Before sending the sculpture to the moon and deploying it, we decided to carry out a test in Low Earth Orbit, aboard the International Space Station. As well as being symbolic and inspiring, the test would demonstrate the performance of one of the proposed materials: “Shape memory alloy” in microgravity. This is the “living” material that will form the main “skeleton” of the Dish/Cocoon, and probably the People too, that make up the lunar sculpture.
We delivered the sculpture to the ISS via the Nanoracks ”DreamUp” program.
In this program, a small box (typically a 10 cm cube with a mass of no more than 1kg) containing the experiment has been transported to the ISS and the experiment has beeb carried out by an ISS crew member : Thomas Pesquet ! The immediate step called V-III wass to deploy a shape memory alloy/Mylar sculpture in microgravity.
More technical informations
The Dragon cargo carried about 7 metric tons of cargo in its pressurized compartment. That cargo included supplies for the station’s crew as well as hardware and experiments, including Vitae III.
The Houston-based NanoRacks received the Flight Model Vitae III that successfully passed Electromagnetic Interference tests, and NASA Flight Safety Review.
The Flight Model can be squeezed into a100x100x100mm box.
When deployed, it is around 450mm diameter, and its mass is about 120g.
We set a project goal to create a reliably-deployable sculpture that could expand from 95mm diameter to 450mm diameter.
Shape memory alloy is very flexible and plastic when “cold”, and so it can be compressed into a very small space. Once heated (beyond about 40C) it begins to become stiffer, and returns to its original shape.
Heating the structure on board the ISS to deploy the sculpture was a major challenge. The microgravity environment means that there is no significant convection to help transfer heat-transfer is predominantly via internal “Joule heating” in the wire, and conduction through the material. We also had to be careful not to have too much heat on the space station, so we had to choose suitable materials and electrical power.
This was the first time that a self-deploying, “living” sculpture has been placed in orbit, to our knowledge.