NASA Astronauts killed by accident or a higher power?

Many deaths of NASA Astronauts are highly suspicious. 

Is it the government or just coincidence ? :

31 October 1964 - Theodore Freeman (Plane Crash)

28 February 1966 - Charles Basset and Elliot See (Plane Crash)

27 January 1967 - Roger Chaffee, Virgil Grissom , and Edward White were killed killed in the space ship.

6 June 1967 - Edward Givens (car accident)

5 October 1967 - Clifton Williams (Plane Crash)

28 January 1986; Space Shuttle Challenger crash

Ronald McNair , 

Ellison Onizuka, 

Judith Resnik , 

Francis Scobee  , and Michael Smith. 

24 May 1986 - Stephen Thorne (Plane Crash)

17 June 1989 - S. David Griggs (Plane Crash)

5 April 1991 - Sonny Carter  (Plane Crash)

22 May 2001 - Patricia Robertson (Plane Crash)

1 February 2003; Space Shuttle Columbia exploded 

Michael Anderson  , David Brown, 

Kalpana Chawla  , Laurel Clark, 

Rick Husband  , William McCool, and Ilan Ramon.

Why did so many die through plane crashes ? Did they know too much? Maybe about the (non existing) moon landings?