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Saturday, 19 July 2014

My First Month at NASA, Part I: Configurations and Animations

A month has gone by since I started working at NASA's Johnson Space Center, and I have been quite busy, trying to make the most of this opportunity! I am learning a lot and would like to share my experience with you!
When last I updated you, I had just finished my first week at NASA, and had begun investigating thermal engineering techniques used on spacecraft. elaborate

The official name of the project on which I am working is the Magnetic Architectures and Active Radiation Shielding Study, or MAARSS. A rather cumbersome title, essentially the study is investigating the possibility of using magnetic architectures on spacecraft to block incoming radiation. The Phase I study had investigated the feasibility of creating such a magnetic architecture, and the Phase II study is now dedicated to enhancing that design, and incorporating it into a spacecraft.

I have been been spending the majority of my time at NASA reading. I have been researching general spacecraft thermal control, passive and active thermal systems, heritage techniques (i.e. designs and techniques which have been used on spacecraft already), and datasheets/specifications for cryocooling components. I have been trying to understand the entirety of what is involved with cooling a spacecraft and incorporating this understanding with my knowledge of the requirements of my system.

I have also been working with an animation team in order to create a short video demonstrating the spacecraft concept. So, let us now take a closer look at this.

The spacecraft, in its original configuration, looked like this:
(Westover et al., 2012)
With an internal configuration which can be seen below:
(Westover et al., 2012)
Here, we can see many components including the habitat (seen in the bottom picture in orange), the coils which would create the magnetic fields, several solar panels, propulsion systems, and two "Orion-like" capsules on the left.

The idea was that the spacecraft consisted of two main sections: the coils, and everything else. The coils would be wrapped and launched together into low-Earth orbit (LEO), and everything else including the habitat, solar panels, and propulsion system, would be packed in a separate flight. These two main components would meet in LEO, the coils would be moved apart into a hexagonal shape, and everything else would dock into place, likely requiring some extra-vehicular activities (EVAs, spacewalks), in order to make all the proper connections.

The integrated system would then be propelled into high-Earth orbit (HEO), likely around 50 000 km above the Earth's surface, where the rest of the systems would be activated.

After reviewing the thermal requirements, I determined that the system would likely require a heat shield, as mentioned last time. I will get into the details of this design a little more in a subsequent post, but suffice it to say, I realized that without a heat shield, the active radiation shielding would not work. The superconducting coils must be kept to a temperature below 40 K (-233°C, -387°F) in order to work and while deep space may be cold, the energy coming from the sun amounts to 1367 W/m^2.

Discussing the system with a colleague, a thermal engineer who has worked on several deep space systems, we decided to move the solar panels to one side of the spacecraft, and use them to block the majority of the incoming solar flux. We could then place a heatshield behind them, blocking whatever heat they missed, as well as the radiating energy coming off of the back of the panels.

Since this is a preliminary design study, the solar panels had not been entirely sized so I was free to moved them and resize them as I pleased. The next step involved the mechanisms, how the panels and heat shield would be deployed. I investigated the deployment concept for the James Webb Space Telescope, which can be found here. Deciding that I liked it, and that it had obviously been chosen by a team of engineers with more experience than myself, I came up with some drawings, seen below.

The first image shows my initial thoughts on the dimensions of the panels and the heat shield. The shield is hexagonal in shape, behind the panels, and the 8 panels are mounted to the main cylindrical body in front of the habitat. The 3.5 m circular area in the centre is the habitat itself. The bottom image depicts the deployment of the shield. Starting off as two flat panels, mounted to the cylindrical structure (not drawn to scale here), the panels would fold up, as seen on the left side of the image. Two pole-like structures would extend laterally, pulling material which is connected to the top and bottom panels, forming the final hexagonal shape. It is a simple design, but one the James Webb Space Telescope engineers are hoping to adopt for their system as well.

After drawing these ideas, I communicated them to the engineer who had created the initial CAD models of the spacecraft. He made the changes, adding a suggestion of his own as to the deployment of the shield, which can be seen below.
(Benjamin Houng, 2014)

And, because he could and he wanted to have a little fun, my friend and roommate Adrian made up this little video depicting the spacecraft in action. (Although, without the coils)
(Eilingsfeld, 2014)

This was reviewed by my supervisor before we passed it on to the animation team who would build on this and create the final animation. The interesting thing about this project is that much of the work is preliminary. The focus of this study is primarily in the development of the superconducting coils and their ability to block high-energy radiation. Therefore, much of the other practical details such as the size of the solar panels, and thermal design, while important, are largely underdeveloped. The consequence of this is that there are many aspects missing from the work, but also a lot of freedom since the systems have not been designed yet and are free to change. The final work aims to overcome as many design challenges as possible, so that future work can use this as a basis for developing the design.

Thank you very much for reading, I am sorry that my updates have been so irregular, but I have been working hard and making the most of my time here at NASA. This project has given me confidence and experience in my field, and taught me that spacecraft engineering excites me, and that I want to pursue this in the future. I have been spending my lunch breaks at work researching PhD options, looking for funded opportunities which would allow me to design spacecraft for deep space and beyond. I hope this all works out, but for now, it's back to the grindstone!

Stay tuned for further details concerning the intricacies of designing the thermal control system for this spacecraft!

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