The Senate refused to ratify the treaty of Versailles primarily because they objected to the League of Nations. If the US joined the League, then they would be obligated to fight in future wars and the Senate didn't want that.
Multiple factors were involved in the decision of exploration of Mars.
Mars is similar to Earth in size and it is the next planet. Moreover, evidence was present to suggest that liquid water existed, and may possibly still exist, on Mars. All of these factors led to the planet's exploration.
A. Between Russia and Britain and the Shah of Persia
