Return to the Moon Launch Vehicle - Opening the High Frontier

Return to the Moon Launch Vehicle

As stated in the previous post, this new series of articles is about how to Return to the Moon by 2024 using existing launch vehicles that are lower in cost than the currently planned Space Launch System.

Of all the flight vehicles that will be required for the Return to the Moon program, the Earth to orbit launch vehicle and the upper stage for accelerating from Low Earth Orbit to Lunar Transfer Orbit, are the largest and most expensive. It is the cost of these two vehicles that will determine the overall cost of the entire program. The reason for this is simple, the apparent velocity required to go from the surface of the Earth to a low Earth parking orbit is 9,000 m/s. The velocity change required for going from the parking orbit to a Lunar Transfer Orbit is 3,200 m/s. The velocity change required to go from the Lunar Transfer Orbit to a Low Lunar Orbit is 820 m/s. Landing on the Moon will require an additional 1,600 m/s to 2,000 m/s depending on how much hover time is required to find a suitable landing spot. So of all the velocity change required for going to the Moon, the launch vehicle and upper stage will supply over 80% of the total. This is why the cost of these two vehicles will determine the overall cost of the program. This is also why making this part of the transportation system affordable is so important if the Return to the Moon program is to be a Return to Stay program.

Falcon Heavy w/ Delta upper stage & Orion spacecraft

The initial Return to the Moon launch vehicle will be the flight-proven Falcon Heavy. When flown as an expendable launch vehicle, the Falcon Heavy can launch 63,800 kg into a due east low Earth orbit. To send a crew to a low lunar orbit space station, the Falcon Heavy will need to launch an Orion spacecraft with a Delta IV Heavy upper stage into Earth orbit. The upper stage of the Delta IV Heavy launch vehicle has a total stage mass of 30,700 kg, a propellant mass of 27,220 kg, and a specific impulse of 462 seconds. The Orion spacecraft with Launch Escape Systems has a launch mass of 33,450 kg. The total of these two items comes out to 64,150 kg. The Launch Escape System on the Orion spacecraft, which has a mass of 7,585 kg, is jettisoned at the same time the core stage of the Falcon Heavy drops away. This reduces the amount of payload going to low Earth orbit to 56,565 kg, well within the maximum payload capacity of the Falcon Heavy. Once the orbiting spacecraft is in the proper position relative to the Moon, the upper stage will then accelerate the Orion spacecraft to Lunar Transfer Orbit velocity and the Orion spacecraft will arrive at the low lunar orbit space station with approximately 300 m/s worth of propellant left in its tanks. As a result, the Orion spacecraft will need to take on approximately 4,500 kg of propellant from the lunar orbiting space station for the return to Earth.

Falcon Heavy w/ Delta upper stage & cargo module

This same launch system is also capable of sending a gross payload of approximately 13,000 kg to the lunar orbiting space station when a payload module is substituted for the Orion crew module. This should be sufficient to deliver the components of the lunar orbiting space station to low lunar orbit as well as the lunar landers.

Falcon Heavy w/ Atlas upper stage & cargo module

Another way to send cargo to the lunar orbiting space station is to launch a 9,000 kg cargo module with an Orion service module on an Atlas V upper stage. The total launch mass for this, including the payload fairing, is approximately 47,400 kg, which is well within the payload capacity of the Falcon Heavy when both side boosters are recovered.

In-Space Refueling

The main issue that some people have with this transportation concept is that the Orion spacecraft does not carry enough propellant for returning to Earth from low lunar orbit without refueling. They consider this to be too risky. Yet one of the main reasons for the Return to the Moon program is to develop a local source of propellant that can be used for crewed expeditions to Mars. This requires in-space refueling. The lunar orbiting space station and lunar landers also require in-space refueling. It is also appropriate to point out that the International Space Station is already being refueled on a regular basis. So why not refuel the Orion spacecraft in lunar orbit?

Summary

The two main advantages of using this system are lower cost and the fact that the Falcon Heavy, Delta IV Heavy upper stage, Atlas V upper stage, and Orion service module, are all existing flight-proven vehicles. Using existing flight-proven vehicles will eliminate any chance of not meeting the 2024 deadline due to development delays.

Ad Astra! (To the Stars)

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Note: For those of you who are new to this website, this site is about making spaceflight affordable to everyone so we can finally start building the most incredible civilization the world has ever seen. A civilization that will include planets, asteroids, moons, space-based industries, and space colonies throughout the solar system. For those of you who are fans of space exploration but are new to the subject, the best way to read this site is to start at the beginning and read through to the most current article. If you are already familiar with the subject then feel free to jump around.

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