SpaceX is gearing up for the most ambitious test flight yet of its Starship Mars rocket.

Last month, a Starship prototype aced a high-altitude test flight for the first time, soaring about 6.2 miles (10 kilometers) into the skies above SpaceX's "Starbase" site in South Texas and then touching down safely back at the facility. (Four other Starship test vehicles had tried this uncrewed hop in the previous five months, but none of them managed to stick the landing.) 

Even before achieving that milestone, however, SpaceX had started planning out the first Starship flight to Earth orbit. In March, for example, company founder and CEO Elon Musk tweeted that SpaceX was targeting July for that landmark trial, which will require both elements of the reusable Starship system — the 165-foot-tall upper-stage spaceship, called (somewhat confusingly) Starship, and the huge first-stage booster known as Super Heavy. 

Super Heavy was not involved in the 6.2-mile-high flight; that May 5 jaunt employed just a prototype Starship upper stage, one outfitted with three of SpaceX's next-generation Raptor engines. (The final Starship spacecraft will sport six Raptors and Super Heavy about 30 of them, Musk has said.) 

In mid-May, we learned the details of the coming orbital test, thanks to a document filed with the U.S. Federal Communications Commission (FCC) that was first reported by The Verge.