SpaceX launched 10 Iridium satellites today (July 25) in the seventh and penultimate launch required to complete the communications company's new constellation.

The Falcon 9 rocket carrying the satellites took off from California's Vandenberg Air Force Base at 7:39 a.m. EDT (1139 GMT, 4:39 a.m. local time). The launch had a 1-second window because of the precision needed for the satellite insertion, company spokesperson John Insprucker said during the launch broadcast. The launch went smoothly, even though fog obscured the view of the rocket until after liftoff.

SpaceX hoped to complete two separate marine tasks in addition to the launch itself: landing the first stage of the rocket on the drone ship "Just Read the Instructions" and catching the rocket's fairing with a second boat, which, to date, no launch has accomplished. The company knew both boat maneuvers would be tricky today. "The weather in the Pacific is bad," Insprucker said. "We have choppy seas."

"[The conditions are] the worst that we've ever had for trying to get a first stage on the drone ship," he said later in the broadcast. Nevertheless, the company soon confirmed in a tweet that the rocket successfully landed on the drone ship — despite some initial confusion due to a lack of lighting on the landing platform.

Spectators had hoped the company would attempt to catch the rocket's fairing with "Mr. Steven," a boat equipped with a giant net. Earlier in July, the company tweeted photos of the boat with an upgraded net four times larger than the previous version and stated that it was targeting another recovery attempt for later in the month, and today's launch was the company's last of the month.

SpaceX was not able to specify at launch when it would know whether Mr. Steven was successful, but a later update confirmed the weather was too harsh for the maneuver. "They did see the payload fairing coming down, but they were not able to catch it in the net," Insprucker announced shortly after 8:30 a.m. EDT (1230 GMT).

The Iridium satellites deployed about an hour after launch after a brief cruise phase. They brought the Iridium constellation up to 75 satellites, which, with 10 additional units meant to launch later this year, will run tracking procedures on devices connected to the so-called internet of things.

Today's launch followed a launch from the opposite coast on Sunday, and a third launch is currently scheduled for Aug. 2.

Editor's note: This story was updated to include additional details about the fairing catch attempt and satellite deployment.

Email Meghan Bartels at mbartels@space.com or follow her @meghanbartels. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.