[LUCID LIVING #12]  Nudging the Home of the Little Prince: Protecting the Earth from Impacts

By Piet Hut

This week, exactly fifteen years ago, two astrophysicists and two astronauts started a non-profit organization to protect the Earth from asteroid impacts.  I was one of the two astrophysicists.  We chose the name B612 Foundation in honor of the home of Antoine de Saint-Exupéry's The Little Prince.

Rusty Schweickart, Clark Chapman and I were visiting Ed Lu's home in Houston, when we decided upon the name of our newly minted organization, following an earlier informal workshop at Houston's Johnson Space Center, organized by Ed and me.  In the story, B612 was the name of the asteroid the Little Prince lived on before visiting the Earth.  In our meeting we focused on preventing the opposite: instead of him visiting us, having his asteroid visit the Earth; or other asteroids like his.

Impact_event.jpg

Asteroid impacts have played a major role in at least some of the mass extinctions on Earth, including the one, 65 million years ago, when the dinosaurs died out.  The killer asteroid that hit the Earth at that time was about ten kilometers in diameter, hitting the Earth at a speed of tens of kilometers per second, releasing an energy equivalent to a hundred million megatons of TNT.  The explosion upon impact was thus more than a million times more energetic than the largest hydrogen bomb ever tested on Earth, and more than a billion times more powerful than the nuclear weapons that destroyed Hiroshima and Nagasaki.

During the last few decades, surveys have been conducted to look for similarly large asteroids in the area in the solar system near the orbit of the Earth.  Fortunately, the results have excluded the possibility of the Earth being hit any time soon by an asteroid larger than a few kilometers in diameter. We seem to be safe for at least the next few centuries.

asteroid impacts are the one type of natural disaster that we can accurately predict

The situation is much more worrisome when looking at smaller asteroids, between a hundred meters and a kilometer in diameter. Extrapolations from the small fraction of asteroids discovered so far in this range, tell us that we can expect there to be well over a hundred thousand such asteroids that regularly cross the orbit of the Earth.  Each of those could easily destroy a city, since an impact would liberate more than a Megaton TNT equivalent.  And even today, such an impact could happen with preciously little advance warning.

When we gathered in Ed's living room, one of our concerns was that the rate of discovery of Earth-crossing asteroids was far lower than what we would like to see.  We cannot accurately predict the occurrence of earthquakes or vulcano outbursts or any other natural disasters that are caused by effects on Earth itself.  However, we can very accurately predict impacts of an asteroid, even decades in advance, as long we have found it, and observed it well enough to calculate its orbit accurately.

Artist's concept of a gravity tractor, a concept proposed by Ed Lu and Stan Love to gently change the orbit of an asteroid by letting it slowly "fall" toward a hovering spaceship nearby.

Artist's concept of a gravity tractor, a concept proposed by Ed Lu and Stan Love to gently change the orbit of an asteroid by letting it slowly "fall" toward a hovering spaceship nearby.

Our second concern was that we would like to see a ready ability to change the orbit of an asteroid, soon after the discovery of it being on a collision course with the Earth.  We concluded that it was time for the opposite of target practice. Rather we would like to see us demonstrating the ability to slightly nudge an asteroid away from its target, if that were the Earth.  So we argued for off-target practice to make sure we would be prepared, if the need were to arise.

When discovered early enough, it is not that difficult to nudge the orbit of an asteroid by pushing it ever so gently. Changing the speed in its orbit by less than one millionth, only 1% of 1% of 1%, a decade or so in advance, can be enough to prevent it from hitting the Earth.  That shows how tiny a target the Earth is -- how hard it is to hit the Earth, and how easy it is to sabotage such a potential hit!

The main problem that we ran into, during a year of study before we decided to incorporate as a non-profit organization, was that nobody was in charge of protecting the Earth.  For one thing, within NASA there are powerful lobby groups advocating missions to the major planets, while the "little guys", the asteroids, have a hard time getting the limelight.  Even more importantly, NASA considers itself to have a purely research mission, thus arguing that the military should be in charge.  Meanwhile, the military argued, effectively, that East-West and North-South tensions on Earth were already enough to deal with, and was not interested in the third dimension, Up-Down threats.

So there was nobody planning to do off-target practice on asteroids, fifteen years ago.  Our solution to our goal of nudging an asteroid, as a demonstration project, was an indirect one.  We decided to try to nudge the public to nudge congress to nudge NASA to nudge an asteroid.

nudging the public to nudge congress to nudge NASA to nudge an asteroid

The basic idea was to start with a campaign to increase public awareness, sufficiently large to reach the ears of members of Congress.  Given that the US Congress has the power to instruct NASA how to allocate tax dollars, Congress members could help focus NASA on the threats of asteroid impacts, instructing them to take those more seriously.  And a good place to start, we argued, was a demonstration that, for the first time in history, we could actually change the orbit of a heavenly body.

A lot has happened in the intervening years, which is documented on the B612 foundation website.  As I will discuss in a future blog post, our goals have shifted somewhat, but our basic mission is still to protect the Earth from the utterly preventable disasters that could be caused by asteroid impacts.

Piet Hut is President of YHouse, Professor of Astrophysics and Head of the Program in Interdisciplinary Studies at the Institute for Advanced Study in Princeton, and one of the founders of YHouse.

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