Olympic medals from space carry a warning for us all

By Bob McDonald, Quirks & Quarks

Olympic gold medal winners will receive a second medal this Saturday that contains a piece of the large meteorite that lit up the skies over Russia a year ago. Meanwhile, the United Nations is calling for efforts to ramp up preparations for the next object to hit the Earth.

A huge fireball streaked across the morning skies over the city of Chelyabinsk, just east of the Ural Mountains, on Feb. 15 2013. Images of the meteor were captured by things like dashboard cameras, and through those videos scientists were able to calculate that the object was about the size of a large house, weighed 10,000 tonnes, and exploded in the air with a force many times greater than a nuclear weapon.

Fortunately, the explosion took place very high up in the atmosphere. Even so, shock waves shattered windows for kilometres around, injuring more than 1,000 people and causing more than $30 million in damage. 

Pieces of the asteroid that fell to the ground were scooped up by scientists and collectors for analysis, and were found to be from a typical asteroid that had been roaming through space between the orbits of the Earth and Jupiter.

To commemorate the anniversary of the event, small pieces of the space rock have been embedded in seven medals that will be distributed to Olympic gold medal winners on Saturday. 

These medals will make unique souvenirs for the Olympic athletes, but those pieces of the rock that fell from the sky are also a reminder that the Earth is a moving target for thousands of other objects out there that could strike at any time. 

And we don't know where most of them are.

For years NASA has run the Near Earth Object program, which has systematically catalogued more than 10,000 objects larger than half-a-kilometre wide. Interestingly, these larger "dinosaur-killers" or "city-destroyers" are not the biggest threat. The survey has shown that none of them is heading our way any time soon - although there will be a couple of close passes.

The bigger threat comes from the smaller objects, such as the Chelyabinsk event, that are harder to see with current telescopes and therefore show up without warning.  

That's why scientists gathered in Vienna this week for a meeting of the Scientific and Technical Subcommittee of the United Nations Committee on the Peaceful Uses of Space.
The group agreed that the threat of unseen objects hitting the Earth and causing damage to urban areas is real, so an important step toward protecting ourselves from future strikes is to form an Asteroid Warning Network. 

This would be an array of dedicated telescopes on the ground and in space that would search for threatening asteroids and calculate the time and place of a future strike. Canada has already launched NEOSSAT for this purpose, but more instruments are needed.

The group also suggests facilitating an international effort to construct purpose-built rockets that could be sent out, on short notice, to deflect an incoming asteroid away from the Earth. (Blowing it up is not a good idea, because you would end up with thousands of objects hitting the Earth over a wider area instead of just one.)

The athletes who win gold this Saturday will be thankful to have reached the podium. As they look at their meteorite fragment, they should also be thankful that this one was just a close call.