This video explores the crucial design decision of whether SpaceX's Starship Human Landing System (HLS) variant can land on the Moon without traditional landing legs, a possibility suggested for Mars landings. The analysis highlights that while eliminating heavy legs reduces mass (a primary goal for Starship reusability), the unique physics of the Moon—specifically its low gravity combined with uneven terrain and dynamic instability—makes upright landing extremely challenging for tall vehicles like the 50-meter Starship. Citing failures of previous lunar landers (Odysseus and Athena) that toppled over due to sideways drift, the video explains that resisting the same lateral movement on the Moon would require legs 2.5 times wider than on Earth. Alternative concepts, such as horizontal landings (which introduce significant structural and operational complexities) or building lunar launch towers (which are years away), are examined and dismissed as impractical for the near-term timeline of NASA's Artemis 3 mission (slated for 2027). The conclusion is that SpaceX will likely need to compromise by equipping Starship HLS with large, heavy, non-reusable landing legs to ensure crew safety and stability on the lunar surface.
Starship HLS Lunar Landing: The Need for Landing Legs
0:00 - 0:21: The Central Question: Inspired by a SpaceX comment that Starship will land on Mars using its skirt (no legs), the video asks if the same legless approach is viable for landing humans on the Moon.
0:21 - 1:22: The Weight vs. Reusability Trade-off: Starship is much larger than Falcon 9, requiring much bigger, heavier landing legs. Since the Starship HLS variant is a one-way mission (lacking heat shields/flaps), expensive, non-reusable carbon fiber legs present a significant and costly weight trade-off.
1:29 - 3:11: High Landers Are Prone to Tipping: The challenges are highlighted by the failures of Intuitive Machines' landers, Odysseus (2024) and Athena (2025), which toppled over upon landing. The Moon's low gravity (1/6th of Earth's) exacerbates the tendency for tall structures (like the 50m Starship HLS) to tip over due to minimal sideways motion.
3:36 - 4:22: Dynamic Stability Challenges: Static stability (maximum tilt angle before falling) is the same on Earth and the Moon. However, dynamic stability (resistance to tipping while moving) is far worse on the Moon. Calculations show landing legs would need to be 2.5 times wider on the Moon than on Earth to resist the same horizontal velocity at touchdown.
4:30 - 5:08: Design Factors for Height: Starship and IM landers are tall because they stack liquid methane and liquid oxygen tanks vertically to maintain a balanced center of mass. Odysseus tipped over after breaking a leg upon landing too fast on a steep 12° slope.
5:08 - 9:16: Alternative 1: Horizontal Landing: Landing Starship on its side offers benefits (increased ground stability, lower center of gravity, ground-level access for cargo and astronauts), but introduces severe structural challenges. Starship's cylindrical hull is optimized for vertical axial loads, not the lateral bending stresses of resting on its side, and main engines are problematic for vertical ascent from a horizontal position.
9:16 - 10:17: Alternative 2: Lunar Mechazilla: Building local infrastructure, such as a tower catcher on the Moon, is a long-term vision but is years away from feasibility, particularly given the focus on fundamental lunar infrastructure (power, communications).
10:20 - 11:17: Conclusion on Near-Term Requirements: Due to the pressure of the Artemis 3 crude landing timeline (targeted for 2027), advanced, complex solutions are not viable. Despite the weight penalty, Starship will likely need to be equipped with large, heavy landing legs to ensure stability and safety on the Moon.