Apple has hired former NASA employees, robotics experts and ex-Tesla staffers to form part of its driverless car teams, according to official documents released to two media outlets.

On Friday, the Wall Street Journal and Business Insider obtained a permit that was issued to Apple by Californian authorities on March 14 which granted the tech giant permission to test autonomous vehicles. The permit contained names of six Apple employees that are designated as "driver/operators" of the driverless cars.

The names were supposed to be redacted, according to the California Department of Motor Vehicles (DMV), Business Insider said, but both it and the WSJ published the names on Monday.

Searches online revealed that these current Apple employees have had previous experience at space agency NASA, electric car firm Tesla and in the robotics industry, something that Apple is hoping will boost its efforts in the driverless vehicle space.

Apple has been tight-lipped on its driverless car efforts. At one point there were reports that the project had been scaled back. But recent developments show the U.S. firm is still focusing on the technology as it looks to challenge existing auto makers, as well as rival technology companies like Google who has its own autonomous vehicle program via its spin-off company Waymo.

Firstly, Apple's name was added to a list of companies that have secured a permit to test self-driving cars in California. And the permit shows Apple's key hires.

One person on the list is Shilpa Gulati whose LinkedIn profile describes her as an "experienced roboticist" who is working on "special projects at a Silicon Valley company". Apple is not named on her LinkedIn page. In the job description for this role, Gulati describes how she built an organization of "30 world class researchers and engineers" and has been working on this since March 2015.

Gulati's previous jobs include being a senior research engineer at Bosch where she developed "motion planning algorithms for self-driving cars" and a NASA-backed project to create a vehicle to be deployed on one of Jupiter's moons.

Another staffer called Jeremy Ma is a software engineer at Apple's special projects group and has been working there since March 2015. Prior to that, Ma was at NASA's Jet Propulsion Laboratory. Victor Hwang and Paul Herbert, two more named on the DMV permit, were also both ex-NASA employees. Another name on the list is Christopher Gadda, an ex-Tesla staffer.