Ratnakar

A to date remains the only person who has been buried on the Moon. Considered as a possible candidate for the Apollo moon flight, he however had to drop out due to Addison's disease, he however was involved in training the astronauts.B  was a Canadian astronomer, who had authored a book on Clyde Tombaugh, who discovered Pluto.Credited with discovering around 41 asteroids one of which is named after him. Identify A &B.