Original: In light of the 2003 failure of the ADEOS II satellite that was meant to succeed the NSCAT, QuikSCAT is currently the only US-owned instrument in orbit that measures surface winds over the oceans.
Simplified: Because of the 2003 failure of the ADEOS II satellite that was meant to succeed the NSCAT, QuickSCAT is currently the only US-owned instrument in orbit that measures surface winds over the oceans.