We’re just a few hours away from the fourth test launch of SpaceX’s Starship, the tallest rocket in the world. You’ll be able to watch it live on the company’s website starting at around 8 a.m. ET / 5 a.m. PST.
Here’s what you can expect.
Everything That Has Gone Well
SpaceX is using an iterative approach to develop Starship. This means that each launch serves as a learning experience for the team, which then proceeds to implement changes and improvements to the rocket for the next test.
Starship’s first integrated flight test took place on April 20, 2023. It resulted in the launch pad’s destruction, challenged the reliability of Raptor engines, and ended with the rocket spinning out of control.
The second flight test occurred 212 days later. A perfect launch dispelled all doubts about the engines and left the launch pad flawless, aided by a new flame deflector that shoots jets of water to cushion the liftoff. However, the Super Heavy booster exploded after separating from the stage. As a result, Starship failed to reach the expected altitude.
The third flight test occurred 117 days after that. In this flight, the spacecraft finally completed its ascent phase and entered the planned suborbital trajectory. However, an obstruction in the roll control system caused it to lose altitude and disintegrate in the atmosphere. The Super Heavy also didn’t survive the return trip, exploding before it was supposed to splash down in the ocean.
Now, 84 days later, SpaceX is ready to launch the massive rocket for the fourth time, again with several changes to keep it moving forward.
Everything SpaceX Has Improved
A flight profile of Starship's fourth flight and a profile of the Super Heavy launch vehicle.
The Super Heavy booster and Starship spacecraft models that will fly today are Booster 11 and Ship 29, respectively.
The Super Heavy has lost power twice before splashdown due to a lack of pressure in the Raptor engines. Both instances were caused by a blockage in the filter supplying oxygen to the engines.
SpaceX has improved the booster’s filtering systems and internal structures to prevent the rocket’s turning maneuver after stage separation from affecting the performance of the combustion chambers.
For its part, Ship 29 is equipped with additional roll control thrusters so that the spacecraft can reenter on its belly. This helps ensure that friction with hot air is directed at its heat shield.
In fact, SpaceX has also introduced some changes to the heat shield. The manufacturer has tested a new method and material for attaching the ceramic tiles.
Furthermore, it has made several ground infrastructure upgrades, including larger tanks to improve methane and oxygen storage capacity and new shielding for the cables and piping for the mechanical arms on the Mechazilla tower.
Everything SpaceX Will Test on This Flight
SpaceX’s Super Heavy will eject a nine-ton hot separation ring mid-flight to ensure stage separation from the second flight onward.
This ring is so heavy that it prevents the Super Heavy from splashing down with fuel from its secondary tanks, so it’ll jettison two seconds after the return maneuver. The rocket’s splashdown simulates what will happen on future flights next to the launch tower, where the tower’s robotic arms will catch the booster in flight before it touches the ground.
Moreover, Starship won’t repeat the demonstrations of its previous flight, such as the transfer of liquid oxygen between internal tanks or the test opening and closing of the cargo bay (nicknamed “the PEZ dispenser” for the way it deploys satellites).
There are no plans for the Starship rocket to fire an engine to de-orbit. Instead, it’ll re-enter under the effect of gravity and, if it survives re-entry, make a vertical turn and splashdown maneuver in the Indian Ocean.
During atmospheric reentry, SpaceX engineers are most concerned about potential damage to the spacecraft: The loss of even a single ceramic tile from the heat shield could lead to its destruction. The objective of this fourth flight isn’t simply to endure the heat of reentry, but to do so for as long as possible, ideally until the shield reaches its maximum temperature limit.
Image | SpaceX
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