When the S.S. Deke Slayton II launched in December, it was the first mission of the
newly-upgraded Cygnus spacecraft.
The upgrades included an expanded cargo hold and reworked service module, but most striking of all is the new solar panels. Like the rectangular bars on every other spacecraft (including older-model Cygnus spacecraft), the Cygnus now sports a pair of round Ultraflex solar arrays.
The design is not form alone however. The round fan-fold allows for higher performance at a lower mass than typical arrays. The arrays also fold up smaller than traditional arrays, reducing the stowage volume when launching.