With 12,000 bits of space junk in low Earth orbit moving at 5 miles per second, anything in outer space is going to be hit, with potentially deadly effects for anyone in a space suit, a science and technology conference held in Grand Cayman heard last week.
A grain of sand as small as one-tenth of a centimeter can tear the wing of a space shuttle, meaning engineers must design shielding for satellites, the International Space Station, orbiting telescopes and anything else supposed to function in a space environment.
William Schonberg, a professor at Missouri University of Science and Technology, told an auditorium of 100 students and observers at the University College of the Cayman Islands on Thursday that orbiting debris from years of satellite missions, probes, rockets, missiles, space platforms, rubbish and other detritus could soon reach critical levels, creating what he called the “Kessler Syndrome.”
The condition, proposed in 1978 by NASA scientist Donald Kessler, anticipated serial collision of low-orbit objects in a sort of chain reaction, ultimately binding Earth so tightly with debris that the planet is cut off from the universe, encased in a kind of cocoon of waste products.
The problem has only grown worse, Mr. Schonberg said, citing Beijing’s 2007 test of an anti-satellite weapon, exploding the amount of orbiting debris from 7,000 pieces to 10,000, although the total soon climbed to 12,000.
In February 2009, when a 900 kilogram (2,000 pound) Iridium satellite collided with a 685 kg Cosmos satellite at a combined speed of 15,000 miles per hour, the blast scattered another 1,000 to 3,000 bits of “sizable debris,” he said.
“After 55 years of space operations, approximately 8,000 spacecraft have been launched into Earth orbit,” Mr. Schonberg said.
Mr. Schonberg’s address on Thursday was part of UCCI’s three-day Science, Technology, Engineering and Math conference.
Professor and chair of the Civil, Architectural and Environmental Engineering Department at the Missouri University of Science and Technology, who earned a doctorate from Northwestern University, Mr. Schonberg told the Sir Vassal Johnson Hall audience that “only about 3,000 [spacecraft] remain in orbit and only about 800 are still active,” noting that 300,000 pieces of debris are less than half an inch, and include nuts, bolts, lens caps, paint chips, dust from solid rocket motors, circuit-board pieces. Perhaps the most famously orbiting junk is the glove of Gemini 4 astronaut Ed White, who lost the protective covering during a 1965 space walk.
“We have everything from rocket boosters that are 3 feet long, big pieces of rockets that are 30 feet, the size of a big yellow school bus, and smaller bits that are 3 millimeters (0.1 inch).
“It’s grown quite a lot from 20 years ago. We have a little beehive of stuff. It’s everywhere,” he said.
In 2011, NASA said it was tracking 22,000 different objects.
Seen in the night skies
Thursday’s UCCI gathering came in the wake of the early August appearance in Cayman’s night skies of what was initially thought to be a meteorite exploding in a shower of debris and light. Later analysis, however, focused on orbital decay of a Russian rocket booster, initially launched in December 2012, re-entering the atmosphere between 50,000 feet and 120,000 feet over the coast of northern Honduras, tracing a descending arc across the western Caribbean and finally disintegrating over Cienfuegos, Cuba.
Observers pegged the object between 15 feet and 25 feet in diameter, and 50 feet long.
While brief safety concerns were raised for in-flight aircraft and ground-based objects, local aviation officials and the International Civil Aviation Organization minimized the danger, characterizing chances of a collision as minuscule.
Mr. Schonberg was equally dismissive, although in 1969 five sailors on a Japanese ship were injured by space debris, probably of Russian origin. He cited the 1997 case of an Oklahoma woman who was unharmed after being hit in the shoulder by a small piece of blackened, woven metallic material, part of a propellant tank from a Delta II rocket launched the previous year.
He suggested three ways to counter low-orbital debris, suggesting that a passive approach that avoids contact with debris might prove briefly effective. A more active approach, however, might be to blast larger objects with lasers or bombs, although that approach is likely to spawn thousands of smaller pieces in its turn.
Finally, Mr. Schonberg suggested an operational approach, in which spacecraft might fly backward, avoiding head-on collisions, or massive shielding, protecting astronauts and hulls from high-speed, high-density particles.
“We cannot do nothing,” he concluded. “The reality is that it is going to get worse and worse. You have to be smarter about how you build things. Go after the big stuff first. We need garbage collectors in space.
“NASA must design [equipment] to withstand impacts in orbit, but also must do risk assessments: Where is this is this going to come down? What is in its path? NASA must look after end-of-life requirements for satellites.”