Asteroid 2005 YU55 - Radar image taken in 2010 - Credit NASA/Cornell/Arecibo

At about 1,300 feet across, this roughly spherical, charcoal-black space rock would give us quite a wallop if it were to hit the Earth. A bit larger than a typical football stadium (including a bit of the parking lot), if this asteroid were to strike Earth's ocean a powerful tsunami result, and if it struck land, a city-sized hole in the ground. Not to mention a lot of fireworks.

Fortunately, the asteroid's trajectory is well known, and poses no threat to us (at this time).

Asteroids and comets that can come close to the Earth—Near Earth Objects, or NEOs—have been a concern to life on Earth since it began. From the end of the "era of heavy bombardment," when the young Earth endured frequent impacts by asteroids and comets, large and small, debris leftover from the formation of our Solar System still meets up on occasion with our planet. Craters from past large impacts can be found today, camouflaged by millennia or eons of erosion, sedimentation, and tectonic activity—Earth's scar-healing processes.

The crater left by a 10-mile-sized asteroid (that would be the stadium, parking lot, and the surrounding major metropolitan area) believed to have contributed to the demise of the dinosaurs lies hidden and buried at the tip of the Yucatan Peninsula: the Chicxulub crater. (No, Chicxulub is not an all-women car service station….) Other craters masquerade as round lakes and other landscape sculptures.

And some are quite candidly impact craters, like "Meteor Crater" near Winslow Arizona. When I was in the Peace Corps in Cameroon, my house was 2 kilometers from a round lake that is apparently a meteorite crater. (That's Lake Ejagham; check it out at 5.750000 degrees north latitude and 8.987778 degrees east longitude.) Lake Ejagham is about a kilometer in diameter and 60 meters deep (not counting sediment infill). The meteorite that created it wasn't nearly that big—probably the size of a very small house….

Now imagine an object the size of asteroid 2005 YU55 striking Earth, land or sea. It wouldn't cause our demise—except for unfortunate bystanders—but it would create havoc around ground zero.

And even though 2005 YU55 will not hit the Earth on November 8, all NEOs that pass that close (within the Moon's orbit) are considered near misses, and are scrutinized by the "eyes of the Earth": radio dishes and optical telescopes across the planet.

Chabot's own NEO observing team will aim the eye of our 36-inch telescope, Nellie, on the asteroid and measure its trajectory, contributing to our knowledge of this particular NEO's orbit and improving our ability to predict its future passes.

This time, it's a mere field goal.

A few weeks ago, this asteroid came really close to hitting Earth.

Called “2009 DD45”, the asteroid was estimated to be around the same size as the one that exploded in the atmosphere near the Podkamennaya Tunguska River in remote Siberia on June 30th, 1908, flattening 80 million trees across eight hundred square miles of remote forest. Of course, if an asteroid of this size were to hit a city or in an ocean offshore from a populated area, tens of thousands of people would likely die.

Then, just as the last of the night sky observers were completing their collective sighs of relief, on March 17th, 2009 another Tunguska-class asteroid, 2009 FH, passed by about 53,000 miles from Earth. Thankfully, neither of these asteroids actually hit us. But astronomers didn’t even observe 2009 DD45 until 4 days before its closest approach. It's orbit was calculated and it was determined that it would miss the Earth. But it's likely that asteroids of this size are fairly frequently buzzing by the Earth. And until recently, most of them have been undetected.

In 1998, NASA started the Spaceguard Survey which set out to discover 90% of those Near Earth Asteroids (NEAs) 1 km in diameter and larger. An impact by an asteroid this size would likely cause global destruction and an end to much of life as we know it so it’s definitely reassuring that 10 years after its inception, the Spaceguard Survey had found about 80% (CK) of them. But unfortunately, once we’ve found them, there’s still no international concensus or infrastructure in place in how to deflect or destroy them. But the Survey is limited by its mandate to find those mass extinction-sized asteroids as well as by the size and sophistication of the telescopes that are dedicated to searching the skies.

As former Apollo 9 astronaut, Rusty Schweickart said in a recent phone conversation, "in the process of finding the big ones, you also find a bunch of small ones, and the smaller ones are obviously far more numerous than the large ones." But it will take many more resources and new telescopes to continue searching for and tracking the smaller ones. And unfortunately, once we’ve found them, there's still no international consensus or infrastructure in place in how to deflect or destroy them. Raising awareness and building alliances amongst governments and space agencies is Schweikart's current "mission". He founded the B612 Foundation and Association of Space Explorers to tackle these goals on different fronts.

The message that I hope is conveyed with the Asteroid Hunters TV segment is that we are not immune from asteroid impacts here on Earth. Rusty Schweikart puts it best in a portion of his interview that didn’t make it into the final program:

"Well, asteroids and comets are good news and bad news, you know? But for them we wouldn’t be here, and on the other hand, if we don't actually take some action now, at some point we won’t be here anymore, because there's no question that we will be hit by asteroids, and we’ll probably be hit by, we would be hit by comets as well. Unless, we use the technology that we have and the brains that we have in order to protect the Earth from asteroid impacts, and we can do that. We can basically now, with current technology, assure that no asteroid ever hits the Earth again. That can do any serious damage."
-Rusty Schweikart

Here's a little exercise from Rusty that you can do to get a sense of what we know today about exactly what's out there:

• Go to: neo.jpl.nasa.gov/risk
• See two tables, the first table says "Recently Observed Objects" and the table below says "Objects not recently observed." You’ll notice in the bottom table that Apophis is the 4th one listed.
• Click on "Apophis". At the top you see a bunch of boxes, like the diameter at .27 km, or 270 meters.
• Down below that you see 3 lines, those are the 3 potential impacts. The first one is April 13, 2036. Go over to the right on that line you'll see the column "Impact Probability" is 2.3 x 10-5 – click on that. So there is the probability, 1 in 43,000 of that particular impact.
• Now if you go back to the main table you can do the same thing with every single one of those lines.
• Now go to the very top of the page and hit "Discovery Statistics." Scroll down to a blue and red graph "Known Near-Earth Asteroids". This shows the discovery rate beginning back in 1980 going up to almost current time. Notice the knee in that curve in 1998 – that’s when the Spaceguard Survey began.
• Scroll down to table just below the graph and look across that table to the far right side, to see that a a total of 6166 NEOs (of ALL sizes) have been discovered.

Rusty concludes that, "…what we really care about is not only the things that large, we care about things that can hurt us. Things that can hurt us go down to 40 to 45 meters or so. Instead of there being 940 of them, there are more like 600,000 of them. So the new charge for NASA, which they have so far ignored, is to find 90% of the objects 140 meters and larger by 2020. You can't reasonably set a goal to find everything down to 40 meters because it's just beyond the capability of telescopes and the money available. So NASA, working with Congress, set the goal at 140 meters. Now nevertheless, when you are looking for 140 meter objects, it’s going to take bigger telescopes than the ones to find a kilometer. Therefore we are going to find many many smaller objects as well. So 10 to 15 years from now, instead of that number on the far right hand column being 6000, it will be 1 million."

Watch the Asteroid Hunters television story online.

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