OMM spacecraft parameters (CCSDS 502.0-B-3 table 4-3). Present on an OMM when any of its keywords occurs, even with a blank value.
@type t() :: %Sidereon.Format.OMM.Spacecraft{ comments: [String.t()], drag_area_m2: float() | nil, drag_coeff: float() | nil, mass_kg: float() | nil, solar_rad_area_m2: float() | nil, solar_rad_coeff: float() | nil }