The first stage of a SpaceX Falcon 9 rocket lands on a "drone ship" in the Pacific Ocean on Aug. 24, 2017, after helping launch the Formosat-5 satellite. This same booster will launch again on Feb. 18, 2018, lofting the Paz satellite for Spanish operator Hisdesat, along with two SpaceX satellite-internet prototypes.

Update for Feb. 22: SpaceX's Falcon 9 mission to launch the Paz satellite has successfully lifted off. See our full story here: SpaceX Launches 1st Test Satellites for Starlink Internet Constellation Along with Spain's Paz

Update for Feb. 21: High winds scuttled today's launch attempt. The next opportunity comes Thursday, at 9:17 a.m. EST (1417 GMT; 6:17 a.m. local California time).

Update for Feb. 18: SpaceX has delayed the launch of its next Falcon 9 rocket to no earlier than Feb. 21. See our full story here: SpaceX Delays Next Falcon 9 Rocket Launch to Feb. 21

SpaceX plans to launch the first two prototypes for its vast satellite-internet constellation Thursday (Feb. 22), and you can watch the liftoff live.

The satellites are scheduled to lift off aboard a two-stage Falcon 9 rocket from Vandenberg Air Force Base on the California coast on Thursday at 9:17 a.m. EST (1417 GMT; 6:17 a.m. local California time). Watch the launch live here at Space.com, courtesy of SpaceX, or directly via SpaceX's website.

This Falcon 9's first stage has flown once before, helping loft a Taiwanese Earth-observing satellite in August 2017. The first stage landed on one of SpaceX's "drone ships" in the ocean on that occasion, but no such landing will be attempted Thursday, SpaceX representatives said. However, the company will apparently attempt to recover the payload fairing — the $6 million nose cone that will protect the satellites during launch — using a net-equipped boat named "Mr. Steven."

The main purpose of Thursday's launch is getting the Paz satellite to orbit for Spanish operator Hisdesat. Paz will generate sharp radar imagery of Earth for a variety of customers, including the Spanish government, over the course of the satellite's 5.5-year mission.

The two prototype satellite-internet craft will be riding along as secondary payloads, according to documents SpaceX has filed with the Federal Communications Commission. (SpaceX has not said much about the inclusion of these two prototypes, known as Microsat-2a and Microsat-2b, on Thursday's flight.)

The prototypes are designed to help lay the groundwork for SpaceX's Starlink constellation, a network of several thousand satellites in Earth orbit that the company envisions providing low-cost internet service to people around the world. SpaceX representatives have said the company aims to get Starlink up and running, at least in a limited capacity, by 2020.

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