NASA has plans to test a planetary defense system that can divert asteroids away from Earth. They plan to test out their system on a near-earth asteroid, 2012 TC4, that will fly close to Earth on the 12th October.

NASA is very excited indeed to be able to test out their ARM project for the first time. And on a real target. If successful it will provide a vital advancement in our ability to protect the planet. Not to mention provide vital experience for a manned mission to Mars in the 2030's. Exciting indeed!

"This is the perfect target for such an exercise because while we know the orbit of 2012 TC4 well enough to be absolutely certain it will not impact Earth, we haven’t established its exact path just yet.

It will be incumbent upon the observatories to get a fix on the asteroid as it approaches, and work together to obtain follow-up observations than make more refined asteroid orbit determinations possible." says Paul Chodas from NASA's center for Near Earth Object Studies.

The intended target

2012 TC4 is a small asteroid that was identified in October of 2012. At this time, the asteroid sped past Earth at about one-fourth of the distance from the Earth to the Moon. It is estimated to be about 10 to 30 meters in size. 2012 TC4 has also not been seen since its discovery, until now. In 2013 an asteroid that hit Earth's atmosphere near Chelyabinsk, Russia, in February of 2013 was about 20 meters across.

At that size, plus the fact that it will miss us, we shouldn't be overly concerned. For an asteroid to be a real threat to Earth, it needs to be big enough. Most estimates believe over half a mile in diameter. To be a mass extinction event it would need to be about 60 miles (just over 96 kilometers) in diameter, some scientists believe. But smaller ones around half a mile in size (800 meters) in diameter would certainly ruin your day, according to a planetary science professor at MIT.

Smaller asteroids will simply burn up in the Earth's atmosphere.

Because of its size, 2012 TC4 has been too faint to see for the last 5 years. It started its approach towards Earth this summer and large telescopes have been used to re-establish its precise trajectory. Their new observations will be used to pin down our knowledge of its orbit and narrow the uncertainty about how close it will come to Earth this October.

How close will it come?

Pauk Chodas, the manager of the Center for Near-Earth Object Studies (CNEOS), says we don't need to worry. He has assured everyone that the orbit of 2012 TC4 is known well enough to be sure it won't hit Earth.

Phew, that's is a relief.

From their calculations, the asteroid will pass no closer than 4,200 miles (6,800 kilometers). It will also pass no farther than 170,000 miles (270,000 kilometers). The later is about two-thirds the distance from the Earth to the Moon. These estimates are based on seven days of tracking 2012 TC4 after its original discovery. It was tracked by the Panoramic Telescope and Rapid Response System (Pan-STARRS) on the island of Maui, Hawaii.

2012 TC4's predicted orbit. Source: Tomruen/Wikimedia Commons

NASA has identified multiple candidate asteroids to further test their system in the future prior to its official launch in the 2020's. Since it's official announcement in 2013, NASA, through its Near-Earth Object Observation Program, has cataloged over 1000 potential near-Earth asteroids as potential targets.

From this large catalog, they have prioritized four of them as good candidates for Asteroid Redirect Mission (ARM). They anticipate that many more will be discovered over the coming years as NASA study their velocity, orbit, size, and spin before decide on targeting them.

The planetary defense system

NASA has been developing an asteroid-redirecting planetary defense system to keep our planet safe in the future. This is a first of a kind mission for spacecraft to land on asteroids and then re-direct them into a stable orbit around the moon. Though they intend to test it this month, it is officially touted to launch in 2020.

The entire mission will use robotic craft to not only redirect the asteroids but also collect multi-ton samples from their surface. From the 2020's onwards they also plan to have astronauts accompanying the mission to explore the asteroid and also collect samples. NASA's Asteroid Redirect Mission (ARM) is part of their plan to advance new technologies and spaceflight experience needed for a human mission to Mars in the 2030's.

NASA hopes that their robotic missions will demonstrate the viability of the system as a technique to deflect potentially hazardous asteroids away from Earth in the future. Not only will this initiative help keep us all safe from a dinosaur-killing type event but it will provide incredible advancements in our capabilities for future space flight. The ultimate plan for the planetary defense system is to learn enough from the experience to enable a manned mission to Mars in the 2030's.

This world is protected

The lack of certainty around 2012 TC4's exact trajectory is actually a great boon rather than a problem for NASA. It makes the asteroid an even better candidate than others to test their system. Real life is very different to theory and as such the uncertainty around exactly how this asteroid will perform provides a perfect test bed to see how their system can perform under pressure.

Although very unlikely in the foreseeable future, if this mission is successful it will mean we can be more confident in deflecting more dangerous asteroids in the future.

"Scientists have always appreciated knowing when an asteroid will make a close approach to and safely pass the Earth because they can make preparations to collect data to characterize and learn as much as possible about it," said Michael Kelley in a statement.

"This time we are adding in another layer of effort, using this asteroid flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid threat." added Kelley.

Well, that is great news. NASA's planetary defense system should let us all sleep a little sounder at night. Safe in the knowledge that of all the threats to life on Earth, it seems we've crossed one off the list. Plus we get one step closer to visiting the Red Planet. Win, win.