National Missile Defense and the Laws
of Physics
A blanket of space junk could threaten commercial satellites
By Nancy Ellen Abrams and Joel R. Primack
Santa Cruz, California--In all the debates about President George W. Bush’s plan to build a National Missile Defense shield, one critical fact is missing—a piece of basic physics that underscores why this is "a bad idea whose time has come." Simply stated, a war in space will encase the earth in a shell of whizzing debris that will last forever, making space near the earth highly hazardous for peaceful or military purposes.
Every bit of debris in orbit above about 500 miles will stay there for decades. All the "space junk" above 700 miles will remain for centuries, and anything a thousand miles out effectively is there forever. At present, we are tracking over nine thousand objects four inches in diameter or larger, and an estimated 100 thousand bits of debris larger than a marble are also in orbit.
The Bush administration wants to put portions of our missile shield such as Space-Based Lasers and thousands of "Brilliant Pebbles" space-based interceptors in the crowded near-earth orbit area. Such weapons violate the 1972 Anti-Ballistic Missile (ABM) Treaty, but last December President Bush told our Russian co-signatories we are abrogating the treaty.
This whole missile defense idea seems to have a life of its own because so many people have ignored basic, immutable laws of physics. Too many of us live in a Hollywood fantasy world where things blow up in space and the fragments quickly dissipate, leaving the clear, clean emptiness of space. In reality, the debris doesn’t dissipate after a near-earth explosion and the fragments continue circling in random orbits.
Paint chips, lost bolts, pieces of exploded rockets are already creating a cloud of tiny satellites, all traveling about 17 thousand miles per hour—10 times faster than a high-powered rifle bullet. A marble traveling at that speed would hit with the energy of a one-ton safe dropped from a three-story building. We can’t take a broom and bucket—high tech or low—to clean up the mess. Anything these "space bullets" hit will be destroyed, thus adding more debris. At some point, pieces will begin colliding, creating a chain reaction of destruction that will leave a lethal halo around Earth.
Operating satellites within this cloud of millions of tiny missiles would become impossible: no more Hubble Space Telescopes or International Space Stations. Even our communications and GPS satellites in higher orbit would be endangered. Meantime, this short-term, impractical and misguided space shield destroys the "Star Trek" dream we all share, to someday begin exploration, going boldly "where no man has gone before."
We don’t need a space war to create this catastrophe. Any country feeling threatened as we begin putting lasers and other weapons into space can simply launch a payload almost as elementary as a load of gravel to destroy our costly and sophisticated weaponry. And much of this metallic gravel and the weaponry fragments would stay in orbit. Is it inconceivable that someone like Saddam Hussein, who set fire to the oil wells in Kuwait, causing an environmental disaster with no military purpose, would hesitate to launch such gravel if he felt it was in his interest?
And whose fault will it be when we take the next step unilaterally, putting weapons in space despite the protests of even our closest allies? At any moment after that, this planet, so beautiful when viewed from space, will be blanketed in a cloud of metallic garbage, marking forever our cosmic arrogance and stupidity.
Nobel Prizewinning physicists, strategic analysts and technical experts have all said the technologies needed are absent or remain inadequate into the foreseeable future. The space shield also destabilizes the nuclear power balance sparking a spiraling arms race as China builds sufficient weapons to keep its minimum deterrent, causing India, then Pakistan to respond in kind. The project costs many billions. Abrogating the ABM Treaty destroys the cornerstone agreement that allowed nuclear weapons reductions, and, most tragic of all, our space shield doesn’t address the true threats to national security that are so obvious since September 11th.
Billons of dollars aside, the real cost of our missile shield should be measured on a cosmic scale. While a handful of defense contractors get rich on the project, and while George Bush fulfills Ronald Reagan’s Star Wars dream, we march ahead with little debate, blithely ignoring simple laws of physics, imprisoning our planet for all future generations in a halo of bullets.
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Nancy Ellen Abrams is a lawyer and writer. Joel R. Primack is a professor of physics at the University of California, Santa Cruz.