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David Simmons
2001-Nov-10, 01:38 AM
I'm giving my hard-hat to Goodwill. Rogue Asteroids (http://news.bbc.co.uk/hi/english/sci/tech/newsid_1644000/1644899.stm)

DStahl
2001-Nov-10, 06:01 AM
"Rogues! Killers!" This is so anthropomorphic. These gentle, law-abiding space rocks simply want to unite with the Earth! It's lonely way out there, and it would be so nice for them to come down and get warm for the first time since their birth...I just don't know why people are so negative about these poor asteroids.

David Hall
2001-Nov-10, 12:10 PM
"The results of a sky survey have lengthened the odds of such an apocalyptic event occurring {over the next 100 years} to about one in 5,000."


This doesn't ease my mind a lot. I mean, if this was a lottery, I'd be putting down a pretty good pack of money on tickets. I always thought the odds were much lower than this to begin with. But this is supposed to be much better than before? What were the odds thought to be before then? If they were THAT bad, I'm glad I didn't really know! /phpBB/images/smiles/icon_smile.gif

The article goes on to say that they estimate the number of >1km asteroids in the asteroid belt to be about 700,000 (based on a sample of 10,000). So how does this relate to the chance of being hit exactly? The objects in the belt are generally in very stable orbits very very far from the earth. They haven't a snowball's chance in Heck of ever getting close to us.

The important measurement is of how many earth-crossing asteroids there are. While this overall survey may give us a clue as to their numbers, it doesn't directly show that our odds have gotten better.

There may indeed be very good reasons to sleep a little better, but this article doesn't do much to communicate that.

Hey David, how much do you want for that hard-hat? /phpBB/images/smiles/icon_biggrin.gif

David Simmons
2001-Nov-11, 01:14 AM
On 2001-11-10 07:10, David Hall wrote:

There may indeed be very good reasons to sleep a little better, but this article doesn't do much to communicate that.



Your profile lists you as an English teacher. That would probably give you a life expectancy (not to be too morbid) of about 40 years vs. the 100 spoken of in the article. So you have a 50/50 chance of having asteroid-strike-odds of about 1 in 12,500.

I am 79 years old. My life expectancy is somewhat shorter than yours so my 50/50 odds are on the order of 1 in 72,000. I feel really safe from asteroids.

But a worker at a construction site almost dropped a hard hat on me the other day.



<font size=-1>[ This Message was edited by: David Simmons on 2001-11-11 12:07 ]</font>

NottyImp
2001-Nov-12, 10:07 AM
OK, but what are the odds of being involved in an RTA? Comparable or worse? Risk is relative, and my bet is that the bus will get you before the asteroid does...

<font size=-1>[ This Message was edited by: NottyImp on 2001-11-12 05:08 ]</font>

Blob
2006-Oct-24, 05:44 PM
Russia is prepared to repel asteroids to save Earth “if necessary,” deputy head of the Russian space agency Viktor Remishevsky said on Oct. 24.

"If necessary, Russia’s rocket-manufacturing complex can create the means in space to repulse asteroids threatening Earth" - Viktor Remishevsky.

The official stressed that saving Earth from the threat of asteroids demanded international cooperation.

Read more (http://www.defensenews.com/story.php?F=2307529&C=asiapac)

Argos
2006-Oct-24, 06:09 PM
Russia is prepared to repel asteroids to save Earth “if necessary,”

That&#180;s relieving... :rolleyes:

Blob
2006-Oct-24, 06:21 PM
Hum,
with their secret orbiting launch platform "Ivan the Great"...?


According to Russia's Institute of Applied Astronomy, about 400 asteroids and over 30 comets currently present a potential threat to the planet.
The institute's specialists are particularly concerned about an asteroid known as Number 2907, a kilometre-wide chunk of space rock that they believe "with a large degree of certainty" will strike the Earth on December 16, 2880.

Source (http://www.int.iol.co.za/index.php?set_id=1&click_id=31&art_id=qw1161700561572S622)

kheider
2006-Oct-24, 08:07 PM
Given the current orbit of (2907) Nekrasov (1975 TT2), what asteroid/comet is 2907 suppose to have a close encounter with to knock it onto an Earth projectory for December 16, 2880?

Orbital simulation from JPL (Java) (http://neo.jpl.nasa.gov/cgi-bin/db?sstr=2907)

-- Kevin Heider

Blob
2006-Oct-24, 09:05 PM
Hum,
that would be good ol` 1950 DA (http://neo.jpl.nasa.gov/cgi-bin/db?sstr=1950+DA)... (er, on March 16, 2880)

Blob
2006-Oct-24, 09:12 PM
1950 DA is an asteroid for which there is some possibility of impact in March of the year 2880. The case is extraordinary because the current orbit of 1950 DA is very precisely known, which allows us to explore centuries into the future, much farther than is usually possible. The Sentry automatic monitoring system is tailored for objects with poorly determined orbits and it searches for potential impacts only over the next 100 years. More information on 1950 DA.

Read more (http://neo.jpl.nasa.gov/1950da/)

kheider
2006-Oct-25, 12:41 AM
Hum,
that would be good ol` 1950 DA (http://neo.jpl.nasa.gov/cgi-bin/db?sstr=1950+DA)... (er, on March 16, 2880)

Ahh. Another case of don't believe everything you read.

The articles at http://www.defensenews.com/story.php?F=2307529&C=asiapac & http://www.int.iol.co.za/index.php?set_id=1&click_id=31&art_id=qw1161700561572S622 both state:

"The institute’s specialists are particularly concerned about an asteroid known as Number 2907, a kilometer-wide chunk of space rock that they believe 'with a large degree of certainty' will strike the Earth on December 16, 2880." :confused:

They actually meant to say Asteroid (29075) 1950 DA on march 16th, 2880.

-- Kevin Heider

dmill120
2006-Oct-25, 06:03 AM
I don't know if they have also taken into account the theory, and I emphasize Theory! on possible perturbations resulting from our Orbital movement thru Our galactic plane.
from what I understand we are now approaching the dense portion, but this is still a long long time away!
I really believe its not a matter of if but more like when.
I would be more worried about being blind sided by a Comet approaching from our blind spot, the Sun, although I am assuming that SOHO might give us some warning, still I don't like the odds, remember Jupiter?
Dennis:)

Peter Wilson
2006-Oct-27, 07:47 PM
I'm thinking a lot of other things could happen between now and March 16, 2880...
The December date would buy us a little more time

frankuitaalst
2007-Sep-22, 02:50 PM
The recently discovered asteroid 2007SJ may be a tread to earth in the next coming years or further future. After 4 days of observation it is now ranked higher than Apophis . The asteroid is rather big ( almost 2 km in diameter ) . Observations have to continue in order to estimate its orbit . The tread can rise or be reduced . To be continued...
Heres a link to the NearEarthObjects site http://neo.jpl.nasa.gov/risk/
and a link in GravitySimulator forum : http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1175113160/56#56.

antoniseb
2007-Sep-22, 05:23 PM
The recently discovered asteroid 2007SJ may be a tread to earth in the next coming years or further future.

Wow, January of 2017, it is currently predicted to come within 4000 miles of the Earth. This will be an excellent choice for sending robotic probes to match orbits, and land on it for detailed observations and sample return.

frankuitaalst
2007-Sep-22, 06:24 PM
Quote from NEO-site : Distance
The minimum distance on the target plane (scaled b-plane) from the LOV to the geocenter, measured in Earth radii. For these purposes the radius of the Earth, 6420 km, includes some allowance for the thickness of the atmosphere.
Width
The one-sigma semi-width of the LOV uncertainty region, measured in Earth radii. "
This 4000 miles is the minimum distance . Theres also an upper limit which is much bigger . The figures will surely change as more observations become available , hopefully in the next days if the moonlight allows observations...

tony873004
2007-Sep-22, 08:51 PM
Wow, January of 2017, it is currently predicted to come within 4000 miles of the Earth...

hmm... I get 80 to 90 million kilometers in January 2017
Where did you get this figure from? Was it from this page: http://neo.jpl.nasa.gov/risk/2007sj.html ?

In the "distance" column, it states 0.97 Earth Radii on January 24, 2017.
Actually 0.97 would represent a hit since distance is measured from Earth's center, and altitude from its surface. But that's not what this column means. This is not an intuitive table.

Read more here:
http://www.bautforum.com/universe-today-story-comments/51415-close-call-asteroid-2006-xg1-2041-a.html
Specifically the last post in this thread

antoniseb
2007-Sep-22, 10:04 PM
Where did you get this figure from? Was it from this page: http://neo.jpl.nasa.gov/risk/2007sj.html ?
Yes, I got it from that page. Thanks for correcting my misunderstanding of the column meaning.

Kaptain K
2007-Sep-23, 12:14 AM
Wow, January of 2017, it is currently predicted to come within 4000 miles of the Earth. This will be an excellent choice for sending robotic probes to match orbits, and land on it for detailed observations and sample return.
Not necessarily! It's not just distance that's impotanrt. The delta v needed to match orbits is even more important!

antoniseb
2007-Sep-23, 11:00 AM
Not necessarily! It's not just distance that's impotanrt. The delta v needed to match orbits is even more important!

Delta v (about 8 km/sec) is important for getting there, but what is cheap and quick is the return flight.

KaiYeves
2007-Sep-23, 11:22 PM
saving Earth from the threat of asteroids demanded international cooperation.
Duh! Don't you watch movies? Saving the world always depends on co-operation!

Neverfly
2007-Sep-24, 12:08 AM
Naaah... all we gotta do is send Bruce Willis up to kick a little asteroid.

danscope
2007-Sep-25, 02:44 AM
" Hoo boy, Natasha. Vee get mooseberries from Moose and squirrel, and then some upsidaisium, and then we give to Mr Beeeg who can save world!" :)

danscope
2007-Sep-26, 01:10 AM
Wow, January of 2017, it is currently predicted to come within 4000 miles of the Earth. This will be an excellent choice for sending robotic probes to match orbits, and land on it for detailed observations and sample return.

Hi, I am always intrigued by the amazing configurations considered for
alternate vehicle design , both as systems and sub-systems , and the problem solving mind-payload involving so many alied disciplines working in
extraordinary harmony for the successful completion, by stages to it's final glory.
I try to quality it as "Theoretical " , especially when loosely championed
and not widely held.
TIf they can actually Land a robotic probe on an astroid, what charms and info can they with this close-by flyer? Only 4000 miles......Makes our end easier....and a little perilous...
The pictures should be something if there is good viewing.
Best regards, Dan

agingjb
2007-Sep-26, 07:16 AM
If something the size of 2007 SJ were actually predicted to pass Earth at 4000 miles, then it would be at least at Torino 7 - the best yet.

danscope
2007-Sep-27, 12:03 AM
I wonder if you could see it tumble as it passes..with a good pair of binoculars?

tony873004
2007-Sep-27, 12:40 AM
I wonder if you could see it tumble as it passes..with a good pair of binoculars?


Keep in mind that it will not pass 4000 km from Earth. But if it did, and you were on the right spot on Earth where it passed 4000 km from the surface, and you were on the night side of the globe, and the asteroid was not shadowed by Earth, then a pair of 10x binoculars would make it seem like it was 400 km from you. I'm not sure how big this asteroid is, but let's assume that it's the same size as the ISS. This would be like trying to resolve the ISS with the naked eye. It's just too small.

Additionally, it would only be 4000 km away for a single instant. It will quickly distance itself from Earth after this instant. Also, a close approach like this would probably mean that the asteroid would take a few minutes to cross the sky, but its rotation period is probably much slower than this, perhaps several hours. So even if you had a high power telescope that allowed you to resolve its shape, you still would not see it tumble. Just my guess...

Ilya
2007-Sep-27, 12:49 AM
Naaah... all we gotta do is send Bruce Willis up to kick a little asteroid.

But he needs a drunk cosmonaut to knock recalcitrant equipment just right.

"Russian part, American parts -- all made in Taiwan!"

KaiYeves
2007-Sep-27, 01:07 AM
Responding to title:
.... scare the ralbar out of me!

Neverfly
2007-Sep-27, 01:40 AM
But he needs a drunk cosmonaut to knock recalcitrant equipment just right.

"Russian part, American parts -- all made in Taiwan!"

Nitpick:p

Components*

KaiYeves
2007-Sep-28, 01:16 AM
So Taiwan controls space? Maybe I should move...

frankuitaalst
2007-Sep-30, 02:27 PM
According to the latest observations the 2007SJ may NOT be a killer one .
It is now estimated not to come closer than 0.04AU in the next 100 years .
:-)

danscope
2007-Oct-01, 05:14 PM
3,720000 miles ....... I wonder just how visible this object shall be?

frankuitaalst
2007-Oct-01, 05:49 PM
you can compare it with a squah-ball 3 cm in diameter at a distance of 100 km ...Not quite visible with the naked eye I guess.

danscope
2007-Oct-02, 02:19 AM
Yep, that's a little bit small, all right. :doh:

frankuitaalst
2007-Oct-15, 07:43 PM
The treath of the asteroid 2007SJ seems to be gone , but ....
yes ... there's another one approaching , having the record in threat now : 2007TU24 , 250-600 meters in diameter , expected to come close end of januari . heres a link : http://neo.jpl.nasa.gov/risk/
and a link to Gravity Simulator : http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1175113160/65#65

KaiYeves
2007-Oct-16, 01:20 AM
The Council will have my head for this, but...
They're always there, you know...
So *Cough* build off-world colonies* Cough!
It will help me with my case that you're intelligent.

Neverfly
2007-Oct-16, 04:31 AM
The Council will have my head for this, but...
They're always there, you know...
So *Cough* build off-world colonies* Cough!
It will help me with my case that you're intelligent.

You might need an awful lot of help with that...:whistle: