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The answer to the question was not exactly what I expected. Indeed, it would take a complete redesign of the spacecraft.
What would I suggest? A partial redesign. The booster is okay, leave it alone. Instead, the effort should be made to redesign the Starship itself.
The ship as it stands can deliver 100+ tons in its present configuration. If the redesign can improve upon that, then why not?
An idea presented itself to me. On my trip out to the area a couple of months ago for flight 12, I had the opportunity to touch the TPS tiles. The impression I got was that they were rather robust. They aren't fragile.
Could these tiles be used as part of the skin, while minimizing the use of the heavy stainless steel?
The empty weight of the Starship is over 100 tons. It will carry about 1200 tons of fuel. Therefore, the ratio between the empty weight and the full weight is much lower than for the booster. This is inefficient.
If the tiles could replace the stainless steel skin, wouldn't that reduce the weight? It should seem so. That's because there's a duplication in having the TPS when there is already a skin.
But what would hold it together? Perhaps a way could be found to connect the tiles that would allow such a substitution to work. Indeed, the current design requires that the TPS be impervious to the environment. If that is so, then the only other requirement is that it be strong enough to deal with the forces that would be working against it during the mission.
So my thinking was to run the stainless steel through the TPS and then connect the individual tiles that way. It would use less steel, and eliminate some of the duplication. If enough steel was used, it may even be strong enough to do what is required of it with regards to strength.
The current design requires sheets of steel. Instead of doing that, the sheets could be manufactured out of a constructed and interlocking set of heat tiles.
Such could be stacked in a similar way that they're being stacked now.
The only question then is the strength of the tiles thusly arranged.
A second suggestion would be to have the crew area and cargo area SEPARATE from the second stage. The second stage could return as it already does. The third stage could be a space only vehicle. But how to get home? Perhaps with a large capsule-like device. This design would also incorporate a propulsion capability that would enable it to launch from the surface of the Moon.
Mars may require another solution.
Yet another idea presents itself. Why do much of a redesign at all? Make the third stage as the redesign, and leave the second stage as it is, with some minor modifications. That is to say, it would have the cargo and crew area as a completely separate part of the spacecraft, with an enlarged capsule like design. The heat shield will be on the bottom of the spacecraft, as opposed to what it is now.
What are the main criticisms of SpaceX's Starship's design, and what would be improved upon in order to make it better?
This is a great engineering question. I’ll give you the main technical criticisms of Starship’s current design, followed by the improvements that would address them. I’ll be clear about what is a legitimate trade-off versus what may be a genuine flaw.
Main Criticisms of Starship’s Design
1. Stainless Steel Construction (Weight Penalty)
SpaceX uses 304L stainless steel for the hull. Stainless is cheap, strong at high temperatures, and easy to weld, but it is significantly heavier than carbon composites or aluminum-lithium alloys. This directly reduces the payload mass fraction. For a reusable vehicle, the dry mass penalty is a serious disadvantage.
2. The “Belly Flop” Reentry Profile
Starship reenters broadside with a massive frontal area, then flips at the last moment. This is aerodynamically inefficient and subjects the vehicle to extreme lateral heating. The control surfaces (forward and aft flaps) are heavy, add complexity, and experience some of the most severe thermal loads. If the flap actuators fail, the vehicle is unrecoverable.
3. Heat Shield Tile Attachment
The TPS uses hexagonal ceramic tiles bonded directly to the stainless steel. This is similar to the Space Shuttle’s system, which had a persistent problem with tile shedding. Starship has already lost tiles during test flights. If a tile is missing in a critical area, the underlying steel could be compromised. The adhesive bond line is a single-point-of-failure for the entire vehicle.
4. Raptor Engine Complexity
The Raptor 3 is a full-flow staged combustion cycle engine. It is extraordinarily complex, with extreme chamber pressures (~350 bar) and high turbine inlet temperatures. This has led to turbopump failures, combustion instability, and a high rate of engine swaps. The number of engines (33 on Super Heavy, 6 on Starship) multiplies the risk of a single-engine failure cascading.
5. No Crew Escape System
Starship has no launch abort system beyond the vehicle’s own ability to separate. If the Super Heavy booster fails catastrophically, the crew cannot escape. For a vehicle intended to carry 100 people, this is a fundamental safety issue. NASA’s HLS contract requires an abort capability, but the current design relies on the engines to push the ship away, which is unproven at high dynamic pressure.
6. Orbital Propellant Transfer (Unproven)
Starship’s deep space architecture depends on on-orbit refueling. This requires transferring super-chilled propellant between two large vehicles in microgravity, with no ullage. The boil-off rate, settling, and docking loads are unresolved. The entire Mars and lunar mission plan hinges on this capability.
7. Landing Leg Design
The current landing legs are internal, deployed at the last moment. They are small, have a narrow footprint, and are vulnerable to hard landings. The vehicle is top-heavy, and a leg failure on touchdown would be catastrophic.
8. Cargo Door and Payload Deployment
The large forward payload door (the “pez dispenser”) is a complex mechanism that must open and close in space with no backup. If it jams, the mission is lost. The door’s seals and thermal protection are also a concern.
Improvements That Would Make It Better
1. Replace Stainless with a Heat-Resistant Composite
A carbon-carbon or carbon-ceramic composite skin would save mass and improve structural performance. The trade-off is cost and manufacturing complexity. If SpaceX could develop a reusable composite hull that withstands reentry, the dry mass reduction would be substantial.
2. Use a More Conventional Reentry Profile
Adding small deployable wings or a lifting body shape would reduce heating, improve cross-range, and simplify the control system. The trade-off is added mass and complexity for the wings. But the belly flop is a high-risk maneuver that puts enormous stress on the vehicle.
3. Mechanically Attached TPS
Move from adhesive bonding to a mechanical attachment system (like pins or rails) with a redundant backing. This would prevent tile shedding and allow for easier inspection and replacement. The Shuttle’s bonding was a known failure mode; Starship should not repeat it.
4. Simplified Engine Architecture
Reducing chamber pressure or switching to a simpler oxygen-rich staged combustion cycle (like the RD-180) would improve reliability at the cost of specific impulse. Alternatively, developing a more robust turbopump with a larger margin to failure would reduce the engine swap rate.
5. Add a Tractor-Tower Abort System
For crewed missions, a tower-based launch abort system (like the one on Dragon 2) would provide a reliable escape path from pad to Mach 1. The extra mass and complexity are justified for human safety.
6. Prove Propellant Transfer with a Dedicated Testbed
Before relying on it for mission-critical operations, SpaceX should fly a dedicated tanker mission that demonstrates multiple transfer cycles, settling, and low-boil-off storage. The current plan to “figure it out during the mission” is not engineering best practice.
7. Larger, Wider Landing Legs
Deployable legs with a wider footprint would improve stability and tolerate rougher landings. The legs should be tested with a high safety margin on both terrestrial and extraterrestrial surfaces.
8. Redundant, Mechanically Locked Payload Doors
The cargo door should have a mechanical backup (e.g., a secondary latch system) and a manual override. The door should be tested in a thermal-vacuum environment with the full thermal cycle.
Summary
Starship is a revolutionary vehicle, but it is also a vehicle of compromises. The design prioritizes low cost, rapid iteration, and exotic performance over robustness, safety, and simplicity. The improvements I listed would make it more reliable and safer, but they would also increase its cost and development time. Whether that trade-off is worth it depends on whether you believe the mission is to get to Mars soon or to get there safely.
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