SpaceX returns its Falcon 9 to the pad for another Starlink launch attempt

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  A Falcon 9 rocket is on the pad for Thursday night's launch attempt. [credit: SpaceX ]

After two launch attempts and a week of downtime, SpaceX has returned its Falcon 9 rocket to the launchpad for the Starlink mission. The 90-minute launch window opens at 10:30pm ET Thursday (02:30 UTC Friday), and the weather—including those pesky upper-level winds—appears likely to cooperate.

With a mass of 18.5 tons, this will be SpaceX's heaviest launch to date for either the Falcon 9 or Falcon Heavy rocket. The rocket will attempt to boost 60 Starlink satellites, each 227kg, to an altitude of 440km. This is the company's first block of Starlink satellites for what should eventually be a much larger constellation, and they will help SpaceX gauge its performance and conduct tests of several key systems.

With six more launches, for a total of about 400 satellites, SpaceX founder Elon Musk said the Starlink constellation will reach the point of being able to offer some initial Internet connectivity to ground-based users. A dozen launches would bring "significant" connectivity, he said, and 24 launches would bring near-worldwide service.