Lunar  Communications Tower

2020 NASA BIG Idea Awardee

Cambridge, MA & New York, NY & Lee, MA

December 2019-Present

The environment inside lunar polar permanently shadowed regions (PSRs) challenges robotic and human explorers with extreme cold, extended darkness, ice as hard as basalt, challenging terrain, hard vacuum, and the limited, if not non-existent, line-of-sight communications into or out of the PSRs. Taking advantage of the relatively weak lunar gravitational field and the lack of an atmosphere, a tall, lightweight, autonomously deployed tower, situated just outside the PSR, would provide multiple lines of sight to the Earth, the Sun, the lander, the surface inside and outside the PSR and the distant lunar horizon. Payloads at the top of the tower, up to 16.5 m above the lunar surface, could include radio repeaters and remote sensing, imaging, and power beaming systems. A lightweight, self-deployable tower infrastructure will aid NASA in achieving the goals of the Artemis program by enabling the exploration and development of PSRs near the lunar poles. The capabilities designed into this tower are key enablers for small, distributed payloads and autonomous robots that operate synergistically to deliver a robust capability to explore and operate in and around PSRs. 

I contribute to the analysis of the composite boom and the mechanical design and prototyping of its deployer to ensure that it successfully deploys vertically. I am responsible for the structural analysis of the leveler platform and the boom, the design, prototyping, and testing of a 3D-printed brace to support the deployment of the boom, as well as managing some mechanical interfaces for the system. This project was a true test of resiliency, dedication, and collaboration for the team as right in the middle, we were dispersed around the world, from Massachusetts to Australia, due to COVID-19. However, the team adapted quickly and was able to successfully demonstrate the system.

Design+Analysis

I performed finite element analysis (FEA) on the leveler platform in SolidWorks to ensure that it could withstand the desired payload mass

I explained how to use my testing rig to mount the brace to the system prototype over Zoom before creating a CAD in SolidWorks

Please note: Details of the NASA boom cannot be shared due to a pending publication. I performed preliminary analysis of the boom's failure modes in Abaqus.

Prototyping

I 3D-printed all brace segments from home

I iterated the brace to ensure the ideal geometry and friction between the boom and brace

Because of COVID-19, all necessary testing facilities at NASA and MIT were shutdown, so I received the boom from NASA with the failure modes not fully quantified. As a result, I quantified the deployment geometry myself and iterated the brace accordingly. I iterated the brace in 2"-tall 3D-printed segments until the boom could slide through each segment. I then tested the friction between the boom and brace to ensure that it was low enough that the motors could deploy the boom, but that it was high enough to prevent the boom from sliding down during deployment under the force of gravity. 

Testing

I quantified the friction between the boom and each brace segment using a simple, custom rig I built at home. The measurement setup was adapted from string potentiometer and dual force sensor I had from a class lab to measure the material properties of marshmallows. I repurposed the 80-20 testing rig as a support structure for the brace on the deployer system. 

I created a testing setup to quantify the friction between the boom and the brace segments

I modified the boom-payload interface to create an interface between the boom and the sensors

I qunatified the friction between the boom and the brace segments

After determining that the friction between the boom and brace was within a satisfactory range, I shipped the boom, bracing, and 80-20 testing rig to MIT to test the boom deployment and ensure that the system interfaces fit together. The system deployed successfully on the first try.

Deployer system with stowed boom

Eric Hinterman

Deployer system with deployed boom

Benjamin Martell

Successful boom storage

Caleb Amy

Caleb Amy

Full boom deployment, 200x speed

Becca Browder

Applications

MELLTT

MELLTT deploys a 30m tall tower that provides line of sight communication to rovers exploring the Moon’s permanently shadowed regions (PSR). A universal top of tower payload platform can host radio repeaters and imaging instruments that will significantly aid PSR exploration.

SELT-I

SELT-I is a more capable design based on a 27U Cubesat that was created in collaboration with NASA Langley’s Deployable Composite Booms team and proposed to NASA as part of the PRISM RFI call.

Other applications include networked towers an a local navigation grid.

© Natasha Stamler 2020