Watch SpaceX’s Falcon Heavy Second Try for a Satellite Launch

It’s the second try for SpaceX’s second Falcon Heavy.

The planned launch of the giant rocket — the most powerful now in operation on Earth — was postponed on Wednesday night because of windy conditions high above the launchpad. SpaceX will try again Thursday evening.

The rocket could blast off as early as 6:35 p.m. Eastern time; the launch window lasts until about 8:31 p.m. SpaceX will stream the launch on its YouTube channel. Or you can watch it in the video player below.

The majestic test launch of the Falcon Heavy in February 2018 carried the ambitions of SpaceX and Elon Musk, the company’s founder and CEO, to new heights. It also sent Mr. Musk’s red Tesla Roadster into a long orbit around the sun, sending views homes to Earth of a spacesuit-wearing mannequin called Starman.

The spacecraft’s payload this time is mundane and useful: Arabsat-6A, a Saudi Arabian communications satellite which will relay television, internet and mobile phone signals to the Middle East, Africa and Europe.

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Why is Falcon Heavy different from other SpaceX rockets?

The company’s workhorse is the Falcon 9 rocket, which first launched in 2010. The first stage of the Heavy essentially consists of three Falcon 9 first stages bound together. The second stages of the two rockets are identical.

The additional thrust allows the Heavy to propel 140,000 pounds to low-Earth orbit, nearly three times what the Falcon 9 can lift.

How does this Falcon Heavy differ from the first one?

On the test flight, the two side boosters were older versions reused from earlier flights. (SpaceX’s best innovation to date is landing the booster stage of its rockets and launching it again; traditionally, rockets have been one-use throwaways, with the booster stages dropped into the ocean.)

For this one, the side boosters have never before been used. They are the latest version of the rocket, called “Block Five.” (“Block” is what rocket companies call a major upgrade.) That boosts the thrust and how much the Falcon Heavy can carry.

Will SpaceX land the three boosters?

Yes. The two side boosters are to return to landing pads at Cape Canaveral, not far from the launchpad, just as in the maiden flight.

The center booster, which will go higher and farther, is to set down on a floating platform in the Atlantic Ocean. That did not quite work as designed on the first try. The booster missed the platform, hitting the water at more than 300 miles per hour.

Mr. Musk said the booster did not have enough ignition fuel to light the engines for the final burn.

Why hasn’t Falcon Heavy flown in more than a year?

Even though the first Falcon Heavy flight appeared to be nearly flawless, SpaceX probably made adjustments. That, after all, is the reason a rocket company performs a test flight for a new rocket design.

SpaceX also has had a backlog of Falcon 9 missions to fly. It launched 20 Falcon 9 missions in 2018, more than in any previous year, in addition to the one Falcon Heavy launch. The company was also busy at work developing its Crew Dragon capsule for taking NASA astronauts to and from the International Space Station.

The market for the Falcon Heavy is also much smaller than once envisioned. When Mr. Musk first announced the rocket in 2011, he said he expected that there would be a 50/50 mix between the Falcon 9 and the Falcon Heavy. In the years since, improvements have made the Falcon 9 more powerful, and miniaturization of electronics has shrunk the size of many satellites.

The Falcon Heavy is now needed for only the largest satellites like the 13,000-pound Arabsat-6A satellite, which is headed to geosynchronous orbit more than 22,000 miles above Earth.

Are there more Falcon Heavy flights planned?

One more Falcon Heavy flight is scheduled for this year — a mission for the United States Air Force carrying 25 small satellites.

In addition, SpaceX has announced contracts for two Falcon Heavy launches of commercial satellites, and the company has won two competitions to use the rocket for national security missions.

Will Falcon Heavy go to the moon?

At present, no, but that answer could change.

In 2017, SpaceX announced that two space tourists would go on an around-the-moon trip in one of the company’s Crew Dragon capsules launched by a Falcon Heavy. But when the first Heavy reached the launchpad last year, SpaceX said it had decided not to go to the expense and effort of making the rocket safe enough for launching people.

The possibility of using the Falcon Heavy for lunar missions was revived last month by Jim Bridenstine, the NASA administrator, when he told a Senate committee that the big rocket that his agency is developing, the Space Launch System, would not be ready for its first test flight in 2020. NASA was looking into using commercial rockets as an alternative, he said.

One of the alternatives was putting the second stage of the Space Launch System on top of a Falcon Heavy first stage. Mr. Bridenstine later said that option was feasible but could not be done by next year, because major changes would be needed to the boosters and SpaceX’s launchpad to accommodate the Frankenstein rocket combination.

Mr. Bridenstine, however, left the door open, saying that NASA would explore all options to meet the Trump administrations goal of sending astronauts back to the moon by the end of 2024.

What other rockets is SpaceX planning to build?

SpaceX’s next-generation rocket was once known as B.F.R. where “B” stood for “big” and “R” stood for “rocket.” It now has the less colorful name Starship.

SpaceX has begun small hop tests of a preliminary design, nicknamed Starhopper. The full-fledged design is to reach orbit and eventually make distant journeys to the moon and Mars, but that is still years away.