Jump to content




Welcome to Unexplained Mysteries! Please sign in or create an account to start posting and to access a host of extra features.


* * * * * 1 votes

Asteroid 1998 QE2


  • Please log in to reply
25 replies to this topic

#1    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 26 June 2013 - 07:01 PM

Having heard nothing more about the work to determine the density of asteroid 1998 QE2, a key piece of information in determining its composition, I enquired about this to a JPL representative. I heard back promptly from David Agle.
I quote his response in full- - "A very preliminary density estimate ~ 1g/cm^3. So a very high porosity object."  An interesting response. The object appears to fall neatly between the average density of 'primitive', dark, 'rockpile' asteroids (type C) which this object appears to be, and comets. The former average  ~ 1.4 g/cm^3, and the latter about 0.4 g/cm^3.
Type C asteroids typically have a porosity, empty spaces between rocky fragments, of about 27%. In order for this object to have such a low density, it might need to have as much as half its volume taken up by such spaces.


#2    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 28 June 2013 - 07:49 PM

One is tempted to suggest that this object is a short period (extinct) comet. The exhaustion of most of its light, volatile ice, could increase its bulk density to the stated figure.
The only problem with this explanation is that most comets have much longer orbits. There are some short period comets, though. Those the might be likely to pass near Earth are in the Jupiter Family of Comets. The gravity of Jupiter converts a long period comet  to a much shorter orbit.
A combination of orbital factors are used to produce a Tisserand Parameter. In Jupiter Family Comets these are typically less than 3.  In asteroids, greater than three. The Tisserand parameter of 1998 QE2 is given as 3.24, indicating it's probably an asteroid, not a comet.  Could we have a slightly anomalous comet anyway? I looked at a list of nearly 500 Jupiter Family Comets. All but a dozen were under 3. The highest  value, in a single instance, was 3.212.
An unusually porous asteroid looks likelier than a short period comet.


#3    NatureBoff

NatureBoff

    SandersonHapgood

  • Banned
  • 3,491 posts
  • Joined:23 Oct 2009
  • Gender:Male
  • Location:UK

Posted 29 June 2013 - 05:35 AM

Bison, what do you make of the 1998 QE2's moon and the extreme difference in albedo? Why is the moon bright but the main object dark?

The object, known by the locals as "Bicho Voador" (Flying Animal), or "Bicho Sugador" (Sucking Animal), has the shape of a rounded ship and attacks people in isolation.

#4    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 29 June 2013 - 03:18 PM

It was quite intriguing that the asteroid's moon appeared so much brighter than its primary. The initial suspicion was that it must be much more reflective of the radar waves used to make the image. As it turns out, the real reason for the moon's brightness is that it is spinning much more slowly than the asteroid, once in about 32 hours, as opposed to about 5 hours. A feature of the way that the radar images are made is that the faster an object spins, the more spread out it appears. The slower spinning moon appears less spread out, and so its radar returns are more crowded together, and they appear brighter.


#5    NatureBoff

NatureBoff

    SandersonHapgood

  • Banned
  • 3,491 posts
  • Joined:23 Oct 2009
  • Gender:Male
  • Location:UK

Posted 29 June 2013 - 05:56 PM

View Postbison, on 29 June 2013 - 03:18 PM, said:

It was quite intriguing that the asteroid's moon appeared so much brighter than its primary. The initial suspicion was that it must be much more reflective of the radar waves used to make the image. As it turns out, the real reason for the moon's brightness is that it is spinning much more slowly than the asteroid, once in about 32 hours, as opposed to about 5 hours. A feature of the way that the radar images are made is that the faster an object spins, the more spread out it appears. The slower spinning moon appears less spread out, and so its radar returns are more crowded together, and they appear brighter.
Okay, thanks. Is the calculated average density of the moon the same as the primary?

The object, known by the locals as "Bicho Voador" (Flying Animal), or "Bicho Sugador" (Sucking Animal), has the shape of a rounded ship and attacks people in isolation.

#6    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 30 June 2013 - 02:22 PM

View PostRingFenceTheCity, on 29 June 2013 - 05:56 PM, said:

Okay, thanks. Is the calculated average density of the moon the same as the primary?
It's been said by some sources that the density of both the asteroid and its moon could be calculated, other sources neglect mentioning the density of the moon at all. It's not clear if estimating the density of the moon could use the mutual movements of the two object, as they do in determining the mass of the main asteroid, or not. So far, I've only heard of the very preliminary density estimate for the main asteroid.

Edited by bison, 30 June 2013 - 02:26 PM.


#7    NatureBoff

NatureBoff

    SandersonHapgood

  • Banned
  • 3,491 posts
  • Joined:23 Oct 2009
  • Gender:Male
  • Location:UK

Posted 30 June 2013 - 03:42 PM

View Postbison, on 30 June 2013 - 02:22 PM, said:

It's been said by some sources that the density of both the asteroid and its moon could be calculated, other sources neglect mentioning the density of the moon at all. It's not clear if estimating the density of the moon could use the mutual movements of the two object, as they do in determining the mass of the main asteroid, or not. So far, I've only heard of the very preliminary density estimate for the main asteroid.
Don't you think it's odd that the two-body system can be seen quite clearly but only the average density of the primary can be determined?? I suspect NASA are hiding something personally.

The object, known by the locals as "Bicho Voador" (Flying Animal), or "Bicho Sugador" (Sucking Animal), has the shape of a rounded ship and attacks people in isolation.

#8    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 01 July 2013 - 02:13 PM

View PostRingFenceTheCity, on 30 June 2013 - 03:42 PM, said:

Don't you think it's odd that the two-body system can be seen quite clearly but only the average density of the primary can be determined?? I suspect NASA are hiding something personally.
The way the situation was explained to me: they have only a very preliminary estimate of the density of the main asteroid. It obviously needs further work before the most accurate possible figure is obtained. This work is presumably based on the effect the main asteroid has on the orbit of its moon.  Determining the reciprocal case-- the effect the moon has on the asteroid-- will probably be much more difficult, and require some very exacting work. This latter effect is obviously far smaller than the former.


#9    NatureBoff

NatureBoff

    SandersonHapgood

  • Banned
  • 3,491 posts
  • Joined:23 Oct 2009
  • Gender:Male
  • Location:UK

Posted 01 July 2013 - 05:09 PM

View Postbison, on 01 July 2013 - 02:13 PM, said:

The way the situation was explained to me: they have only a very preliminary estimate of the density of the main asteroid. It obviously needs further work before the most accurate possible figure is obtained. This work is presumably based on the effect the main asteroid has on the orbit of its moon.  Determining the reciprocal case-- the effect the moon has on the asteroid-- will probably be much more difficult, and require some very exacting work. This latter effect is obviously far smaller than the former.
Do you think that the exact dynamics of the two body system will be resolved with an accurate simulation model or is NASA 'too busy'?

The object, known by the locals as "Bicho Voador" (Flying Animal), or "Bicho Sugador" (Sucking Animal), has the shape of a rounded ship and attacks people in isolation.

#10    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 02 July 2013 - 02:42 PM

They may eventually do a computer simulation of the shape and motions of the asteroid and its moon. It's not unreasonable that this would take some time. An accurate density figure for the asteroid should come first.
I was also interested in the spectroscopic analysis of the object. This will be key to determining what the object is made of.  I asked Alessondra Springmann, an astrophysicist working on 1998 QE2, what had  been learned. She replied that the asteroid appears to be transitional between asteroid classes D and X.
Class D asteroids are essentially metallic objects, and quite dense. Class X asteroids are made of mixed silicates, carbon compounds, and possibly ice. Its very interesting that an object described as 'primitive'-- meaning largely untouched since its initial formation, should seem to show signs suggesting the complete mergence of two very different sorts of objects, into one, essentially spherical, body

Edited by bison, 02 July 2013 - 02:50 PM.


#11    NatureBoff

NatureBoff

    SandersonHapgood

  • Banned
  • 3,491 posts
  • Joined:23 Oct 2009
  • Gender:Male
  • Location:UK

Posted 02 July 2013 - 04:11 PM

View Postbison, on 02 July 2013 - 02:42 PM, said:

They may eventually do a computer simulation of the shape and motions of the asteroid and its moon. It's not unreasonable that this would take some time. An accurate density figure for the asteroid should come first.
I was also interested in the spectroscopic analysis of the object. This will be key to determining what the object is made of.  I asked Alessondra Springmann, an astrophysicist working on 1998 QE2, what had  been learned. She replied that the asteroid appears to be transitional between asteroid classes D and X.
Class D asteroids are essentially metallic objects, and quite dense. Class X asteroids are made of mixed silicates, carbon compounds, and possibly ice. Its very interesting that an object described as 'primitive'-- meaning largely untouched since its initial formation, should seem to show signs suggesting the complete mergence of two very different sorts of objects, into one, essentially spherical, body
Yes, I agree, it *is* intriguing. Thanks for the detailed reply. All the best.

The object, known by the locals as "Bicho Voador" (Flying Animal), or "Bicho Sugador" (Sucking Animal), has the shape of a rounded ship and attacks people in isolation.

#12    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 03 July 2013 - 01:47 PM

The average density of class X asteroids is about 2.9 g/cm^3, that of class D around 9.6. Interesting that an object that, by dynamical methods, seems to have a density of approximately 1 g/cm^3 should appear to be made of materials,that, if combined, could make for a density of 6 or 7. Although 1998 QE2 left the vicinity of Earth over a month ago, it seems that it may still hold some surprises for us.


#13    NatureBoff

NatureBoff

    SandersonHapgood

  • Banned
  • 3,491 posts
  • Joined:23 Oct 2009
  • Gender:Male
  • Location:UK

Posted 03 July 2013 - 03:14 PM

View Postbison, on 03 July 2013 - 01:47 PM, said:

The average density of class X asteroids is about 2.9 g/cm^3, that of class D around 9.6. Interesting that an object that, by dynamical methods, seems to have a density of approximately 1 g/cm^3 should appear to be made of materials,that, if combined, could make for a density of 6 or 7. Although 1998 QE2 left the vicinity of Earth over a month ago, it seems that it may still hold some surprises for us.
Agreed.

The object, known by the locals as "Bicho Voador" (Flying Animal), or "Bicho Sugador" (Sucking Animal), has the shape of a rounded ship and attacks people in isolation.

#14    bison

bison

    Psychic Spy

  • Member
  • PipPipPipPipPipPipPipPip
  • 1,352 posts
  • Joined:13 Apr 2011

Posted 04 July 2013 - 10:50 PM

After being told that 1998 QE2 has a spectrum combining characteristics of class  X and D asteroids, I began to wonder where I had gotten the idea that it was  class C.   I then found that spectra of the object had been made on June 5th with the 5 meter Hale telescope, at Palomar observatory. This was only a few days after the nearest approach of 1998 QE2. It was still quite close. They found that the asteroid most closely matched class C. When or where the information suggesting class X and D was obtained, I couldn't say, as yet.


#15    Waspie_Dwarf

Waspie_Dwarf

    Space Cadet

  • 32,178 posts
  • Joined:03 Mar 2006
  • Gender:Male
  • Location:Bexleyheath, Kent, UK

  • We are all in the gutter, but some of us are looking at the stars.

    Oscar Wilde

Posted 04 July 2013 - 11:57 PM

Bison,are you ever actually going to get to the point?

Please make your point otherwise your posts could be considered thread bumping.

From the rules:

Quote

1d. Thread bumping: Do not post 'bump' messages solely to return a thread to the top of the topic index.


"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

Posted Image
Click on button




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users