Douglas Aircraft had been selected to build the missiles for Zeus, known under the company designation DM-15.
This was essentially a scaled-up Hercules with an improved, more powerful single piece booster replacing Hercules' cluster of four smaller boosters.
Intercepts could take place at the limits of the Wilson requirements, at ranges and altitudes of about 100 miles (160 km).
Prototype launches were planned for 1959.
For more rapid service entry there had been some consideration given to an interim system based on the original Hercules missile, but these efforts were dropped.
Likewise, early requirements for a secondary anti-aircraft role were also eventually dropped.

Wilson signaled his intention to retire in early 1957, and Eisenhower began looking for a replacement.
During his exit interview, only four days after Sputnik, Wilson told Eisenhower that "trouble is rising between the Army and the Air Force over the 'anti-missile-missile'."
The new Secretary of Defense, Neil McElroy, took office on 9 October 1957.
McElroy was previously president of Procter & Gamble and was best known for the invention of the concept of brand management and product differentiation.
He had little federal experience, and the launch of Sputnik left him little time to ease into the position.

Shortly after taking office, McElroy formed a panel to investigate ABM issues.
The panel examined the Army and Air Force projects, and found the Zeus program considerably more advanced than Wizard.
McElroy told the Air Force to stop work on ABM missiles and use Wizard funding for the development of long-range radars for early warning and raid identification.
These were already under development as the BMEWS network.
The Army was handed the job of actually shooting down the warheads, and McElroy gave them free hand to develop an ABM system as they saw fit, free of any range limitations.

The team designed a much larger missile with a greatly enlarged upper fuselage and three stages, more than doubling the launch weight.
This version extended range, with interceptions taking place as far as 200 miles (320 km) downrange and over 100 miles (160 km) in altitude.
An even larger booster took the missile to hypersonic speeds while still in the lower atmosphere, so the missile fuselage had to be covered over completely with a phenolic ablative heat shield to protect the airframe from melting.
Another change was to combine the aerodynamic controls used for control in the lower atmosphere with the thrust vectoring engines, using a single set of movable jet vanes for both roles.

The new DM-15B Nike Zeus B (the earlier model retroactively becoming the A) received a go ahead for development on 16 January 1958, the same date the Air Force was officially told to stop all work on a Wizard missile.
On 22 January 1958, the National Security Council gave Zeus S-Priority, the highest national priority.
Additional funds were requested to the Zeus program to ensure an initial service date in the fourth quarter of 1962, but these were denied, delaying service entry until some time in 1963.
Douglas Aircraft had been selected to build the missiles for Zeus, known under the company designation DM-15. This was essentially a scaled-up Hercules with an improved, more powerful single piece booster replacing Hercules' cluster of four smaller boosters. Intercepts could take place at the limits of the Wilson requirements, at ranges and altitudes of about 100 miles (160 km). Prototype launches were planned for 1959. For more rapid service entry there had been some consideration given to an interim system based on the original Hercules missile, but these efforts were dropped. Likewise, early requirements for a secondary anti-aircraft role were also eventually dropped.
Wilson signaled his intention to retire in early 1957, and Eisenhower began looking for a replacement. During his exit interview, only four days after Sputnik, Wilson told Eisenhower that "trouble is rising between the Army and the Air Force over the 'anti-missile-missile'." The new Secretary of Defense, Neil McElroy, took office on 9 October 1957. McElroy was previously president of Procter & Gamble and was best known for the invention of the concept of brand management and product differentiation. He had little federal experience, and the launch of Sputnik left him little time to ease into the position.
Shortly after taking office, McElroy formed a panel to investigate ABM issues. The panel examined the Army and Air Force projects, and found the Zeus program considerably more advanced than Wizard. McElroy told the Air Force to stop work on ABM missiles and use Wizard funding for the development of long-range radars for early warning and raid identification. These were already under development as the BMEWS network. The Army was handed the job of actually shooting down the warheads, and McElroy gave them free hand to develop an ABM system as they saw fit, free of any range limitations.
The team designed a much larger missile with a greatly enlarged upper fuselage and three stages, more than doubling the launch weight. This version extended range, with interceptions taking place as far as 200 miles (320 km) downrange and over 100 miles (160 km) in altitude. An even larger booster took the missile to hypersonic speeds while still in the lower atmosphere, so the missile fuselage had to be covered over completely with a phenolic ablative heat shield to protect the airframe from melting. Another change was to combine the aerodynamic controls used for control in the lower atmosphere with the thrust vectoring engines, using a single set of movable jet vanes for both roles.
The new DM-15B Nike Zeus B (the earlier model retroactively becoming the A) received a go ahead for development on 16 January 1958, the same date the Air Force was officially told to stop all work on a Wizard missile. On 22 January 1958, the National Security Council gave Zeus S-Priority, the highest national priority. Additional funds were requested to the Zeus program to ensure an initial service date in the fourth quarter of 1962, but these were denied, delaying service entry until some time in 1963.
Nike Zeus