Per ardua ad astra

Per ardua ad astra ("Through adversity to the stars" or "Through struggle to the stars") is the motto of the Royal Air Force and other Commonwealth air forces such as the RAAF, RCAF, RNZAF, the SAAF, as well as the Royal Indian Air Force until 1947. It dates from 1912 and was used by the newly formed Royal Flying Corps.

The first Commanding Officer of the Royal Flying Corps (Military Wing) was Colonel Frederick Sykes. He asked his officers to come up with a motto for the new service; one which would produce a strong esprit de corps.

Not long after this, two junior officers were walking from the Officers' Mess at Farnborough to Cody's Shed on Laffan Plain. As they walked they discussed the problem of the motto and one of them, Lieutenant J. S. Yule, mentioned the phrase Sic itur ad Astra, from Virgil. He then expanded on this with the phrase Per Ardua ad Astra, which he translated as, "Through Struggles to the Stars". Colonel Sykes approved of this as the motto and forwarded it to the War Office. It was then submitted to the King, who approved its adoption.

The question of where this motto had come from can be answered by the fact that Yule had read it in a book called The People of the Mist by Sir Henry Rider Haggard. In the first chapter was the passage: "To his right were two stately gates of iron fantastically wrought, supported by stone pillars on whose summit stood griffins of black marble embracing coats of arms and banners inscribed with the device 'Per Ardua ad Astra'".

...
Wikipedia