LONDON, 6 September 2006: In the event of an Armageddon-like asteroid collision with Earth, a new system of deflecting asteroids – named Don Quixote, after the legendary knight – is being developed to ‘lance away’ foreign bodies that might be on a collision course with Earth.
Asteroids can pass uncomfortably close to Earth. One with a diameter of 500 metres, known as Apophis and weighing nearly 1,000 million tonnes, is expected to pass within 30,000 kilometres of Earth in 2029 – scaled down, that’s similar to a fly buzzing past your ear.
That’s the good news. The bad news is that astronomers are concerned that Apophis could pass through a gravitational ‘keyhole’ that could cause it to crash into Earth in 2035, 2036 or 2037. Among known asteroids, Apophis has the highest rating on the Torino scale, a scale used to measure the risk of an asteroid impact.
It is believed that 2029 will be the first time in human history that such a large object has passed near enough to our planet for it to be seen with the naked eye. The chances of Apophis (named after the ancient Egyptian god, the Destroyer) hitting Earth are only one in 6,250; that’s a 99.98 per cent chance that it will miss. But if it did hit, the impact would be 65,000 times greater in force than the atomic bomb dropped on Hiroshima in 1945.
Now, a consortium led by the UK-based QinetiQ group – the UK’s largest independent science and technology company – has won a 450,000-Euro (A$750,000) contract to design a satellite mission that could one day be used to deflect an asteroid threatening our world. The European Space Agency (ESA) will assess the resulting mission design proposals from the QinetiQ team and two other consortiums awarded similar contracts, before selecting the preferred design in early 2007.
After that, the ESA expects to award further contracts to build and implement Don Quixote. Later, an asteroid tens of millions of kilometres from Earth – one that doesn’t present a danger to us – will be selected as a target for testing the asteroid deflection system.
“As a space scientist, this is the kind of mission that you dream of being involved in,” said Sima Adhya, a member of QinetiQ’s Don Quixote team. “While the likelihood of a major asteroid collision with Earth is slim in the near future, such an eventuality would be of truly global significance.”
QinetiQ’s team will involve two spacecraft in their Don Quixote mission. The first, an orbiter called Sancho (named after Quixote’s trusty servant), will orbit the target asteroid, measuring its position, shape, mass and gravity field with great accuracy over several months.
The second craft, an impactor spacecraft will then smash or lance into the asteroid at a relative speed of 36,000 kilometres an hour. Sancho will image the impact and continue to monitor the asteroid’s position in order to determine the deflection caused by the impact.
The ESA has been addressing the asteroid problem for some time. In 1996, the Council of Europe called for the ESA to take action and contribute to a “long-term global strategy for remedies against possible impacts”.
Recommendations from other international organisations, including the United Nations, followed. In response, the ESA commissioned a number of threat evaluation and mission studies. This preliminary phase was completed in July 2004 when a panel of experts recommended pursuing the Don Quixote asteroid deflection concept.
Asteroids – most of them stony, but some containing iron and nickel – are believed to be matter left over during the formation of our solar system more than 4.5 billion years ago. Tens of thousands of asteroids, most no bigger than boulders, are known to be orbiting the sun in a vast belt between the orbits of Mars and Jupiter.
Throughout their history, Earth and its neighbouring planets have been like sitting ducks in a cosmic shooting gallery. A glance at our moon shows the scars left by thousands of collisions with asteroids and comets. In fact the moon is thought to have been created when part of the early Earth was ripped away in a cosmic impact with an object the size of Mars.
Earth also has scars, but most have been hidden by vegetation or eroded by geologic processes such as rain and wind. About 170 major impact sites have been identified across the globe. The most recent large asteroid to hit us was in 1908 when a 100-metre-wide mass of red-hot rock and rubble exploded over Siberia’s forests, setting fire to million of trees.
Few outside scientific circles took the threat posed by near-Earth objects seriously until 1980. Then, Luis and Walter Alvarez published a study based on geologic evidence that theorised that an asteroid or comet impact 65 million years ago caused the mass extinction of two thirds of all plant and animal life on Earth. Objects that size are thought to hit Earth about every 100 million years.