Good thing we don’t have to rely on Boeing nor the Russians for access to space.

Curiosity rover was powered by RTG so it doesn’t have solar panels.

The design requirements for the rovers (spirit and opportunity) only calls for them to work for months. These rovers weren’t designed to work indefinitely and so they weren’t build as such because if the weight and powerbudget went to a wiper then it is taken away from the science payload; doing science is why they are there in the first place. If the mission is only suppose to last for months, why spend the weight and power on something that only helps with the longevity of the vehicle when it’s operated on the scale of years. Operations with spirit and opportunity for years also shows that you didn’t need wipers for the dust since the Martian winds periodically blew them off anyways.

Edit: curiosity uses RTG for power so it doesn’t have solar panels.

To put that into context, something that was 1mm apart is now 10.57 million light years apart after a 10^26 x expansion.

It depends on what you call a ship. Theoretically you can just tie a bunch number of ships together and make it into a really big ship. Floating bases with some limited propulsion have been proposed before to pre-stage logistical items for the US military. In WW2 the British had the idea of either co-oping an iceberg or build one with ice+wood chips that would be the size of a small island to serve as an aircraft carrier (Project Habakkak). The question is whether you'd still consider these things as a ship, if you do count it as a ship then there's no reason why you can't tie enough ships together to fill all of the oceans theoretically.

Generally the limit to the size of a ship hull (and thus the upper limit of an independent ship hull) has more to do with the size of port facilities, dry docks and canals. You can really only build a ship hull to a size that will fit in your biggest dry dock because otherwise you wouldn't be able to launch the ship and put it into the water once it's done. Even if you build a ship that's bigger than any dry dock by building it in a temporary coffer dam or something, presumably you'll eventually need to bring a ship into a dry dock to perform maintenance and repairs on the hull so you don't really want to build a ship any bigger than what your biggest dry dock can support.

I mean this is why rockets are staged and non single stage to orbit vehicles have been put into service. During early part of the flight you have massive engines/power and once you are at high speed and high altitude you drop your boost stage to dump the engine and Fuel/O2 tanks you don’t need anymore and continue to orbit using a much smaller second, 3rd or even 4th stage.