Asteroid to Make Closest Recorded Pass to Earth

unassimilatible writes "A 100-ft diameter asteroid will make the closest (26,500 miles, or about 3.4 Earth diameters) pass of earth ever detected in advance today, NASA reports. Asteroid 2004 FH's point of closest approach with the Earth will be over the South Atlantic Ocean. Using a good pair of binoculars, the object will be bright enough to be seen during this close approach from areas of Europe, Asia and most of the Southern Hemisphere. While we are in no danger this time, it is good to know NASA's LINEAR guys are on the job, for when that Death Star-sized object pays us a visit."

Comments

Huh?

[dolo666]

"100-ft diameter asteroid" ... "that Death Star-sized object"
The Death Star was bigger than 100 ft dia! Maybe the miniature Lucas used was that size? :-) If LINEAR can pick up 100ft dia objects, anything bigger would be easy. Now I can feel safe until this one veers off due our shoddy ozone, and smacks down on my hometown.

Re:Huh?

[Fishstick]

Really. Being hit by a planetkiller that causes extinction of humans on the earth doesn't worry me. Who will miss us?

My biggest fear is that we will be hit by a not-quite planetkiller that will cause enough devastation to ensure the survivors live in misery for the rest of their (short) lives. That would suck.

Lucky

[Space cowboy]

According to the article there are normally 2 of these every year. It seems a bit tongue-in-cheek to say "The important thing is not that it's happening, but that we detected it" [Chesley]. They were lucky, that's all.

It *will* give them a chance to study the thing as it passes, since all the other ones were only detected after they'd gone (and presumably therefore couldn't be easily studied). If it's close enough to see with binoculars, it ought to be possible to resolve quite well in a good optical 'scope.

The other point I guess is that it's only 100 ft across (why not 30m ?) so it would have burnt up on entry into the atmosphere, but still, good to know about these things. An asteroid that big would make quite some bang on entering the atmosphere, I reckon :-)

Simon

Re:Lucky

[lukewarmfusion]

I remember reading about NASA's (and others') ability to detect these in advance... apparently this science has improved immensely over the last ten years.

But you do bring up a good point - if this object would have hit Earth, would it have burnt up, or would something dangerous remain?

Much smaller items hit Earth all the time - they don't get burnt up completely. Of course, many end up the size of maybe pebbles or baseballs...

Re:Lucky

[Slowtreme]

Would this really burn up? Skylab was less than 50ft long and hollow inside. Many of it's parts made it to the ground. I'd image a solid rock hitting our atmosphere at that speed would not lose too much mass on the way in and do some pretty significat damage if it hit near a populated area.

This one is flying pretty darn close for comfort.

Re:Lucky

[pe1rxq]

A solid mass entering the atmosphere would explode due to the pressure differences inside.
You get really big fireworks.

Jeroen

Re:Lucky

[sponge_absorbent]

it depends on the composition of the object and the angle and speed at which it enters the atmosphere.
I imagine that if it were a roughly spherical, dense, metallic object it would have a good chance of hitting the surface.

Re:Lucky

[Eevee]

Except if you read the NASA site, they use metric measurements, then give the "stupid american" measurements. You have to blame the Associated Press for not using metric when they reported this on the wire.

For those too lazy to click the link, this is the relevent quote from the press release.

...is roughly 30 meters (100 feet) in diameter...

Re:Lucky

[Catbeller]

A hundred foot object would punch through at many miles per second, so time to ablate would be short. A few seconds in the atmosphere at most. (The scenes in Armaggedon of rocks tumbling down were silly; in reality you would barely have time to blink before you were dead from the shock wave. FLASH: blink: dead) It may break up into fragments, which doesn't help much in the kinetic energy department, IE we still get hit with tens of thousands of tons at many miles per second.

Little objects like a grapefruit weren't a hundred feet wide. A hundred foot wide ball or potato-shaped rock could break up and would rain down millions of grapefruits at n miles/sec., if it broke up at all. Think of a hundred thousand ton blast of buckshot at 5 miles/sec. Or a 100K ton cannonball at the same speed.

Big mess.

Re:Lucky

[mikerich]

you are an idiot, right? pressurce differences inside a solid mass?

No he's not.

It depends if it solid rock. many stony asteroids are apparently spongy having once contained volatiles that have subsequently been lost to space. These fragile objects will disintegrate in the atmosphere as atmospheric deceleration crushes them.

Its for this reason that carbonaceous chondrite meteorites - the black ones with the exciting organic compounds are relatively rarer on Earth than their abundance in space would suggest. We're regularly encountering them, they just don't make it through to the surface.

Having said that a 25m chunk of anything disintigrating in the atmosphere would produce a blast in the high kiloton, low megaton range. One of these smashing into a city would be a catastrophe.

And they seem to be more common than we think - there is obviously Tunguska in 1908, but then there are reports of something exploding over the Amazon basin in the 1930s, the more than 100 small impacts that hit Sikhote-Alin in Russia in 1947 and the most recently uncovered biggish impact at Wabar in Saudi Arabia - a Hiroshima-sized explosion in either 1863 or 1891 (there is no agreement on the date, since Arabic scholars saw two bright meteors heading in that direction on different dates, it's only recently that scientists have been able to determine the relative youth of the Wabar craters).

Best wishes,
Mike.

Re:Lucky

[flewp]

But if the object is broken up, it increases surface area, and the smaller parts will burn up at a faster rate than as if it were a whole piece, wouldn't they?

Also, wouldn't these smaller parts have the potential to have a much slower terminal velocity? Sure, it might not have time to slow down to terminal velocity speeds, but you never know.

Of course, it all depends on where it breaks up. If it's a loosely enough packed ball of rubble, the gravity of earth may break it up before it even reaches our atmosphere. Also, depending on where it breaks up, parts may go into the ocean that would have landed on land and vice versa.

BTW, I have absolutely no idea if what I'm saying is in any way based on fact or even following any form of logic.

Re:Lucky

[Catbeller]

The rock would be moving at something like Mach 30 - at any rate at miles per second. The atmosphere is around 60 miles deep. It would be a blink. For it to be faster than a blink, for you, you'd have to know it was coming, be focused on the spot in the sky, and follow it. 60 miles/7 mps (supposing)= 9 and a fraction seconds to boom. Then you'd wait for the supersonic shock wave. Depends on how close you are to the impact(s). If you don't know it was coming, you'd maybe see a short flash of light, followed by death in a second or at most a minute or two. As for my Armageddon reference, I belive I was dead on. If you were in Manhattan, ground zero, you'd have seen a brief flash followed by a supersonic shock wave in less than a couple of heartbeats. It'd be like nuclear detonations, only without the radiation. As Heinlein said in The Moon is a Harsh Mistress, just like a sparks from a hammer. Just a really BIG hammer.

And shock waves aren't sound, so they can move quite quickly. The air itself would be moving at hypersonic speeds, mixed with vaporized solid matter from ground zero. Dust, really fast dust, and gravel.

And if...

[ForestGrump]

it was going to hit the earth and cause a massive extinction of the human race...
I highly doubt we will be told about it. Instead, our world leaders will gather in a cave somewhere with their mistresses and 500 years worth of refried beans...that ought to keep the human race going.

-Grump

Gravitational Effects?

[fishdan]

Any astronomers out there know if this will have a measurable gravitational affect on the planet? I know it's awfully small on a planetary scale -- but it's mass might be great. And, as I understand it, we're pretty good at detecting gravitational shifts. I know there won't be high tides or coastal flooding -- just if an object that small will have ANY noticable effect.

Hmm

[Czernobog]

Either there's an ever increasing number of asteroids coming ever closer to Earth (unlikely methinks) or this is truly indicative of how blind we have been all thse years to what was happpening in space.
Sort of puts our achievements into perspective...

also to be noted

[cda]

from http://impact.arc.nasa.gov/

THE SAGA OF ASTEROID AL00667 = 2004 AS1

Brian G. Marsden (from CCNet, 15 January 2004)

"That this latest PHA should have generated so much heated discussion on numerous mailing lists and the internet on the basis of four observations covering a time interval of one hour on the morning of Jan. 13 is surely quite amazing. On the routine arrival of the night's LINEAR data at the Minor Planet Center at 5:15 p.m. EST that day, the usual computations on them were quickly done, and, within a matter of minutes, five of the objects were placed on the MPC's WWW "NEO Confirmation Page" as being of potential NEO interest, predictions of the expected positions and their uncertainties being provided in the hope of securing early confirmation from observers in Europe. It was evidently cloudy over most of the continent, however, and the only follow-up observations immediately forthcoming were in fact from a single observer in the U.K. Also according to usual procedures, on the receipt of these U.K. observations, the predictions on the WWW could be quickly and significantly refined, well in time for further observations to be presumably made from North America. There was in fact also rather extensive cloud cover that night over North America, particularly over the numerous professional and amateur observatories in the frequently blessed Southwest.

Re:NASA's on the job. Can they save the world?

[shibbie]

I find it amusing that a threat to everyone thats a far bigger catastrophe than terrorism has no defence (I'm British, this is our spelling 8P ). In all likelyhood (imho) its the biggest continents that will suffer the most. The UK will either just be wiped out or get missed entirely (we've always had bad weather)...

Re:The big one...

[Xzzy]

You're right, the scary part about armageddon is actually surviving the initial event, and being forced to adapt your strategy instantly.

Talk about the ultimate episode of survivor.

Re:How far away?

[interiot]

Also note that geosynchronous orbit is at 42,250 km. Which means this asteroid is potentially coming very close to some of the satellites we've put up there.

So, a question for the astronomers

[Walkiry]

That good fellow is going to pass quite close to earth. Now, the question I have is, how close does an asteroid such as this have to pass so that it is captured by Earth's gravitational field and become a satellite? It could be useful to have a big rock in stable orbit.

I'd hate to be a

[Gr8Apes]

geo-synchronous satellite. 26km is just about their orbit. Shouldn't we try to protect them?!?

Re:How far away?

[TigerNut]

They didn't say anything about the relative angle at which the asteroid would be approaching. Geostationary sats occupy a fairly narrow belt around the equator (see, for example, this applet - assuming your computer is less Java-hostile than mine) 3D satellite simulator

Any object approaching from angles significantly above or below the equator will have only a very small chance of nailing a geostationary satellite.

We came pretty close.

[icejai]

It takes the earth about 6 minutes to travel a distance equivalent of its own diameter.
So basically, to avoid a direct hit, the the timing of of a near-earth-asteroid only needs to be altered by 6 minutes over the course of its orbit(s).

What I can't get over is that we *missed* this asteroid by only 12 to 18 minutes!

That's just crazy.

Re:100 ft may seem small, but ....

[Glock27]

According to the "Solar System Collisions" page:

---begin results---
YOUR COLLISION PARAMETERS

Projectile: Rocky Asteroid
Diameter: .03 kilometer(s)
Velocity: 20.0 km/s
Target: Earth

RESULT: Explosion 5-20 km Above Tibet [note: they made this part up;)] in Asia!!
Energy Released = 2 MT (MegaTons of TNT)
(Largest Nuclear Weapon: 100 MT)

A collision this large occurs roughly once every 58 years.
---end results---

Now, we don't know much about this object's composition, so it could be iron. If so, and if it were moving a bit faster (30 km/s), this is what we get:

---begin results---
YOUR COLLISION PARAMETERS

Projectile: Iron Asteroid
Diameter: .03 kilometer(s)
Velocity: 30.0 km/s
Target: Earth

RESULT: Impact into Australia [note: they made this part up;)] in Oceania!!
Energy Released = 12 MT (MegaTons of TNT)
(Largest Nuclear Weapon: 100 MT)

QUAKE!! Magnitude 6.3 (largest recorded Earthquake: 9.5)

Crater Diameter: 752.0 meter(s)
Crater Depth: 146.0 meter(s)

A collision this large occurs roughly once every 280 years.
---end results---

If the iron version hit the ocean, it'd create quite a significant tsunami - though not a catastrophic one unless it hit near the shore.

From the book of Revelation:

[Non Dufus]

Rev 8:10 And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers, and upon the fountains of waters;
Rev 8:11 And the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter.
Rev 8:12 And the fourth angel sounded, and the third part of the sun was smitten, and the third part of the moon, and the third part of the stars; so as the third part of them was darkened, and the day shone not for a third part of it, and the night likewise.

Now just hope they don't name some asteroid "Wormwood".

Crushing it to small pieces won't help.

[Ralph Spoilsport]

It's all mass. A billion ton rock flying through space at 50,000 miles per hour hitting the earth all at once is mechanically no different from a billion tons of loose sand flying through space at 50,000 miles per hour hitting the earth all at once.

"Oh - we'll blow it up. That'll make it go away."

Wrong. Mass and inertia are mass and inertia. The results might be a bit different - a dense solid object will tend to penetrate the surface a bbit deeper, but the heat generated from a billion tons of sand travelling 14 miles a second would instantly superheat the atmosphere, and the impact on the earth would be incredibley destructive - the silicon, magnesium, sodium, etc. in the stuff isn't going to disappear, and the associated mass has to transfer its inertia into some other form of energy, and a billion tons of inertia is a billion tons of inertia.

The best thing to do is to a solid chunk is to deflect it. If the asteroid is solid metal and valuable metal at that, it might be a good idea to dump it on the moon or Mars, where the metal can be used to make buildings and space craft.

Otherwise, pitch the sucker into the sun. Or Venus. Or someplace else. In fact dumping it into Venus might be cool - see what kind of wreckage develops...

Now, if it's a loose piece of crap, like a semi-shattered dead comet, that would*suck* because deflecting something like that would be pretty difficult. A billion tons of ice and gravel is still a billion tons of ice and gravel.

RS