The Little Joe rocket booster was developed  as a cheaper, smaller, and more functional alternative to the Redstone rockets. 
Little Joe could be produced at one-fifth the cost of Redstone (below)  rockets and
still have enough power to carry a capsule payload.  Seven unmanned Little Joe rockets were launched at Wallops Island, Virginia, from  August 1959 to April 1961.

Rocco Petrone

In 1969, the year of the historic Apollo 11 moon landing, he was named director of the entire Apollo program.

"The NAA team that in my opinion worked on the X-15 program with complete brilliance and dedication. My list is as follows: Chief Project Engineer Charles Feltz; Assistant Project Engineers Bud Benner and Ron Robinson; Power Plant Engineer Bob Fields; Regulators and Relief Valves Expert John Gibb; Chief of Aerodynamics Larry Greene; Project Aerodynamicist Bill Johnston. The remaining two individuals who are very outstanding in my mind are Scott Crossfield and Al White. Crossfield had flown the X- I and D-55 8 and left the government to fly the X- 15. He desired to participate in the complete program; however, this ended up as not being possible. Unfortunately, he was restricted to relatively low speeds of M = 2 to 3. There were many who thought he would break this restriction; knowing Scott, I knew that would never happen as he is a very dedicated professional test pilot and a man of his word. Several years before the flight operations started, he worked very diligently with the engineering group to ensure we designed in the maximum flight safety and to learn in complete detail how each of the subsystems operated. This knowledge was of extreme value to the program in the early debugging flights". Dr. Harrison Storms Jr.
30th Anniversary Speech

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