Space only ships

A flyable ship that cannot make landfall upon a planet. Something like the Lynx Bulk Carrier, although it doesn't necessarily have to be that large. For whatever gameplay balance reason used, a ship might not be able to land on a surface under gravity, or might not be able to use atmospheric shielding. These could be given advantages to offset the disadvantage.

• The powerful ventral thruster used to take off from a planet need not be quite so powerful.
• The ship could have a more generous thrust.
• It could be an interesting shape.

Care would have to be taken that such ships weren't sold from a planet-based shipyard. (implemented: governed by the xistence of the atmospheric shield slot)