Comet exploding over Russia

Sixty-five million years ago, the fifth and most recent mass-extinction famously brought an end to dinosaur kind. It occurred when a massive asteroid about 10 km in size impacted the Earth by the modern day Yucatan Peninsula. While it is certainly unlikely that Earth will be hit by an asteroid large enough to cause a mass-extinction event any time soon (experts predict odds of about 1 in 600,000), the topic of asteroid avoidance is taken very seriously by world governments and space agencies. Perhaps this is because modern humanity is no stranger to the perils of what comes from beyond the atmosphere. On June 30, 1908, for example, the Earth was taken by surprise in what is now referred to as the Tunguska Event. Out of nowhere, an explosion more than 100 times as powerful as the atomic bomb dropped over Hiroshima decimated 2,000 square kilometers of forest in rural Russia. Residents 35 miles away reported having been blown off of their feet. Most recently, in 2013, 1,500 people were injured after a meteorite exploded 12 miles above Chelyabinsk, Russia. Scientists did not see it coming. Since then, the topic of thwarting credible threats from medium sized space rocks (164-492 feet in diameter) has been the subject of many studies and proposals. The questions I pose are: is it possible to use nuclear weapons to thwart these threats? Can they be deployed effectively on short notice? Is this idea actually being considered?

Who is considering this?

In 2005, the United States Congress mandated that NASA develop strategies to detect and subsequently deflect or destroy incoming meteors that can potentially cause loss of life or serious damage on Earth. In March of 2007, NASA presented Congress with a detailed report outlining plans to coordinate with other government agencies to improve detection and response capabilities. The report concluded that nuclear scenarios are 10 to 100 times more likely to be effective against asteroids when compared to any non-nuclear option considered. It did express concern, however, that destroying the target could be potentially hazardous as the broken pieces might still head to Earth. To account for this, other options involving nuclear detonation should be considered. For example, computer simulations have suggested that detonating underneath the asteroid could potentially alter its path to miss the Earth depending on its distance and trajectory at the time. The significance of this NASA report is that they do in fact feel that nuclear weaponry is our best hope at thwarting these types of threats should we need to in the near future.

Feasibility and deployment:

Nine countries command a combined stockpile of 15,375 nuclear weapons, roughly 2,000 of which can be deployed on a moment’s notice. While these facts certainly have some frightening implications for mankind, perhaps they can save lives without every having to take one. These bombs vary in their yields and sizes and can be chosen based on which best suits the situation. Blast yield is not the biggest concern, as we have seen weapons with yields of 100 megatons of TNT developed before (The USSR’s Tsar Bomba). The current problem is with regards to delivery methods. Modern day Intercontinental Ballistic Missiles cannot feasibly be shot into space at an asteroid successfully, and the famous human sacrifice scene from the movie Armageddon is certainly not ideal. According to researchers at Iowa State University, deflection is not possible if

Tsar Bomba

we are given short (several weeks) notice of an impending collision. Fortunately, they are not without a potential solution. They pitched a design for what they call a Hypervelocity Asteroid Intercept Vehicle (HAIV). With this idea they managed to solve two key problems: first, that the bomb would be far more effective if denoted inside the asteroid rather than on the surface and secondly that a high speed impact my diffuse the nuclear warhead by failing to ignite. They solved them with a two piece spacecraft. The first piece would smash into the asteroid, creating a crater. It would be followed by the nuclear warhead which would detonate in the crater immediately before a disarming impact. The lead researchers, Brent Barbee and Bong Wie, claim that $500 million is needed to test it, and so far it has gone unfunded. NASA has acknowledged the idea however, and has expressed enthusiasm at the idea of further collaboration.

Conclusion: 

Getting hit by asteroids is not something that should keep us up at night, but the thought that we can use one of our thousands of nuclear weapons to save us in a doomsday scenario is quite captivating. This is not science fiction, and it will be interesting to see what progress is made on this front in the years to come.

Note: Pictures themselves are links to sources.