Bruce Willis in Armageddon, about to blow himself up (spoiler alert!) to save the world from an asteroid
If you think about them long enough, comets can be a cause for concern—they’re pretty enough streaking through the sky, but if one ever flew straight at Earth, we’d presumably be in a lot of trouble. But how likely is that? Should we actually be worried, or could that anxiety be better directed elsewhere, such as toward our personal appearance and poor life choices?
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On Monday, Australia’s Siding Spring Survey—the only dedicated comet/asteroid-tracking program of its kind in the Southern Hemisphere—closed due to a lack of funding. Brad Tucker, an astronomer at the Australian National University in Canberra, told the Guardian that this new blind spot could put Earth at risk. Which sounds like something we should potentially be worried about.
I called Tucker for a thorough explanation.
Brad Tucker next to the Uppsala Telescope, which was used in the Sliding Spring Survey. Photo courtesy of Brad Tucker
VICE: So what’s your link to the Siding Spring Survey?
Brad Tucker: Well, Mount Stromlo Observatory runs two sites—Mount Stromlo, where I’m an astronomer, and Siding Springs, which is their dark site. My interest is in finding exploding stars. But one of the things I do is work with the public in outreach and education. I’m involved with the Siding Spring Survey by trying to attain funding for Robert McNaught, who’s running it, to keep the survey operational.
One of the things I was doing last year was lobbying in Washington, DC to try and get funding for the project. NASA were actually the ones operating the Siding Springs Survey in Australia.
So what happens now that the survey’s been closed down? We’re left with a big blind spot in the Southern Hemisphere?
That is certainly part of the issue. There are surveys operating in the Northern Hemisphere, and NASA has invested in some new projects. There was a meteor explosion over Chelyabinsk, Russia, last year, which most people remember. That was partially due to budget cuts at NASA, and specifically cuts to the Near Earth Object Program, which funds a lot of asteroid detection surveys. A lot of these surveys have been cut and it snuck through.
The explosion in Russia actually triggered the US government to start refunding some of these surveys. The problem with Siding Springs is that when the NASA money was reduced, it was the first to be cut due to being out of sight and out of mind in Australia. There are no other programs running in the realm of what Siding Springs was doing—so yes, there’s now a blind spot in the Southern Hemisphere.
A meteor exploding over Chelyabinsk, Russia, in February 2013
So NASA’s chosen to focus almost exclusively on the Northern Hemisphere?
They have. There’s a project in Hawaii called ATLAS that was funded, and there are a few other ones, but really there’s nothing in the Southern Hemisphere. There are a few surveys looking for them, but they’re not efficient at finding the objects we need to find. It’s easier to find large asteroids, say 100 kilometers (62 miles) wide. But for comet and meteors that are five to 50 meters [16 to 32 feet) wide—which won’t destroy a planet, but will do a lot of damage—you need a survey like the Siding Springs Survey, or something like it, to be productive at finding them.
So you’re saying these detection surveys need to be seen as an early warning system, rather then a purely academic pursuit?
Definitely. We’re interested in studying asteroids and comets for scientific value—for instance, (the unmanned spacecraft) Rosetta is landing on a comet, and that’s very cool and exiting. But tracking asteroids and comets is no different to tracking cyclones, hurricanes, or tornados. There’s a clear interest in studying the science behind it, but really it’s about trying to allow for an early warning system. And it shouldn’t be seen as a research endeavor or the responsibility of a university. There needs to be global view. There needs to be a change in how we view it.
Have we come close to impacts recently?
Quite often a survey will find a small to medium-sized object measuring a few meters or feet. They have, largely speaking, passed by the Earth. But we’re talking skimming it—around 20,000 to 30,000 kilometers[12,000 to 18,000 miles] above the Earth. Given how large space is, that’s actually relatively close. We’re talking about the distance between the Earth and the moon. Quite a few of these have happened recently. We do expect something like the size of the Chelyabinsk meteor to hit Earth once every ten to 20 years. That’s not too often, but when something like that occurs you’re essentially detonating a nuclear bomb in the atmosphere.
That doesn’t sound good.
Yeah, if you detonate a nuclear bomb over a city… it’s pretty self-explanatory. But if we know it’s coming we can get people out of the way. For example, the comet Siding Spring was detected by a survey 22 months before it could potentially crash into Mars. When Robert McNaught discovered it, it had a possible trajectory that could see it smash into Mars. If you have a 22-month notice that something is headed for Earth, there’s a lot of investigating that can be done to find possible solutions.
Could we ever hope to alter a comet’s course if it was headed for Earth?
Well, you have Hollywood clichés, such as Armageddon. However, while its clichéd, there is a good example in John F. Kennedy—who, in the 1960s, challenged the US to land on the moon, and within a few years the space program had been revolutionized and we had landed someone on the moon. If you have a challenge and some pressure, things can get done, so it’s not out of the realm of possibility that we could avert an impact.
Is there anything in the works to that end?
There are some projects we’re working on to deal with man-made space junk floating around Earth. The Australian government has been investing in a program to track small objects with a laser thousands of miles above Earth, then tune the laser so we can deflect objects. We’re practicing on small man-made things, but if it works there’s no reason why it can’t be ramped up to target larger objects.
A few years ago, China demonstrated they could send a missile and destroy one of their defunct satellites. People are working on these things. If there was something potentially dangerous, astronomers would no doubt work with the military and defense agencies to come up with a solution. We’re a creative bunch, but again it goes back to the fact that we have to know it’s coming. We’re not just having fun naming comets; it serves a purpose. And people need to realize that, as if we’re not looking then we’re blind.
A time sequence of Shoemaker-Levy 9’s collision with Jupiter
How destructive are events like the Chelyabinsk meteor? Could we be looking at extinction?
Well, what actually happens is that these meteors essentially do a belly flop. Imagine someone traveling fast as they dive into the water—you have that initial impact when you run into a surface, and that’s what these meteors do. They run into the atmosphere at tens of thousands of miles an hour, then explode in the air and rain down debris. But it depends—in 1994, comet Shoemaker-Levy 9 crashed into Jupiter and we were able to monitor it with telescopes.
It was pretty cool, but that created a hole 7,000 miles wide—the size of Earth. Life can certainly be wiped out by these kinds of objects. Smaller objects can impact, create a crater, block out the sun, and create an extinction-level event that way. Large ones aren’t as big of a concern, as we largely know where they are. It’s smaller asteroids that won’t destroy the Earth, but can cause bad localized damage, which are of concern.
Is there a protocol if you discover an asteroid like that? I’d imagine putting the news out into the public sphere would cause mass panic.
It would certainly cause panic. So, for example, with the comet Siding Spring, Robert McNaught discovered it, followed it to establish its trajectory, and it was announced to other surveys who followed it for a couple of months. Its size and orbit were well defined, so we knew where it was going to go. There are a large number of things to establish before we announce it widely. We’re careful with what we do. But again, this kind of thing requires funding for telescopes to operate, and we can go from there.
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