I realized today that I’ve been in the lab for over three weeks now, and I haven’t shared what I’ve been working on…so I thought today was as good a time as ever to share what I’m working on.
As I mentioned in my last post, I am working on the integration and testing of ³Cat-1 (read CubeCat-1), a 1 U satellite named in honor of Catalunya, the autonomous community Barcelona is in. It has been in the works for many years and will be launched this December from Vandenberg Air Force Base in Lompoc, CA. This means that it needs to be delivered around September 1, so we have about 2 months to assemble and do extensive testing on the satellite. Last week, we performed a test of the experiments that the satellite will perform in orbit in the lab’s vacuum chamber and assembled the boards to make sure everything will fit within the structure.
Here it is, midway through assembly. The board on top has a Geiger counter, camera, and monatomic oxygen detector, and the yellow strips hanging out of the sides are the antennae, made from tape measure.
Once we finished, we disassembled the boards, as there was an issue that we needed to debug in the EPS (electrical power subsystem), which is very important to solve before launch.
This week, the electrical engineers on the integration and testing team worked on determining the source of the error, I finished work on a project that I had to take a break from last week because of the testing and assembly. One of the launch requirements for the satellite is that its center of mass must be within 2 cm (about 3/4 inch) of its geometric center. Also, knowing the center of mass is useful for attitude control in future (larger) satellite projects, so being able to determine its location is important. Most of the challenge in the design was to hold the satellite in a known position to do the math without damaging the solar panels, which allows the calculation to be made. After some SolidWorks modeling, here is what I came up with…
Essentially, each of the three “feet” rests on a scale, and you plug the scale readings into a MATLAB program I wrote. By rotating the satellite and taking three measurements – one per axis – you can obtain the 3-D center of mass. The device can also be scaled to different-sized satellites by replacing the disk-shaped section on top – CubeCat-2 is launching a few months after CubeCat-1, and CubeCat-2 is 6 U, so it is 30 x 20 x 10 cm. The pieces are currently being printed, so the story will continue once I assemble it, hopefully by the end of the week.