And because mg=GMmR2, we get: GM=R2g, so V = GR2R.

The speed of the satellite approaching the planet surface is the first cosmic speed, v=gR,

Because the surface gravity acceleration and radius of the moon are smaller than that of the earth, the first cosmic velocity of the moon is 7.9 km/s smaller than that of the earth.

From v=GMr, it can be seen that the larger the orbit radius, the smaller the speed, so the running speed of the satellite in orbit II is less than 7.9km/s, so A is correct.

B when the satellite passes through point p of the I orbit, the ignition is accelerated, so that its centripetal force is greater than gravity, and it can only enter the II orbit by centrifugal motion. Therefore, the speed of the satellite passing through point P of orbit I is greater than that of point P of orbit II, so B is wrong.

C. When passing through point P on track I, ignition accelerates, kinetic energy increases, mechanical energy increases, and then enters track II, so C is wrong.

D. When the satellite moves from perigee to apogee, gravity does negative work and its gravitational potential energy increases, so when the satellite runs in orbit I, the gravitational potential energy of perigee is less than that of apogee, so D is wrong.

So choose: a.