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View Full Version : If tout would hit where would it hit



bmpbmp
2004-Sep-27, 08:53 PM
I am curious for my own personal knowledge and how much damage would it do

ToSeek
2004-Sep-27, 09:12 PM
Much, much worse than Tunguska but not as bad as the dinosaur killer of 65 million years ago.

You can go here (http://janus.astro.umd.edu/astro/impact/) and enter 3.0 km for the diameter and 20 km/sec for the speed to get some idea of the result.

frogesque
2004-Sep-27, 09:32 PM
I think there would be a fair chance that it could hit the Moon. Lunar orbit encloses a greater target area than Earth even though at any one instant the 'at risk' Lunar surface is less than that of Earth. Other than that there is a higher probability that it would strike an Ocean so either the Pacific or Atlantic would be odds on.

Not familiar with real estate damage estimates but I know it's heavily dependant on how much of an airburst accompanies it's entry, relative velocity, angle of strike, type of terrain/depth of water, etc,. I can say with confidence that I'm glad it's on a miss this time round and next time it will be someone else's worry. :lol:

Grand Vizier
2004-Sep-27, 10:01 PM
I think there would be a fair chance that it could hit the Moon. Lunar orbit encloses a greater target area than Earth even though at any one instant the 'at risk' Lunar surface is less than that of Earth. Other than that there is a higher probability that it would strike an Ocean so either the Pacific or Atlantic would be odds on.

I seem to recollect that some studies showed that a seastrike would be worse than a landstrike, simply because the volume of water thrown into the atmosphere would take much longer to settle out than dust, so the resultant 'nuclear winter' would last much longer. Presumably there would be immensely chaotic and powerful hurricanes too.

Kind of an academic viewpoint for something the size of Toutatis. We'd be sunk either way.

Bmpbmp, there is no danger from Toutatis this century. But the orbit does change, so no-one can speak for the next few thousand years. Plenty of time to work up solutions...

bmpbmp
2004-Sep-27, 10:06 PM
Yes but what I dont understand is how can this object be free floating out there and yet keep such an accurate predcted path.

Even amateur astronomers how would you actuly check the cooridnates and match them properly to what they should be.

I have looked through telescopes before and can't figure out how i would use the telescope to make the orbit calculations

Andreas
2004-Sep-27, 10:41 PM
Yes but what I dont understand is how can this object be free floating out there and yet keep such an accurate predcted path.
Unline Nancy Lieder's Planet X, it doesn't just zip around here and there like a rabbit on illegal substances. If we know it's location as well as speed and direction of motion, we can compute its future path by plugging the data into the appropriate equations - as far into the future as the limited precision of our measurements and computations allow.


I have looked through telescopes before and can't figure out how i would use the telescope to make the orbit calculations
So? I don't know the process either, but that doesn't mean that there aren't people who know and who actually can do that.

Kaptain K
2004-Sep-27, 10:46 PM
Yes but what I dont understand is how can this object be free floating out there and yet keep such an accurate predcted path.

Toutatis is not "free floating"! It is following a path that is determined by the combined gravitational effects of every body in the Solar System. To calculate the orbit, JPL takes into account the gravitational effects of the Sun Mercury, Venus, Earth and the Moon (separtely), Mars, Jupiter, Saturn, Uranus, Neptune and the four largest asteroids.


have looked through telescopes before and can't figure out how i would use the telescope to make the orbit calculations

Orbit determination involves more than just looking at the object. It requires precise measurements of position (RA, DEC and the time of the measurement). At least three coordinates are necessary to define an orbit. More give better precision. Newton invented calculus, at least in part, so he could predict orbits.

bmpbmp
2004-Sep-27, 11:32 PM
So calculating is not something you can do in your own back yard so we have to reply on agencys to do it right

Musashi
2004-Sep-28, 12:33 AM
Not exactly. You could calculate Tout's orbit if you made a few observations and knew the physics.

planetbarb
2004-Sep-28, 12:37 AM
Ephemeris generator instructions a few paragraphs down...

http://story.news.yahoo.com/news?tmpl=story&cid=96&ncid=753&e=10&u=/space/20040927/sc_space/hugeasteroidtoflypastearthwednesday

Spotting Toutatis


Toutatis will not be visible to the unaided eye. Experienced telescope users can see it now from the Southern Hemisphere, and in early October it will be visible from the north.


Finding Toutatis will be challenging, Harris said, due to a combination of the asteroid's position in the sky and interfering moonlight.


Because the asteroid is so close, its location in the sky will vary significantly for skywatchers in different places on Earth at any given moment. And because it moves quickly, the location changes constantly. Printed sky maps struggle to provide enough detail to be useful.


"In a large telescope the motion would be perceptible against any stars in the field more or less in real time, sort of like watching the second hand on a clock," Harris said, adding that the movement would be "not quite that fast, but noticeable."


Highly experienced observers will use complex plotting information known as ephemeris data. Others can use software programs that generate maps for specific times and locations.



Ephemeris Generator
Instructions
Current Settings
Target Body: Asteroid 4179 Toutatis (1989 AC)
Observer Location: [Code=500]

From: A.D. 2004-09-22 00:00 UT
To: A.D. 2004-10-07 00:00
Step: 1 day
Format: Calendar Date and Time

Output Quantities: 1,3,9,19-20,23-24,33,36
Ref. Frame, RA/Dec Format: J2000, HMS
Apparent Coordinates Model: Airless


--------------------------------------------------------------------------------

1. Modify current settings as desired: (help)


2. Select desired options: (help)

Suppress output during daylight
Suppress output when body below horizon
Extra precision (RA/Dec)
Use CSV (spreadsheet) format
Include $$ keys
Include body information page

3. Request the ephemeris:


--------------------------------------------------------------------------------
Credits/Awards

One Day More
2004-Sep-28, 02:52 AM
Referring back to the previous post...

Where did all that come from? :o

Musashi
2004-Sep-28, 03:08 AM
Don't question her, she may call you an obnoxious goofball. :roll:

A Thousand Pardons
2004-Sep-28, 04:48 AM
I think there would be a fair chance that it could hit the Moon. Lunar orbit encloses a greater target area than Earth even though at any one instant the 'at risk' Lunar surface is less than that of Earth.
I'm not even certain what it would mean to enclose a target area with an orbit, but the cross-section of the Earth is 16 times that of the moon, and the Earth is eighty times more massive. The orbit has almost nothing to do with it--the moon only orbits the Earth once every 27 1/2 days. In that time, the object would be here and long gone.

At least three coordinates are necessary to define an orbit.
I'd say at least six.

So calculating is not something you can do in your own back yard so we have to reply on agencys to do it right
No, I think you probably could, if you took the time.

Cylinder
2004-Sep-28, 06:04 AM
The following excerpt from NASA NEO Impact Risk (http://neo.jpl.nasa.gov/risk/) page gives a good description of the assessment process:


Every day, observations and orbit solutions for Near-Earth Asteroids (NEAs) are received from the Minor Planet Center (MPC) in Cambridge, Massachusetts. Once classified as an NEA, the asteroid is thereafter given automatic orbit updates within our Sentry system. A new orbit solution for an NEA is computed whenever new optical or radar observations for that object become available. Some high-priority objects are observed daily, while other objects go unobserved for days or weeks, even though they may still be bright enough to be seen. Optical observations cease when an object recedes from the Earth (becoming too faint to be seen even with moderate-size telescopes), or when the object moves into the daytime sky. Similarly, radar observations are possible only when the object is near enough to the Earth for the echo of a radar bounce to be detected. Once all the observations for an object have been collected, an orbit determination process is used to find the orbit which best fits all the observations.

The orbit is defined by six parameters (called the orbital elements) at an initial time (called the epoch). An object's orbit is constrained to follow equations of motion which model the forces expected to be acting on that object at any given time. These forces are primarily the gravitational attraction of the Sun, the planets, the Moon, and the three largest asteroids, Ceres, Pallas, and Vesta). Given the six orbital elements at the epoch, the object's positions at other times are computed by a numerical integration, or propagation, of the equations of motion. In particular, the object's position is computed at all the observation times, and given the position of the Earth and the observatory locations at those times, the expected values of the observations themselves are computed (e.g., the sky positions at the observation times). The difference between the computed value for the observation and the value actually measured by the observer is called the observation residual. The orbit for an object is determined using a process called differential correction, which iteratively adjusts the six orbital elements until the sum of squares of all the observations residuals reaches a minimum value. The final result of the orbit determination process is called the best-fit or nominal solution. Note that the nominal orbit will not fit all the observations perfectly (i.e., the residuals will not all be zero), but it should fit all the observations to within their expected accuracies (typically less than 1 arc-second for optical observations). Also note that when new observations of the object become available, a new orbit solution must be determined in order to fit the augmented observation set.

It is important to understand that an object's orbit is never known perfectly. Although the nominal orbit solution fits the observations best, slightly different orbits may still fit the observations to within their expected accuracies. There is in fact a whole set orbits around the nominal which will fit the observations acceptably well: these all lie within what we call the uncertainty region about the nominal orbit. The 'true' orbit is expected to lie somewhere within this region. As new observations of the object are made, the uncertainty region becomes more tightly constrained and the range of possible values for the orbital elements narrows. As a result, objects which have been observed for decades will have highly constrained, well known orbits, while newly discovered objects tracked for only a few days or weeks, will have relatively poorly constrained, uncertain orbits.

Kaptain K
2004-Sep-28, 08:44 AM
Kaptain K wrote:
At least three coordinates are necessary to define an orbit.

I'd say at least six.

OK. Three sets of coordinates! #-o Happy now?

Kaptain K
2004-Sep-28, 09:08 AM
So calculating is not something you can do in your own back yard so we have to reply on agencys to do it right
Observing or calculating?

The observations can be made from your backyard, if you have the proper equipment.

Calculating from your backyard requires a laptop computer! 8) The math is freely available (Any copyright Newton might have had expired centuries ago. :wink: ) The math is not that difficult, but since there is no way to directly solve an "N-body" problem, it requires numerical integration to solve. This can be fiendishly tedious to do by hand, but there are computer programs available to do the "drudge work".

Simply put, any astronomer (professional or amateur) without access to (or who distrusted) the "agencies" could do the calculations themselves.

frogesque
2004-Sep-28, 10:42 PM
I think there would be a fair chance that it could hit the Moon. Lunar orbit encloses a greater target area than Earth even though at any one instant the 'at risk' Lunar surface is less than that of Earth.
I'm not even certain what it would mean to enclose a target area with an orbit, but the cross-section of the Earth is 16 times that of the moon, and the Earth is eighty times more massive. The orbit has almost nothing to do with it--the moon only orbits the Earth once every 27 1/2 days. In that time, the object would be here and long gone.

Possibly wooly thinking on my part, what I had in mind was that, although the Moon is only 1/16th Earth's diameter, because it orbits the Earth there is a greater chance that any asteroid would collide with the Moon bearing in mind that any close Earth object's orbit has a range of probabilities of being in any one place at a given time. It is also possible that a strike could occur because the Moon is at a point in its orbit where the Earth would be in the 'umbra' and the Moon would take the hit instead.

Is it possible to calculate Toutatis's orbit for next closest approach with sufficient accuracy to know if the Moon would be shielding the Earth?

It was late when I made my first post and it kind of made sense to me at the time, not so sure now :lol:

Brady Yoon
2004-Sep-29, 01:08 AM
From personal opinion, I'd rather have the asteroid hit the ocean. It would be possible to escape the tsunami by moving to high ground, but the blast wave and heat from a land strike would be very hard to escape.

One Day More
2004-Sep-29, 01:46 AM
Don't question her, she may call you an obnoxious goofball. :roll:

What do you mean? You're not saying I am a obnoxious goofball? Just wondering... :)

Grand Vizier
2004-Sep-29, 02:41 AM
From personal opinion, I'd rather have the asteroid hit the ocean. It would be possible to escape the tsunami by moving to high ground, but the blast wave and heat from a land strike would be very hard to escape.

Hey, it may be the other way round. 'Prompt' effects, in the event of a big strike, will kill far fewer people (and/or species) than the follow-on effects, e.g nuclear winter. It is possible that a seastrike could be worse than a landstrike, simply because the huge volume of water vapour transferred to the atmosphere could do far worse things to the climate than a few gigatons of dust could do. (Think albedo.)

ToSeek
2004-Sep-29, 02:44 AM
Possibly wooly thinking on my part, what I had in mind was that, although the Moon is only 1/16th Earth's diameter,

1/4 Earth's diameter (2160 miles versus about 8000).

frogesque
2004-Sep-29, 02:38 PM
ToSeek wrote:


1/4 Earth's diameter (2160 miles versus about 8000).

Even woolier thinking on my part :oops:

Also, thinking about this some more, if any asteroid (not necasarily Toutatis) were to be incoming off the ecliptic (say at 90 deg to it) there is no way the Moon could shield us.

However, there must have been some times in the past when Earth would have been the bull's eye but for our heavenly neighbour.

A Thousand Pardons
2004-Sep-29, 03:03 PM
However, there must have been some times in the past when Earth would have been the bull's eye but for our heavenly neighbour.
Sure, but that's offset by how many times an asteroid would not have hit the Earth, but was deflected by the moon's gravity so that it did hit the Earth. Either situation is still extremely rare.

Bottom line is, the chances of it hitting Earth are about 16 times that of the moon, and the reduction in total asteroids because of moon hits is miniiscule, so it doesn't change Earth's chances much at all.

Candy
2004-Sep-29, 03:25 PM
Don't question her, she may call you an obnoxious goofball. :roll:

What do you mean? You're not saying I am a obnoxious goofball? Just wondering... :) I believe Musashi was talking about planetbarb (http://www.badastronomy.com/phpBB/viewtopic.php?p=264636#264636). 8-[

russ_watters
2004-Sep-29, 05:23 PM
Simply put, any astronomer (professional or amateur) without access to (or who distrusted) the "agencies" could do the calculations themselves. Wouldn't pretty much every major observatory (and probably every college observatory connected to an astronomy class) be capable of doing this without much trouble at all (a la the opening scene of Deep Impact[yes, I know it would take measurements over time])? I'd be extremely disappointed (and I'd imagine Kepler would be too) if a typical astronomy senior couldn't write a simple fortran/basic program to calculate the orbit of an object when given a history of earth-based observations.

And no one answered the first part of the question: where would it hit? That's a meaningless/unanswerable question. If I were a dog, what breed would I be? Or, perhaps, the only useful answer is simply: I'm not a dog, and its not going to hit.

Musashi
2004-Sep-29, 10:34 PM
Don't question her, she may call you an obnoxious goofball. :roll:

What do you mean? You're not saying I am a obnoxious goofball? Just wondering... :) I believe Musashi was talking about planetbarb (http://www.badastronomy.com/phpBB/viewtopic.php?p=264636#264636). 8-[

Yeah. Sorry for not being more clear. :)

Maksutov
2004-Sep-30, 03:29 AM
I am curious for my own personal knowledge and how much damage would it do

There's always the possibility that Toutatis collided with one or more small, unobservable bodies during its pass by Earth. Small fragments could have been thrown into different trajectories, some of which might intersect with Earth's surface. In fact, one of these fragments, which though unobservable could be house-sized or larger, could be heading for you right now!

Good luck!

:o

Grand Vizier
2004-Sep-30, 03:49 AM
I am curious for my own personal knowledge and how much damage would it do

There's always the possibility that Toutatis collided with one or more small, unobservable bodies during its pass by Earth. Small fragments could have been thrown into different trajectories, some of which might intersect with Earth's surface. In fact, one of these fragments, which though unobservable could be house-sized or larger, could be heading for you right now!

Good luck!

:o

Hey, there could even be dust-sized Toutatis granules in our roofing gutters right now. Micrometeorite alert! Scary.

bg_26934
2008-Oct-11, 11:47 AM
Wouldn't pretty much every major observatory (and probably every college observatory connected to an astronomy class) be capable of doing this without much trouble at all (a la the opening scene of Deep Impact[yes, I know it would take measurements over time])? I'd be extremely disappointed (and I'd imagine Kepler would be too) if a typical astronomy senior couldn't write a simple fortran/basic program to calculate the orbit of an object when given a history of earth-based observations.
...
They certainly could. There are already free programs available for Earth satellites, perturbed by Moon, Sun and Earth's distorted gravity field.
I would assume free or cheap programs can be found for solar system orbits as well.

I was very impressed in March 1995 by a Basic program by James Miller of AMSAT (http://www.amsat.org/amsat/articles/g3ruh/114.html) to predict the decay of satellite OSCAR-13,
18 months in advance with good accuracy. The short program is linked from this page.

BTW, Toutatis is passing Earth at 5M km range Nov.9 2008, and might be magnitude +9. See JPL Horizons, cited in this thread!