book title or author

[brunoiam]

OK I read a series of book in the early 1990's that involved Americans, Russians and Brazilians building huge ring shaped ships and launching them using atomic bombs, the Americans had to travel out past Jupiter before they could turn on they're faster than light drive. they all travel to a mysterious planet where the Americans set down and start building a society while trying to search the rest of the planet that is parttialy covered in mist. which is hiding the planets inhabitants who have weapons powered by the son. I thought it had 2050 in the title but have been unable to find anything similar.