It would weigh 4000 tons which is about the mass of some nuclear submarines. It was also a bit more than the 3350 tons of the Saturn V.

We do not have advanced ion drive now and we do not have the proposed small nuclear reactors. It will likely take 10-30 years to develop them.

We also do not have working magnetic or e-sail systems for slowing ships down at target stars.

We have had the technical capability and knowledge to make spaceships that can travel at 2-10% of light speed. The more moderate size ships of 4000-10000 tons could go up to 2% of lightspeed and at 400,000 tons a ship could go up to 4% of lightspeed.

The technology was of course Project orion, nuclear pulse propulsion.

A preliminary design for a nuclear pulse unit was produced. It proposed the use of a shaped-charge fusion-boosted fission explosive. The