467 Device #2 is another shape memory alloy device. This device uses a shape memory alloy to actuate a  ball detent mechanism which releases a deployable item. Its load capacity is far beyond what is needed for many CubeSats or small instruments. It uses very little power and has an almost instantaneous actuation. It’s also much larger and more massive than could be used in this APL CubeSat. It draws far more current than a CubeSat could supply without dedicated capacitor banks. While it produces much less shock than a pyrotechnic device, it still produces shock, which must be evaluated in the design process.  Device #3 uses a resistive heater that heats paraffin wax. When the wax is heated, it expands. The  actuators are designed to produce linear motion with a defined output force. They are compact, highly reliable, and insensitive to contamination. They require a companion mechanism to affect the release of a deployable device. They consume much more energy than any other device compared.  Device #4 uses shape memory alloy wires to rotate a cam which allows a four segment nut to separate  and release a bolt. They have a much higher load capacity than is needed for the reference application. They use very little energy and are near-instantaneous actuators. They are much larger and massive than could be used in this APL CubeSat. They draw much more current than is available in a CubeSat.    Prior to conducting the trade study, we eliminated pyrotechnic actuators from consideration, because the  CubeSat specification forbids their use. We also considered two other custom designs, one that operated by cutting ‘fishing line’ and the other that operated by vaporizing a Ni-Chrome wire. Enough work was completed on each design to determine that for the particular combination of available volume, power and holding force of this application, the designs were overly complex and difficult to manufacture and assemble. We conducted creep testing on available polymer lines compatible with a low power line cutter, and concluded that the lines’ creep would result in loss of preload in the restraint, causing gapping and unacceptably high loads during flight. We also had contamination concerns arising related to melting plastic and its possible re-solidification on solar array cells or optical surfaces. While promising, given a different situation, these ideas were eventually shelved for this application.  Design Function & Development  The first generation device  (Figure 1) used parts without any surface coatings and used a single 30-W  thick film power resistor as the heater element. It served as a proof-of-concept, but was not suitable for flight use. The outer cup was fabricated from 6061-T6 aluminum, the inner plug from 6AL4V titanium. The machining tolerances for the cup (high CTE) and plug (low CTE) parts were critical, since the interference fit between the two was just 15 µm (0.0006”), nominal OD to ID. Because of this, we machined the parts to a diametrical tolerance of 3.81 µm (± 0.00015”). A simple tension-only test stand was used for testing the single first generation prototype. The first generation actuator consisted of an un-plated aluminum body fabricated on a manually operated lathe, and single 30-W 3- Ω thick film resistor, an interface plate  with fiberglass thermal insulators, and an un-plated titanium plug.  Figure 1 – First generation device with a bare  aluminum body and a single 30-W resistor  The second generation device  featured redundant heaters, a kick-off spring and a vent hole, and is  depicted in Figure 2. The heaters have a temperature limit of roughly 135°C at our highest operating current, and the operating range of the actuator needed to be well below this temperature during operation. Our reference mission didn’t have the capability to sense the temperature of the actuator (this  Cup Resistor