By: Kobi Hudson –
On March 11, 2015, the world’s largest and most powerful solid fueled rocket motor was test fired in Promontory, Utah. This test was a qualification for the motor to be used in the Space Launch System (SLS), a rocket NASA is developing to send people on long-distance missions into space.
The motor was strapped down on its side and butted up against a massive block of concrete. The nozzle of the motor was pointed at the side of a hill and then ignited at around 9:30 a.m. Throwing dirt and exhaust hundreds of feet into the air, the motor burned successfully for about two minutes.
Developed and constructed by Orbital ATK, the motor is the biggest solid-fueled motor ever built. The motor itself is 177 feet long, or when stood on its end, around 17 stories tall. The rocket, which has a diameter of 12 feet, weighs 1.6 million pounds, or about the same weight as about 94 elephants. The motor has a maximum thrust of 3.6 million pounds, making the motor more than capable of moving a large payload. To achieve this massive amount of thrust, the motor needs to burn about 5 tons of its fuel per second. This massive amount of energy release creates a sound level of about 200 decibels for the two-minute burn. A typical stun grenade creates a sound level of about 190 decibels for an instant. This difference of 10 decibels represents a 10 fold, or 1,000 percent increase, in sound intensity, so the motor sound was 10 times louder than a stun grenade and it went on for just over 2 minutes. Along with all the size, thrust, and sound, the motor generated 22 million horsepower which is about 16.5 million kilowatt hours (or the amount of power that it would take to run 275 million 60-watt light bulbs for the same amount of time the motor burned).
Not all of this motor is brand new. Many of the parts are heritage parts and have been changed or modified to fit the motor’s needs. Originally the space shuttle had booster motors similar to the SLS boosters, but only had 4 segments. This motor is, in many ways, a refurbished version of those booster motors with an additional segment added to them to make them the largest and most powerful ever made. David Wood, NASA Booster chief engineer, stated that this project brings a lot of heritage hardware from the 1970s, but some of it has had to be rethought. The Integrated electronics system was on one large box in the beginning, according to Wood. Wood mentioned that this was a pain to debug because it was one big piece so they ended up breaking it down into three main parts.
The motor also had two midspans to help support the midsegment of the motor as opposed to the one it had in the previous test. This was to help eliminate irregular nozzle erosion, according to Julia Khodabandeh, subsystem and test stand manager. Khodabandeh also stated that the test had 102 objectives, of which 75 of those objectives are for NASA qualifications. The test also had 531 different instruments, where the majority were used for measuring ballistics of the motor and 150 for load and environmental readings. She also stated that to prep for the test, they begin running dry runs of the test 14 days before the launch.
Charlie Precourt, the vice president and general manager of Orbital ATK’s space launch division and former astronaut, stated that this program represents a national opportunity for students. The SLS plans its first flight for 2018 and hopes to put humans on the surface of other space objects in 2030, according to Precourt. Precourt explained that this project is one that will be taken over by the students who are in college and highschool right now. Twenty years from now, the students will be building this to discover bigger and greater things, Precourt mentioned. In terms of future development, Precourt expressed that the space program and the SLS need people from every field and discipline.
*Sophomore Kobi Hudson, a Computer Science major, had the honor of attending this great qualification test on behalf of …. representing Rocky Mountain College and The Summit.