Complex sentence: Globus II has two tasks within the stated task of watching space is to gather metric data from satellites, which is used by the US Space Command to produce and maintain the Space Catalog, which contains orbit data on all man-made objects in outer space.
Split into simpler sentences: Globus II has two tasks within the stated task of watching space. The first task is to gather metric data from satellites, which is used by the US Space Command to produce and maintain the Space Catalog, which contains orbit data on all man-made objects in outer space.