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On February 15, asteroid 2012 DA14 will pass within 22,000 miles of Earth: less than a tenth of the distance to the Moon.
Although this 45-meter rock has a zero percent chance of hitting us,
near-earth asteroids in general raise a number of interesting scientific questions.
What makes the difference between a near-miss and an impact?
How would we navigate a spacecraft around an asteroid in the future?
And what can we learn from the asteroids themselves?
To answer these questions, NASA is sending the OSIRIS-REx spacecraft to another near-earth asteroid designated 1999 RQ36.
When it arrives in the year 2018, OSIRIS-REx will study a property called the Yarkovsky Effect,
where the Sun's illumination of a rotating asteroid can change its direction over time.
As the asteroid rotates, the sun heats one side of the surface.
Once that side rotates away from the sun, however, it radiates the heat into space.
This can act as a sort of mini-thruster that slowly changes the asteroid's direction,
potentially making the difference between a near-miss and an impact.
OSIRIS-REx will also study the gravitational properties of asteroids, providing useful insights for follow-up visits.
Because asteroids have a small and variable gravitational pull,
new techniques will need to be developed to help spacecraft approach and fly around them.
Finally, OSIRIS-REx will take a direct sample of the asteroid and return it to Earth.
This could perhaps yield the most interesting results of all,
as 1999 RQ36 is thought to be a leftover from the formation of our solar system.
By studying its composition, scientists will be looking at a snapshot of the solar system
taken four-and-a-half billion years ago, one that may even hold clues to understanding our own origins.
So although 2012 DA14 will miss us when it flies by in February,
NASA isn't missing an opportunity to study near-earth objects,
and OSIRIS-REx will provide the best results yet when it visits 1999 RQ36.
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