the platform? You know what his answer was? ‘That’s not cool.’

“It’s a true story: ‘That’s not cool.’ Hey, you can’t win them all.”

Rockets don’t follow Moore’s Law, but satellites do and Halliwell had promised SES investors that the company would bring down the cost of a given 36-megahertz transponder, or its equivalent, by 20 percent between 2009 and 2018.

With the last three satellite orders ­— for SES-14, SES-15 and SES-16, all carrying high-throughput spot-beam capacity in addition to wide beams — the company has secured a 12-percent reduction per transponder.

SES-14 is being built by Airbus Defence and Space of Europe. SES-15 is under construction by Boeing Space and Intelligence Systems of El Segundo, California, and SES-16, also known as LuxGovSat, is from Orbital ATK of Dulles, Virginia.

Halliwell said the price reductions came despite the fact that three different vendors are building three satellites. “We’ve got to squeeze,” Halliwell said. “The vendors understand this. They know we’ll be coming back for more.”

SES-14 and SES-15 are all-electric satellites, meaning their launch weight, for the same payload, is 40-50 percent less than it would have been using conventional chemical propellant. That alone reduces launch cost and, in the case of the Boeing-built SES-15, allowed SES to book a launch aboard Europe’s Ariane 5 rocket as a co-passenger.

Measuring the cost advantages of high-throughput satellites remains a subject of debate in the satellite industry even as many operators move to add HTS capacity on their future spacecraft.

Christophe De Hauwer, SES’s chief development officer-designate, told the investor conference that SES computes HTS’s potential using megahertz, not megabits, as the measure.

Four megahertz of HTS capacity, De Hauwer said, has about the same revenue-generating capability as 1 megahertz of traditional wide-beam capacity for data applications.

Using the example of SES-12, under construction by Airbus Defence and Space, De Hauwer said its 14 gigahertz of HTS capacity, divided by four, is equivalent to 3.5 gigahertz of conventional-satellite bandwidth. That is equal to 97 36-megahertz transponders.

One transponder for data applications is presumed to generate $1 million per year in revenue.