Asteroid 2004 FH

Spaceweather.com ^ | 3/18/2004 | NASA

[Orlando]

Newly-discovered asteroid 2004 FH is going to fly-by our planet TODAY, March 18th , 2200 GMT) 5:08 pm, est. only 43,000 km , which is only 26,500 miles from Earth.

[STARWISE]

Oh no .. I heard it was Halliburton's fault.

[Capt.April]

I wouldn't worry too much. I just checked the NEAT (Near Earth Asteroid Tracking) website and couldn't find any info on this object. I'm begining to wonder if we've been had.

Even if there is a 100ft space rock that close the odds of a hit are pretty big and even if it enters the atmosphere alot of it would burn up and what's left only has a 25% chance of hitting the ground.

[Geritol]

"would that reduce the damage of the impact enough to merit interception?"

That is an interresting question. The first mistake is in thinking that if we use explosives or nuclear something to convert it from a bowling ball traveling at us at 15,000 miles an hour into a pile of BBs weighing the same as the bowling ball and still traveling at us at 15,000 miles an hour, only now containing some quantity of radioactive fallout, that it will make a really huge difference in what it would do to us.

Making broad assumtions, a sphere 100 feet in diameter at 2.5 the density of water would weigh about, well, a bunch. something with 7 zeroes, 40,000 tons or so. According to this site at http://personals.galaxyinternet.net/tunga/I2.htm,
KE = 6.256 x 10-8 x (diameter)3 x (velocity)2 x (density)
Where KE is expressed in Megatons of TNT
Where diameter is expressed in meters
Where the velocity relative to Earth is expressed in kilometers per second
Where density is expressed in grams per cubic centimeter
Assuming 1 megaton of TNT is equivalent to 4.185 x 1022 ergs

6.7 kilometers per second closing speed
2.5 times density
30 meter diameter gives us
.19megaton in kinetic energy.

Added to this would be the energy released from whatever chemical reactions (fires) occur to both the object and the terrain and geology surrounding the impact site. This "secondary" reaction would be multiplied by fracturing the object. I have no idea how to calculate the energy released from vaporizing and instantly combusting several city blocks and igniting hundreds or thousands of acres. Nor do I know how to compare that energy to the energy released from instantly igniting 10 or 100 times that area with the fragmented object's spread.

[StriperSniper]

Tunguska redux?

Hope they don't have their 'meters' and 'feet' mixed up. (:-/

Get your crash helmets on!

[Diddle E. Squat]

Well, even if it hits the earth, the odds of it hitting land is just 1 in 3. To hit somewhere in the US is what, 1 in 50 or more? I doubt the US takes up more than about 1-2% of the earth's surface. And even if it hits the US, there is a 95% or greater chance that it hits a rural area.

So I'm not real worried.

But I do wonder how the Spaniards will react if it hits Spain...

[Centurion2000]

Even if there is a 100ft space rock that close the odds of a hit are pretty big and even if it enters the atmosphere alot of it would burn up and what's left only has a 25% chance of hitting the ground. 25% ? That's a guaranteed hit if it hits atmosphere .... meteorites form up from pieces as small as the size of your fist.

Or do you have calculations to prove your assertion ? Serious question by the way.

[Capt.April]

"do you have calculations to prove your assertion ?"

Nope! All guess work. I have no idea how accurate any of these figures are. I do know 75% of the earth is water so the odds are it'd land in the ocean. The odds of it hitting us is 50/50 considering how close it is (approx 50,000miles).

To quote another famous American "what? me worry?"

[Centurion2000]

If it is mostly nickel iron like earth .. try 5.5 gr/cm3 .... comes closer to .714 MT of KE

[Centurion2000]

Oh... I was thinking that you are assuming it would breakup in the atmosphere. oops.

A water strike of 700 kiltons is still a pretty big bang

[StriperSniper]

[Capt.April]

Southhak seems to have pretty good info(and seems to know what he's talking about).

How about it southak? think this one will wack us? "busy searching kitchen draws for tin foil"

[Cold Heat]

This is close !

Very!

[Prince Charles]

Full story from link:

Steven R. Chesley
Paul W. Chodas
NASA's Near Earth Object Program Office
Wednesday, March 17, 2004

A small near-Earth asteroid (NEA), discovered Monday night by the NASA-funded LINEAR asteroid survey, will make the closest approach to Earth ever recorded. There is no danger of a collision with the Earth during this encounter.

The object, designated 2004 FH, is roughly 30 meters (100 feet) in diameter and will pass just 43,000 km (26,500 miles, or about 3.4 Earth diameters) above the Earth's surface on March 18th at 5:08 PM EST (2:08 PM PST, 22:08 UTC). (Close approach details here).

On average, objects about the size of 2004 FH pass within this distance roughly once every two years, but most of these small objects pass by undetected. This particular close approach is unusual only in the sense that scientists know about it. The fact that an object as small as asteroid 2004 FH has been discovered now is mostly a matter of perseverance by the LINEAR team, who are funded by NASA to search for larger kilometer-sized NEAs, but also routinely detect much smaller objects.

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.

Scientists look forward to the flyby as it will provide them an unprecedented opportunity to study a small NEA asteroid up close.

[Prince Charles]

Doh! I need to read further into a thread before posting!

[Cold Heat]

Asteroids start at several kilometers in diameter, do they not?

I do not think that they change to the meteor terminology unless an astroid hits the atmosphere.

Then it becomes a meteor or meterorite if it survives.

[reg45]

The ones that hit should be called disasteroids!!

[Tolerance Sucks Rocks]

Clinton blames the NRA.

Damned assault asteroids!

Isn't Clinton a lifetime member of the NRA? :-)

[Capt.April]

I seem to remember from my old college astronomy days there's a "meteoroid" -> "meteor" -> "meteorite" which is from space to atmosphere to impact. Does that sound right?

Where's Sean Connery & Brian Keith when you need 'em?
(if you get that reference your as geeky as me!)

[LibWhacker]

You can play around with Jay Melosh's Crater Calculator to see approximately how large the crater would be from something like this smacking into us, and also calculate the energy release. Making bad case (instead of worst case) assumptions, I get a rim-to-rim crater size of about 800 meters and an energy release of about 300 kilotons of TNT. Nasty consequences for such a little guy!

[leadpenny]

Knowing what you know about this Asteroid (speed, size, distance from Earth), how close would it have to be to glow as it goes by? I'm thinking about a night time sky and I'm assuming it will be too far away to show any signs of heating up.