Orbital traffic cop: Mark Matney ’85

Protecting orbiting spacecraft and earthbound humans from runaway space trash is a full-time job for Mark Matney ’85.

Orbital traffic cop: Mark Matney ’85

Astronomer-physicist Mark Matney '85 holding a metal plate that was perforated by a small metal sphere traveling at typical orbital velocities. (Photo courtesy NASA)

Orbital traffic cop: Mark Matney ’85

Protecting orbiting spacecraft and earthbound humans from runaway space trash is a full-time job for Mark Matney ’85.

Ask astronomer-physicist Mark Matney ’85 if he thinks an American will ever get hit by a piece of plummeting space junk, and as the lead scientist for NASA’s Space Debris Modeling program, Matney will surprise you by pointing out that one already has.

Then he’ll tell you the story of Lottie Williams — a 44-year-old postal worker who was walking through a Tulsa, Okla., park early one morning in January 1997 when a visitor from outer space suddenly tapped her on her left shoulder.

Lottie whirled to confront the tapper, but found no one there.

As NASA officials would later confirm, she’d been lightly (and harmlessly) swatted by a piece of space junk — a cloth-like, five-inch-long section of fiberglass from a tumbling Delta II rocket’s disintegrating fuel tank. Only a few minutes before, the fire-blackened hunk of space debris had come plunging back into the earth’s atmosphere, after falling out of its earth-circling orbit and streaking toward rural Texas at an initial speed of about 10,000 miles an hour.

Fortunately for the startled Williams, who retrieved the tiny chunk of space debris and still owns it, the long trip through the earth’s atmosphere had slowed the tiny fuel tank fragment to a relative crawl. And although her space junk encounter would soon land her on several network news shows, it did no injury at all.

As you might expect, Williams’ unusual story is music to the finely-tuned ears of Matney — the former TCU astronomy and physics whiz (as in Phi Beta Kappa) who now directs one of the most exotic-sounding operations to be found at NASA’s Johnson Space Center in Houston. “Fortunately for all of us, the mathematical odds that a human will be injured by falling space debris are extremely remote,” says the 48-year-old scientist, who since 2003 has been in charge of the giant space agency’s Space Debris Modeling program, which now keeps track of more than 16,000 pieces of globe-circling space junk.

While pointing out that Williams’ adventure in 1997 was “a huge statistical aberration,” and that she “holds the dubious distinction of being the only person we know of ever hit by re-entering space debris,” Matney likes to point out that the odds against any particular individual being struck by space junk are actually trillions to one.

“We really don’t recommend that people walk around wearing hard hats, or anything like that,” he adds. “By and large, we think we’ve got a pretty good handle on the space debris that now encircles the planet, and we’ve been able to determine mathematically that the risks to humans from falling orbital objects are quite small.”

Photo Although Matney’s NASA team of half a dozen astronomers and physicists keeps a close eye on space objects that seem in danger of falling out of orbit (such as the agency’s six-ton Upper Atmosphere Research Satellite, UARS, which broke into 26 pieces and then splashed harmlessly into the Pacific late in September), his specialized task force actually faces a much greater challenge in making sure that human-launched space objects don’t crash into each other while circling the earth.

“One of our toughest tasks is trying to monitor the more than 16,000 objects — including many no longer functioning satellites and fuel tanks — which are moving along at speeds of 15,000 miles an hour or more,” says Matney. “These larger objects can pose a significant threat to both robotic and human spacecraft, such as the International Space Station (ISS).”

Along with these 16,000 larger-size debris objects, says Matney, there are now hundreds of thousands of smaller objects, ranging in size from four inches in diameter (about the size of a softball) to the size of a small pebble. These fragments are also typically traveling at speeds of 10,000-15,000 miles an hour, or about 10 times faster than an average bullet.

“Let’s face it, we’ve got a lot of rush-hour congestion going on up there,” says the orbital traffic cop, adding that accidental collisions between orbiting spacecraft and space junk could easily wind up costing tens or even hundreds of millions of dollars for the nations involved.

In order to prevent these hugely expensive collisions (such as the 2009 crash with the Russian satellite Kosmos 2251 that destroyed the U.S. communications satellite Iridium 33 in an exploding fireball), Matney and his crew of data-crunchers spend their workdays designing mathematical models aimed at creating orbital “traffic advisories,” which national space agencies can then use to keep their spacecraft out of harm’s way.

Photo“One of our biggest jobs is to try to figure out where all the major populations of space junk are located,” says Matney, who enjoys working on the complex algorithms required to draw maps of the worst traffic snarls. “I think the greatest difficulty we face,” he adds, “is that we have to use partial data most of the time, and then extrapolate from there.

“When you can only see part of the picture, it isn’t easy to create the mathematical-statistical models you need to tell you where all these objects are headed.”

Another important assignment for Matney, who spent 11 years working on orbital debris for Lockheed Martin prior to joining NASA in 2003, is to help the U.S. space agency educate the world about the need to begin preparing strategies now for dealing with the ever-increasing traffic jam in the “low-Earth orbit” regions of space.

“Right now, we still have enough room to maneuver up there,” he says thoughtfully. “But in the coming decades, we’ll face increasing hazards and increasing costs if we don’t start establishing methods for reducing the level of space pollution. Sure, you can design spacecraft with extra armor for protection during collisions — heavily armored space ships like the ISS, launched in 1998 — but the extra weight means greatly expanded costs.

“If we’re going to maintain our weather and communications satellites and our other low-orbit resources in the decades ahead, we need to begin thinking now about ways to reduce the amount of space junk we’ve put up there since the late 1950s.”

To support his argument, Matney points to an eye-opening chart recently prepared by his colleagues at NASA’s Orbital Debris Program Office. The chart shows that the major nations of the earth have fired more than 3,400 payloads into space since the first Russian Sputnik roared off into the heavens back in 1957. Over the last half-century, those various robotic spacecraft and human-piloted vehicles have left behind a staggering 16,108 pieces of larger-sized space junk — all of which are ceaselessly orbiting the planet and all of which will one day be falling back onto terra firma.

“We’ve made quite a mess up there, there’s no doubt about that,” says Matney with a sigh as he heads back to his data sheets and his algorithms at the NASA complex in Houston. “Really, a lot of people don’t realize how frequent and routine space launches have become over the years. The tools they provide are extremely useful, of course. Just think of how much our communications satellites have helped with things like GPS and cell phones and hurricane warnings in advance — all of which we now take for granted.

“But there’s also a price to be paid for our success in space, and part of that price will be dealing with the huge amount of low-orbit clutter we’ve created over the years. One way or another, we’re going to have to clean up our mess — and the sooner we get started, the easier it will be to make sure we don’t end up causing disastrous traffic-congestion problems for generations yet to come.”

On the Web:
NASA Orbital Debris Program Office