Download Reentry Vehicles and Orbital Mechanics Subcommittee

Reentry Vehicles and Orbital Mechanics
Grades 9-12
The focus of the “Reentry Vehicles and Orbital Mechanics” subcommittee is the
flight performance of vehicles that orbit planets or reenter planetary atmospheres. Orbital
mechanics involves the motion of spacecraft, such as rockets and satellites, and includes
interplanetary transfers and orbital maneuvers. Orbital mechanics is used by mission
planners to design propulsive maneuvers. Figure 1 illustrates the interplanetary trajectory
of the Cassini spacecraft from launch to arrival at Saturn. Atmospheric reentry occurs
Figure 1
Source: NASA
when a vehicle transitions from space to a
planetary atmosphere. Vehicles designed
to survive this reentry are termed “reentry
vehicles”, and this subcommittee
considers the aerodynamic performance,
trajectory, deceleration, and attitude
dynamics
of
these
vehicles.
Aerodynamics involves the prediction of
forces produced on the vehicle by the
atmosphere. Deceleration involves safely
reducing the very high speed required for
space flight. Trajectory and attitude
Source: NASA
Figure 2. Galileo Probe Entering the Atmosphere
dynamics involves the prediction of the vehicle’s motion and control as it flies through
the atmosphere. Reentry vehicles include interplanetary spacecraft and ballistic missiles.
Figure 2 depicts the Galileo Probe entering an atmosphere at very high speed and
decelerating by means of a heat shield and parachute. The highest speed for a man-made
reentry was achieved by the Galileo Probe, which entered Jupiter’s atmosphere at over
105,000 miles per hour and experienced a peak deceleration of 230 g’s during reentry.
Engineers that work in the area of “Reentry Vehicles and Orbital Mechanics” apply
technical, scientific, and mathematical knowledge to the design of spacecraft, satellites,
and rockets for spaceflight or atmospheric reentry. The design process can involve hand
calculations, computer simulations, ground testing, and flight testing to predict the
aerodynamics, deceleration, trajectory, and attitude dynamics of the vehicles.
Measurements obtained during the actual flight of the finished vehicle are also used to
compare with the pre-flight predictions to improve future predictions.