My heart pounded and my legs shook as I stood watching the world's largest solid rocket booster fire at the Orbital ATK facility in Promontory, Utah on Tuesday. These motors will be used to launch the most powerful rocket in the world, SLS, NASA’s acronym for Space Launch System.
"To get big heavy things off the planet, you need a lot of thrust very quickly and that’s what the solid rocket motors do,” said Kent Rominger, Vice President of Strategy and Business Development at Orbital ATK, and former NASA astronaut.
“There will be two [boosters] strapped alongside the core of this giant rocket. The booster, when it’s stacked on the rocket, will be about 180 feet tall. That’s like an 18 story building. It’s got almost 1.4 million pounds of solid propellant, so it’s a very heavy motor. The most mind boggling thing is that it will produce 3.5 million pounds of thrust and burn for only about 2 minutes and 6 seconds. At that rate, you are burning 5.5 tons of propellant every second. When I flew the space shuttle, the boosters were a smaller version of this one and when they lit, you immediately knew you were going somewhere fast. The acceleration that you get out of a rocket motor like this is incredible.”
The booster was locked horizontally into a test stand. The crowd waited anxiously as the clock ticked...3…2…1...FIRE. Massive flames spewed into a bare mountainside and grey smoke clouds rose as the motor burned through the propellant. Surrounding sand melted to glass as excessive heat exited the end of the booster. The rumbles and vibrations emanating over great distances took my breath away.
Rocket motor testing is important because NASA and Orbital ATK scientists have to predict performance and ensure reliability. They have 82 specific parameters to examine, one of which is the pre-ignition temperature of the motor. It is critical to validate booster performance at a minimum and maximum launch temperature to determine how factors such as thrust are affected. If it’s cold on launch day, for example, the booster’s thrust will be a little less. A previous test had the booster propellant conditioned to 90°F prior to firing, while this test was conducted at 40°F.
Tuesday’s firing was the final qualification test and serves as an important milestone in the journey to complete the first SLS. Stan Love, chief of exploration, has been an astronaut for 18 years and flew on the Atlantis in 2008. He said the new rocket is going to take humans where they have never gone before- deep space.
“The SLS is a very big rocket. For the last 40 years, we have been doing things in low Earth orbit, just barely above the cloud tops. We haven’t sent anybody except robots, beyond low Earth orbit since Apollo. The time has come to fix that,” he said. “In order to do that, we need a rocket like the Saturn that took astronauts to the moon in the 1960s and 70s. The SLS is that rocket.”
Low Earth orbit is about 250 miles above the planet, and the moon approximately 250,000 miles away from Earth. But, plans for SLS include using it as a launch system to Mars, which is 35,000,000 miles away at its closest point to our planet.
“Someday we want to go to Mars. Great plan- quite hard to do. We might want to practice a little closer to home before we go to Mars. We are talking about practicing in high orbit around the moon, or maybe we could send people to a near-Earth asteroid. All of these things would be very valuable for getting ready to go to Mars, which is an enormous and very difficult journey,” Love said.
I looked at the crowd as the engine fired. There were smiles, possibly tears in the eyes of some who worked so hard for this achievement, and even a little terror sparked by the magnitude of the power we were witnessing.
“As a Utahn, I’m really proud. We have a unique capability right here for our nation’s space program and for the whole world,” Rominger said.
The first launch of NASA’s SLS with the Orion spacecraft will be uncrewed and is scheduled for 2018.
Watch the test fire here (credit: NASA's Marshall Center).