The Cygnus is a Kestrel designed as an SSTO or, at least, a space hopper
, jumping to high altitudes without making an orbit. Small and fast, this little arrow can do many things, and could eventually be used as an interceptor or spy plane, despite its lack of fuel, when the KIV and the KV aren’t operable.
Carrying up to 4 sats, you can easily deploy them around any ceclestial body. However, if you want to go further than Kerbin, Mun and Minmus, you’ll need an orbital refueling station, as this SSTO doesn’t have Nervs.