These satellites are suspected to be stealthy electro-optical reconnaissance satellites. The program name for developing an stealth IMINT capability is reportedly "Misty".
The first one was Misty 1 (aka USA 53 and AFP-731), deployed from Shuttle in 1990. Misty-1 remained in orbit for at least 7.5 years.
USA 144 was probably the Misty 2 mission. Launched from Vandenberg in May 1999 aboard a Titan-4(03)B with no upper stage, USA 144 probably has an IMINT mission, but its orbit is a mystery. Hobbyist satellite observers continue to track an object from that launch in a 2700 km × 3100 km, 63.4° orbit, but detailed orbital analysis reveals significant solar radiation pressure perturbations, from an area to mass ratio of about 0.1 m2/kg, 10 to 20 times that of a payload, and more akin to debris or a decoy, can be deduced. It appears to be no more than 5 to 10 m across, and only a few hundred kilograms in mass. If USA 144 is Misty-2, then it is likely to be in a 700 to 800 km, quasi 65° orbit. These orbits are low-drag, so orbit maintenance manoeuvres are not required.
The status of a third mission is unknown and it is likely cancelled.
|Type / Application:||Reconnaissance, electro-optical, stealth|
|Lifetime:||+ 7.5 years|
|Orbit:||800 km × 808 km, 64.99° (#1); 2682 km × 3137 km, 63.44° (#2 ?)|
|Misty 1 (AFP-731, USA 53)||1990-019B||28.02.1990||CCK LC-39A||Shuttle||with Atlantis F6 (STS 36)|
|Misty 2 (USA 144, NROL 9)||1999-028A||22.05.1999||Va SLC-4E||Titan-4(04)B||with Decoy ?|