Answer:
ice age/ Quaternary glaciation
Explanation:
Ice ages have occurred in the earth history and do occur more or less regularly in a cycle. It is believed that ice ages are as a result of small changes in the earth's orbit and also dependent on the solar cycles. The temperatures on the earth reduce causing the ice sheets in the poles to extend to the subtropics.
The Apollo program was designed to land humans on the Moon and bring them safely back to Earth.
