SpaceX's first mission since its rocket explosion is now scheduled for early January, which is hailed as setback for the company, when a Falcon 9 booster is set to begin a 70-satellite deployment for Iridium's next-generation voice and data relay network, the company announced Wednesday. 

Iridium revealed last week that the launch could take place on 16th Dec but officials said that SpaceX engineers are still wrapping up the investigation of September 1 explosion which grounded Falcon 9 rocket flights for almost three months.

SpaceX said in a statement that: "We are finalizing the investigation into our September 1 anomaly and are working to complete the final steps necessary to safely and reliably return to flight, now in early January with the launch of Iridium-1."

The 10 Iridium communication satellites and both core sections of the two-stage Falcon 9 rocket are at Vanderburg preparing for the liftoff from Space Launch Complex-4 East.

The SpaceX is under contract of seven Falcon 9 launches for the Iridium Next satellite fleet, which will replace all of the company's existing spacecraft in orbit.

Each launch will put 10 satellites into polar orbit around 388 miles (625 kilometers) above Earth. The early January launch will mark the third Falcon 9 mission from the West Coast Complex, and the 29th Falcon 9 launch overall since SpaceX's workhorse booster debuted in June 2010. We all know about the failed Falcon 9 launch in September of this year.

Iridium was OK with the decision to push back the date of Falcon 9 launch, just four months after the failed mission launch mishap that had put the flight on hold.

"Iridium supports SpaceX's announcement today to extend the first Iridium Next launch date into early January, in order to help ensure a successful mission," the company said. "We remain as confident as ever in their ability to safely deliver our satellites into low Earth orbit." 

The launch delay caused by grounding of Falcon 9 rocket will mean the Iridium Next constellation will not be fully deployed until at least early 2018,  

After the first Iridium Next flight, SpaceX is scheduled to pick up launches on its Florida manifest with the liftoff of the EchoStar 23 communications later in January from the launch pad 39A.