Скачать 87.96 Kb.
The objective of this design project is to construct a CubeSat deorbit device. Using applicable research sources, a best practice design for an inflatable deorbit device will be constructed and demonstrated. The device shall be a payload for a 1U CubeSat, meeting all of the standards under the CubeSat heading.
The benefits of constructing this device are proof of concept. The first concept to be proved is that this payload can meet the constraints of a CubeSat payload (size, mass, etc.). The second benefit is the development of a low cost, reliable method to deorbit a CubeSat. The removal of high altitude CubeSats will reduce a significant source of space debris.
The approach chosen to create this CubeSat deorbit device is that of an inflatable balloon or pillow. This design offers a less complicated option to a fixed folding array design. Depicted in (Lokcu)Figure : Predicted lifetime of a 1U CubeSat without deorbit module (Lokcu). It can be seen in the figure that the predicted lifetime is well in excess of 400 years. Depicted in Figure is the predicted lifetime of a 1U CubeSat with an arbitrary, increased surface area deorbit device. The deorbit device successfully removed the satellite from orbit within the prescribed 25 year life span.
Figure : Predicted lifetime of a 1U CubeSat without deorbit module (Lokcu)
Figure : Predicted lifetime of a 1U CubeSat with deorbit module (Lokcu)
The actual shape of the inflatable structure is dictated by the complexity of constructing the volume. It is for this reason that a pillow shape, as shown in Figure , will be used. The pillow design need only be sealed along the edges, and thus lends itself to a simpler design. Material selection of the pillow is critical. In the harsh low earth orbit regime, radiation and atomic oxygen are the primary concerns (Lokcu). The material chosen to survive this environment is a polyimide film known as Kapton®. Kapton is a product of the DuPont Company and has a proven track record for long term space applications (DuPont).
The inflation of this balloon must be done with a reliable gas source. There are two main options in this area. The first is a cool gas generator, and the second is a stored refrigerant. Several companies specialize in developing space qualified cool gas generators for various applications. One company specifically, Bradford Engineering, has developed a 2 gram cool gas generator. This is a perfectly viable method to inflate a small deorbit mechanism for a CubeSat (Bradford Engineering). For the refrigerant option, a simple pressure vessel containing the fluid would be sufficient (Lokcu).
Figure : Deorbit Pillow Construction (Lokcu)
The actual triggering of the deorbit device can be accomplished either by an onboard timer or with ground based signaling. The actual activation will be processed through the main bus of the CubeSat and should require a minimal fraction of the total CubeSat’s available power (~5%). The housing for the deorbit device will be constructed of the 6061-T6 aluminum alloy, per NASA and California Polytechnic guidelines. This alloy is common to the entire CubeSat and P-Pod launcher, and offers the best density option for design integration and weight minimization.