SpaceX launched an experimental rocket prototype on a "hop test" this week during which the giant tank-like vehicle — reminiscent of an old metal grain silo — soared nearly 500 feet above ground before touching down safely on a nearby ground pad.
The vehicle, dubbed "SN5," does not look like an ordinary rocket, but rather a large, steel cylinder with a rocket engine strapped underneath. The brief straight-up-and-down test flight was carried out Tuesday evening at SpaceX's development site in south Texas, and it's meant to help SpaceX figure out how to launch and land a large spacecraft with extreme precision.
The prototype is the latest in a lineup of test vehicles SpaceX has constructed over the past year as the company races to develop a massive spaceship and rocket system called Starship, which CEO Elon Musk bills as the vehicle that will carry the first humans to Mars.
Last year SpaceX carried out three brief hop tests using an earlier prototype, nicknamed Starhopper. But that vehicle was retired one year ago, and the company has spent the past 12 months assembling much larger testing vehicles and putting them through a series of ground tests.
Most of those were destroyed during pressurization tests, where the vehicles are filled with extremely cold liquid to ensure they won't buckle under the intense temperatures and pressures associated with fueling, including the towering prototype vehicle Musk had shown off to reporters during a September 2019 media event.
The previous Starship prototype, SN4, which is about twice as tall as Starhopper, was the first to make it through pressurization tests, though it was destroyed during a test fire of its rocket engine last month.
The success of SN5's Tuesday test flight will set SpaceX up to conduct "several short hops to smooth out launch process," before the company moves on to test flights that soar higher than 500 feet.
It's not clear when SpaceX will attempt to send its first Starship spacecraft into Earth's orbit, a far more dangerous and difficult journey than suborbital hop tests.
And SpaceX's current prototypes are — to be clear — still a long way from the final Starship design. SN5, like its predecessors, has only one rocket motor. According to current mockups, the final spacecraft will need as many as six engines. And, to reach orbit, SpaceX will also need to launch the Starship spacecraft atop a massive rocket booster, dubbed the Super Heavy, that will need more than 30 engines at its base.
Starship is designed to carry massive loads of up to 100 tons of cargo — such as satellites or space telescopes — into Earth's orbit. And, SpaceX pledges, the vehicles can be retrofitted to carry dozens of passengers to the International Space Station, the Moon, or Mars.
SpaceX has been pouring significant resources into Starship development since early 2019, and Musk has called the project his top priority. But his vocal excitement about the project has occasionally rubbed some of SpaceX's government partners the wrong way.
Last year, NASA administrator Jim Bridenstine called Musk out on twitter for hosting a glitzy press event about Starship while the company's Crew Dragon — a separate and much smaller crew-worthy spacecraft that SpaceX developed for NASA — had yet to launch its first operational mission.
Last weekend, however, Crew Dragon completed its first-ever crewed mission by safely bringing NASA astronauts Robert Behnken and Douglas Hurley to a splash landing in the Gulf of Mexico. That paves the way for Crew Dragon to begin regularly flying crewed missions to the International Space Station and for SpaceX to begin publicly shifting its focus to its experimental prototypes.