NW054 1/144 Delta M6
The Thor missile program was initiated in December 1954, when
USAF headquarters issued requirement for a tactical missile
intended to travel a distance of between 1 150 and 2 300 miles.
Thor was undertaken as a high-risk program having the goal of
achieving flight within the shortest possible time. The Thor had
its first complete launch pad test in January 1957 and a
full-range flight test in September 1957.
In 1959, the newly formed NASA asked Douglas to create a civilian
launch vehicle based on Thor Able. The new rocket was presenting
the fourth configuration for the Thor, so it was named Delta -
the military code for the fourth letter of the alphabet. The
Delta M (introduced in 1968) represented siginificant leap in
Delta evolution. With its Long Tank Thor first stage it hardly
resembled the original Thor. The long, untapered tanks
siginificantly increased propellant capacity. It retained the 2nd
stage of Delta E, but it used the TE 364-4 3rd stage, developed
from the Surveyor Moon lander's retro-motor.
On March 13, 1971 Delta M6 (562/D83) succesfullly launched the
Explorer 43 satellite. Explorer 43 was one of last IMP
(Interplanetary Monitoring Platform) program satellites. IMP
satellites were designed to observe and measure cosmic radiation,
magnetic fields and solar wind in interplanetary space and
discovered a region of high-energy radiation beyond the Van Allen
Belt.