# Novel 3U Stand-Alone CubeSat Architecture for Autonomous Near Earth Asteroid Fly-By
## 5 Results--Instantiated Architecture
It is the case of the star tracker, which should be used both for attitude determination and navigation in the second phase, the propulsion system, which beside the main function of orbit control, needs to ensure also reaction wheels de-saturation, or the payload camera, which should be used also as NAVcam for the third navigation phase. The differences between these physical architectures are then strongly related to the actual mission constraints and required functionalities. Thermal subsystem design has not been included, as it depends on a detailed mission description which is required for future stages. The market offers a wide range of both passive and active solutions for CubeSat thermal control. Multi-Layers Insulation (MLI) have been widely used for space applications and many companies offers solutions: Shelladhl, Dummore, Aerospace, Fabrication and Materials, MLI Concepts inc.. In particular the Dunmore Aerospace Satkit including standard STARcrest materials, is optimized for small satellites and CubeSats, and it represents an excellent solution for deep-space CubeSats. Deployable radiators are currently produced by Thermal Management Technologies, and Kaneka Corporation together with JAXA proposed another excellent solution. Coatings (paint and tape) are offered by a wide range of companies: AZ Technology, MAP, Astral Technology Unlimited, Inc., Lord Technark, Inc., Sheldahl, Akzo Nobel Aerospace Coatings. Sierra Lobo has developed a Sun shield, applicable to a 3U CubeSat (CryoCube), interesting in case of cryogenic experiments, but not needed in this application. A large number of flexible thermal straps, to allow passive thermal transfer to heat sink, in various materials: copper or aluminum by Thermal Management Technologies, K-Technology by Thermacore, Graphite Fiber by Technology Applications Inc.. Heat pipes for small satellites are offered by Advanced Cooling Technologies, Orbital ATK and Thermocoax. Concerning active thermal control, electric heaters are offered by Minco Products Inc. and All Flex Flexible Circuits LLC, while mini cryocoolers by Ricor-USA Inc., Creare, Sunpower Inc, Northrop Grumman, and Lockheed Martin [24]. For this architecture a passive control strategy can be adopted, as all the components work in wide temperature ranges (at least \(-20^{\circ}\), \(40^{\circ}\)). Concerning radiation, it may affect the CubeSat operations in two ways: Total Ionizing Dose (TID) and Single Event Effects (SEE). Many companies in the component datasheets claim their radiation tolerance. However few datasheets present information on the TID, so it is difficult to compare the performances among them. The few data available show a minimum TID tolerance around 10 krad, with peak up to 70 krad. Van Allen belt and solar particle flux may affect strongly the TID. For LISA pathfinder, a 100 krad TID has been computed around Sun-Earth Lagrangian points, while for a 3U CubeSat fly-lying an asteroid from the same point for 150 days, it has been computed a 10-20 krad TID with 0.5-1 mm thickness of aluminum shielding [13]. A proper radiation protection scheme needs to be designed for each application.