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INCOMING!, Detection and observation of Earth-approaching asteroids.
ngunn
post Nov 19 2014, 06:48 PM
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An accident with liquid sodium perhaps?
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hendric
post Jan 27 2015, 05:08 PM
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Looks like 2004 BL86 is a binary!

Primary body is ~325m across, with a moon ~70m across.

http://www.jpl.nasa.gov/news/news.php?feature=4459


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tanjent
post Jan 28 2015, 08:49 AM
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Two hasty comments:
a) The smaller body appears to be smaller than the stated 70:325 ratio would imply.
cool.gif The larger body appears to be rounder than most of the asteroids we have seen in that size range.
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Phil Stooke
post Jan 28 2015, 12:02 PM
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Re: size of the moon: you have to use the length of the radar echo, not the width, for the calculation. Width depends on the Doppler shift caused by motion of the object, not its physical width, and in this case it will have been scaled to suit the main body, not the moon.

Phil



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hendric
post Jan 28 2015, 04:00 PM
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Looks like any serious Asteroid Redirect mission will need to be able to deal with additional moonlets - Would a moonlet stay in orbit of the primary under the acceleration need to redirect? I assume it would. Heck, an asteroid with a moonlet might be easier to redirect, if we use the tug to move the moonlet itself. Instead of sending a 10+ton vehicle and using the tiny tug of gravity to move the primary, we could use the vehicle to hover the moonlet over the surface, with a much larger mass it will pull harder at the same distance. Would be a crazy 3 body ballet to plan!

Assuming a similar density to Gaspra, 2.7 g/cm^3, I get 450,000 metric tons for the moonlet. I guess that might be too big to control so close to the primary...


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Paolo
post Jan 28 2015, 08:38 PM
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the AIDA mission to test kinetic deflection techniques would aim at the satellite of a NEO. detecting the solar orbit change of a NEO would be difficult and probably require a second observer spacecraft, while changing the orbit of a satellite should be detectable from Earth.
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Gerald
post Jan 29 2015, 12:42 AM
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To deflect an asteroid binary it would probably be most efficient - in some cases - to deflect the two objects in opposite directions via actio = reactio, either via a linkage (how in detail?), or via stepwise momentum exchange using a third body as "exchange particle", ambitious in any case with objects of that mass. Elastic collision with the exchange object (using e.g. gas springs) needs less energy than separate propulsion for the two bodies to gain the same delta momentum. The orbit would get more and more eccentric, before the two bodies finally separate from gravitational binding. At the end the barycenter of the two objects may collide with Earth, but not the individual objects.
Applicability depends on the initial gravitational binding energy.
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Explorer1
post May 21 2015, 03:37 PM
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New video of the proposed AIDA mission that would shed light on binary deflection (I didn't want to make a thread for something not officially approved, yet, but this is too cool a video to pass up).

https://www.youtube.com/watch?v=h4lpu8HbpFY
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Mongo
post Aug 25 2015, 12:56 AM
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Chasing the Chelyabinsk asteroid N-body style

On 2013 February 15 a small asteroid rammed against the atmosphere above the region of Chelyabinsk in Russia, producing the most powerful superbolide since the Tunguska event in 1908. Lacking proper astrometric observations, the pre-impact orbit of this object has been determined using videos, satellite images, and pure geometry. Unfortunately, more than two years after the event, the published estimates vary so much that there is no clear orbital solution that could be used to investigate the origin of the impactor and the existence of dynamically, or perhaps even genetically, related asteroids. Here, we revisit this topic using a full N-body approach. A robust statistical test is applied to published solutions to discard those unable to produce a virtual impact at the observed time (03:20:20.8 s UTC). The same N-body methodology and the latest ephemerides are used to compute a new orbital solution: a=1.6247 AU, e=0.5318, i=3.9750 degrees, Omega=326.4607 degrees, and omega=109.7012 degrees. This new solution --which has an impact probability > 0.99999 and uncertainties in time and space of 0.2 s and 6 km, respectively-- is utilized to explore the past orbital evolution of the impactor as well as the presence of near-Earth objects moving in similar paths. A dynamical link between asteroid 2011 EO40 and the Chelyabinsk impactor is confirmed. Alternative orbital solutions are extensively explored.

2011 EO40

Recent calculations indicate that this object is a plausible candidate to be the parent body of the Chelyabinsk superbolide, since its orbit is very similar to the computed, pre-impact path of the Chelyabinsk meteoroid. It has relatively frequent close encounters with Venus, the Earth–Moon system, and Mars. It had a close encounter with Earth on January 28, 2011 at 0.0953 AU (14,260,000 km; 8,860,000 mi), and it will have a nominal Earth approach on September 23, 2025 at around 0.06 AU (9,000,000 km; 5,600,000 mi). Asteroid 2011 EO40 experiences close approaches to the Earth–Moon system following a rather regular pattern, every 17 years approximately due to the combined action of multiple secular resonances.

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Geert
post Sep 7 2015, 03:12 PM
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Bangkok Post 07 Sept

http://www.bangkokpost.com/vdo/thailand/68...red-by-netizens
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moustifouette
post Nov 24 2016, 06:37 PM
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current impact risk

A newly discovered neo, 2016 WJ1, have reached a Torino scale score of 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. "
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nprev
post Nov 24 2016, 10:51 PM
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Apparently discovered just a few days ago, so all of this will doubtless be revised considerably soon.

The predicted perigee distances are interestingly close, however, and the object's estimated size is quite large in comparison to most detections over the past few years. Since the size estimate depends on an albedo model, seems possible that this may be another expended booster stage, which would normally be much brighter than any asteroid and thus much smaller than the estimate.


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Explorer1
post Nov 24 2016, 11:57 PM
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http://lagniappeobserving.blogspot.ca/2016...2016-11-24.html

Flyby of around 21 LD on December 16. A good time to make observations (perhaps radar too?)
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moustifouette
post Dec 5 2016, 12:05 PM
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After Recovery of 2016 WJ1 on images from 2003, the orbit is well defined and TS risk is 0.
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g4ayu
post Dec 7 2016, 05:24 PM
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A small meteorite in Siberia reported by the BBC (With video):-
http://www.bbc.co.uk/news/video_and_audio/headlines/38241233
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