NOAA 18, 19 (NOAA N, N')

NOAA 18 [NOAA]

The launch of the NOAA-N and -N' spacecraft will bring about a number of changes compared to the preceding NOAA KLM series of NOAA satellites. These changes are associated with: the substitution of the Microwave Humidity Sounder (MHS) for the AMSU-B instrument; replacement of HIRS/3 with HIRS/4 instrument.

Additionally the change to the Delta-7320-10C launch vehicle enables direct orbit insertion, so the solid rocket motor has been ommited in these two satelites.

NOAA N' was severly damaged in an factory accident in September 2003.