I'm looking for a book I've read in my teenager years. I believe it was set in late 80s or 90s. Both America and the Soviet Union were building colony ships. The American ship arrives at a giant planet. The planet had a lower density than Earth, yielding a similar gravity. The Americans then start dismantling their ship and building a colony using its parts. I think there was a suspicion of a traitor among the colonists. I can't recall the title or the name of the planet.