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Wed Jan 9, 2013, 07:05 PM

'Doomsday' asteroid Apophis more massive than first thought

Watch its Earth flyby live tonight at 0100 UTC

By Iain Thomson in San Francisco • Get more from this author

Posted in Science, 9th January 2013 22:19 GMT

Astronomers following the so-called doomsday asteroid Apophis, which will be whizzing past Earth on Thursday morning, have found the rock is much larger than had previously been assumed. Since the asteroid could hit Earth in 2036, that's a problem.

The asteroid, named after an Egyptian god of death, had been thought to be around 885 feet (270 meters) wide, plus or minus a couple of hundred feet (60 meters). But as Apophis approached last weekend, astronomers at the Herschel Space Observatory took new observations and have concluded that astronomers have seriously underestimated both its size and its mass.

"The 20 per cent increase in diameter, from 270 to 325m, translates into a 75 per cent increase in our estimates of the asteroid's volume or mass," said Thomas Müller of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.

"These numbers are first estimates based on the Herschel measurements alone, and other ongoing ground-based campaigns might produce additional pieces of information which will allow us to improve our results." ...

http://www.theregister.co.uk/2013/01/09/apophis_size_mistake/

31 replies, 2689 views

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Arrow 31 replies Author Time Post
Reply 'Doomsday' asteroid Apophis more massive than first thought (Original post)
struggle4progress Jan 2013 OP
still_one Jan 2013 #1
greytdemocrat Jan 2013 #2
struggle4progress Jan 2013 #3
cthulu2016 Jan 2013 #8
Buns_of_Fire Jan 2013 #14
ThoughtCriminal Jan 2013 #4
lumberjack_jeff Jan 2013 #5
struggle4progress Jan 2013 #6
uponit7771 Jan 2013 #9
leveymg Jan 2013 #29
LineReply .
DogPawsBiscuitsNGrav Jan 2013 #7
randome Jan 2013 #12
Blue_In_AK Jan 2013 #10
Heywood J Jan 2013 #11
Tyrs WolfDaemon Jan 2013 #17
hobbit709 Jan 2013 #13
muriel_volestrangler Jan 2013 #15
ChisolmTrailDem Jan 2013 #22
muriel_volestrangler Jan 2013 #25
sadbear Jan 2013 #16
Tyrs WolfDaemon Jan 2013 #18
theKed Jan 2013 #19
Tyrs WolfDaemon Jan 2013 #20
theKed Jan 2013 #21
NickB79 Jan 2013 #23
theKed Jan 2013 #24
Whovian Jan 2013 #26
leveymg Jan 2013 #28
bluestateguy Jan 2013 #27
RC Jan 2013 #30
ThoughtCriminal Jan 2013 #31

Response to struggle4progress (Original post)

Wed Jan 9, 2013, 07:13 PM

1. That's it, I am moving

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Response to struggle4progress (Original post)

Wed Jan 9, 2013, 07:15 PM

2. Mars is lovely this time of year...nt

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Response to struggle4progress (Original post)

Wed Jan 9, 2013, 07:20 PM

3. Predicting Apophis' Earth Encounters in 2029 and 2036

... While trajectory knowledge was substantially corrected by the Arecibo data, a small estimated chance of impact (less than 1 in 45,000 using standard dynamical models) remained for April 13, 2036. With Apophis probably too close to the Sun to be measured by optical telescopes until 2011, and too distant for useful radar measurement until 2013, the underlying physics of Apophis' motion were considered to better understand the hazard ...

It was found that small uncertainties in the masses and positions of the planets and Sun can cause up to 23 Earth radii of prediction error for Apophis by 2036 ...

The future for Apophis on Friday, April 13 of 2029 includes an approach to Earth no closer than 29,470 km (18,300 miles, or 5.6 Earth radii from the center, or 4.6 Earth-radii from the surface) over the mid-Atlantic, appearing to the naked eye as a moderately bright point of light moving rapidly across the sky. Depending on its mechanical nature, it could experience shape or spin-state alteration due to tidal forces caused by Earth's gravity field.

This is within the distance of Earth's geosynchronous satellites. However, because Apophis will pass interior to the positions of these satellites at closest approach, in a plane inclined at 40 degrees to the Earth's equator and passing outside the equatorial geosynchronous zone when crossing the equatorial plane, it does not threaten the satellites in that heavily populated region ...

neo.jpl.nasa.gov/apophis/

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Response to struggle4progress (Reply #3)

Wed Jan 9, 2013, 08:30 PM

8. "4.6 Earth-radii from the surface..." (!!!)

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Response to struggle4progress (Reply #3)

Thu Jan 10, 2013, 08:30 AM

14. Whew. It'll miss our geosynchronous satellites. I feel much better now.

Oh, wait. No, I don't.

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Response to struggle4progress (Original post)

Wed Jan 9, 2013, 07:53 PM

4. Radar Measurement adds 2x10^10 kg

I hate that about radar.

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Response to ThoughtCriminal (Reply #4)

Wed Jan 9, 2013, 07:54 PM

5. Heh. +1

This orbital inclination makes my equator look big.

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Response to ThoughtCriminal (Reply #4)

Wed Jan 9, 2013, 07:54 PM

6. The obvious solution is to stop measuring asteroid size by radar!

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Response to ThoughtCriminal (Reply #4)

Wed Jan 9, 2013, 08:34 PM

9. +1!

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Response to ThoughtCriminal (Reply #4)

Thu Jan 10, 2013, 05:01 PM

29. Anyone want to estimate how many megatons it would take to vaporize a stone potato 1000 feet long?

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Response to DogPawsBiscuitsNGrav (Reply #7)

Thu Jan 10, 2013, 08:07 AM

12. Good God, that's frightening!

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Response to struggle4progress (Original post)

Wed Jan 9, 2013, 08:38 PM

10. I'm not worried.

The psychics have told me I'm going to live to 93, which doesn't happen until 2039. You can all relax now.

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 08:04 AM

11. Is it pyramidal?

Are there ring-like objects descending from it?

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Response to Heywood J (Reply #11)

Thu Jan 10, 2013, 10:20 AM

17. I guess we need to start looking for the launch of Death-Gliders

This is just great. The last thing we need is for symbiotes to infiltrate our govt. The Teabaggers are enough of a pain as is.

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 08:09 AM

13. Not quite a dinosaur killer but big enough to cause some major disruptions in climate and ecology.

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 09:36 AM

15. NASA: no chance of a 2036 impact

Astronomers surely enjoy dramatic stories as much as the rest of us. But today they played spoilers with the welcome announcement that the sizable Earth-crossing asteroid 99942 Apophis will pose no threat when it comes near our planet in 2036.

Right now Apophis is in the midst of a rather distant yet much-awaited pass in Earth's vicinity, coming within 9 million miles (14½ million km) earlier today. It's been tracked for about a week by NASA's 230-foot (70-m) Goldstone radio/radar dish in California, and those observations have given astronomers the confidence to issue an "all clear" for the foreseeable future.

"Goldstone single-pixel observations of Apophis have ruled out the potential 2036 Earth impact," says Jon Giorgini, a dynamicist at NASA's Jet Propulsion Laboratory. Based on revised orbit calculations, he says Apophis will then come no closer than about 14 million miles — and more likely miss us by something closer to 35 million miles. Moreover, the radar data have improved the asteroid's positional uncertainty so much that dynamicists can now accurately predict its trajectory decades into the future.

"We're observing it at 75-meter resolution, which is better than we expected," notes Lance Benner (Jet Propulsion Laboratory), who's leading the radar effort. "The signal-to-noise ratios are a bit stronger than we thought they'd be, so the radar astrometry is more precise than we expected."

http://www.skyandtelescope.com/news/Asteroid-Apophis-Takes-a-Pass-in-2036-186245171.html

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Response to muriel_volestrangler (Reply #15)

Thu Jan 10, 2013, 01:29 PM

22. It was actually closer yesterday as I watched it go by

on a live broadcast on Slooh.com. I was under the impression it would be within the orbit of our geosynchronous satellites in '29 or '36. Now this guy is saying 35 million miles?

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Response to ChisolmTrailDem (Reply #22)

Thu Jan 10, 2013, 04:40 PM

25. Very close in 2029; they weren't sure if that would change the orbit enough for 2036

to become a collision - but now they know it won't:

We know it will make a very close shave of the Earth in April 2029, passing so low it will actually be under many of our satellites! While it will certainly miss on that date, there was a problem: The Earth’s gravity would bend the asteroid’s path, and if it passed us at just the right distance (through a region of space nicknamed the keyhole), it would move into an orbit that would cause an impact in April 2036, seven years later.

The problem was we didn’t know the trajectory of the asteroid well enough to say if there would be an impact or not. There simple weren’t enough accurate observations, so trying to predict where it would be more than two decades in the future introduced a fuzziness to its position. There was a small but significant chance it would pass through the keyhole in 2029, leading to a later impact.

Observations taken a couple of years ago nailed down the orbit better, and the odds dropped to about one in a million. Yay! But still, a better number would be zero.

And that’s where we are now. Apophis is currently making a pass of Earth (at a distance of 14 million kilometers, or 9 million miles), which is favorable for observing it. Astronomers used NASA’s Goldstone radar facility to send pulses of radar to the asteroid and back, which yield highly accurate positions for the rock. When the new data were added to what was already known about its orbit, it was found the asteroid will definitely miss the keyhole in 2029, and thus miss us in 2036. By a large margin, actually: more than 20 million kilometers (14 million miles), or 50 times the distance to the Moon. And that’s a minimum distance, so it looks like we’re safe from this rock.

http://www.slate.com/blogs/bad_astronomy/2013/01/10/apophis_impact_new_observation_show_it_to_be_bigger_but_no_longer_a_threat.html

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 09:44 AM

16. Has anyone seen it yet?

Nobody else is even talking about it.

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 10:24 AM

18. Has anyone thought of trying to catch it?

It would be cool to make it land/crash on the moon so we could study it. Who knows what kind of things we might glean from an in depth examination.

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Response to Tyrs WolfDaemon (Reply #18)

Thu Jan 10, 2013, 10:40 AM

19. The fuel cost

to stop an asteroid like that would be absolutely ridiculous. The sheer amount of delta-v to brake it enough to land or brake would be huge. I don't recall seeing a velocity anywhere but, we'd have had to start a deceleration burn quite some time ago - which means heaving a whole bunch of dead weight into space (fuel) just to even start...we're really not set up for that kind of op

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Response to theKed (Reply #19)

Thu Jan 10, 2013, 11:26 AM

20. That makes sense

I really hadn't given it that much thought.

We ought to prove it though by launching GOPers at it. They are so into stopping things these days, perhaps they might be able to slow it down, even if only by a millimeter/sec or so. Finally, a scientific use for Repubs.

We might even get them to launch themselves at it if we told them it had oil or tons of gold.

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Response to Tyrs WolfDaemon (Reply #20)

Thu Jan 10, 2013, 01:23 PM

21. dont get me wrong

it would be fantastic if we could do such a thing. unfortunately, we seem content to keep to our ball of rock for the time being. an orbital fueling station would be an excellent start for such a thing, or manned planetary trips. some of the non-rocketry ascent prospects on the horizon are very promising - ie. space elevators - and make hauling fuel out of the deepest part of earth's gravity well much more feasible. that eliminates a huge hurdle.

much like last time, the next wave of colonization will probably be fueled by resources and population pressures - and accomplished with a lot of commercial backing.

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Response to theKed (Reply #19)

Thu Jan 10, 2013, 01:46 PM

23. Probably have to aero-brake it in the atmosphere

And there is NO FUCKING WAY I'd be comfortable with that.

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Response to NickB79 (Reply #23)

Thu Jan 10, 2013, 03:01 PM

24. If it didn't shatter into hundreds of pieces in the process

Yeah. No goddamn way anyone would willingly aerobrake a massive asteroid in our own atmosphere. Not without a damn good reason.

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 04:47 PM

26. Maybe if everybody with a gun shot at it at the same time?

 

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Response to Whovian (Reply #26)

Thu Jan 10, 2013, 04:55 PM

28. People are more likely to all begin shooting each other if they were told it was going to hit us.

Out with a bang, a whimper, and then a great BIG BANG.

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 04:50 PM

27. I think that is still not big enough to destroy all life on Earth

Just do a hell of a lot of damage, to be sure.

And I think that is small enough of a rock that we could shoot it down with a missile.

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Response to bluestateguy (Reply #27)

Thu Jan 10, 2013, 05:31 PM

30. Sure and turn the asteroid into a shotgun blast, endangering an even larger area.

 

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Response to struggle4progress (Original post)

Thu Jan 10, 2013, 06:40 PM

31. No longer a threat in 2036

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