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AI Overview
SpaceX's Starship can carry a maximum of 100 metric tons of payload to the Moon, but this requires refueling the spacecraft in Earth's orbit. Without orbital refueling, Starship's cargo capacity for a lunar mission is significantly reduced.

Orbital refueling for lunar missions
Because Starship is designed for full reusability, it expends most of its propellant getting into Earth orbit. To have enough fuel to travel to the Moon, land, and return, it must be refueled by multiple "tanker" Starships in low-Earth orbit (LEO).

Mission architecture: This architecture involves launching a Starship lunar mission vehicle into LEO, followed by several tanker Starship launches to transfer propellant.

Payload capacity: With in-orbit refueling, the Starship Human Landing System (HLS) variant is designed to land up to 100 tons of payload on the lunar surface.

Number of refuels: The exact number of tanker flights required is still under development, with estimates ranging from 4 to over a dozen.

Payload for NASA's Artemis missions

For NASA's Artemis program, Starship will serve as the Human Landing System (HLS), which will ferry astronauts from lunar orbit to the surface. The HLS variant of Starship is specifically designed with modifications for lunar landing and operation.
Crew and cargo: The HLS includes features like an elevator to deploy crew and cargo to the lunar surface.

Recent progress: As of late August 2025, a Starship test flight successfully deployed a test payload into Earth orbit, a crucial step towards demonstrating its payload capabilities. However, the much larger challenge of orbital refueling has yet to be demonstrated

AI Overview
An on-orbit payload half-fueled for a lunar mission is a theoretical scenario that does not align with SpaceX's current plan for Starship. For crewed lunar missions, the Starship Human Landing System (HLS) variant is designed to be fully fueled in low Earth orbit (LEO) by multiple tanker flights before departing for the Moon.

The main reason for this full refueling is the physics of orbital mechanics:

Massive fuel requirement: A Starship carrying a significant payload requires nearly its full fuel load to achieve a lunar trajectory and land on the surface. It must rendezvous with multiple tanker Starships in LEO to receive enough liquid oxygen and methane to top off its tanks.

Delta-V demand: The change in velocity (delta-V) required to leave LEO, travel to the Moon, and descend to the surface is very high. A fully fueled Starship with a payload is designed to use almost all of its propellant for this portion of the mission.

Lunar landing: Unlike returning to Earth where atmospheric drag can assist with deceleration, the Moon's lack of atmosphere means the Starship must perform a propulsive, or rocket-powered, landing. This requires a substantial amount of fuel.
The Artemis III mission profile

As an example, consider NASA's Artemis III mission, which will use a Starship HLS to land astronauts on the lunar surface. The planned mission profile highlights why a half-fueled payload is not feasible:
A Starship HLS launches with its payload into LEO.

The HLS is met by 10 to 20 tanker Starships to transfer propellant.
Once fully fueled, the Starship HLS departs Earth orbit for the Moon.
After landing, the HLS uses its engines to lift off from the lunar surface and return to lunar orbit, where it is not required to return to Earth as part of the initial contract.

While early estimates from SpaceX indicated that only half-refueling might be necessary for the lunar HLS mission due to lower gravity, the most recent information and assessments suggest a much higher number of refueling flights are needed to fill the tanks completely. This is also due to the possibility of "boil-off," the evaporation of cryogenic propellants in orbit, which reduces the amount of usable fue

AI Overview
While specific fuel amounts are subject to change during development, SpaceX's Starship Human Landing System (HLS) requires a full propellant load of roughly 1,200 tons to return from the lunar surface to lunar orbit. This is followed by a journey back to Earth and is made possible by extensive refueling in Earth orbit.

The departure profile for an Artemis mission
The Starship HLS lunar departure is part of a larger, complex mission architecture designed in cooperation with NASA for the Artemis program.

Astronaut transfer: After exploring the lunar surface, astronauts board the Starship HLS from the Moon's surface.
Lift-off from the Moon: Using its powerful Raptor engines, the Starship HLS launches vertically from the lunar surface. It will use a combination of vacuum-optimized Raptor engines for primary ascent and side-mounted cold-gas or RCS thrusters for final adjustments and to mitigate lunar dust kick-up near the surface.

Rendezvous in lunar orbit: The Starship HLS will then rendezvous and dock with a waiting Orion spacecraft in a Near-Rectilinear Halo Orbit (NRHO).
Transfer and return: The crew will transfer from Starship back into the Orion capsule, which will then transport them back to Earth.

Why Starship needs to refuel for the moon mission
Unlike the Apollo lunar module, which was much smaller and had a two-stage design with a disposable ascent stage, Starship is a fully reusable, single-stage-to-orbit-from-the-moon system. It requires a significant amount of fuel for every stage of its journey:
Leaving Earth orbit (Trans-Lunar Injection): The ship needs fuel to depart low Earth orbit (LEO) and head toward the Moon.

Landing on the Moon: Maneuvering into lunar orbit and performing a soft landing requires a substantial amount of propellant.
Leaving the Moon: Taking off from the lunar surface to rendezvous with the Orion capsule in NRHO requires a very large amount of fuel.

The role of orbital refueling
Due to Starship's mass and the fuel needed for the round trip, it is impossible for a single launch to carry all the necessary propellant.

Tanker flights: Multiple Starship tanker vehicles will launch from Earth and refuel a Starship propellant depot in Earth orbit.
Depot rendezvous: The Starship HLS for the lunar mission will launch, dock with the depot, and take on its full load of fuel before departing for the Moon. SpaceX's orbital refueling system is currently still under developmen

AI Overview

The Falcon Heavy has a maximum payload of 63,800 kg (140,700 lbs) to Low Earth Orbit (LEO) when fully expendable and about 26,700 kg (58,860 lbs) to Geostationary Transfer Orbit (GTO). With boosters recovered, the LEO payload is around 57,000 kg, decreasing further if the core stage is also recovered. The payload capacity depends on the mission profile and whether the boosters are recovered for reuse.
Payload Capacities by Orbit and Mode

Fully Expendable:
LEO: 63,800 kg (140,700 lbs)
GTO: 26,700 kg (58,860 lbs)

Mars: 16,800 kg (37,040 lbs)
With Boosters Recovered:
LEO: ~57,000 kg (126,000 lbs)

Key Factors Influencing Payload Mass

Expendability:
The highest payload mass is achieved in a fully expendable configuration, where booster recovery is not prioritized, and therefore all available fuel is used for lift.
Booster Recovery:

Recovering the two side boosters and the center core reduces the rocket's maximum lift capability to space because less fuel is available for the mission, according to Wikipedia.
Mission Profile:

The intended orbit and trajectory for the payload significantly impact the required launch energy and, consequently, the maximum attainable payload mass, notes Space Exploration Stack Exchange.

AI Overview
For version 2 of Starship, SpaceX promised a payload mass of 100–150 metric tons to low-Earth orbit (LEO) in a fully reusable configuration. This represents a significant increase over the payload capacity of its predecessor, Block 1.

Payload mass by version
While SpaceX continues to rapidly iterate, the progression of Starship payload capabilities can be tracked by its different "Blocks".

Block 1: An early version used for orbital test flights, with a reusable payload mass of about 15 tons.

Block 2 (Current): Features a stretched propellant tank, reduced dry mass, and a more robust heat shield design. This allows it to meet the promised reusable payload capacity of 100 to 150 metric tons.

Block 3 (Future): This next-generation version is expected to further increase payload to 200 metric tons in a reusable configuration and up to 400 metric tons in an expendable mode. It will be taller and will use more powerful Raptor 3 engines.
Factors influencing version 2 payload

The higher performance of Starship version 2 compared to version 1 is achieved through several key upgrades:
Stretched tanks: Increases propellant capacity to boost performance.
Reduced dry mass: Optimizes the vehicle's structural design to carry more payload relative to its own weight.

Advanced heat shield: Enhances thermal protection during re-entry to improve reusability.
Upgraded avionics: Supports more complex missions and capabilities, such as on-orbit refueling.

Primary payloads for version 2

A primary driver for the increased payload capacity is the deployment of next-generation Starlink satellites, known as "V3" satellites.
Each V3 satellite is much larger and heavier than previous versions.

A single Starship launch is expected to deploy a massive number of V3 satellites, potentially adding 20 times the network capacity of a Falcon 9 launch.

In addition to Starlink, the version 2 Starship will also be used for other critical missions, including the Human Landing System (HLS) for NASA's Artemis program

Air speed, mass, and force are related through the principles of aerodynamics and Newton's laws of motion. Force is the product of mass and acceleration (F=ma). For objects moving through air, the speed (specifically, the velocity relative to the air) influences the aerodynamic forces acting on the object, such as lift and drag. These forces are proportional to the density of the air, the relative velocity squared, and the object's frontal area.
How they are connected:
Force & Mass/Acceleration:
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Newton's second law states that a net force applied to an object causes it to accelerate, changing its speed. An object's mass dictates how much it resists this change in motion (inertia).
Air Speed & Aerodynamic Force:
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When an object moves through air, it experiences aerodynamic forces. The faster the relative air speed, the greater the force exerted by the air on the object, with the force increasing by the square of the velocity.
Mass Flow Rate:
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The mass of air passing a point over time is the mass flow rate, which can be calculated by multiplying density, velocity, and area.
Examples:
Aircraft Lift:
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A wing is shaped to make air travel faster over the top surface than the bottom. This increased speed reduces pressure, creating an upward lift force.
Falling Objects:
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As an object falls, air resistance (a form of aerodynamic drag) opposes gravity. This resistance, which depends on the object's speed, increases as the object falls faster.
Terminal Velocity:
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Eventually, the drag force equals the force of gravity, and the object stops accelerating, reaching a constant speed called terminal velocity. A parachute increases drag by increasing the surface area, which slows the descent

Wind turbine blades generate force from the interaction between their speed, the air's speed and density, and their shape, but the mass of the blade itself is a factor that influences how quickly it accelerates and its resistance to changes in motion, affecting the turbine's overall rotational dynamics. Specifically, the blade experiences aerodynamic lift and drag forces as it moves through the wind, with the tips moving faster and generating more lift than the base. This interaction, combined with the mass of the blade, creates a system where the blade's mass affects the overall moment of inertia, influencing how the blade responds to the varying forces of the wind and how quickly it reaches an optimal operating speed.
Aerodynamic Forces & Blade Motion
Air Speed:
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The speed of the air passing the blade is a combination of the real wind speed and the "headwind" created by the blade's own rotation.
Lift and Drag:
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The air moving over the blade's surface creates aerodynamic forces: lift, which causes rotation, and drag, which opposes motion.
Relative Air Speed:
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The relative air speed varies along the blade, with the tips moving much faster than the roots, resulting in greater lift at the tips.
Angle of Attack:
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Blades will gather speed until their motion reduces the angle of attack of the air to approximately zero, at which point they stop generating lift and maintain their speed.
Mass of the Blade
Moment of Inertia:
A blade's mass is a crucial component of its moment of inertia, a measure of its resistance to changes in rotational motion.
Acceleration:
A larger mass (and thus greater moment of inertia) means a smaller acceleration, which affects how long it takes for the blades to reach their steady-state operational speed.
Fatigue and Design:
Blade mass is also an important consideration for fatigue loading and the overall design of the wind turbine, with longer, heavier blades generally being characteristic of turbines with higher power ratings.
Relationship Between Factors
Energy Transfer:
A turbine's blades extract power from the moving air, converting kinetic energy into rotational mechanical energy.
Mass and Speed:
While the mass of the air is what carries the energy, the mass of the blade itself is what receives the force from the air and translates it into rotation.
Dynamic Balance:
There is a complex dynamic balance between wind speed, blade speed, blade geometry, air density, and the blade's mass to achieve efficient power generation