Oct 4 (Reuters) - Boeing ( BA ) and Lockheed Martin's ( LMT )

joint venture, United Launch Alliance, said on Friday

its Vulcan rocket successfully launched its second mission, in

what is a crucial step to receive certification for Pentagon

missions.

Vulcan, developed to replace ULA's workhorse Atlas V rocket

and rival the reusable Falcon 9 from Elon Musk's SpaceX, took

off from the Cape Canaveral Space Force Station in Florida.

It had successfully debuted in January this year.

With the launch, ULA is looking to fulfill flight test

obligations and complete its certification process with the U.S.

Space Force, which requires two verification flights before it

can put national security payloads aboard.

ULA said the U.S. Space Force - a key customer for Vulcan -

will review the data and compare it to ULA's first certification

mission to ensure that the vehicle performed as expected, before

it can be certified.