Question

Problem 6

A spacecraft is in orbit around Earth with an eccentricity of e = 0.25 and apogee altitude of 5000km. At

the orbit's perigee, the spacecraft is slowed by the application of braking rockets, which produce a thrust

of 1.0x10 N, to put the spacecraft into a new orbit having an eccentricity of 0.2. The total angular

momentum of the spacecraft before the application of the braking thrusters is 4.0x1013 kg m²/s (note this

is not per unit mass). Neglect the change of position of the spacecraft with respect to Earth during the

thrusters' firing and calculate the mass of the spacecraft, the lowest altitude of the orbits, the velocity

increment at the perigee provided by the thrusters and how long the thrusters must fire.

(Answers: 686kg, 449km, -172.6m/s, 11.8s)