One of Therion’s two payloads is a plasma physics experiment. It’s designed to induce roll torque on the rocket without any moving components. By creating a strong, pulsed electric wind along the surface of four small high angle of attack canards, it changes the aerodynamic characteristics to produce a net torque on the rocket. This is done using a cold plasma discharge (dielectric barrier discharge) excited on kapton and copper electrodes by a flyback transformer operating at 8 kHz. Pulsing the plasma during ascent and measuring the roll rate allows the team to characterize the drag effects across a wide range of velocities. Therion’s second payload is an imaging experiment that makes use of the Lucas-Kanade method to acquire rotation data by comparing pixel displacement between frames. The data is compared to measurements from an onboard inertial measurement unit to determine its accuracy. Successful recovery is a critical part of the competition. The recovery system consists of a small drogue parachute, which deploys at apogee to stabilize the vehicle, but not provide so much drag as to cause it to drift with the wind. Once near the ground, a pyrotechnic link is detonated, allowing the drogue to pull out the main parachute so the rocket touches down softly. The team keeps track of the rocket during its mission with live telemetry updates, which include critical information such as GPS location, altitude, and speed. This also helps the team recover the rocket. The Rocket Team’s 12-foot-tall Therion rises from the pad at the 2016 Intercollegiate Rocket Engineering Competition. (MIT Rocket Team photograph)
The team launched Therion in June at the 2016 Intercollegiate Rocket Engineering Competition, and achieved 14th place out of 44 teams. The pyrotechnic link, a critical part of the recovery system, did not separate after receiving the signal from onboard avionics, which caused the rocket to touch down using only a drogue chute. The structure held up surprisingly well against the impact, but one broken fin meant it was not in re-flyable condition. At the time of this writing, the team is analyzing the payload results.
Published on Nov 18, 2016
Annual magazine review of MIT Aeronautics and Astronautics Department research and educational initiatives.