A day after SpaceX's first attempt to launch the Starhopper test vehicle to an altitude of 150 meters, the company plans to try again as early at 5pm ET Tuesday (21:00 UTC).
The company went all the way through the countdown on Monday before the test vehicle's single methane-burning Raptor rocket engine failed to ignite. The fault lay with a wiring or other connector issue within the engine's igniter, SpaceX founder Elon Musk said on Twitter.
The Raptor engine uses a new kind of igniter to start the combustion process between oxidizer and methane propellants, which Musk characterized as "dual redundant torch igniters." This ignition process will be more reliable in the future, he said, but it has proven "finicky" during development.
For its Falcon 1, Falcon 9, and Falcon Heavy rockets, SpaceX uses a volatile chemical mixture known as TEA-TEB to ignite the Merlin engines. This is a combination of triethylaluminum (TEA) and triethylborane (TEB), which are essentially two different elements each linked to three hydrocarbon atoms. These molecules are held together by rather tenuous bonds that will break easily. In fact, when TEA-TEB comes into contact with oxygen, it spontaneously combusts, producing a green flame.
Local residents at the Boca Chica launch site in southern Texas have received notices again on Tuesday informing them of a likely test window between 5pm and 8pm ET (21:00-00:00 UTC). We will add an official livestream to this story if and when it begins Tuesday evening. Informal streams can be found here.
After the 150m Starhopper test, SpaceX founder Elon Musk has said he will provide an update on the development of Starship during a presentation in Boca Chica. He has not set a firm date for the presentation but has said it probably will occur in mid-September.
This will be the stubby Starhopper's final flight. It is a test vehicle intended to validate the company's ability to control the flight of the new Raptor engine. In recent months, separate teams of SpaceX engineers in Boca Chica, as well as Cocoa, Fla., have been working on full-sized prototypes—Starship Mk1 and Mk2 respectively. These vehicles will fly, initially at least, with a complement of three Raptor engines. Suborbital flights could begin this fall.
The full-scale Starship, which will launch into space on a rocket called "Super Heavy," is planned to have six engines; it will be capable of landing on and taking off of distant worlds, including the Moon and Mars.
