SpaceX Starship SN8 passes key proof test ahead of test flight

Featured Image Source: @NASASpaceflight via Twitter

SpaceX engineers are performing preflight preparations of the next Starship prototype that will conduct a test flight at the Boca Chica Beach, Texas facility. The prototype, Serial Number 8 (SN8), will be the first stainless-steel vehicle to attempt a high-altitude test flight of approximately 50,000 feet (15-kilometers).

Starship is under development to take humans back to the moon and colonize Mars. The aerospace company runs around-the-clock operations to accomplish this ambitious endeavor. The founder of SpaceX Elon Musk hopes to manufacture a fleet of Starships that will transport hundreds of passengers and tons of cargo to the Red Planet to build a sustainable settlement before the year 2050. SpaceX's targets to launch a couple of uncrewed Starships with cargo to the Martian surface by 2022. If the cargo mission is a success, the first Starship voyage with an astronaut crew would be until the year 2024. Mars' orbit gets closer to Earth's orbit around every two years; A closer alignment enables a fuel-conserving, shorter-duration voyage in between planets.

This week, engineers performed a couple of routine pre-flight preparations of the Starship SN8 vehicle that is scheduled to conduct test launch this month. To assess the stainless-steel prototype's strength, engineers conducted a proof test with cryogenic (cryo) liquid nitrogen that causes the structure to experience extreme pressure. This key test is done to submit the structure to the type of stress it would likely experience in-flight. Engineers performed a proof test on on October 5/6, the test was aborted and they tried again the next day. On October 7, teams successfully loaded SN8's propellant tanks with liquid nitrogen; the test was stopped in the process. Musk shared the test went well but a leak in the structure caused the test abort. --"Cryo pressure test succeeded, but a small leak opened up near the engine mounts, possibly due to differential shrinking," he wrote via Twitter.

Cryo pressure test succeeded, but a small leak opened up near the engine mounts, possibly due to differential shrinking

— Elon Musk (@elonmusk) October 7, 2020

A Starship vehicle needs to withstand extremely high pressure between 6 bar and 8.5 bar. ~6 bar is needed for orbital flights and ~8.5 bar is the strength that would be safe to carry out space flights with astronauts aboard. Musk shared Starship SN8 withstood a pressure of 7 bar. --"7 bar absolute, which is fine for flight. This was a proof test, rather than a burst test. We’ll hopefully fix the leak today & retest," he wrote on Thursday.

7 bar absolute, which is fine for flight. This was a proof test, rather than a burst test. We’ll hopefully fix the leak today & retest.

— Elon Musk (@elonmusk) October 7, 2020

SpaceX teams fixed the leak on the SN8 test vehicle to conduct another round of cryogenic proof testing. Last night, October 8/9, SpaceX filled Starship SN8's propellant tanks with liquid oxygen again. Local reporters from NASASpaceflight captured footage of the frosty test, in which the stainless-steel structure experienced high pressure, shown below. After the test was completed at around 2:00 a.m. Central Time (local), Musk announced Starship SN8 passed the key proof test that will enable it to conduct a debut flight, -- "Passed cryo proof," he stated.

Passed cryo proof

— Elon Musk (@elonmusk) October 9, 2020

In the days ahead, engineers are expected to mount a trio of Raptor engines. These unique, methane-fueled engines will showcase their power during an upcoming static-fire test, in which engineers will briefly ignite each engine to ensure they are ready to lift Starship SN8 into Boca Chica Beach's sunny sky. Starship SN8 will be the first prototype to take flight with three Raptor engines that can each produce over 200 tons of thrust at full throttle. SN8 will also be the pioneer to test out aerodynamic fins during flight. This month is guaranteed to be exciting for SpaceX's Starship development.