The game automatically selects the pre configured vehicles that will be able to solve a mission (completely in one approach). For example choose a "T5 Lander", because T1 Lander does not have the proper equpipment for the misson.
When running the mission it might come up, that one is not able to finish (i.e. due to broken equipment).
There is of course the possibility to send a second rover or platform. The game will then recalculate what is neccessary to finish the mission and offer different vehicles to launch.
Before launching a vehicle one is able to modify the vehicle in the lab.
At this point the game requires to install all originally required equipment parts on the new vehicle (not only those for the rest of the mission).
Constructing a proper vehicle in the lab, then switching over to the map will show up the vehicle in valid vehicle list for the mission and allow to launch the vehicle.
Hope this has not already been reported, didn't found it in the list prior to writing this...