When Kennedy mentions "those who came before us" he is referring to other great leaders throughout American history other great leaders throughout American history our forefathers who founded the United States our forefathers who founded the United States other presidents other presidents scientists like Newton and Galileo

other great leaders throughout American history

Explanation:

When Kennedy says "those who came before us" he is referring to great American leaders inserted in the most diverse branches of industry, politics and science. Kennedy claims that it was these great leaders who allowed the United States to receive a wave of industrialization that promoted the country's advance and it was the duty of future leaders and Americans in general, not to allow these advances to go back, but to go even further.

elon musk, ceo of spacex, a startup space company is planning to head to mars by 2023. nasa is planning to go to mars at around 2025. both are just for a basic colony.