Should Earth's close encounter trigger asteroid avoidance research?

After yet another narrow encounter with an asteroid the size of an airship earlier this week, do we need to pay more attention to technology that could protect our planet and its inhabitants from these turbo-charged cosmic fireworks?

Asteroid 2005 YU55 - which is 400m in diameter - raced past Earth at 30,000mph on Tuesday, reaching its closest point (only 201,700 miles away) at 23:28 GMT. Scientists claimed that if the asteroid had hit Earth it could have wiped out an entire city or caused a 70ft tsunami had it landed in the ocean.

The asteroid, which was first spotted by Arizona University in 2005, swung between the Earth and the moon, and is said to be the closest asteroid to Earth in 200 years. So, has this near miss been a lucky one?

Scientists and politicians who decide to talk seriously about collisions with asteroids are often regarded as cranks. When former Lib-Dem MP Lembit Opik said we needed to invest in asteroid-avoidance technology in 1999 he was widely dismissed as being a bit of an oddball.

However, there are 374 near-Earth objects (NEOs) on NASA’s radar, all of which have the potential to collide with our planet in the next 100 years.

On average, a 10km diameter asteroid strikes the Earth every 26-30m years, while every hundred years there is a Tunguska class (100m-diameter) asteroid impact. What’s worrying is that the last one, which wiped out the dinosaurs, occurred 65m years ago, so you could say we’re overdue.

Scientists claim they are usually aware several years in advance of any large NEOs heading in our direction and during this period they can take the necessary actions.

Apparently, the trick is to gently nudge the asteroid out of the way instead of the preferred disaster movie approach of attempting to blow it to smithereens, which according to NASA would only add to the problem by creating scores of smaller earth-bound asteroids.

Here in the UK, Researchers at Strathclyde University’s engineering department are looking at a number of methods to keep asteroids at bay should they head our way, and there are some intriguing approaches to the problem.

As you might expect, one of the simplest ways to deflect an asteroid is to use a kinetic impactor, such as a spacecraft. Alternatively, a nuclear blast detonated near the surface could also produce the desired effect by vaporizing part of the surface and nudging it off course with the reaction.

A slightly more obscure approach is to use a space mirror that focuses solar energy onto the surface of the asteroid, as a child would with a magnifying glass and a leaf. The concentrated heat sublimates the surface material and creates jets of gas and dust, which reduce the weight of the asteroid and ultimately cause the asteroid’s path to deviate.

Similarly a drilling machine, or something to that effect, could collect material from the asteroid and catapult it into deep space, thus reducing the weight of the asteroid and causing its path to deviate once again. Another slightly bizarre idea is to use propulsion technology, as seen on spacecraft, to thrust the asteroid off course.

All these ideas are great and could potentially save millions of lives, although as with many technologies, an ability to propel objects rapidly through space could have a worrying flip-side. In his book Pale Blue Dot, celebrated science writer Carl Sagan warned that any method capable of deflecting potential impactors away from Earth could also be used to divert non-threatening objects toward the planet. Indeed, our planet’s history of genocidal political leaders led Sagan to conclude that Earth is at greater risk from a man-made impact than a natural one.