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View Full Version : Asteroid Apophis coming within 20 k miles of earth



Gsquare
2006-Jun-27, 08:32 PM
I'd be far more concerned with Asteroid Apophis than with XP-14 scheduled to fly by this july 3rd.
I'm referring to the 2029 approach, not the return trip of 2036.

It is predicted to come over 10 times closer than XP-14, at a close encounter of only 20,000 miles! AT 1000 feet or so in diameter, that's close enough to hit with police radar! ;) Well, OK,... at least you'll be able to see it with the naked eye, (yours, not mine; I wear coke bottles:))

However, more seriously, that's close enough to take out a satellite (or two), and at such a high incoming velocity, possibly alter the asteroid's course ....or at least cause the asteroid, being subject to huge tidal forces of earth already, to break apart and change trajectory toward earth.
Just speculating;...What do you think?

More on the 2029 close encounter: http://www.space.com/scienceastronomy/050822_asteroid_apophis.html

Gsquare

Eckelston
2006-Jun-27, 09:42 PM
I wouldn't be concerned about either. The probablility of impact for Apophis in 2029 is nil. Same for XP-14. Why should anyone be concerned about something we know absolutely for sure, won't happen? If you want to worry about something look up the NEO page at JPL, find an asteriod which has a positive probability for impact for a relatively near time and be concerned about that one :) Actually Apophis for 2036 may be a good guess. BTW Apophis is 2029 won't be too big a hazard for satelites. Even if we didn't know it was there the chance of random impact with a satelite is tiny, much smaller than meeting a piece of space junk.

Which brings me to my answer on what I'm worried about. I'm not worried about any of the NEOs we've found. It seems neither is a substantial hazard and in any case we should have an advance warning if one of them were to hit. I'm worried about the ones we haven't found yet. Especially the ones which are mostly within Earth's orbit becouse they are next to impossible to find from the ground. Those are the real danger becouse a large one could hit without us knowing anything about it beforehand.

Eckelston
2006-Jun-27, 09:52 PM
However, more seriously, that's close enough to take out a satellite (or two), and at such a high incoming velocity, possibly alter the asteroid's course ....or at least cause the asteroid, being subject to huge tidal forces of earth already, to break apart and change trajectory toward earth.
Just speculating;...What do you think?

More on the 2029 close encounter: http://www.space.com/scienceastronomy/050822_asteroid_apophis.html

Gsquare

One more comment about this one. Imagine you're on the motorway driving at 180 kilometers hour. Suddenly your car hits a fly. Would you expect your car to go off the motorway and hit a house 500 meters off the motorway directly to your right? Well, I wouldn't. Even if you hit something bigger, a deer for example and the car slid off the road, I'd still be safe in the house becouse the car would continue to go forward thus missing the house. And no we don't have anything comparable to that in high orbit.

tony873004
2006-Jun-28, 01:46 AM
Aphphis is estimated to be about 50000000000 kg. Eckelston summed it up nicely. If it hit a satellite, it wouldn't feel it anymore than your car feels a bug hitting the windshield.

However, it won't hit any satellites. It will be above the plane of the geostationary satellites when it passes their distances. Even if it wasn't, there's just too much space for it to have a realistic chance of hitting anything.

Apophis' self-gravity will be at least a magnitude stronger than the tidal force from Earth. So it will remain intact.

01101001
2006-Jun-28, 02:36 AM
How many Apophis 99942 (2004 MN4) threads do we need?

Asteroid Apophis (http://www.bautforum.com/showthread.php?t=36362)
Apophis (http://www.bautforum.com/showthread.php?t=35609)
Apophis - What should we do? (http://www.bautforum.com/showthread.php?t=34937)
Asteroid Close Call Will Be a Gain for Science (http://www.bautforum.com/showthread.php?t=30124)
Moving asteroid 99942 Apophis (http://www.bautforum.com/showthread.php?t=34660)
Asteroid heads for Earth (http://www.bautforum.com/showthread.php?t=34400)
Will it happend? (http://www.bautforum.com/showthread.php?t=31049)
asteroid strike.. should we be worried???? (http://www.bautforum.com/showthread.php?t=19884)

Bet I can find more.

Ara Pacis
2006-Jun-28, 06:18 AM
We need more 1950DA threads :D

ToSeek
2006-Jun-28, 04:20 PM
How many Apophis 99942 (2004 MN4) threads do we need?

Asteroid Apophis (http://www.bautforum.com/showthread.php?t=36362)
Apophis (http://www.bautforum.com/showthread.php?t=35609)
Apophis - What should we do? (http://www.bautforum.com/showthread.php?t=34937)
Asteroid Close Call Will Be a Gain for Science (http://www.bautforum.com/showthread.php?t=30124)
Moving asteroid 99942 Apophis (http://www.bautforum.com/showthread.php?t=34660)
Asteroid heads for Earth (http://www.bautforum.com/showthread.php?t=34400)
Will it happend? (http://www.bautforum.com/showthread.php?t=31049)
asteroid strike.. should we be worried???? (http://www.bautforum.com/showthread.php?t=19884)

Bet I can find more.

Obviously Apophis needs its own forum.

Tom Mazanec
2006-Jun-28, 06:37 PM
True. If Peak Oil/Nuclear War/Something gives a whole new meaing to the term "post-industrial" this could really mess up 2880.

Trantor
2006-Jun-28, 06:55 PM
Man! I so want to somehow capture that rock and turn it into a space station! Anybody know if it's metallic?

It's strange that I've yet to hear of any doomday cults talking about this asteroid. Maybe the date is a bit too far for them to get worked up over - yet. Give it some time, for now they seem to like 2012 better!

publiusr
2006-Jun-29, 09:40 PM
It would be a nice second moon if we could grab it.

Māori
2006-Jul-07, 12:21 PM
A Narrow Miss for Earth (http://www.abcnews.go.com/GMA/Science/story?id=2147872&page=1)

July 3, 2006 While most Americans were fast asleep Sunday night, an asteroid came within 270,000 miles of hitting Earth about the same distance between our planet and the moon, and a close call in space terms.

The asteroid called 2004-XP-14 traveled at 11 miles per second, or 40,000 mph, and was nearly 1,300 feet in diameter.

Better luck next time, Apophis. :shifty:

NEOWatcher
2006-Jul-07, 12:36 PM
A Narrow Miss for Earth (http://www.abcnews.go.com/GMA/Science/story?id=2147872&page=1)


Better luck next time, Apophis. :shifty:
I'm assuming that speed is relative to earth...

A few nitpicks...
would come within 20,000 miles of Earth close enough to hit some weather satellites.
And miss all the others?

would crash into the planet, or could land in the Pacific Ocean
Land?

If an asteroid hits Earth, Oppenheimer says there are only two things that people can do: Move out of its way or move the asteroid itself.
I would say that when it hits the Earth, it's already too late.

"The best thing to do, actually, is to fly a spaceship up to the asteroid and attach itself,
Not really a nitpick, but I would think for this particular "rock" that the rocket option to shift it's next pass would be extremely difficult due to having to rendezvous so far away. (quite a chace)

Māori
2006-Jul-07, 12:44 PM
Oops, I think I got the two asteroids mixed up (2004-XP-14 & Apophis). :o

Eckelston
2006-Jul-07, 12:59 PM
It would be a nice second moon if we could grab it.

If we could just grab those things we would never need to worry about an asteriod hitting Earth. Distance has never been the problem. The problem is slowing them down enough to be captured by Earth's gravity.

Extravoice
2006-Oct-05, 01:01 PM
I was watching the PBS "Nova Now" program the other night, where they had a short segment on Apophis. While <those who calculate such things> are quite sure Apophis won't strike the Earth in 2029, they are less certain about 2036. If I remember correctly, it is not possible at this time to exactly predict how the close pass to the Earth in 2029 will disturb Apophis' orbit.

The show went on to identify a rectangle in space. If Apophis passes through that box, it will come back to strike Earth 2036. The show even predicted that if Apophis hit the center of the box that it would strike the Earth in the Pacific Ocean off the coast of California. I'm not sure how much of this is hype (no probabilities of hitting the rectangle were given).

Still, it got me wondering if would seven years be enough time to mount an adequate defense if it looks like Apophis is on a collision course with our home planet on the second pass.

tony873004
2006-Oct-05, 07:28 PM
The box is not hype. It is the keyhole. If Apophis passes through it, it will strike the Earth in 2036. The last time new observations adjusted the 2029 pass position, they adjusted it farther from the keyhole.

Think of the keyhole as the sweet spot on a small hill in the middle of a golf putting green. If you aim just perfect, your ball will roll up the hill to its high point, turn (break as they call it in golf) roll down the hill and into the cup. But if you miss this sweet spot by even 1 milimeter, your ball will roll right past the cup. Miss the sweet spot by 1 inch and your ball will miss the cup by several feet.

This is why it is so difficult to predict whether or not it will hit in 2036. Referring to my golf example, we don't know "down to a milimeter" how far the ball will miss the sweet spot on the hill.

If Apophis were found to be on a collision course after the 2029 Earth passage, a strike in the middle of the Pacific Ocean would kill billions as the tidal waves would affect most of the the Pacific Rim. Or more likely, fewer people would die as they had 7 years notice to abandon the coast.

But I would imagine that unlimited resources would be dedicated to deflecting it, and we would be successful.

I didn't agree with the Nova piece's conclusion that nuking it would be a bad idea because we'd get hit with an equal mass of small debris. This is only if we nuked it hours before it hit. Nuke it 3 years before it hits, and the average spacing between particles will exceed 1 Earth diameter.

agingjb
2006-Oct-05, 08:26 PM
Apophis seems to be down to 0 on the Torino scale now. In fact there's only one object at 1 - 2004 VD17, in 2012.

(reference: http://neo.jpl.nasa.gov/risk/)

Superluminal
2006-Oct-06, 01:06 AM
I agree with Tony on nuking an asteroid. Nuke it far enough away, and it will be like flying through the tail of a comet, we might take a hit or two, but nothing that will threaten civilization.

But we don't know what would happen, that's why we need to experiment with nuking an asteroid. But an experiment will never happen, I can just imagine how people around the world would freak out if the U.S. announced such an experiment.

HypothesisTesting
2006-Oct-09, 07:29 PM
No earth space agency has a division devoted to diverting NEOs . It is very advisable to put some of NASA,ESA's budget and found a new division. Any object like Apophis (which has a dangerous Torino number of 1) should be destroyed or diverted within the next decade before astronomers realize it is too late.

An asteroid the size of Apophis would be expected to damage at least an area the size of Los Angeles or create a moderate tsunami in the ocean.

I am surprised that NASA/ESA didn't make this a priority back in the 1970s .

Blob
2006-Oct-09, 07:56 PM
I agree with Tony on nuking an asteroid.

Hum,
recent discoveries and computer simulations on the effect of smaller `broken-up asteroidlets` show that they can be far more devastating than a single impact.
Multiple airbursts would create a superheated shock blast that would incinerate hundreds or thousands of square kilometres.

Nuking an asteroid may be the worst thing to do.

See `Libyan glass` or `Kebira Crater`


This week the Space Foundation debuted "Asteroid Challenge, Target: Earth," a virtual lab and video science education program featuring the real asteroid Apophis. Third grade students from Manitou Springs Elementary School in Colorado were the first class nationwide to participate in this interactive science program and use scientific methods in a virtual lab to save our planet from destruction by Apophis, now on a path that could bring it dangerously close to colliding with Earth in 2036.

The release of the lab follows the Oct. 3 premiere of NOVA scienceNow on PBS, which also addressed near-Earth asteroids, including Apophis. Dr. Neil deGrasse Tyson is both the host of NOVA scienceNow and featured in "Asteroid Challenge, Target: Earth." Tyson is a Space Foundation board member, astrophysicist, and director of the Hayden Planetarium in the Rose Centre for Earth and Space at the American Museum of Natural History in New York City.

Read more (http://news.spacefoundation.org/printable.cfm?releaseid=1911D92F-C675-47C1-AF067B503010DFCF)

agingjb
2006-Oct-09, 08:36 PM
Apophis remains at Torino 0:

(reference: http://neo.jpl.nasa.gov/risk/)

It may be worth quoting the definition of Torino 1:

"A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. New telescopic observations very likely will lead to re-assignment to Level 0."

Blob
2006-Oct-09, 08:43 PM
Hum,
It s also worth quoting the definition of Torino 10 (for future reference)


A collision is certain, capable of causing global climatic catastrophe that may threaten the future of civilization as we know it, whether impacting land or ocean. Such events occur on average once per 100,000 years, or less often

The probability of an Impact with a asteroid/comet sometime in the future is 100%

agingjb
2006-Oct-09, 08:55 PM
Indeed, but sadly for those of us with rather short life expectancies (mine is, optimistically, around 10 years) this certainty will be overtaken by the probability of a more mundane mortality. Pity, in some ways; when one of the various rocks achieved Torino 4 it was, briefly, worth reflecting on the outcome. Sadly or not, that statistic receded.

Eckelston
2006-Oct-09, 09:21 PM
What we should focus on now is detection. It might not have the appeal of actually blowing something up but with esentially current technology and reasonable funds we could completely rule out (or confirm with absolute certainty) any major impact for the near future and predict minor ones early enough so we could evacuate people if it became necessary. All we'd need is an LSST type survey telescope and a dedicated space telescope at L1 for interior asteriods.

I guess PAN-STARRS and Gaia will go a long way to addressing these issues. Then if we find something we can start to think about how we can best address the problem and if we don't we can run a relatively cheap program that can give ample warning (20-30 years for anything over 200 m would be good enough) if something is about to hit.

agingjb
2006-Oct-09, 09:34 PM
Absolutely, detection. Keep looking. Map our environment. And if any perceived threat helps to justify a larger budget, grab it with both hands. Just don't panic. Yet.

Oh, and if there is a threat, I'd guess that careful deflection would usually beat attempts to shatter the rock.

01101001
2006-Oct-09, 10:29 PM
Apophis remains at Torino 0:

(reference: http://neo.jpl.nasa.gov/risk/)

It may be worth quoting the definition of Torino 1:

"A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. New telescopic observations very likely will lead to re-assignment to Level 0."

They should add:

Rash attempts to destroy or divert, may lead to re-assignment to Levels 2, 3, or worse.

Superluminal
2006-Oct-10, 12:29 AM
Did those computer simulations take into account the debris spreading out over a couple of years? If disrupted soon enough before the expected impact date could Earth sail through the trail and not get hit by a significant number of objects? Obviously hitting an asteroid the day before impact would not be a good idea. But at our present level of technology and the long period time other scenario's would take, such as the Zarkovsky effect, nukes would most likely be our only alternative.

Blob
2006-Oct-10, 11:13 AM
Hum,
indeed,
if it were possible to shift the orbit just by a few centimetres at the correct time then it would not matter if the detonation broke the asteroid up into a deadlier swarm of asteroidlets, (er, Small Solar System Bodies)...
It would be even better if the swarms orbit could be sent completely away from the Earths orbit (captured & mined, or collision with another planet, etc, )

HypothesisTesting
2006-Oct-10, 02:47 PM
I am surprised Apophis doesn't have a Torino number of 2, or maybe reconsider the Torino scale so it would. Specifically, I would worry that if Apophis passes through the keyhole in 2029, then it'll only be less than a decade to divert it, which is cutting it close. It seems like it would be better to get it out of earth's environment now when we have time, that way there will be no danger. I'd take care of the VD17 asteroid at the same time also.
These are pretty big asteroids.

Tom Mazanec
2006-Oct-11, 01:52 PM
More troublesome after we get the asteroids down (I doubt one will hit before we do) will be comets. We don't detect those until the nucleus is fuzzed by the coma, and not long before they would hit anyway.

Lord Jubjub
2006-Oct-12, 12:28 AM
Apophis will make another relatively close approach in 2012-2013. At that point (if not sooner), they should be able to forcecast whether it has ANY chance of hitting the keyhole. If they cannot rule the possibility out at that point, NASA has talked of sending of probe to land on Apophis to continuously transmit its location. That should mean that well before 2029 we should know if Apophis will hit the keyhole and divert it BEFORE 2029 to prevent it from going through the keyhole.

At present, Apophis between the Sun and Earth, making it very difficult to track. Its orbit is very similar to Earth's and it travels only slightly faster (the orbit is also more elliptical than Earth's).

Matthaeus
2007-Feb-19, 10:09 AM
One more comment about this one. Imagine you're on the motorway driving at 180 kilometers hour. Suddenly your car hits a fly. Would you expect your car to go off the motorway and hit a house 500 meters off the motorway directly to your right? Well, I wouldn't. Even if you hit something bigger, a deer for example and the car slid off the road, I'd still be safe in the house becouse the car would continue to go forward thus missing the house. And no we don't have anything comparable to that in high orbit.

What about the moon? It's big and dense enough to crash into the moon and alter it's course, possibly resulting in a bigger disaster if the Earth is in the way of its altered course, this would also be very unlikely but probably wouldn't global destruction due to lack of velocity. The only concern i have with the moons part in all this is that its gravity may swing the asteroid into the Earth whilst increasing its velosity.
Suppose the moon was so obvious that it didn't cross your mind.:doh: :wall:

Kaptain K
2007-Feb-19, 10:33 AM
Mass of Apophis = 2&#215;10^10 kg
Mass of Moon = 7.383 &#215; 10^22 kg
Thus the mass of the Moon is on the order of 4 trillion times that of the asteroid. Orders of magnitude greater than the difference between a fully loaded semi and a mosquito. Apophis is not nearly big enough to significantly alter the orbit of the Moon, but it would be a pretty good light show.

Ken G
2007-Feb-19, 06:08 PM
But note that there's no need to worry about it hitting the Moon, because it has to be at least 20 times more likely to hit the Earth, and that would be something we'd care a lot more about anyway! (Question: what is the "keyhole", and is this a real idea or a make believe one?)

joema
2007-Feb-19, 07:09 PM
...Question: what is the "keyhole", and is this a real idea or a make believe one?...
"Keyhole" has referred to a target region in space at least since Apollo. In that case hitting the keyhole at a certain distance from earth meant the reentry trajectory would intercept the earth's atmosphere at the correct angle for safe return. Don't know if the term was used in a space navigation context before then. It's also been used to describe the target region required for an unmanned probe to execute a maneuver, say a planetary flyby.

The trajectory of all bodies in space is perturbed by effects sunlight, radiation, outgassing, other bodies, etc. Those affects can be quantified to a fairly high degree, depending on how much data is available.

After all those effects are calculated to the available accuracy, there remains an uncertainty since we don't have absolute accuracy in measurement or perfect data about the deep space environment or the object. I think the term is "trajectory dispersions".

I think "keyhole" refers to a 2D region in the trajectory path which if intersected would result in the object hitting a certain target, even if the normal perturbations -- all dispersions -- happened.

I think the keyhole size varies depending on object distance from target. The farther away from target, the larger the keyhole is. In this sense, there's not one keyhole, but many, depending on the distance to target.

The keyhole also isn't a fixed size based on physical laws, but a navigation construct based on available data. IOW higher accuracy data (more observations, better software, etc) could shrink the size of a keyhole, even though nothing physical changed in space or the body.

Don't know what the etymology is -- whether the physical region has a keyhole shape if plotted or if it simply came from "looking through a keyhole" as defining a narrow trajectory angle.

If someone has more information, please correct me.

Argos
2007-Feb-19, 08:04 PM
Don't know what the etymology is -- whether the physical region has a keyhole shape if plotted or if it simply came from "looking through a keyhole" as defining a narrow trajectory angle.

I think its just a metaphor for a hole. this article (http://men.msn.com/articlepm.aspx?cp-documentid=1628365&GT1=8991) says it is only 2,000 ft in diameter.

mantiss
2007-Feb-19, 10:48 PM
I was just checking today on the list of close approaches and now both 2032 and 2036 are at Torino 0. New calculations made in the last weeks?

clop
2007-Feb-19, 10:56 PM
I think the keyhole size varies depending on object distance from target. The farther away from target, the larger the keyhole is. In this sense, there's not one keyhole, but many, depending on the distance to target.hrough a keyhole" as defining a narrow trajectory angle.

Wouldn't the keyhole have to be smaller the farther away from the target, not larger?

clop

jami cat
2007-Feb-20, 01:37 AM
If NASA eventually does get the nod -- and more important, the budget -- from Congress, the obvious first move would be a reconnaissance mission to Apophis. Schweickart estimates that "even gold-plated at JPL," a transponder-equipped gravity tractor could be launched for $250 million.
Ironically, that's almost precisely the cost of making the cosmic-collision movies Armageddon and Deep Impact. If Hollywood can pony up a quarter of a billion in the name of defending our planet, why can't Congress?

Sure shows where our priorities are as a nation...

joema
2007-Feb-20, 04:36 AM
Wouldn't the keyhole have to be smaller the farther away from the target, not larger?
clop
Yes, I got it backward. Thanks for the correction.

Kaptain K
2007-Feb-20, 08:00 AM
...and we spend half of NASA's annual budget in Iraq every month!

dtilque
2007-Feb-20, 08:14 AM
Anyone know how close Apophis will get in 2013 and 2021? Also, what magnitude will it reach during those approaches?

Dana_Mix
2007-Feb-20, 09:08 AM
Anyone know how close Apophis will get in 2013 and 2021? Also, what magnitude will it reach during those approaches?

In 2013, 14.5 Gm in January and 36.4 Gm in July.
In 2021, 16.9 Gm
don't know the magnitudes.

edit: actually, I found them. Put the mag from JPL in my Solex9.0.
15.5 for the January 2013 approach, and 15.4 in 2021

Blob
2007-Feb-20, 06:45 PM
Hum,
if you do a forum search for "Apophis" or "2004 MN4" or "Killer asteroid" , "not again" or "death from the sky" etc, there will be no doubt a predicted forecast; but, i would guess that it would be visible to the naked eye as a mag 3 - 4 moving star during the 2029 encounter, (and in the worst case scenario as a growing ball of light brighter than the sun).