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search.filters.applied.f.advisor: Braun, Robert D. × End date: 2019 × Start date: 2016 × Item Type: Publication × search.filters.applied.f.isOrgUnitOfPublicationTitle: Space Systems Design Laboratory (SSDL) ×

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Development of an Earth SmallSat Flight Test to Demonstrate Viability of Mars Aerocapture

2017-05-01 , Werner, Michael S.

A smallsat mission concept is developed to demonstrate the feasibility of an aerocapture system at Earth. The proposed mission utilizes aerocapture to transfer from a GTO rideshare trajectory to a LEO. Single-event drag modulation is used as a simple means of achieving the control required during the maneuver. Low- and high-fidelity guidance algorithm choices are considered. Numeric trajectory simulations and Monte Carlo uncertainty analyses are performed to show the robustness of the system to day-of-flight environments and uncertainties. Similar investigations are performed at Mars to show the relevance of the proposed mission concept to potential future applications. The spacecraft design consists of a 24.9 kg vehicle with an attached rigid drag skirt, and features commercially-available hardware to enable flight system construction at a university scale. Results indicate that the proposed design is capable of targeting the desired final orbit, surviving the aerothermodynamic and deceleration environments produced during aerocapture, and downlinking relevant data following the maneuver

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Supersonic Vehicle Configuration Transitions to Enable Supersonic Retropropulsion during Mars Entry, Descent, and Landing

2016-02-29 , Blette, David J.

This paper investigates types of supersonic vehicle configuration transition events nec essary to initiation supersonic retropropulsion as part of human-class Mars entry, descent, and landing. This research assumes an entry vehicle with a 105 mT entry mass and an ellipsled aeroshell similar to the NASA EDL Design Reference Architecture 5.0. All entry architectures are assumed all-propulsive. Three transition architectures are considered: a pitch-around maneuver, an aeroshell front-exit, and an aeroshell hinged-exit. Propulsive subsystem thrust requirements are defined for the pitch-around maneuver. For transitions involving solid mass ejections, debris flight envelopes are determined and compared to a descent vehicle trajectory under a modified gravity turn. It is shown that far-field recon tact risks exist for the proposed architectures involving solid mass ejections and recontact mitigation schemes are required.

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Trajectory Trade-space Design for Robotic Entry at Titan

2017-05-01 , Roelke, Evan

In recent years, scientific focus has emphasized other ocean worlds such as Europa, Enceladus, and Titan, due to their potential for harboring life. The only spacecraft ever to land on these moons was the Huygens Probe in 2005; however, this probe’s main purpose was to study the atmosphere and surface of Titan, with no real landing target. Future missions to other ocean worlds would likely require a science target and thus add several constraints to the mission such as arrival time, entry state, and aeroshell geometry, among others. Of the three ocean worlds previously mentioned, Titan is an optimal target for initial mission concepts for several reasons. The atmospheric composition, winds, and surface features are well studied by Cassini and the Huygens Probe. Additionally, of the aforementioned moons, Titan does not have a thick ice sheet to penetrate in order to sample the surface and/or liquid seas, enabling such mission to double as a stepping stone for missions to other ocean worlds. Finally, Titan exhibits a myriad of interesting planetary features that, if studied, could further the understanding of both Titan’s and the solar system’s geologic history. In this paper we analyze the trade-spaces of various important parameters involved in Entry, Descent, and Landing (EDL) as it pertains to robotic missions for Titan in order to provide a guideline for optimizing a mission’s system parameters while minimizing both system complexity and the landing footprint. It is found that the ideal geometry is a ballistic spherecone body entering from orbit to allow flexibility in the entry state vector. The aerothermodynamic environment is most affected by the entry velocity and the vehicle bluntness ratio, while the peak deceleration is most influenced by the entry velocity and entry flight path angle. In addition, multiple parachutes decrease the landing footprint, impact speed, and descent time compared to single parachute systems, at the expense of being more complex. Larger ballistic coefficients decrease the landing footprint and descent time while increasing the impact speed. Finally, it is discovered that the uncertainty in the entry altitude and flight path angle have the most impact on the final state vector.

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Entry Characteristics of a Half-Ogive Aeroshell at Earth

2016-02-05 , Booher, Robert M.

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Mechanical Design of a Cubesat Aeroshell for an Earth Demonstration of Single-Stage Drag Modulated Aerocapture

2016-08-01 , Woollard, Bryce A.

The following article documents the conceptual study of a smallsat entry vehicle to be implemented for demonstration of single-stage drag modulated aerocapture at Earth. The specific nature of the contents below focuses on the mechanical design and analysis of the aeroshell and drag device, as well as the mechanisms by which all parts are to be manufactured, assembled and actuated in order to perform the intended orbital maneuver. The results of this study show that accomplishing aerocapture with a cubesat entry vehicle appears to be feasible with a 2U payload and would require approximately 20 kg and 0.1 m3 of secondary payload mass and volume, respectively. First order stagnation point thermal protection sizing suggests that 4.2 cm of PICA would be required globally around the vehicle, although potential exists to optimize this value relative to geometric location. Static stability analysis indicates that the designed vehicle is nose-forward stable for a majority of the atmospheric interface with outstanding questions pertaining to atmospheric egress. Manufacturing costs for a full scale aeroshell would be approximately $15,000 and require roughly 2 months of lead time, dependent on presently available machine shop capabilities.

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