Asteroids

[Sparky]

It wouldn't hold still for it's picture....
http://news.discovery.com/space/first-p ... 10627.html

[Lloyd]

* Wow. It was estimated at only 5 to 20 meters wide. Even if it hit the Earth, it wouldn't have penetrated the atmosphere. It would have been nice to see lightning strike it as it approached.

[StefanR]

9.1. Summary
A description of space weathering on asteroids that is
most consistent with the available evidence is as follows.

(1) Some lunarlike optical maturation occurs and its strength
is dependent on the composition of the target material; however,
it is not as effective on asteroids as it is on the Moon.
The main process is probably deposition of condensates
bearing SMFe on grain surfaces from vaporization of target
material by solar wind sputtering and micrometeorite bombardment.
(2) Some spectrally neutral darkening occurs and
is probably related to the processes of shock, solar wind gas
implantation, and contamination by carbonaceous material.

Space-weathering effects on asteroids strongly depend
on the composition of the target. Some asteroid types show
very little evidence of optical alteration (C types), while
other types show strong evidence of optical alteration (S
types). These trends indicate that objects composed of dark,
relatively opaque components exhibit minimal space-weathering
effects while objects composed of bright, relatively
transparent components exhibit maximal space-weathering
effects. Availability of Fe in target minerals influences the
abundance of SMFe. Experiments indicate that olivine is
more easily weathered than pyroxene, perhaps explaining
some of the variations in the degree of weathering observed
within an asteroid class.
A prediction of the model is that a pristine sample of
asteroid regolith in which space weathering has occurred
should possess a weak ESR ferromagnetic resonance.

9.2. Remaining Unresolved Issues and Problems
Soil samples from several different asteroid spectral
types are needed to verify the compositional dependencies
of space-weathering effects. There is no quantitative understanding
of the relative rates of the space-weathering processes
and their optical effects. In particular, it is not clear
why the color and albedo trends due to space weathering
on 951 Gaspra and 243 Ida differ from those on 433 Eros.
The values of the complex spectral refractive index of
Fe measured by various workers vary greatly (by more than
a factor of 2), probably because of surface oxidation effects.
Accurate values appropriate to the space environment are
badly needed for reliable modeling.

http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3023.pdf

[bdw000]

Anyone (more expert than me about EU) want to comment on this pic of Vesta (and comments below second image with arrows)??

Looks to me like we're going to have the usual electrical explanations here.

http://gizadeathstar.com/2011/09/more-curious-images-from-nasas-dawn-mission-to-asteroid-vesta/

[Sparky]

Interesting image......what caught my attention first was the apparent melting of the large crater...then i noticed bright areas.
the bright areas could be continued electrical discharges which overload the camera to create overexposed areas.

[tayga]

The bright spots reminds me of some images of Venus which have been discussed here. This could be St Elmo's fire. There are also what appear be radiating filaments associated with each of the bright spots. It would be interesting to see how the bright spots relate to the topography of this area; I'd guess that they're the highest points.

[substance]

Not meaning to highjack your thread but this is just too good, not to share it here:

NASA's Journey Above Vesta --> http://www.youtube.com/watch?v=IIUdww7_zvw

I almost laughed out loud at the crater chain they called "Snow man"... Also, there are a couple of hexagonal craters clearly defined even in the 3D model.

[shadowmane]

So the prediction on the predictions page of Thunderbolts says the following:

Thornhill: I predict that the crater on Vesta, when photographed more closely, will be circular also.

Looks like another prediction that can be moved. They found out that it wasn't a crater, per-se, but it was a circular formation.

[MrAmsterdam]

http://neo.jpl.nasa.gov/news/news171.html

Near-Earth asteroid 2005 YU55 will pass within 0.85 lunar distances from the Earth on November 8, 2011. The upcoming close approach by this relatively large 400 meter-sized, C-type asteroid presents an excellent opportunity for synergistic ground-based observations including optical, near infrared and radar data.
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Although classified as a potentially hazardous object, 2005 YU55 poses no threat of an Earth collision over at least the next 100 years. However, this will be the closest approach to date by an object this large that we know about in advance and an event of this type will not happen again until 2028 when asteroid (153814) 2001 WN5 will pass to within 0.6 lunar distances

[Sparky]

-no threat of an Earth collision over at least the next 100 years-

Such a prediction should not be taken as fact. Any small nudge along it's orbit could bring the asteroid closer or take it away from Earth's orbit, during the next 100 years.

It appears to get closer to our moon than to Earth. What other planets or moons will it be passing close by.?

[MrAmsterdam]

http://www.nasa.gov/mission_pages/aster ... 11025.html

Earth, the mean radius is 6371.009 km (≈3958.761 mi; ≈3440.069 nmi).

magnetosphere radius

15 x earth radii = 95670 km

geotail 200 x earth radii = 1275600 km

I was wondering if the asteroid is going to interact with earths plasma field, but it does not seem likely if you look at the distances.

[sol88]

Well I'm hoping that serendipity steps in and sunspot 1339 emits an Earth bound X-Class flare, about the same time the full moon moves into our magnetotail, this will of course coincide with 2005 YU55's passage by us while a lot of amateur and professional equipment are watching!!

Explain that!!

[MrAmsterdam]

http://www.nasa.gov/mission_pages/aster ... 11107.html

Asteroid 2005 YU55 Approaches Close Earth Flyby

This radar image of asteroid 2005 YU55 was obtained on Nov. 7, 2011, at 11:45 a.m. PST (2:45 p.m. EST/1945 UTC), when the space rock was at 3.6 lunar distances, which is about 860,000 miles, or 1.38 million kilometers, from Earth.

[MattEU]

More evidence that geology features are not formed or created in the way geologists believe. Perhaps with the visual evidence that similar geology features are found on asteroids, mercury, venus, earth, mars and even titan it may be time to change the idea of gradual geology changes caused by events in a gravity universe?

The giant asteroid Vesta possesses many features usually associated with rocky planets like Earth, according to data from a Nasa probe.

Vesta has been viewed as a massive asteroid, but after studying the surface in detail, scientists are describing it as "transitional".

The Dawn spacecraft has been orbiting Vesta - one of the Solar System's most primitive objects - since July 2011.

They have documented many unexpected features on its battered surface.

Mission scientists presented their latest results at the Lunar and Planetary Science Conference (LPSC) in The Woodlands, Texas.

Dawn's principal investigator, Christopher T Russell, told the meeting that the science team found it hard not to refer to the object as a planet.

He said the rounded asteroid showed evidence of geological processes that characterise rocky worlds like Earth and the Moon.
http://www.bbc.co.uk/news/science-environment-17481911

[PersianPaladin]

I want to highlight a particular asteroid called 2002 AA29. The asteroid is in a co-orbital configuration with the Earth, albeit it's orbit is periodically ahead of the Earth at considerable distances. The orbit of the asteroid around the sun is in a cork-screw pattern. It's behaviour as part of a "horse-shoe" orbit also does not seem to follow the behaviour of Larangian Points and their various behaviour:-
http://en.wikipedia.org/wiki/Lagrangian_point

Worth noting:-

Asteroids that have a 1:1 orbital resonance with a planet are also called co-orbital objects, because they follow the orbit of the planet. The most numerous known co-orbital asteroids are the so-called Trojans, which occupy the L4 and L5 Lagrangian points of the relevant planet. However, 2002 AA29 does not belong to these. Instead, it follows a so-called horseshoe orbit along the path of the Earth.

http://en.wikipedia.org/wiki/2002_AA29

Asteroid 2002 AA29 is an asteroid that is in a 1:1 resonance with the Earth. Such asteroids are often refered to as co-orbital with the Earth. It spends much of its time in a horseshoe orbit. But every few hundred years, it leaves its horseshoe orbit and occupies the area normally avoided by its horseshoe orbit. During a period that lasts a few decades, asteroid 2002 AA29 never strays far from the Earth as it circles the Earth/Moon system in a quasi-orbit. Eventually, it will leave this configuration and exit the Earth system from the same direction it entered.

http://www.orbitsimulator.com/gravity/a ... 2aa29.html

In this animation, we look down on the Solar System and rotate our view with the Earth as it goes around the Sun, much like a cameraman filming from the roof of a rotating merry-go-round. This makes the Earth appear to be fixed, allowing us to see just the motion of the asteroid relative to our planet. The animation begins in 1903, when 2002 AA29 was on the trailing side of Earth. The asteroid traces small loops because of variations in both its orbital speed and that of the Earth.

For the first few years after 1903, the asteroid loops towards our planet, but then it reverses due primarily to gravitational interaction with the Earth. It then begins a 95-year trek all the way around the Earth's orbit to our planet's leading side, where it will make a close approach on January 8, 2003, and reverse itself once again. Never passing through the gap near the Earth, the asteroid traces out a horseshoe pattern.

http://neo.jpl.nasa.gov/2002aa29.html

The Wikipedia explanation for the spiral morphology of its orbit around the sun, is not satisfying for me:-

As it moves along the Earth's orbit, it winds in a spiral about it, in which each loop of the spiral takes one year. This spiral motion (in the Earth–Sun reference frame) arises from the slightly lower eccentricity and the tilt of the orbit: the inclination relative to the Earth's orbit is responsible for the vertical component of the spiral loop, and the difference in eccentricity for the horizontal component.

http://en.wikipedia.org/wiki/2002_AA29# ... _the_orbit

Neither is this explanation as to HOW:-

The loop results from AA29’s 10.7 degree inclination with respect to the ecliptic plane.

http://ccar.colorado.edu/asen5050/proje ... 4/mlarson/

Larangian points of L4 and L5 cannot account for this spiral movement. Neither can proximity to the Earth's gravity given what we've seen regarding the variability of its location with respect to the Earth. Importantly, one has to ask why "gravity" of an object would behave this way. The movement is somewhat reminiscent of an object traversing a magnetic field:-


Source:-
http://scientopia.org/blogs/galacticint ... ic-fields/

NASA states its looping behaviour is because of velocity variations:-

The asteroid traces small loops because of variations in both its orbital speed and that of the Earth.

What other looping phenomena changes temporal speed like this?

First consider centripetal forces within radial movements with acceleration occuring as a result of changes in direction:-
http://www2.ignatius.edu/faculty/decarl ... 0force.htm

The same centripetal acceleration occurs within synchrotron radiation:-
http://hyperphysics.phy-astr.gsu.edu/hb ... otron.html

Obviously, this is not to imply that electrons are moving within this morphology. Just that the nature of acceleration was interesting as a parallel to what can occur in the context of magnetic behaviour.

Please provide feedback if you can (as I obviously can get ahead of myself and sometimes make silly mistakes).

Regards,

~PP