Spacecraft Assembly Fit Check
The term assembly refers to a product which is assembled from multiple parts. Each part needs to fit together correctly in order for the product to be assembled. A fit check is the process of assembling the product while checking the fit of all the parts. Do the parts go together? Are they too tight or too loose? Do the mounting/mating features line up? Do the fastener holes align? Are there any manufacturing mistakes? Are there any design mistakes. Until the fit of the assembly is checked, the designers cannot be confident that it is going to work. Something as simple as two parts being fastened together can prevent the whole assembly from fitting together if the holes are not aligned within the correct tolerance. Sometimes fit issues can be corrected with sandpaper and elbow grease, other times entire parts have to be re-manufactured.
Due to the lead time with manufacturing parts, and the hand-off date of ORCASat rapidly approaching, it is extremely crucial to perform an assembly fit check as soon as possible. ORCASat will have many assembly fit checks, the initial assembly fit check includes most of the components for it to resemble the flight spacecraft, but as the last components are manufactured, they are added into the assembly fit check to confirm that they do indeed fit. By the time the flight spacecraft is ready for assembly, every single part that is required has been tested and confirmed to fit, and there is minimal risk of the flight spacecraft not fitting together.
This update is around the initial assembly fit check of ORCASat. This fit check did not include the payload module, or solar panels with solar cells attached to the. The solar panels do not need the solar cells to perform the fit check and due to the high cost of solar cells, we don’t want to risk damaging any of them, especially since it’s the first time we are handling a spacecraft that resembles the flight unit. The payload module is currently being assembled, and will be included in the fit check in the new year.
In some of the photos you may notice that the rails go from being raw aluminum to black. The black rails are hard anodized as per the launch provider requirements, and were included in the fit check slightly after these photos were taken.
Although the nadir panel looks matte black, we still have to paint the nadir panel black with a special paint that reflects almost no visible light to help minimize uncertainties during payload operation from light the spacecraft is reflecting and not emitting. The payload light exit cone is included, but also made of reflected aluminum and will be painted black.
There is lots of work to do, but we are incredibly excited to report that we performed the first-ever fit check and everything we have ready to check seems to fit together perfectly. We will continue to post updates around more flight-like fit checks as we do them.