Asteroid Threat

Space is not an uneventful void. On a cosmic time and space scale, over millions of years and millions of miles, there are soundless, smell-less, visually-undetected threats to humankind, threats that might develop over several lifetimes but suddenly cross into our currency, thus changing our lives.

Using visible or invisible waves of energy, generally heat from the asteroid or the Sun’s reflection, only a small percentage of such objects in space – mainly asteroids – are detected. Consequently, by the time undetected physical threats approach our atmosphere, it is too late.

Our most recent shock to Earthly senses was a sixty-foot-diameter boulder, which had been dislodged from the asteroid belt over 290 million years ago, joining an Apollo class of asteroids in near-Earth orbit (regularly crossing the Earth’s orbit) – that is, until something disrupted its orbit and spun it inexorably toward and finally into Earth’s atmosphere (orbit track). Reaching our atmosphere, it glowed brighter than the Sun, witnesses feeling its intense heat. Its ear-shattering explosion sent shockwaves that damaged over 7,000 buildings and injured 1,500.

The Chelyabinsk meteor in 2013 was an asteroid event that happens perhaps once every sixty years. That asteroid was some sixty feet in diameter and its angle of approach was 20 degrees, travelling at 43,000 MPH before exploding at 97,000 feet over Russia. Research scientists estimate that a forty-five degree angle of approach would have caused it to explode at 40,000 feet and yielded 10 times the blast effect. In fact, in a major population area, it is estimated that such an event could yield tens of thousands of deaths.1

By contrast, the asteroid that ended the dinosaur reign some 65 million years ago was over 30 miles in diameter and impacted the earth at more than 250,000 MPH. As an earth-impact event, its frequency of occurrence is once every 65 million years.

The late Eugene Shoemaker of the US Geological Survey estimated that an event the size of the nuclear weapon destroying Hiroshima occurs about once a year. Such events are rarely noticed because much of the Earth is covered with water and if occurring over land, it’s often unpopulated. Furthermore, the explosions generally occur at relatively high altitudes, with the result of a huge flash and a thunderclap but no damage. Distinctive impact event frequencies – airburst and earth — are indicated in Wikipedia (Asteroid Impact Frequencies).

More recently, the B612 Foundation, a planetary defense group, estimated that a decent-sized metropolis could be reduced to smoldering ruins by a boulder less than soccer-field size. Its CEO, Ed Lu recently estimated, “There is a 30% chance of an asteroid with a 5-megaton impact hitting Earth during our lifetime.” In testimony before the Senate last year, Ed said that research indicated that if all near-Earth orbit asteroids of Chelyabinsk’s size or larger were discovered, we would find over a million.

B612’s threat estimates come in part from data collected by a global network of sensors designed to detect nuclear explosions. During the decade it was an operating network, its sensors detected 26 asteroid blasts equivalent to at least 1,000 tons of TNT, four greater than the Hiroshima A-bomb. The house-size asteroid off of Indonesia in 2009 was more powerful than three Hiroshima bombs, with the Chelyabinsk asteroid explosion even bigger.

A modicum of NASA money has funded research that would help detection and deflection of near-earth objects, considering that in our solar system, there are some 600,000, many capable of being dislodged from an orbit between Jupiter and Mars. Currently, like the Chelyabinsk asteroid before its untimely appearance over Russia, nearly 10,000 near-Earth objects (NEO) are known to cross the orbital path of Earth in their own orbit around the Sun.

Detection systems are costly, but a few systems are promising in their cost and their effectiveness. The B612 Foundation, through efforts by former astronauts, Ed Lu and Rusty Schweickart, is sponsoring the Sentinel Mission which plans to build, launch, and operate an infrared space telescope to find and track hundreds of thousands of threatening asteroids. Other research projects seek to use existing technology like tiny smart phone circuit boards.

One such detection study involves producing millions of microchip sensors, each with an antenna, a solar cell, and tracking sensors, called chipsets, which are tracked with smart phones. A “cubeset” will be launched in a vehicle headed for the International Space Station, ejected into orbit, where it will dispense 180 chipsets into a scattered array like NECCO wafers. Each chipset will cost $20 to build.

One of the most promising deflection plans involves a huge spider-like robot with 6 legs, several solar panels and the ability to grasp a troublesome, sometimes tumbling, low-gravity asteroid with those 6 legs. This would be accomplished first with 6 wheels that would position it for solar panel access to the Sun, to stop tumbling, if that’s a problem, and also for most effective steerage of the asteroid. Then drills in each leg would bite into the asteroid to anchor the robot on the low-gravity boulder.

These spider-like robots would use the power of the Sun to divert the asteroid away from an Earth-collision trajectory, perhaps with thrusters from an ion propulsion system. Eventually a robot army could transfer from asteroid to asteroid, as threatening asteroids are discovered.

Of all of the threats to humankind’s future, the B612 Foundation has calculated wayward asteroids to be the most serious, considering that in 2013 Chelyabinsk was hit by one, which at a steeper angle would have done great damage in a metropolitan area, and then the next year, 2014RC passed within 21,000 miles of Earth. Neither one was discovered soon enough before approaching Earth.

The key is first detection many months beforehand, and then have the capability to divert them, if given enough time.

  1. Man vs. the Universe, How to Kill an Asteroid. Science Channel. []
James Hoover is a recently retired systems engineer. He has advanced degrees in Economics and English. Prior to his aerospace career, he taught high school, and he has also taught college courses. He recently published a science fiction novel called Extraordinary Visitors and writes political columns on several websites. Read other articles by James.