A Booster The Blows Up As Often As It Goes Up

Part 1 of 2 By Wes Oleszewski

On the 12th day of April 1961, deep behind the Iron Curtain of the Soviet Union and under absolute secrecy, cosmonaut Yuri Gagarin was launched into orbit. After circling the earth one time his Vostok spacecraft reentered the Earth's atmosphere. Somewhere around 23,000 feet Gagarin blew the hatch, ejected from the spacecraft and parachuted to the earth. He thus became the first human to orbit the earth. At that exact moment in time the schedule for astronauts of United States to fly in space consisted of a series of seven manned Mercury Redstone suborbital flights followed by an equal number of manned Mercury Atlas orbital flights. First of these flights were scheduled to take place on the second day of May 1961 and its pilot would be Alan Shepard.

Vostok Capsule

Exactly where the Soviets were in their progress toward achieving spaceflight was unknown to everyone in the West prior to Gagarin’s flight. Indeed NASA's manned space efforts were trudging along lethargically constrained by politics and a meager budget allotted it by the Eisenhower administration. When the success of Gagarin’s spaceflight was revealed to the West everything changed.

Similar to the situation our nation finds itself in today, on that April day in 1961 NASA found itself without the capability to place US astronauts into orbit aboard any launch vehicles in the United States inventory while Russia was happily and successfully able to place people into orbit atop their reliable R7 booster. The difference between then and now being that not only were the American people actually paying attention to the shortcoming but the President of the United States himself was actually willing to lead the nation toward rectifying the situation. In less than one month president Kennedy challenged the nation and the Soviet Union to a space race. Although today it seems to be politically acceptable for the president to offer the premise that the United States can "lead from behind," such was not the case in 1961. It was the era of the "Cold War" between the United States and the Soviet Union and JFK was not about to allow the Soviets to win this skirmish. Likewise, the United States Congress unified behind the president and provided the funds requested to energize America's space program.

Immediately the schedule of flights for United States astronauts was drastically revised. The suborbital, manned Mercury Redstone flights were scaled back from seven flights to only two flights. Following that second manned Mercury Redstone flight the effort was to be directed toward manned orbital flights atop the Atlas booster. In the scheduled flight rotation of astronauts the third man up was slated to be Marine Corps Lieut. Col. John Glenn.

Atlas Booster Failures

Unfortunately, the Atlas booster that Glenn would ride had seen a troubled childhood. In 1958, 6 out of 14 launches failed and 1959 was not much better as 10 out of 23 failed. In that same year, from January to June, a total of 8 vehicles in a row failed and the most embarrassing had to be number 7. On May 18, Atlas 7D was launched with the brand new Mercury 7 astronauts there as spectators. The vehicle exploded almost directly overhead as range safety hit the “Command Destruct” button. In the year of 1960 the Atlas was still batting about 500 as 14 out of 33 launches failed, not counting Agena vehicle failures. In 1961, just one year before manned flights on the Atlas were scheduled, 13 out of 37 Atlas launches failed. Granted, most of the failures were “R&D” launches, but the reputation still hung over the Atlas.

Still, the space race was fresh off the starting line and Mercury was America’s only bet to put a man into orbit. Atlas was not a 2 stage rocket, rather it was a single stage rocket that dropped 2 of its 3 engines at two minutes and 10 seconds after launch. The center “sustainer” engine would continue to burn until the 5 minute point after liftoff and then shut down. Two small Vernier engines that had done some of the steering during powered flight would continue to burn shortly and correct trajectory errors. For manned flight a Launch Escape System (LES) was added along with the Mercury spacecraft and the Mercury Atlas was pressed into service.

Recovered MA-1 Capsule

First of the Mercury Atlas launches took place on September 9, 1959, consisted of the Atlas D booster with a boilerplate Mercury capsule minus the escape tower. Planned to send the capsule on a ballistic, sub-orbital path the test was dubbed “Big Joe.” At BECO (booster engine cut-off) the two dead engines failed to drop off of the Atlas and then at SECO (sustainer engine cut-off) the capsule failed to separate. After several minutes and depletion of all the RCS fuel, the capsule came loose and dropped inertly into the atmosphere. Because the capsule was designed with an off-set center of gravity that would allow it to passively seek a blunt end forward attitude as it contacted the atmosphere, it survived reentry and was actually recovered. Nearly 11 months later on July 29, 1960 the test was repeated with MA-1. On that flight the Atlas exploded while trying to push the Mercury capsule’s mass through the area of maximum aerodynamic pressure (Max-Q). Strengthening a small area of the Atlas adapter was the proposed cure to get the vehicle through Max-Q and MA-2 would be the test flight. A full Mercury spacecraft was loaded onto Atlas 67-D and on March 21, 1961 that time the sub-orbital flight was a complete success. Oddly, the “fix” to the adapter was only needed for MA-2 because Atlas 67-D was the last of the all “thin skinned” boosters to be used in Mercury, MA-3 would fly with Atlas 100-D a thicker skinned version of the booster. MA-3 turned out to be a successful failure as the booster lifted off on April 25, 1961 and went straight up… and just kept going straight up when it should have pitched over. Again, Range Safety hit the command destruct and the Atlas blew up directly overhead. This time, however, the capsule had an active LES tower and the abort sequence activated with the booster’s destruct. It pulled the capsule clear in an unplanned, but successful test of the abort system. MA-4 was to place a full Mercury spacecraft into orbit with an electronic “astronaut simulator” aboard. For the first time a Mercury spacecraft was placed into earth orbit for a once around mission that was completely successful- the date was September 13, 1961. Two months later, November 11, 1961, Enos the chimp rode MA-5 on a successful flight.  NASA felt that the time had come to launch astronauts on the Atlas booster.

All of the Mercury Atlas launchings took place at Cape Canaveral’s Launch Complex 14. So it was at that place that on February 20, 1962 John Glenn boarded his Friendship 7 spacecraft that sat atop a booster that many thought blows up as often as it goes up. Glenn, like most folks inside the program had a different perspective. He knew that each individual booster and each individual launch was its own individual event and every failure had been a page added to the learning manual that improved the system as well as his chances of a successful mission. As the year 1962 started, John Glenn was ready to go… but would take nearly two months for him to complete his three orbit ride into history.

…To be continued. (Images provided by NASA)

FMI: www.nasa.gov