A 10,000 kg spacecraft is in a circular orbit 400 km above the surface of the Earth. It fires its rockets and quickly doubles its kinetic energy, putting it into an elliptical orbit. What is the semimajor axis (km) of the orbit? The radius of the Earth is 6.37×106 m and its mass is 5.98×1024 kg. 3200 infinity 1.60×103 9.57×103 1600 6.94×103 800 566 7.97×103 7.17×103