The secret story of creating the Lego MMX

(Article by Keisuke Sugawara, R & D department, third research unit)

I am Keisuke Sugawara from JAXA’s Research and Development Department. My research usually focusses on artificial intelligence and support for Earth satellite projects but since last autumn, I have also begun to participate in the MMX project.

When I first saw the three-dimensional model of the MMX explorer on the website, I said “cool!” and “this is very different from Earth orbiting satellites… I will definitely have study deep space explorers.” From experience, I feared that this would involve examining texts and illustrations of specifications, or become a lonely task which would only make progress slower. So I started to think about how to study efficiently.

One day, I saw a senior colleague from the same office building a model of a spacecraft with Lego. As I watched, I felt nostalgic as I remembered playing with Lego as a child. Then at the same time, I thought “Let’s make a model of MMX with Lego!” and my child’s heart leapt. (Strangely, the first LEGO block set I bought when I was in primary school was a Mars base from a “Life on Mars” theme series. I felt this was fate.)

While actually making the model, I thought about the structure and the role of the equipment and this started to advance my understanding. We were also able to discuss the structure and operations with multiple people while creating the completed model. For example, we had the idea for the direction of the attitude control thruster while tinkering with the LEGO thruster parts with senior colleagues on the mission.

The final construction was in three steps:

1. Development of the SAP thin film

When I looked at the 3D model of MMX, I was really impressed by the SAP bent thin film (SAP = Solar Array Panels that provide power to the spacecraft) and tried to express this curved surface by overlapping thin plate LEGO blocks. We also made use of joint parts so we could fold and unfold.

2. Separation of forward module

One of the characteristics of the MMX spacecraft is that the spacecraft is divided into an outbound module and return module. The separation of the main body is never seen on an Earth orbiting satellite, which does not change its shape after SAP deployment, and I wanted to reproduce this in the LEGO model! I thought about the problem and then assembled our model spacecraft. The two modules are pinned and can be separated by pulling them apart.

3. Landing legs with shock absorption

The landing gear on the spacecraft has adopted a mechanism that absorbs shocks. In the 3D model seen on the website, the landing gear is fixed to the main body of the spacecraft and nothing seems particularly moveable. So in the landing mechanism for the LEGO model, I had to use my imagination.

The mechanism I added allows you to land safely even if you drop the LEGO model from a high point. So the merit of the model is that “I can actually drop it” and the merit of LEGO is that “if you do drop it and it breaks, you can reassemble it according to the instructions”.

With these three points, you can recreate and enjoy a series of mission sequences: “SAP deployment after rocket separation → inter-planetary navigation → forward module separation → landing → return”. If someone builds an H3 rocket, we can reproduce the sequence from launch to fairing separation!

(The model is 2018 version.)

Like to build it yourself? The necessary parts are right here: List of MMX parts

And the LEGO Digital Designer for step-by-step instructions: How To