# A Morphing Deployable Mechanism for Re-Entry Capsule Aeroshell
## 1 Introduction  
The demand for deployable re-entry systems that leverage and accommodate CubeSat or small satellites for high-speed entry at destinations with atmospheres has constantly increased in recent years [1; 2; 3]. A number of studies have proposed CubeSat design concepts that directly incorporate deployable de-orbit and re-entry modules within a standard form factor (1U-16U) to offer delivery capabilities for single CubeSats or constellations [4; 5; 6]. The related entry systems, known as mechanically-deployable or inflatable deployable systems, can be deployed via mechanisms or inflated once in space. Typically, mechanically deployed systems consist of ribs and struts supporting a mechanism that deploys a load-bearing flexible skin after launch [7]. Inflatable deployable systems use pressurized gases to inflate an aeroshell, which are also made of flexible thermal protection system (TPS) material [8]. Both aerocapture and entry, as well as descent and landing can be potentially performed by using a single re-entry system for science missions at planets. Several concepts of deployable aerodecelerators for satellite de-orbit and/or re-entry using flexible heatshields exist in the literature [9; 10; 11]. Additionally, various assessments have taken place by investigating aerodynamics and heating of flexible thermal protection systems that can deform under static and dynamic loads [12]. Due to the larger wetted area, both deployable and inflatable aeroshells ensure a lower ballistic coefficient, which is a non-dimensional ratio of the vehicle's entry mass to the product of the drag coefficient (CD) and the projected reference area, thus making it possible to fulfill the tight volumetric constraints imposed by the CubeSat platform. The ADEPT concept, developed by NASA [13; 14], does integrate the entry system around standard CubeSat units in order to increase the volume/mass available for science payload. By expanding to a larger diameter prior to entry in order to increase drag, such a concept has shown to achieve a stowed diameter a factor of 3-4 times smaller than an equivalent rigid aeroshell, thus enabling higher entry performance suitable for a variety of planetary or earth high speed entries that require high temperature materials [15]. Similarly, a novel deployable Mars aeroshell concept consisting of thermal protection system (TPS) panels that are fitted between retractable ribs was developed at Imperial College London [16]. As well as enabling higher payload mass suitable for scientific instruments, morphing technology can provide mechanically deployable aeroshells with improved entry conditions than previous paradigms, suitable for the safe and timely recovery of payloads and samples in a desired landing site with reduced risks and costs [17; 18]. Their potential ability to either globally or locally modulate the drag profile during re-entry operations by using flexible morphing heat shields offers considerable benefits over traditional rigid aeroshells including higher volume, mass and payload form factor, more accurate guidance trajectories, and improved landing accuracy by using aerodynamic drag. Additionally, lower peak decelerations, heat loads, and fluxes can be effectively achieved to protect the payload from the re-entry environment. Prior work on drag modulation has proved the ability to guide a satellite to a desired re-entry interface point [19; 20; 21; 22]. In ref. [23], the results show that aerodynamic drag modulation of umbrella-like heat shields is an efficient way to control the re-entry location. An adaptive aerobrake using aerodynamic flaps is also addressed in ref. [24] to efficiently steer the vehicle during re-entry. In ref. [25], such a technology is also combined with a fiber-optic-based closed-loop feedback monitoring system in order to realize a full autonomous re-entry system.