Hi, Joe,
Basically D-STAR (registered trademark) is designed to be used only in FM mode. (Has VO-52 a FM transponder ?)
Currentry only the ICOM supplies D-STAR comtatipble TRX on to the market. However, it seems that even the ICOM does not have suitable TRX for Sat communication on DV mode. For example, look their new mobile TRX, IC-2820. This radio is of course D-STAR compatible TRX. This radio can handle both 144/430MHz in FM and full duplex operation may be available. ( This radio may be able to use on the AO-51)
But, most important point is the radio has only One DV mode circuit and because of this reason, there is no possibility to enter duplex operation on DV mode. In another word, on DV mode, only simplex operation is avilable.
Please note above is current situation in Japan and may differ on the oversea market and of corse two years ahead or even one year ahead may be in different situation.
Toyo JA0CQP