This commentary originally appeared in the April 25 issue of SpaceNews Magazine.
There are over a half million pieces of human-made material in orbit around our planet. Some are the size of school buses, some the size of BB gun pellets. They all had a function at some point, but now most are simply space debris littered from 100 to 22,000 miles above the Earth. Yet, all behave perfectly according to the laws of physics. Many in the space community have called the collision hazard caused by space debris a crisis.
Popular culture has embraced the risks of collisions in space in films like Gravity. Some participants have dramatized the issue by producing graphics of Earth and its satellites, which make our planet look like a fuzzy marble, almost obscured by a dense cloud of white pellets meant to conceptualize space congestion.
Unfortunately, for the sake of a good visual, satellites are depicted as if they were hundreds of miles wide, like the state of Pennsylvania (for the record, there are no space objects the size of Pennsylvania in orbit). Unfortunately, this is the rule, not the exception, and almost all of these articles, movies, graphics, and simulations are exaggerated and misleading. Space debris and collision risk is real, but it certainly is not a crisis.
So what are the facts?
On the positive side, space is empty and it is vast. At the altitude of the International Space Station, one half a degree of Earth longitude is almost 40 miles long. That same one half a degree at geostationary orbit, some 22,000 miles up is over 230 miles long. Generally, we don’t intentionally put satellites closer together than one-half degree. That means at geostationary orbit, they are no closer than 11 times as far as the eye can see on flat ground or on the sea: That’s the horizon over the horizon 10 times over. In addition, other than minute forces like solar winds and sparse bits of atmosphere that still exist 500 miles up, nothing gets in the way of orbiting objects and they behave quite predictably. The location of the smallest spacecraft can be predicated within a 1,000 feet, 24 hours in advance.
Since we first started placing objects into space there have been 11 known low Earth orbit collisions, and three known collisions at geostationary orbit. Think of it: 135 space shuttle flights, all of the Apollo, Gemini and Mercury flights, hundreds of telecommunications satellites, 1,300 functioning satellites on orbit today, half a million total objects in space larger than a marble, and fewer than 15 known collisions. Why do people worry?
Sir Isaac Newton said it best: “F=ma”, force equals mass times acceleration. An object the size of a marble, traveling at 17,500 miles per hour will hit with the force of a 400-pound motorcycle going 60 miles per hour! The International Space Station, too big to fit onto a football field, can easily be demolished by a piece of debris no larger than a tennis racket.
So what’s the answer? Space situational awareness. Once we can track all objects larger than a golf ball in Earth orbit and can make small adjustments to active satellite orbits we can avoid many of the worst collisions. However, space situational awareness is expensive, very expensive, and the smaller the object tracked the more expensive it becomes. There are many things space agencies, warfighters and entrepreneurs want to do in space, many more things than for which there are funds available. So, every dollar, euro, ruble or yuan spent on space situational awareness is money not spent on doing things in space that create science, build businesses, protect strategic assets and create strategic advantages.
Many experts are focused on negotiating international ‘space debris rules of the road’ that could potentially reduce the risk of collision by strictly limiting debris creation and through self-monitoring. There are committees at the UN and even interagency groups within the U.S. government focused on negotiating and implementing just such space ‘rules of the road’ aimed at reducing debris and the risk of collision. The problem is that most spacefaring nations, and those who wish to be, don’t want to conform, and don’t want to be limited. New entrants, both public and private, start the space exploitation process in the least expensive, and therefore messiest way, which causes more debris problems. Experimentation results in messy lessons, and countries are happy to avoid collateral problems in space, unless it impedes their access to all the prestige and benefits of space exploitation. Not to mention maintaining secrecy for their own national security objectives. It is simply not realistic to count on agreements alone to handle the space debris and collision risk problem.
Humans are in space to stay, and over time, more and more actors will populate the stage. Many collisions in space can be avoided, but in order to do so, we will need a robust space situational awareness capability and the capability to respond and maneuver assets in space quickly. No amount of hysteria at home or jawboning abroad will eliminate the need for monitoring, avoiding and someday, cleaning up space debris. It’s time to get on with it.
Mark Albrecht is chairman of the board of USSpace LLC. He was head of the White House National Space Council from 1989 to 1992. Paul Graziani is CEO and founder of Analytical Graphics, an Exton, Pennsylvania, company that develops software and provides mission assurance through the Commercial Space Operations Center (ComSpOC).