After a one-day delay to exchange a failed grid fin actuator, SpaceX is now lower than 24 hours from the second test flight of Starship. SpaceX could have a 20-minute launch window that opens at 7:00 AM CT (13:00 UTC).
Making this test flight is Ship 25 and Booster 9. Ship 25 is powered by 6 Raptor engines (3 sea level and three vacuum), and Booster 9 is powered by 33 Raptor engines.
Booster 9 features many upgrades during the last booster to take flight, including higher engine shielding and a switch from hydraulic thrust vector controls to electric TVC. Ship 25 didn’t see as many upgrades because the booster, and never much has been shared of any major changes that were made. One change to each vehicles was the development of the Flight Termination System, which took for much longer to destroy the rocket than expected in the course of the first test.
T minus 2 hours before the scheduled liftoff, the SpaceX launch director will give the go for propellant loading. This process will begin at t minus 1 hour and 37 minutes, and at this point, Booster 9 will begin loading with each liquid oxygen and liquid methane.
T minus 1 hour and 17 minutes, liquid methane will begin loading onto Ship 25, followed by liquid oxygen 4 minutes later at t minus 1 hour and 13 minutes.
T minus 19 minutes and 40 seconds, the 39 Raptor engines on Booster 9 and Ship 25 will begin chilling to arrange for the extremely cold fuel to flow through and stop thermal shock to engine hardware.
T minus 10 seconds, the flame deflector installed after the primary IFT will begin flowing water.
Super Heavy Booster 9 static fire successfully lit all 33 Raptor engines, with all but two running for the total duration. Congratulations to the SpaceX team on this exciting milestone! pic.twitter.com/1hzs768vHg
— SpaceX (@SpaceX) August 25, 2023
T minus 3 seconds, Raptor engine ignition begins, and thrust begins to construct to permit for liftoff.
T+ 2 seconds, the 2nd Integrated Flight Test should now be officially underway, with Booster 9 thundering away from the orbital launch mount.
Liftoff from Starbase pic.twitter.com/rgpc2XO7Z9
— SpaceX (@SpaceX) April 20, 2023
T+ 52 seconds, Starship and Booster 9 reach Max Q, the realm of maximum dynamic pressure on the vehicle will occur here. If (or most) all Raptor engines on Booster 9 are performing nominally, the vehicle will go through this fairly quickly.
T+ 2 minutes and 39 seconds, Staging. This will probably be the primary time SpaceX has ever attempted hot staging. Just about all of Booster 9 engines will cut out, and Ship 25 will ignite its Raptor engines to separate from the booster. That is all unknown territory from this point on for SpaceX, as the primary test flight didn’t make it this far. SpaceX has yet to make clear what number of Ship 25 engines will ignite during this process.
If all goes well, Booster 9 will begin its flip and boost backburn at t+ 2 minutes and 53 seconds, which can last ~54 seconds. Unlike the Falcon 9, the booster isn’t designed to perform an entry burn.
T+ 6 minutes and 30 seconds after lift-off, Booster 9 will begin its landing burn for a hopeful soft touchdown within the Gulf of Mexico 18 seconds after landing burn ignition. The planned landing area is ~20 miles (32 km) downrange.
Meanwhile, Ship 25 will proceed burning its 6 Raptor engines until t+ 8 minutes and 33 seconds, inserted right into a sub-orbital trajectory, after which enter a coast phase until its planned reentry North of the Hawaiian islands.
At t+ 1 hour and 17 minutes, Starship will begin feeling the results of the atmosphere, its first real test for the heatshield. If it survives atmospheric entry, Starship will splash down within the Pacific Ocean at t+ 1 hour and half-hour after lift off. SpaceX has said Ship 25 is not going to attempt a landing burn during this test.
If Starship is in a position to make it past staging, SpaceX will almost definitely consider this test a hit, however it can be a serious accomplishment for Ship 25 to survive entry back through the atmosphere and gather essential data for the corporate.
If you will have a probability to make it to South Texas and even the opposite side of the Rio Grande in Mexico, it’ll be a sight you’ll always remember. In case you’re watching from home, SpaceX will begin streaming the launch on X and their website 35 minutes before lift-off.