Though the Keith community native describes his early years as “a pretty normal, ordinary life similar to what a thousand other kids have,” his later years have been anything but that.
Mullins, an aerospace engineer working for the National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center in Huntsville, Ala., led a team of scientists who selected the flight path for the Chandra X-ray Observatory that houses Chandra — the world’s most powerful x-ray telescope.
Every 64 hours, NASA’s Chandra X-ray Observatory follows a path that dodges darkness, stretches one-third of the way to the Moon and has a more elliptical shape than most orbiting satellites.
Chandra’s orbit is a reflection of the unique requirements needed to ensure the telescope could deliver its groundbreaking images to Earth.
Mullins, who graduated from Ringgold High School in 1958, said he had an interest in all forms of science and math while growing up here.
His late father Rankin Mullins worked for the Tennessee Valley Authority. His mother Lucy currently lives in Cherokee Valley. His sister Dolores McKeehan lives in Catoosa.
“I think by about the 10th-grade I had decided I wanted to go to college and major in science,” he said.
He shared that two of his RHS teachers played a part in his success.
“I had an excellent algebra teacher named “Doc” Peterson,” he said. “I also remember Lola Emberson. She was our English teacher. She was a very excellent teacher.”
He received a bachelor of arts degree from Berry College in Rome, Ga., and then in 1962 went to work for NASA at the Marshall Space Flight Center.
“I did not have a lot of money, so I got the opportunity to go to Berry College and work my way through down there,” he said. “Fortunately, they had a very good science program.”
Working in orbital mechanics virtually his whole career at Marshall, Mullins started attending the University of Alabama in Tuscaloosa early in his career and eventually earned a Master of Science and Doctorate degrees.
One step closer to infinity
His work on Chandra has helped open up a new world of astronomy research.
“It is an astronomy mission,” he said. “Most astronomy you think of is taking pictures in the visual part of the spectrum. This particular instrument takes pictures in the x-ray portion of the spectrum which is not available to observatories on earth because that part of the spectrum is blocked by the atmosphere.”
Chandra began collecting unprecedented images of the universe in August 1999. In just over two years, the unique telescope has found the most distant x-ray cluster of galaxies, captured the deepest x-ray images ever recorded and discovered a new size of black hole.
“So once we get above the earth’s atmosphere and above the earth’s radiation belts, then we can get pictures of stars and galaxies in the x-ray portion of the spectrum,” he said. “That gives astronomers more information about the stars.”
But before Chandra could achieve those firsts and long before the observatory was launched, engineers had to determine precisely the best path for Chandra to take.
“There were several challenges to overcome,” Mullins said. “One challenge was the sheer height of the orbit needed.”
At its high point, 200-time higher than the Hubble Space Telescope, Chandra’s orbit takes it 75,000 miles from earth and far outside the belts of radiation that surround our planet. This radiation — while harmless to life on earth — can overwhelm an x-ray observatory’s sensitive instruments.
With a great deal of hard work and planning, Mullins and the trajectory team came up with a flight plan which is now paying tremendous scientific dividends — not just for National Aeronautics and Space Administration but for astronomers around the globe.
Mullins lives in Madison, Ala., with his wife Onie, a 1959 RHS graduate who is the daughter of Sam Johnson and the late Pauline Johnson. The couple have two children, David and Andrew and two grandchildren, Megan and Michael. He attends the First Baptist Church of Madison and is a member of the American Physical Society.
Creating Chandra’s orbit
During each 64-hour orbit, Chandra remains outside the radiation belts long enough to take 55 hours of uninterrupted observations. To achieve this unprecedented altitude for an orbiting satellite, the Marshall engineers crafted an elliptical, or oblong, orbit.
“It would have been simpler to create a circular orbit, but at that altitude, it was out of the question because at its highest point, Chandra flies about 75,000 miles higher than the space shuttle can travel,” Mullins said.
A space shuttle flies as high as 350 miles from earth. Even at its closest approach to earth, Chandra’s altitude is about 6,000 miles from our planet. Space Shuttle payloads such as Chandra destined for altitudes above the Shuttle’s range have rocket motors attached. Fired after the spacecraft is a safe distance from the shuttle, these rocket motors propel the spacecraft to its final destination.
The Chandra X-ray Observatory was the largest and heaviest payload ever launched by the space shuttle.
The wide variation between the observatory’s highest and lowest point from earth is the result of the elliptical orbit designed by the Marshall Center trajectory team led by Mullins.
To achieve this unusual orbit, rocket boosters propelled the observatory to the required altitude.
“In its simplest terms, the concept is similar to a sling-shot,” said Russell Stone, an aerospace engineer in Marshall’s Space Transportation Directorate.
But the implementation was anything but simple, according to NASA officials. It took two years just to create the computer software that would enable the team to predict the evolution of Chandra’s orbit over its expected 10-year lifetime.
Another challenge was ensuring Chandra had nearly uninterrupted access to its power source — the sun.
Although the observatory has three batteries that store power, the sun is the sole source of power to those batteries.
“The observatory’s battery life is two hours,” Stone said. “That’s how long it can operate on the solar power it’s collected, so Chandra can’t be in darkness for more than two hours at a time. We had to find a path that minimized its time in earth’s shadow.”
“We did some parameter studies and found the size and orientation of an orbit that fit all these criteria,” said Steve Evans, another member of the Chandra Trajectory team at the Marshall Center. In fact, the engineers don’t expect Chandra to go into a shadow for more then two hours at a time for the next 10 years.
“Chandra’s orbit is so high that it doesn’t move into earth’s shadow for every one of its orbits,” Evans said. “In fact, it is infrequent enough to result in only two eclipse seasons a year, each with about a dozen eclipses.”
Based on the observatory’s outstanding results, in September 2001 managers at NASA Headquarters in Washington, D.C., decided to extend Chandra’s mission from its original five-year mission to a 10-year mission.
The extended mission will support five additional years of day-to-day operations such as controlling the spacecraft, observing celestial targets, processing data and passing it on to scientists around the globe. It also includes continuing the administration of hundreds of science grants for astronomers to analyze their data and publish their results.
What Chandra will discover during its additional five years remains to be seen, but thanks to the efforts of NASA engineers, including Ringgold’s Larry Mullins, there’s no mystery to the path the observatory will take while delivering its groundbreaking images to stargazers on earth