The spacecraft are probably the next generationt for the Trumpet and 'Trumpet-F/O' SIGINT satellites operating in a Molniya orbit. As no name is known, these are referred here as "Trumpet Follow On 2".
These satellite most likely use a large, unfurlable dish antenna to collect the signals.
A official reported, that, although the satellite shares the same name with its precedessors, it is nearly 90% different in terms of technology.
'Trumpet-F/O-2' 1 is the host for the SBIRS-HEO-3 early warning sensor.
'Trumpet-F/O-2' 1 (or NROL 35) is the host for the SBIRS-HEO-3 early warning package.
'Trumpet-F/O-2' 2 (or NROL 42) likely carries the SBIRS-HEO-4 early warning package.
|Type / Application:||SIGINT, early warning|
|Orbit:||2101 km × 37748 km, 62.8° (#1)|
|'Trumpet-F/O-2 1' (USA 259, NROL-35, SBIRS HEO-3)||2014-081A||13.12.2014||Va SLC-3E||Atlas-5(541)|
|'Trumpet-F/O-2 2' (USA 278, NROL 42, SBIRS HEO-4)||2017-056A||24.09.2017||Va SLC-3E||Atlas-5(541)|
Further high orbit SIGINT missions:
Geostationary orbit COMINT (Canyon-Chalet-Vortex-Mercury series)