SpaceX has achieved another significant milestone in the development of the Starship spacecraft, successfully meeting the primary objective of its fourth test flight: a successful atmospheric re-entry. Additionally, the company accomplished two secondary objectives: a successful landing maneuver of the booster rocket, followed by the spacecraft itself.
A near-flawless execution
The Starship system embarked on its fourth test flight on Thursday from the company's launch site in South Texas. The launch was a resounding success, with only one of the 33 Raptor engines of the booster rocket, named "Super Heavy," failing to operate. Roughly three minutes after liftoff, at an altitude of approximately 80 kilometers, a successful "hot separation" occurred, activating the spacecraft's engines just before detachment from the rocket.
Three and a half minutes later, the booster rocket, Super Heavy, executed a landing maneuver simulation above the waters of the Gulf of Mexico. The rocket stabilized for a vertical landing and briefly hovered above the water as planned. SpaceX's founder and CEO, Elon Musk, recently stated that the company aims to successfully complete such a maneuver over water at least twice before attempting to land the rocket at the launch site, where special arms of the launch tower are expected to catch it while it hovers nearby.
The spacecraft itself, the "Ship," continued its journey into space propelled by its six Raptor engines. At an altitude of 150 kilometers, the engines were shut down as planned. It did not enter Earth's orbit but undertook a suborbital flight, reaching an altitude of over 180 kilometers.
The flight trajectory led the spacecraft to re-enter the atmosphere over the Indian Ocean, approximately 50 minutes after launch, allowing SpaceX to assess the effectiveness of the spacecraft's heat shield, testing whether it would withstand the high temperatures as well as the company’s capability to orient the spacecraft so that the heat shield faced downward.
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The International Space Station with the Dragon spacecraft by SpaceX
(Illustration: vastspace.com)
In the third test flight, conducted in March of this year following a similar plan, the spacecraft experienced spinning during atmospheric re-entry. This resulted in its burning and eventual explosion due to the overheating of the side not protected by the heat shield.
Contrary to the previous flight, in this test, the spacecraft did not spin, and the heat shield successfully faced downward, completing all stages of atmospheric re-entry in a horizontal flight. Although in the early stages of the landing, the intense heat initially seemed overwhelming, with part of the spacecraft's fin burning and detaching, it eventually reached the water surface almost intact. Upon reaching the water, the spacecraft executed a successful landing maneuver, aligning itself vertically before touching down.
The primary focus of this flight was testing the heat shield, which comprises approximately 18,000 hexagonal ceramic tiles covering slightly over half of the ship's cylindrical body. During atmospheric re-entry, temperatures soar to over 1,400 degrees Celsius due to air friction. SpaceX CEO Elon Musk recently emphasized that the heat shield remains the primary challenge and that no one has yet succeeded in producing a truly reusable heat shield.
It appears that this test was very successful, though naturally, data analysis from the experiment is awaited before definitive conclusions can be drawn. Musk tweeted immediately after the mission: “Despite loss of many tiles and a damaged flap, Starship made it all the way to a soft landing in the ocean! Congratulations @SpaceX team on an epic achievement!!”
Progress with each test
In the current test, success was achieved in the primary objectives that had not been previously met: both the booster rocket and the spacecraft executed successful atmospheric re-entry and landing maneuvers. These crucial elements had all failed in the third test, with the spacecraft burning up during atmospheric re-entry and the booster rocket exploding during an attempted landing maneuver.
However, the third test also marked significant progress compared to the second test flight, where the spacecraft exploded in space, and compared to the first test, where the spacecraft failed to separate from the rocket, and both were destroyed in a controlled explosion without reaching space.
Nonetheless, the third test also represented notable progress compared to the second test flight, during which the spacecraft exploded in space, and compared to the initial test, where the spacecraft's failure to separate from the rocket resulted in a controlled explosion before reaching space.
In upcoming tests, the company will need to overcome more significant challenges, including achieving orbital flight around Earth, conducting atmospheric re-entry from such an orbit at higher speeds, reactivating engines in space, maneuvering in space, docking with other spacecraft, refueling in orbit around Earth, and more. All these are essential milestones on the path to utilizing Starship for its near-term objectives, such as landing astronauts on the moon and establishing it as a significant vehicle for deploying satellites in space.
Bigger, Stronger
The Starship system was engineered to transport larger and heavier payloads into space than any previous launch rocket, all at a reduced cost, thanks in part to the potential for fully recycling both the booster rocket and the spacecraft. In contrast to modern rockets constructed from lightweight yet strong materials such as aluminum, carbon fibers, and lightweight alloys, both Starship components are made of stainless steel, which is heavier but also much more resistant to mechanical stresses and extreme temperatures. This design is intended to enable rapid and cost-effective preparation for the reuse of both the rocket and spacecraft.
To enable reusability, both system components are designed for soft vertical landings, a capability developed and refined by SpaceX over years of using its main workhorse, the Falcon 9 rocket. As mentioned, special arms at the launch site are designed to facilitate gentle landings of the rocket and spacecraft.
Additionally, the spacecraft must be adaptable for soft landings in other locations. Starship is intended to venture beyond Earth's orbit: NASA has selected it as the lunar landing vehicle for the Artemis program. Furthermore, in the more ambitious plans of SpaceX founder and CEO Elon Musk, such spacecraft will spearhead human settlement efforts on Mars.
- Content distributed by the Davidson Institute of Science Education