Space X rocket
Kinematic Analysis of Rocket Velocity
Author:
Title 4
Learning objectives :
This activity allows students to analyze the controlled descent program of a reusable rocket. It develops the ability to interpret kinematic data and understand aerospace engineering strategies.
Concepts covered
Movement at controlled speed; Space propulsion; Kinematic analysis; Back-drive braking; Position and speed
What students will do :
The student uses the FizziQ Kinematics module to analyze the descent movement of a Falcon 9 rocket from a video. After calibrating the scale using the actual size of the rocket, the student performs precise pointing of the positions then analyzes the speed and position graphs to determine the braking strategy programmed by SpaceX and evaluate its effectiveness.
What is required :
Smartphone or tablet with the FizziQ application; Falcon 9 rocket landing video available via FizziQ map link; Information on the size of a Falcon 9 rocket (70 meters); FizziQ experience notebook
Scientific background :
The controlled vertical landing of a Falcon 9 rocket first stage represents a major technological feat for SpaceX. This process involves precise control of trajectory and speed to minimize fuel consumption while ensuring a smooth landing. Kinematic analysis generally reveals a descent profile in several phases: 1) A high-speed atmospheric reentry phase, with the use of aerodic grids to stabilize the rocket; 2) A main braking phase with ignition of 3 of the 9 Merlin motors; 3) A final phase at constant or slightly decreasing speed. It is this last phase which is particularly visible in the video. The final descent speed is typically maintained around 5-8 m/s until the final seconds, where further deceleration reduces the impact speed to around 2 m/s. This strategy of controlled speed rather than continuous deceleration has several advantages: it allows better predictability of the trajectory, reduces the risk of engine flameout at low thrust, and minimizes fuel consumption. On the velocity graph, this results in a plateau rather than a continuous decrease, and on the position graph, a straight line of constant slope rather than a parabolic curve. FizziQ's kinematics tool makes it possible to precisely quantify these phases and appreciate the ingenuity of the landing program. This technique has revolutionized the space sector by making it possible to reuse launchers, thus considerably reducing the cost of putting them into orbit.