If Starship lander doesn't work on the moon, what could take its place, while still using its massive capabilities? This is what I speculated upon with the AI vetting my ideas. The best response seemed to be in using the Blue Origin lander inside of the Starship.
Blue Origin also wants to go to the moon. Would a moon lander fit inside of the Starship cargo area?
Yes, an entire Blue Origin lunar lander—specifically their Blue Moon architecture (such as the MK1 cargo variant or the larger MK2 human-landing system being developed for NASA's Artemis V mission)—could fit inside the Starship cargo area, provided it is engineered to respect the dimensional limits of the bay.
Blue Origin's Moon Landers vs. Starship's Cargo Bay
Blue Origin has two primary lunar lander concepts in development:
1. Blue Moon MK1 (Cargo Variant): Designed to deliver up to 3 metric tonnes of payload to the lunar surface. It has a diameter of roughly 7 meters and stands around 10 to 12 meters tall.
- Fit Test: Because its diameter is around 7 meters (fitting within Starship's 8-meter dynamic envelope) and its height is well under the 17–22 meter length of the cargo bay, the MK1 lander can easily fit entirely inside Starship's cargo hold.
2. Blue Moon MK2 (Human Landing System / Artemis): This is a much larger vehicle designed for crewed descents. It utilizes a BE-7 engine powered by liquid hydrogen and liquid oxygen. While its exact fully-outfitted dimensions are tightly guarded, the descent stage diameter and height are tailored to fit inside traditional commercial heavy fairings (like New Glenn's 7-meter fairing).
- Fit Test: If a MK2 lander (or a scaled version of it) is designed with a diameter under 7.5 to 8 meters and a length under 15 meters, it could be packed into Starship's cargo bay and deployed in Low Earth Orbit or lunar orbit. However, because hydrogen tanks are notoriously voluminous (due to hydrogen's low density), a fully assembled human-class hydrogen lander might push right up against the absolute limit of Starship's volumetric capacity.
The Irony of Competitors Utilizing Starship
While Blue Origin and SpaceX are fierce commercial rivals in the new space race, the math of heavy-lift logistics creates a fascinating scenario: SpaceX's Starship is essentially the only vehicle currently operating or in development with a cargo bay large enough to swallow a competing company's heavy lunar lander whole.
If an agency or private entity wanted to launch a Blue Origin-style lander into Earth orbit or onto a trans-lunar trajectory using a vehicle other than New Glenn or SLS, Starship's 1,000-cubic-meter volume and 150-tonne capacity make it the ultimate universal heavy-lift delivery truck. Instead of building a custom, multi-billion-dollar rocket to launch their lander, a competitor could theoretically buy a Starship ride, pop the lander out of the side-door "PEZ dispenser" in LEO, and send it on its way to the Moon.
Here's another idea: What about the Falcon 9 and Dragon? What is the masses and dimensions of the second stage Falcon 9 rocket and dragon capsule?
If a second stage of Falcon 9 and Dragon were to be launched on a Starship, what could that combination do? Could it get to the moon?
Launching a Falcon 9 second stage and a Dragon spacecraft inside of Starship’s cargo bay as a secondary payload combo sounds like a wild sci-fi concept, but purely from a rocketing and delta-V perspective, it opens up some fascinating orbital mechanics.
The Setup: What You're Deploying
If you eject the Falcon 9 second stage and the Dragon capsule out of Starship's cargo door in Low Earth Orbit (LEO), you essentially have a completely independent, highly capable orbital stack.
- The Falcon 9 Second Stage brings its single Vacuum Merlin engine and roughly 111.5 tonnes of RP-1/LOX propellant.
- The Dragon 2 brings its own Draco thrusters, SuperDraco abort engines, life support systems, avionics, and a pressurized cabin.
Could It Get to the Moon?
Short answer: Yes, but with some heavy modifications and severe operational caveats.
If the Falcon 9 second stage were fully fueled in LEO (which would require Starship to act as a gas station to pump propellants into it, or launching the stage pre-fueled inside a pressurized/safe Starship bay), let's look at the delta-V math:
1. Delta-V Budget: The Falcon 9 second stage with a lightweight payload like Dragon has a massive vacuum specific impulse ($I_{sp} \approx 348\text{ seconds}$) and a great mass ratio. Unloaded from Earth's deep gravity well (since Starship did the heavy lifting to LEO), that second stage sitting in orbit possesses roughly 4,000 to 5,000 m/s of delta-V.
2. Trans-Lunar Injection (TLI): To get from LEO to a lunar intercept requires roughly 3,100 to 3,200 m/s of delta-V. Mathematically, the F9 second stage has more than enough energy to push Dragon out of Earth orbit and onto a trajectory toward the Moon.
The Massive Engineering Hurdles
While the raw math works out, executing this in reality would be an engineering nightmare for several reasons:
- Propellant Boil-Off and Compatibility: Falcon 9 uses RP-1 (refined kerosene) and Liquid Oxygen (LOX). While LOX requires cryogenic cooling, RP-1 is stable at room temperature, which is nice. However, the Falcon 9 upper stage avionics, batteries, and pressurization systems (helium tanks) are not designed for long-duration coast phases in deep space. Falcon 9 upper stages typically burn out within hours of launch; keeping one alive and functional for a multi-day lunar transit would require completely rewriting its electrical and thermal control systems.
- Thermal Protection for Lunar Reentry: Dragon is engineered to survive reentry from Low Earth Orbit (returning from the ISS at roughly 7.8 km/s). If Dragon is sent to the Moon and comes back, it will hit Earth's atmosphere at trans-lunar return speeds of roughly 11 km/s. Dragon's PICA-X heat shield is fundamentally not designed or certified to handle the extreme thermal and radiative flux of a lunar return without burning through.
- Redundancy: Dragon lacks a deep-space habitation environment, heavy radiation shielding, and long-duration life support for a crew to travel to the Moon and back safely outside of Earth's magnetosphere.
Why Do It When Starship is Already There?
The ultimate irony of this thought experiment is that Starship itself is already a vastly superior vehicle for the job.
If Starship has already hauled the Falcon 9 stage and Dragon up to LEO, Starship itself has 1,000 cubic meters of volume, life-support capabilities, and with orbital refueling, enough delta-V to land on the Moon and come back directly (as seen in the Artemis HLS contract). Using a Falcon 9 second stage as a makeshift lunar kick-stage for a Dragon capsule would be like packing a smart car inside the back of a semi-truck, only to hitch a lawnmower engine to the smart car to finish the trip.
Still, it highlights the sheer scalability of Starship—the fact that you can fit an entire traditional orbital launch vehicle inside of another rocket's payload bay proves just how much the paradigm of spaceflight has shifted.
How much payload could it land on the Moon?
If you were to use a fully fueled Falcon 9 second stage as a lunar kick-stage to push a Dragon capsule toward the Moon, how much payload could it actually land on the lunar surface?
The short answer is: Zero, because neither the Falcon 9 second stage nor the Dragon capsule is designed to land on the Moon.
Unlike Starship (which has its own heat shield and massive Raptor engines for a propulsive touchdown) or a dedicated lunar lander, neither piece of this hardware has landing legs, surface engines, or a descent guidance system.
However, if we adjust the thought experiment—turning the Falcon 9 second stage into a lunar orbital insertion and landing stage, or assuming we strap a makeshift landing frame to it—let’s look at what the math says about its mass limits on the lunar surface.
1. The Mass Budget in LEO
Once delivered to Low Earth Orbit by Starship, your stack looks like this:
- Falcon 9 Second Stage (Dry): ~4,000 kg
- Falcon 9 Second Stage Propellant (RP-1/LOX): ~111,500 kg
- Dragon 2 Capsule + Trunk (or equivalent payload): ~12,000 kg (max)
- Total Stack Mass in LEO: ~127,500 kg (~127.5 tonnes)
2. The Delta-V Journey to the Moon
To take that entire 127.5-tonne stack from LEO, inject it to the Moon (TLI), capture into lunar orbit, and de-orbit/land, you need a staggering amount of delta-V:
1. Trans-Lunar Injection (TLI): ~3,150 m/s
2. Lunar Orbit Insertion (LOI): ~900 m/s (assuming you go into orbit first)
3. Powered Descent & Landing: ~2,000 m/s (since the F9 engine cannot throttle down low enough to hover a heavy vehicle on the Moon, you would need an entirely different landing engine, but let's assume ideal rocket math).
Total required delta-V from LEO to the lunar surface is roughly 6,050 to 6,500 m/s.
3. Running the Tsiolkovsky Rocket Equation
The Falcon 9 second stage's single Vacuum Merlin engine has a specific impulse ($I_{sp}$) of about 348 seconds in a vacuum.
If you burn the entire 111,500 kg of propellant available in the second stage to push the dry stage (4,000 kg) and a payload all the way to a lunar landing:
- With a total initial mass of 127.5 tonnes and a total delta-V requirement of ~6,200 m/s, the exponential mass ratio eats away at your capacity very quickly.
- By the time the second stage performs TLI and decelerates into a lunar landing trajectory, the remaining payload mass you could safely set down on the lunar surface is roughly 2 to 4 metric tonnes—assuming you added landing legs, guidance computers, and a secondary low-thrust landing engine to handle the final touchdown.
The Ultimate Reality Check
While you could theoretically squeeze 2 to 4 tonnes onto the Moon using a hacked-together F9 upper stage, it highlights why this approach is completely impractical:
1. Dragon Can't Land There: Dragon relies entirely on Earth's atmosphere for parachutes and a water landing. On the Moon, it's a dead brick with no air.
2. Merlin Can't Hover: The Merlin 1D Vacuum engine is optimized for high-thrust space burns; it cannot throttle down low enough to soft-land a vehicle on the lunar regolith without digging a crater and destroying itself.
3. Starship Does It Better: Starship HLS (Human Landing System) is designed to land 100 metric tonnes directly on the Moon and lift crew back off, all using a single vehicle that launched from Earth (with orbital refueling).
So, while putting an F9 upper stage and a Dragon inside Starship is a fun geometry puzzle, trying to turn them into a lunar lander is like trying to turn a speedboat into a submarine—it's the wrong tool for an entirely different ocean!
What if we add landing legs and engines?
Isn't the Dragon used as an escape stage if something goes wrong with the launch? If that's true, then how does dragon land?
You are thinking of the Launch Abort System (LAS), which is a critical safety feature for crewed spacecraft. However, how the Dragon handles aborts and how it lands are two different mechanisms, and there is a unique twist with how SpaceX designed the Dragon 2.
How Dragon's Abort System Works
Unlike older spacecraft (like Apollo or Orion) that use a giant tower with solid-propellant rockets on top of the capsule to pull it away from danger, SpaceX’s Crew Dragon does things differently.
- Integrated SuperDraco Thrusters: Crew Dragon has 16 SuperDraco engines built directly into the side walls of the spacecraft's hull.
- The Abort Sequence: If the Falcon 9 rocket suffers a catastrophic failure on the pad or during ascent, the SuperDracos instantly fire with immense thrust (pushing the capsule away at over 400 miles per hour in seconds) to tear the Dragon clean away from the exploding booster.
- The Trunk Separation: Once the capsule is safely clear of the danger zone, the unpressurized "trunk" (which houses the solar panels and grid fins) is jettisoned, and the capsule orients itself for a safe parachute descent.
How Dragon Lands
Despite early plans by SpaceX to have Dragon land propulsively on solid ground using those same SuperDraco thrusters and deployable landing legs, that concept was scrapped.
- Water Landings: Today, every operational Crew Dragon and Cargo Dragon lands exclusively in the ocean (the Atlantic Ocean or Gulf of Mexico off the coast of Florida).
- The Parachute Sequence: After reentering Earth's atmosphere, the capsule deploys two drogue parachutes to stabilize itself, followed by four massive main parachutes to slow its terminal velocity down to about 16 to 18 mph (25 to 29 km/h).
- Splashdown: The capsule splashes down into the water, where recovery ships scoop it up. The water acts as the ultimate shock absorber, eliminating the need for heavy landing legs or propulsive landing engines.
What About Cargo Dragon?
It is also worth noting that Cargo Dragon (Dragon 2)—the version used to resupply the International Space Station—does not even have SuperDraco abort engines. Because there are no humans on board, it doesn't need a launch abort system. It relies purely on the Falcon 9's normal flight safety systems during launch, and it returns to Earth using the exact same parachute and ocean-splashdown method as the Crew Dragon.
Why was propulsive landing scrapped?
SpaceX’s decision to scrap propulsive landing for the Crew Dragon capsule—originally designed to touch down on solid ground using its SuperDraco thrusters and deployable landing legs—was one of the toughest engineering pivots in the company's history.
Elon Musk announced the cancellation in 2017, and it came down to a combination of regulatory roadblocks, engineering complexity, and the realization that the juice simply wasn't worth the squeeze.
Here are the primary reasons why propulsive landing was dropped:
1. NASA’s Certification and Safety Requirements
When SpaceX signed its Commercial Crew contract with NASA to ferry astronauts to the International Space Station, safety was the absolute non-negotiable priority.
- Unproven Tech for Human Return: Landing a capsule propulsively on land had never been done before in human spaceflight (the Soviet/Russian Soyuz uses parachutes and soft-landing solid retrorockets right at the ground, but it still lands under a canopy; Apollo splashed down in the ocean).
- The "Factor of Safety": NASA's safety panels were deeply skeptical. Proving that a propulsive landing system would work with a 100% success rate under every conceivable failure mode (such as an engine failing to ignite, guidance software glitches, or high crosswinds at touchdown) required mountains of paperwork, testing, and risk analysis that threatened to delay the program for years.
2. Qualification of the Landing Legs
Designing structural landing legs that can fold tightly into the aerodynamic contour of a spacecraft, survive the blistering heat of atmospheric reentry (up to 1,600°C), and then successfully deploy and lock in place right before touchdown proved to be a brutal engineering challenge.
If the legs failed to deploy, the capsule would essentially crash onto its side, risking the lives of the crew. Qualifying those mechanisms to NASA's standards was a massive hurdle.
3. The Path of Least Resistance (Parachutes Already Worked)
SpaceX had decades of historical precedent and existing data showing that parachutes and ocean splashdowns work reliably.
- While parachutes require naval recovery teams, ships, and a bit more logistical turnaround time than touching down on a concrete pad at Cape Canaveral, they are fundamentally simpler and have a predictable physics profile.
- By dropping the propulsive landing requirement for Dragon, SpaceX could focus its engineering talent and capital entirely on perfecting Falcon 9 and Starship booster landings (where propulsive landing does make immense economic sense).
The Ultimate Irony
While propulsive landing was scrapped for Dragon, the lessons learned from trying to make it work directly fed into Starship.
SpaceX took the core concept—using heavy retro-propulsion to land a spacecraft vertically without runways or parachutes—and scaled it up to the massive Starship vehicle. So, while Dragon settled for a traditional ocean splashdown, the ghost of propulsive landing lives on in every Starship test flight today.
's book 
. I suspect that a lot of the fear has to do with a lack of understanding which is exacerbated by the way that mishaps get reported in the news. Hence, the Three Mile Island incident effectively shuts down the nuclear industry here. A few years later, Chernobyl reinforced that fear. Now Fukishima just adds to the climate of fear of things nuclear- these things just don't seem safe. Now, Germany abandons nuclear power. All of this is an overreaction. Sadly, it may be unavoidable. People will fear something they don't understand. What to do?