Could the Apophis Asteroid Strike Earth in 2036?

Apophis Course in 2036

A 2009 animation (click image for animation on JPL's website) shows the window of uncertainty about where/when Apophis will cross Earth's orbit on Sunday April 13, 2036. There is only a small chance of collision, but calculations don't rule it out.
A 2009 animation (click image for animation on JPL's website) shows the window of uncertainty about where/when Apophis will cross Earth's orbit on Sunday April 13, 2036. There is only a small chance of collision, but calculations don't rule it out. | Source

Too Close for Comfort

On December 26, 2004, the world's eyes were fixed in horror and compassion on the appalling tragedy happening around the Indian Ocean, where a tsunami triggered by a massive earthquake claimed the lives of over 200,000 people.

Astronomers, meanwhile, were grappling with a future horror: a 1 in 37 chance that the newly-discovered asteroid Apophis could hit Earth on Friday, April 13, 2029, raising 800-foot-tall tsunamis if it struck the ocean, or wiping out a city-sized area if it struck land. In addition to millions of casualties, a terrestrial strike could produce a year of no winter like the Tambora volcanic eruption of 1815.

On December 27, 2004, astronomers breathed a sigh of relief: a previously-unrecognized photo of Apophis from a few years earlier let them plot its course more precisely, ruling out a 2029 impact. However, it will come so close — 18,000 miles away — that it will be inside the orbits of Earth's geosynchronous satellites.

Luckily, those satellites orbit the Earth's equator, whereas Apophis' tilted angle of approach means it will not cross that plane. So we are not expected to have our satellites shaved off by a close buzz. But Apophis should briefly be visible to the naked eye in Europe, Asia and Africa, which is pretty incredible for a rock as opposed to a shiny metal satellite.

Unfortunately, Apophis will be back, and we're not out of the woods quite yet.

Apophis in 2036: Here It Comes Again

When Apophis wings by Earth in 2029, Earth's gravity will alter its course slightly. It's extremely difficult to predict this course alteration precisely without knowing the asteroid's exact shape and spin: it's like guessing a baseball's path before the bat hits it. At the moment, the window of uncertainty includes a remote (1 in 250,000, downgraded from 1 in 45,000) possibility that Apophis could impact Earth in 2036 (or, even less likely, 2053).

When the uncertainty window was greater, astronaut Rusty Schweickart started lobbying NASA to launch a mission to Apophis to get an accurate prediction of its course as soon as possible. It's much easier to alter an asteroid's course a few decades ahead of impact. The Russians are still thinking about plans to deflect it, which might not be a bad idea as a trial run for the next Near Earth Orbit asteroid that threatens us. The only problem with a dress rehearsal is the risk of accidentally sending it towards us due to a miscalculation, glitch or programming error like the last several failed Russian space probes.

Tunguska Explosion, 1908

In 1908, a 120-foot meteor exploded over Siberia, leveling 800 square miles of forest, lighting up the sky, and sending out a heat wave that threw people from their chairs and burned them 40 miles away. Asteroid Apophis is about 885 feet in diameter.
In 1908, a 120-foot meteor exploded over Siberia, leveling 800 square miles of forest, lighting up the sky, and sending out a heat wave that threw people from their chairs and burned them 40 miles away. Asteroid Apophis is about 885 feet in diameter. | Source

The Risk Is Low: Why Worry?

The risk of Apophis hitting Earth in 2036 is tiny. But if it did hit, the effects could be catastrophic, worldwide, and last for decades, or even centuries. If it hits land, it could wipe out a small country and throw up enough of a dust cloud to block sunlight for several years, which could play havoc on climate and the world's food supply.

If it hits ocean, it could send several hundred-foot-tall tsunamis crashing around all the low-lying cities of the Atlantic or Pacific. Even with a few years' warning, there's no way to mitigate the economic impact of losing, say, New York and London, or the port of Los Angeles. The early projected risk area for impact also includes oil-producing countries in South America, and perhaps the Panama Canal.

Even though the possibility of Apophis hitting anywhere is extremely low, the result of such an impact is so devastating that we need plans in place. We should have more information in the next year or so, as Apophis emerges from the sun's glare and allows ground-based telescopes to take new sightings and get a better fix on which way it's spinning and exactly where it's headed. This is one case where even a foot or two now can make a big difference 20 years from now.

Jupiter After Being Hit By Comet

This is what Jupiter looked like in ultraviolet after a fragmented comet, Shoemaker-Levy 9, slammed into it in 1994. Many of those scars are larger than Earth. This is why blowing up an asteroid may not be the best approach.
This is what Jupiter looked like in ultraviolet after a fragmented comet, Shoemaker-Levy 9, slammed into it in 1994. Many of those scars are larger than Earth. This is why blowing up an asteroid may not be the best approach. | Source

Could Apophis Be Deflected?

Apophis can probably be deflected, if world governments decide that the threat is serious and commit to a deflection mission soon enough. If we wait until 2029, when Apophis swings by, it will be too late to alter its course enough to miss in 2036.

The only technology we've tested that works is to ram it with a spacecraft at least a decade ahead of of impact, creating a minute course change that would add up to enough deviation to miss Earth in 2036. NASA successfully hit a comet with the Deep Impact mission in 2005, so we know it can be done.

Any other asteroid-deflection plan is merely theoretical, and we won't have much time to test theory before putting it into practice. Space is still not 100% routine. The U.S. and other countries have had their share of failures. Intercepting a small, irregularly-shaped asteroid, tumbling and moving at thousands of miles an hour, is tricky even for modern space technology.

One asteroid defense method that's popular in Hollywood, but which probably would not work in reality, is to detonate the asteroid with nuclear or conventional bombs. It's unlikely that explosives would reduce an asteroid to harmless dust: there are just too many unknown factors like its shape, weak points, varying composition, and so on to plan a controlled demolition. Such an attempt would be far more likely to break an asteroid into fragments, some of which might be too large to burn up in the atmosphere. This 1994 photo of Jupiter shows what happens when fragments of a comet hit a planet.

Our best bet is to place something on or near the asteroid that gives it continuous small nudges (like a rocket nozzle or a jackhammer that thumps it continually), or slamming a spacecraft into it. Each of these methods would create a small deviation that would add up to a miss with enough lead time— hopefully a decade or more. Since a major mission like this would have to be organized, funded, designed, and built from scratch, we would be cutting it very close with Apophis if it turns out something needs to be done.

[Recommended Article: Five Plans to Head Off Killer Asteroid Apophis in Popular Mechanics Magazine]

It's a good thing we already know about it— what if it hadn't been spotted in 2004?

Apophis (Apep) the Serpent

Discoverers  Roy Tucker, David Tholen and Fabrizio Bernardi of Kitt Peak Observatory named the asteroid Apophis, Greek name for the Egyptian god of destruction Apep, also a villain in the TV series Stargate (Tucker and Tholen are reportedly fans).
Discoverers Roy Tucker, David Tholen and Fabrizio Bernardi of Kitt Peak Observatory named the asteroid Apophis, Greek name for the Egyptian god of destruction Apep, also a villain in the TV series Stargate (Tucker and Tholen are reportedly fans). | Source

A Valuable Wake-Up Call?

I'm not very worried about Apophis hitting Earth in 2036; at this points the odds are pretty good that we'll just be treated to a couple of dramatically close fly bys. That's actually exciting: telescopes are going to get a great look at an asteroid at extremely close range, and some space agencies may be able to get a probe up there and take samples, if they hurry!

I'm more interested in Apophis as a learning experience and trial run. It's close enough to galvanize public interest and (I hope) encourage space agencies to prepare and test asteroid-deflecting methods, so that we'll be ready if and when a direct threat arises. There are a lot of Near Earth Objects out there, and sooner or later, one is going to hit us and cause major destruction, unless we prepare for it. Unlike volcanic eruptions and most natural disasters, asteroid impacts are one threat that we can avert, if we have several decades to prepare.

Let's take this chance to learn all we can and get ready. And let's also be crossing our fingers that U.S. budget cuts don't shut down the Aricebo Observatory, whose highly accurate radar measurements are expected to help astronomers lock down Apophis' precise path once it emerges from the sun's glare. Near Earth Object Detection is one NASA mission where budget cuts to save money now may wind up costing us bigtime in the future.

NASA / JPL Video on Apophis Discovery and Threat

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Comments 12 comments

physics-boy profile image

physics-boy 4 years ago from England

Very interesting hub. I would like to hear your views on using a gravitational tug to pull the asteroid off course. Do you think it's a viable idea?

From a physicist's point of view, I'm also glad you didn't go for the "OMG We're all gonna die!" type hub! Far too many around with the 2012 hysteria!

I hope to read more of your work!


Greekgeek profile image

Greekgeek 4 years ago from California Author

I think so, but I've forgotten nearly every bit of physics I knew, so I defer to your judgment! I generally trust space.com for space news, and here's an article on that theory, but it doesn't give many specifics:

http://www.space.com/1763-gravity-powered-asteroid...

The thing that concerns me about that method is that a 20-ton spacecraft sounds like a lot of work to build, and it would take a lot of thrust to get up there. It seems like every time we want to send a spacecraft away from Earth, to explore Mercury or Mars or Jupiter, we wind up having to do a number of slingshot orbits around this planet and that to get lined up and moving at the right speed. Apophis' 2036 encounter doesn't give us many years to fiddle with trajectories. But we've still got some time.

Then again, whichever method we use will require a lot of fiddling with trajectories and orbits to get a booster, thumper, tug, or whatever mechanism we plan to use in place. I don't have the training to know which would be the best approach; all I know is that we *did* manage to ram Comet Tempel with the Deep Impact probe. My money's on a method we've already tested at least once. But maybe better ways will be devised by the time we actually need them.

Confession: as you can tell from some of my articles, I'm fascinated by what I call "exciting geology" (and astronomy). However, I try to research reputable sources and temper my "holy cow!" reaction with actual facts. My parents are scientists, even if I'm a mythology buff. ;)


scottcgruber profile image

scottcgruber 4 years ago from USA

Great hub! Well-researched, well-written, and fact-based!

I like the gravitational tug idea as well. The only problem with it, or so I've heard, is that we don't yet have a launch vehicle that could lift it. NASA's SLS may not be ready in time. I wouldn't be surprised if the mission to save us from an asteroid launches on a SpaceX Dragon Heavy...


physics-boy profile image

physics-boy 4 years ago from England

All very good points. My personal concern with the gravitational tug, is that you have to be quick. Apophis will have to pass through a 'keyhole' in space to make an impact certain. What's harder to do? Miss a keyhole, or miss a planet?

I'm sure when and if the time comes, some brilliant person will have the answer. For now though, I agree with you. An impact into the asteroid might be our best hope!


ED80 4 years ago

Great Hub - comprehensive and well researched. Also my very first comment!

Another idea would be to build and launch a solar collector.

A big concave mirror could be made of aluminised mylar or similar and folded up for transport. It would be light and shouldn't need much in the way of support after it's been deployed. As long as it's roughly parabolic, the surface curve wouldn't need to be too accurate.

Sunlight would be focussed, directed on to a steerable plane mirror and pointed at the surface of the asteroid. The sunlight (if it's concentrated enough) would ablate the surface material, in effect creating a very, very low thrust rocket engine and gradually nudge Apophis into a different orbit. The only problem I can see apart from getting the thing to the asteroid in the first place would be to keep it in place. The effects of the solar wind could be significant with such a large area of collector.

Solar powered ion engines maybe?

Of course, as mentioned in Greekgeek's article, the sooner we start the better!

By the way, as an astronomer I hope I'm still around for the 1929 pass. (I'm 60) It should be awesome.


ED80 4 years ago

2029 even!


Maggie12 3 years ago

Perhaps we should worry more about the results of the close encounter rather than an actual hit. I would like to know what we could expect in say the earths axis changing because of a disruption in connection with this object.


Greekgeek profile image

Greekgeek 3 years ago from California Author

It's tiiiiiny compared to the whole earth, masswise, and gravitational impact decreases with distance. What happens when a baseball flies past you at 100 mph? Nothing, although it looks alarming. What happens when it hits you in the head? Serious damage at the point of impact. Same effect on a much larger scale, except that Apophis compared to the size of the Earth is smaller than a baseball compared to you. With asteroids, much like bullets, the danger comes mostly from their speed -- several thousands of miles per hour. Add to that the heat of entry, and you see why incoming meteors melt, fall to pieces or even explode.


Vin Chauhun profile image

Vin Chauhun 3 years ago from Durban

Fascinating hub ! Astronomers and NEO are not concerned so much with asteroids the size of Apophis but the smaller ones. These asteroids although small, are in their thousands and could still cause havoc, and are similar in size to the ones which caused the the recent Russian explosions


Greekgeek profile image

Greekgeek 3 years ago from California Author

Well, really, they're concerned with both. The Apophis-sized ones could wipe out most life on Earth, whereas the ones like the Russian meteorite, while locally catastrophic, will not impact the human race (or other life) on a large scale.

Unfortunately right now our technology is not up to finding all the ones the size of the Russian meteorite; small, dark and fast-moving rocks are just hard to spot unless you already know where to point the telescope. The bigger ones, though, we should be able to find soon enough to do something about them. We just need the sustained funding and the preparation to do it.


Vin Chauhun profile image

Vin Chauhun 3 years ago from Durban

the max rating for an impact for Apophis is 750 megatons[air-burst]...it would leave a crater roughly 3km wide. Population loss, that is just a guess, at the moment, between 10 mil and 25 mil. It all depends on the composition of the asteroid and if disintegrates on entering the atmosphere. The latest study on the Tunguska Impact show the heating effects on entering the atmosphere are much greater than thought.


Greekgeek profile image

Greekgeek 3 years ago from California Author

Yes, a very good point. It appears that Tunguska almost completely vaporized before it reached the surface, much like last fall's meteorite (which was smaller). And Apophis is much larger than either of them.

Luckily, it sounds like Apophis will almost certainly miss. That "almost" is still unsettling!

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