The chances of a wayward asteroid colliding worth seem to be more a case of ‘when’ rather than ‘if’.
In fact, dozens of tiny fragments bombard our planet all the time and burn up in our atmosphere. Once a year or so, a car-sized space rock will hit Earth and create an impressive fireball which is occasionally caught on camera.
Plenty of experts at space agencies and organisations around the world are constantly tracking asteroids out in the void of space to try and get an idea of any potentially hazardous ones coming our way.
Unfortunately, the International Astronomical Union (IAU) has revealed that it lost track of more than 900 near-Earth asteroids following its last official count.
The US-based organisation said that between 2013 and 2016 its Minor Planet Center (MPC) conducted an extensive search of objects orbiting around space. They found a total of 17,030 potential near-Earth asteroids.
It’s the MPC that is funded by Nasa and is tasked with identifying, tracking and working out the orbits of minor planets, asteroids, comets and other irregular ‘natural satellites’.
Worryingly, the team labelled 11% of that total (almost 1,900) as ‘initially unconfirmed’ – meaning their exact location was not known.
That’s a bit of a cause for concern. Asteroids could measure up to 3,200 meters wide and can be travelling at speeds of up to 45,000mph. Any kind of collision with Earth could be catastrophic.
The asteroid which killed the dinosaurs was believed to be more than seven miles wide, but space rocks don’t need to be this huge to cause some serious damage.
When a 20-metre-wide asteroid exploded in the skies over the Russian city of Chelyabinsk in 2013, the resulting ‘airburst’ caused by the detonating meteorite left about 400 people injured, with most wounds caused by shards of flying glass from windows smashed by the shockwave.
In 1908, 80 million trees were knocked down over an area of 800 square miles hidden deep in the Siberian forest when a meteor which was up to 190 metres wide crashed into Earth. If the object which caused this devastation had hit a populated area, it could have killed millions and razed a city to the ground.
The mysterious ‘Tunguska event’ was the largest asteroid impact in recorded history and caused an explosion 1,000 times more powerful than the bomb which destroyed Hiroshima.
Nasa and the European Space Agency are already hatching a plan to try and save us from any of these kinds of impacts.
This mission is called the Asteroid Impact Deflection Assessment (AIDA) and will attempt to redirect the smaller part of a double asteroid called Didymos. In the first stage of the mission, a spacecraft will smash into the space rock. Then a second ship will assess the crash site and gather data on the effects of the collision. Nasa is already working on a craft called Double Asteroid Impact Test, whilst Italy will send a cubesat satellite to monitor the action.
The ESA mission is called Hera and will perform a ‘close-up survey of the post-impact asteroid’ and gathere measurements such as the asteroid’s mass as well as the size of the crater left behind after impact.
‘DART can perform its mission without Hera – the effect of its impact on the asteroid’s orbit will be measurable using Earth ground-based observatories alone,’ said Ian Carnelli, who is managing the Hera mission.
‘But flying the two missions together will greatly magnify their overall knowledge return. Hera will in fact gather essential data to turn this one-off experiment into an asteroid deflection technique applicable to other asteroids. Hera will also be the first mission to rendezvous with a binary asteroid system, a mysterious class of object believed to make up around 15% of all known asteroids.
‘And our mission will test a variety of important new technologies, including deep space CubeSats, inter-satellite links and autonomous image-based navigation techniques, while also providing us with valuable experience of low-gravity operations.’
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