Featured Image Source: Elon Musk
Starship is SpaceX's next-generation vehicle, under development at SpaceX South Texas located in Brownsville’s Boca Chica beach. NASA recently selected SpaceX to develop a Starship lunar lander to take humans to the moon under the agency’s Artemis program. Ultimately, the rocket company’s mission is to transform humans into a multi-planet species and enable life on Mars. The founder and Chief Engineer at SpaceX, Elon Musk, runs 24/7 operations at the Texas assembly facility manufacturing multiple shiny, stainless-steel Starships to make that ambitious goal a reality.
Engineers are currently working on the fourth prototype built this year. Starship SN4 recently underwent a vital pressurization test, in which the vehicle was filled up with cryogenic liquid nitrogen, to determine how much strength the structure could withstand. The test vehicle withstood a pressure of 4.9 bar which Musk said is “good enough to fly!” Future vehicles will have to endure a bar strength of at least ~6, which is needed for orbital flights. Starship SN4 became the first large-scale prototype to not collapse during cryogenic pressure testing. Passing the test enabled engineers to move to the next phase of testing – the static-fire test of SN4’s Raptor engine.
SN4 🔥 soon. Raptor looks so smōl. pic.twitter.com/WcMdo6wAtj— Elon Musk (@elonmusk) May 4, 2020
SN4 will only use a single Raptor engine during its debut test flight. The final Starship will require 6 engines. Musk shared a photograph last night of a newly installed Raptor engine under the massive Starship vehicle. "SN4 fire soon. Raptor looks so smōl," he wrote. As seen in the photo above, Starship is an enormous vehicle – standing about 50 meters high, the Raptor looks small in the center of Starship’s 9-meter-wide diameter. Each Raptor is 1.3 meters in diameter, with a height of 3.1 meters. Raptors are powered by cryogenic methane (CH4) and liquid oxygen (LOX). This is not a common propellant combination in the rocket industry. "Other rocket engines were designed for no, or almost no reuse," Musk stated last year, "Raptor is designed for heavy and immediate reuse, like an aircraft jet engine, with inspections required only after many flights, assuming instrumentation shows it good." Besides reusability, SpaceX designed the Raptor engine with Mars on mind. Raptors fuel can be made on the Red Planet’s surface upon arrival by extracting carbon dioxide (CO2) from the planet’s atmosphere and subsurface ice-water (H2O) to synthesize methane (CH4) through electrolysis and the Sabatier process. So, Raptor engines give future Martians the option to build a propellant plant to refuel Starship and return to Earth.
The Raptor will soon be ignited during a static-fire test, in which the engine will be briefly turned on while the rocket is tied down to the launch pad at Boca Chica. Each Raptor engine is capable of producing over 200 tons of thrust at full throttle. SpaceX attempted to perform the test Sunday night but it was postponed due to the propellant getting too warm, “Liquid CH4 [methane] temp got too high this time. Offloading propellant. Will we retry later today [May 4],” Musk said. Raptor propellant needs to be super-chilled. The next static-site test attempt will take place soon. According to city’s Boca Chica beach closures, SpaceX could perform tests on May 5 from 9:00 p.m. to 6:00 a.m. with a back up opportunity scheduled for May 6 from 9:00 p.m. to 6:00 a.m. Central Time. If the static fire test goes well, SpaceX will launch the Starship SN4 prototype about 150-meters above Boca Chica beach in Texas. Future prototypes will conduct higher-altitude test flights starting at 20-kilometers to 100-kilometers, with the power of 3 to 6 Raptor engines.