With the arrival of the new Raptor engine SN4 at their Boca Chica launch facility, SpaceX is gearing up its Starhopper for the second hop test, but this time without it being tethered to the ground. The latest test campaign is slated to begin in mid-June and is expected to include the first untethered hop of Starhopper.
In the meanwhile, SpaceX continues to make progress with their plans to utilize Pad 39A for the Starship program in Florida.
The Starhopper is the test vehicle for the development of SpaceX's upcoming Starship spacecraft. Starship is a two-stage launch vehicle with a reusable single stage booster - Super Heavy, which the company hopes to one day utilize the fully reusable Starship system to launch humans and cargo to the Moon and Mars.
Starhopper performed its first two hot-fire tests at the beginning of April. During the tests, a single Raptor engine was fired for a couple of seconds to verify that Starhopper was ready for more rigorous testing including an untethered hops to higher altitudes.
Following the previous two tests, the Raptor engine SN2 was trucked away for post testing analysis. The, work quickly began to prepare the Starhopper vehicle for the next phase of testing.
This work included the installation of quick disconnect umbilicals, altitude control systems, and shock absorbers on the legs of the Starhopper. These installation will allow Starhopper to perform the untethered hops from SpaceX's launch facility in Boca Chica.
SN4 arrived at Boca Chica for the fit checks on Friday afternoon. Meanwhile, the SN5 Raptor engine is already at SpaceX's test facility in McGregor Texas for verification testing before being shipped South. Currently, there is no confirmation on whether the SN4 or SN5 engine will be used for the Starhopper untethered test.
Raptor is a full flow staged combustion cycle engine running on methene as fuel. An engine of the class has never been used to launch a vehicle into space. Therefore, its development is heavily subject to growing pains. Below is a video made by Everyday Astronaut on how the Raptor engine works.