Taking Aim at Errant Rocks
Remo got his Ph.D. in quantum optics in 1979 after developing the mathematics that would make lasers more powerful, stable and efficient. His journey through graduate school took longer than usual because he taught at several universities, traveled quite a bit and undertook extensive research in astrophysics, looking in particular at how the composition of asteroids and meteoritic fragments affects their size. He became absorbed in this line of study, even though it set him back on his dissertation. At the time, Remo wasn’t thinking about near-Earth objects, bodies in the solar system whose orbits may one day intersect with Earth’s. He was more interested in the solar system’s origins, viewing each extraterrestrial rock he came across as “a poor man’s space probe.”
Upon graduating from the Polytechnic Institute of New York, he decided he could best maintain his independence, and carry out the most innovative work, by forming his own company. His firm, Quantametrics, developed technology for high-powered space lasers, working for clients like the “Star Wars” missile defense program and NASA, which relies on lasers for certain types of astronomical observations. The holder of about 20 patents, Remo continued his research on meteorites on the side, and both strands of work brought him into contact with scientists at various national labs.
Owing to his combined expertise, he spoke at a 1992 Los Alamos National Lab conference on asteroid defense. This was the first major meeting to explore options for intercepting near-Earth objects that threatened Earth, and it brought about a rare commingling of astronomers and weapons lab researchers.
The civilian scientists who attended, notes astronomer Clark Chapman of the Southwest Research Institute, “went expecting it to be unusual, and we weren’t disappointed.” There was talk of “fringe stuff like antimatter weapons,” he says, “and other outlandish proposals.” Edward Teller, the father of the hydrogen bomb, spoke of developing a nuclear device 10,000 times more powerful than anything yet devised.
However, most of the ideas discussed at Los Alamos focused on deflection, giving an asteroid a push to dislodge it from a dangerous course. The most straightforward way to do this is the “kinetic energy” approach — simply ramming a spacecraft into an asteroid. But during the conference, Remo was struck by a realization already familiar to attendees more experienced in the subject: When you’re talking about deflection, nothing can match the energy density of nuclear weapons.
Pound for pound, nuclear explosives — which derive their power from runaway chain reactions in their radioactive fuel — carry about a million times the energy density of chemical explosives. If you need to move a big rock (more than 3,300 feet), or if you’re in a hurry to move a smaller rock (about 330 feet), nukes may be your best shot. The devices could be armed once they’re out of Earth’s atmosphere, and the intervention can occur far enough from our planet to keep any fallout or explosion risk well beyond the biosphere — the goal being to save the world without harming it.
Of course, the energy density of a nuclear device is not the whole story. Remo also realized during the conference that we can’t predict how an asteroid will respond to a nuclear blast without a clear understanding of the object’s material properties. Contrary to what intuition might suggest, a crumbly, carbonaceous asteroid can actually be nudged far more readily than a solid, iron-filled body. The biggest unknown at the time was how much momentum the nuclear radiation would impart to the asteroids — how big a push the blast would provide. “That question can only be addressed experimentally, not theoretically,” Remo says.
He resolved to figure out just that, and for many years Remo used the proceeds from his laser work to privately support his asteroid studies. (He eventually received funding from the National Nuclear Security Administration and other federal agencies.) “John’s experiments were the first to use real extraterrestrial objects — a collection of meteoritic material of various kinds,” says Barry Shafer, a physicist formerly based at Los Alamos. And Remo was just getting started.