Kerr Watch

Number of days writer Richard Kerr has failed to inform his Science readers of the confirmation of nanodiamonds at the YDB: 3 years, 7 months, and 6 days

CT Post Calendar

July 2014
M T W T F S S
« Jun    
 123456
78910111213
14151617181920
21222324252627
28293031  

The Cosmic Tusk Newsletter

Loading...Loading...


More “Current Events”

 

Sliding Spring Update: Getting closer 

See 3:40

V. Hippies?

Dr. V!

I’m getting dragged into the future again. But click above for a fascinating report.

It brought to mind: He who shall not be named in Science: Dr. V. If Dr. V had said we might see such a thing in our lifetime (he tended to stick to the past too) he would have been strung up. Oh…that’s right

 

14 comments to More “Current Events”

  • Trent Telenko

    So, our NASA Mars orbiters & rovers are going to have a front row seat to either a comet tail interpenetration or a flat out Martian comet impact in 2014?

    I foresee a cognitive dissonence attack at NASA as _that data_ flows in.

    I also forsee a lot of Tusk readers & posters breaking out the gourmet popcorn awaiting those same pictures.

  • Trent Telenko

    Astroblogger is working on his dry humor understatement schtick —

    The nominal close approach is now 0.0007 AU. This is much closer than the previous 0.006 AU, but still further out than the 0.00023 AU close approach of 2012 DA14, which missed us by two Earth diameters.

    The error associated with this estimate still includes an impact though (and a maximum miss of 0.008 AU), so an impact can’t be ruled out at this stage.

    As I wrote before, as further observations are added and the orbit is refined, we will have a better idea of whether it will impact. Even if it doesn’t impact it will look pretty good from Earth, and specacular from Mars (probably a magnitude -4 comet as seen from Mars’s surface), which might be observed by the plethora of orbitig spacecraft and the rovers. A collision would also be spectacular, but the rovers may not fare so well.

  • George Howard

    Phil Plait gritting his teeth here: http://www.slate.com/blogs/bad_astronomy/2013/02/28/mars_impact_the_red_planet_may_get_hit_by_a_comet_in_october_2014.html

    So, because the true sectional area of the potentially dangerous material is larger than the comet itself, balls from hells can actually impact a planet if the comet does not? Well, that is what Bill Napier was saying and Mark Boslough was ignoring:

    And there’s still more. Comets aren’t generally very solid; you can think of them as loose piles of rubble held together by those ices. As the ice sublimates, the comet dissolves a little, and that rubble can escape. This material, usually objects the size of grains of sand up to small rocks, orbit along very nearly the same path as the comet nucleus itself (which is why we get meteor showers). The gas expands into a large fuzzy cloud around the nucleus, called the coma (which is Latin for hair). Although the nucleus may be a few kilometers in diameter, the coma can be several hundred thousand kilometers across!

    What makes this so very interesting is that the coma can be bigger than the predicted distance by which the comet will pass Mars. This means it’s entirely possible, even likely, Mars will pass right through this cloud of material. And the closer the comet gets, the more likely it is Mars will get pelted by the debris set loose from the nucleus itself.

    If that does happen, it’ll be the gods’ own meteor shower for the red planet.

  • Steve Garcia

    George – You are talking awfully Velikovskian there. The next thing you know Martians are going to be writing legends about manna from heaven.

    / / / / /
    …Boslough (and most astronomers:

    Comets aren’t generally very solid; you can think of them as loose piles of rubble held together by those ices. As the ice sublimates, the comet dissolves a little, and that rubble can escape. This material, usually objects the size of grains of sand up to small rocks, orbit along very nearly the same path as the comet nucleus itself (which is why we get meteor showers). The gas expands into a large fuzzy cloud around the nucleus, called the coma (which is Latin for hair).

    This mechanism Bos talks about doesn’t hold water, liquid or solid, not if you follow the whole cycle.

    Okay, let’s say that on one orbit the ice is gluing the agglomerate together. As it approaches the Sun, as he says, the ice sublimates. It doesn’t even turn to water (which is the only state during which it can “hold rubble together”). That is problem #1. Then the agglomerated materials begin to wander away, pushed mostly by the solar wind, we should imagine. Fine, so then it rounds the Sun, this cloud of sublimated water and dust/rocks, surrounding what is left of the comet core. Now as it departs the Solar neighborhood, what happens? The sublimated water will re-freeze long before the dust and rocks are re-attracted to the remaining core. (If the H2O re-freezes last, even better for my argument.) The ice, too, will float down to the surface. I say “float” because the core’s gravity is about the gravity of a building here on Earth – not enough to attract a feather if any resistance (like, say, friction with the ground) is encountered. So, they all – rocks, duct, ice – land like a feather on the core. And then sit there. Doing nothing.

    What makes the rocks and dust re-fuse into the ice? I can see possible re-fusing if the ice turned to water and stayed that way long enough for the dust and rocks to “sink” to the bottom of the water puddles (which at that gravity wcould be a LONG sinking time. But at what point was the H2O water? How does this dust and rock get glued to the core again for the next pass around the Sun? How does ICE that was never water glue the rocks to the core?

    All this just does not make any sense. Pardon my skepticism.

    The explanation is inadequate. The whole concept is half-baked and not thought through – even if parts of it sound reasonable. Some other mechanism was involved for the whole comet structure to occur. There is no mechanism by which the dust and rok – and ice – are fused/held to the core, other than simply gravity – and perhaps weak electromagnetism and/or chemical bonds.

    Corollary: This explanation is an off-shoot of the agglomeration of planets out of the protoplanetary disk idea. If this doesn’t hold water for comets, then does that theory need to be looked at, too?

  • Trent Telenko

    So…exactly how many tons of 56 kilometer per second impact velocity dust & H2O particles does it take to superheat the Martian atmosphere?

    This Mars/Comet rendezvous seems set to test the YD impact hypothesis, as a spread out dust & ice cloud will convert far more kinetic energy into atmospheric heat than a solid object.

  • Robert Grant

    And, Mars has a very thin atmosphere. In the end, the samples left on the planet would be perfect for research. That is to say, if the rover is still functioning.

  • Jonny

    More observations have now got a nominal pass distance of 0.000276 AU for the comet, but with still a large enough uncertainty that a collision is not yet ruled out http://spaceobs.org/en/2013/02/27/new-data-concerning-the-close-approach-of-comet-c2013-a1-to-mars/

  • Robert Grant

    I tend to think that Firestone had the right idea in his book “The Cycle Of Cosmic Catastrophies.” There was a wave of debris that passed through our solar system 12,900 years ago, from a supernova. Some of that debris was captured by our sun’s gravity, and some hit the planets. We can only, with today’s technology, see a result on the moon and Mars. The result is still here on Earth, but, it has been obscured by our water rich environment.

  • Jonny

    Another archival image of C/2013 A1 has been found, taking the observation period to 148 days. Using this and recalculating using all other observations, the nominal distance of the comet from Mars is 0.00039 AU (http://astroblogger.blogspot.com.au/2013/03/yet-more-updates-on-potential-impact-of.html) with a calculated impact probability of 0.08% (http://spaceobs.org/en/2013/03/03/probability-of-collision-with-mars)

  • Jonny

    This graph is a histogram of close distances of C/2013 A1 based upon a Monte Carlo run using the known uncertainty http://spaceobs.org/wp-content/uploads/2013/03/C2013A1-CA-histogram-20130303.png

    The horizontal axis is the pass distance, with the width of each bar equal to the radius of Mars. the vertical axis is the number of “test particles” (out of 10,000) that passed the planet at that distance. Red marks a collision, and Orange marks distances within the Roche limit (the limit of tidal disruption), based on typical comets.

    One can see that the most likely pass distance is somewhere greater than 9 Mars radii from centre, and less than 23 Mars radii (that is between about 0.00015 and 0.000525.

    Calculations by Leonid Elenin http://spaceobs.org/en/2013/03/04/histogram-of-close-approach-distances/

  • E.P. Grondine

    Jonny – What times would be optimal for observations by Hubble, to see if there are any fragments near the core?

    resolution, distance, ir levels etc.?

  • Jonny

    Unfortunately observations will be stopping soon as the earth-sun comet geometry makes observation unfavourable due to low elongation. It should resume again some time in the summer when the geometry becomes favourable again.

    Given that Hubble is in earth orbit, then it is restricted to these same conditions. However, I cannot see the comet being a priority target for Hubble at the moment. Perhaps if an impact is confirmed, it may become an opportunity target.

Leave a Reply

  

  

  

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>