ENGS 89/90 Reports

Project Advisor

Laura Ray

Instructor

Solomon Diamond and Rafe Steinhauer

Document Type

Report

Publication Date

2021

Abstract

Problem Significance: Advances within the space industry are expected to continue with the development of NASA’s Artemis missions, which are due to launch in 2024. To mitigate the risks inherent to spaceflight, NASA Search­and- Rescue (SAR) must be prepared and equipped to respond to unpredictable and dangerous scenarios, such as a launch abort. According to NASA studies, 26 out of 28 launch aborts culminate in a capsule splashdown in the open ocean. Former NASA astronaut Jay C. Buckey emphasized that launch aborts are violent procedures, during which the crew capsule may become damaged and present a hazardous environment; in this case, the astronauts are required to egress from their capsule and enter the water. Due to the rapid and unpredictable nature of launch aborts, SAR personnel may be hours from the splashdown site and need to ensure scene safety to mitigate harm to rescue personnel. To remotely evaluate the splashdown site before human responders arrive, SAR will deploy a video­-enabled drone. This drone provides critical on­site information to SAR personnel, but is unable to directly contact the stranded astronaut(s) and provide physical assistance. This lack in capability can be addressed by deploying an unmanned, Surface Autonomous Vehicle for Emergency Rescue (SAVER) via the same initial response drone.

Technical Overview: SAVER has been designed to meet NASA/SAR needs as specified in this year’s Micro­g NExT Challenge, which will culminate in prototype testing at the Neutral Buoyancy Laboratory (NBL) in June 2021. With a hy- drodynamically stable design, SAVER will autonomously navigate towards the astronaut(s) to deliver commu- nication devices and survival equipment. SAVER uses two directional loop antennas that enable radio direction finding of the 121.5 MHz distress signal that astronauts emit via their Advanced Next Generation Emergency Locator (ANGEL) beacon. SAVER will continuously track the relative heading of the distress beacon using its antennas and onboard sensors, allowing it to engage in closed­loop direction control to travel towards the astro- naut(s). A water jet thruster, powered by a brushless 3­phase motor, and steering servo motor will propel and guide SAVER until it is within 1.5 meters of the astronaut(s). SAVER’s thruster motor will then shut down to prevent harm to the astronaut(s). During the rendezvous, the astronaut(s) will access survival equipment stored within SAVER’s watertight hull. This equipment includes a spare life preserver unit, 1L of water, a medical kit, a spare ANGEL beacon, and a survival radio. By employing lightweight and cost effective materials, particularly a foam core and composite skin hull, SAVER will have a total loaded weight of approximately 30lbs.

Deliverables: In order to ensure the success of SAVER’s future development, the team is delivering tested subsystems to verify SAVER’s ability to meet our specific design requirements. The team has produced a complete CAD model of the final hull design and conducted various dynamics calculations, simulations, and tests to classify SAVER’s stability and hydrodynamics. The theoretical and experimental analysis of the thrust system, coupled with the dynamics of the final hull, have verified SAVER’s speed and maneuverability. Additionally, SAVER’s steering control system is able to successfully direct the vessel towards a reference heading. Lastly, the radio direction finding array can identify whether a measured signal is to the left or right of SAVER’s heading. The verification of these subsystems will inform final design changes ahead of SAVER’s complete system integration.

Broader Context: In any SAR situation, the safety and performance capabilities of rescue personnel is paramount. SAVER boosts the capabilities of SAR forces in applications beyond the spaceflight industry. Any maritime disaster ­ such as shipwrecks, military and civilian airplane crashes at sea, or offshore oil rig accidents ­ that results in injured individuals stranded in the water could benefit from SAVER’s technology. SAVER’s deployment will help attend to victims before the scene is declared safe and reachable by human responders.

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Restricted: Campus/Dartmouth Community Only Access

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Available to Dartmouth community via local IP address.

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