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Go Back   IceInSpace > General Astronomy > Celestial and Astronomical Events

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  #21  
Old 28-02-2013, 02:35 PM
carl37 (Carl)
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Quote:
Originally Posted by mithrandir View Post
I tried generating a 3D plot with gnuplot from JPL ephemeris for the two. This is the closest they appear to get. They cross at close to 90° - Mars moving in RA, C/2013 A1 moving in Dec.
That's a very cool graphic Andrew - I like it!

That looks about right using the MPC/JPL ephemeris, but my link a few posts ago is to a blog post by Leonid Elenin in which he states he has made new calculations including a further 6 days of observation arc.

These have not been published at the MPC yet, which is where the JPL data comes from.

Carl
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  #22  
Old 28-02-2013, 03:56 PM
Scopie (Brad)
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Iceinspace in the news

Iceinspace also noted on news.com.au

http://www.news.com.au/technology/co...-1226587784458
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  #23  
Old 28-02-2013, 04:09 PM
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rustigsmed (Russell)
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This is very interesting, could either be spectacular for the rovers on mars or destructive. I wonder if the event would be visible from earth?
A collision you'd think would pump some more funding into the system!
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  #24  
Old 28-02-2013, 05:23 PM
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mithrandir (Andrew)
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Quote:
Originally Posted by carl37 View Post
That's a very cool graphic Andrew - I like it!

That looks about right using the MPC/JPL ephemeris, but my link a few posts ago is to a blog post by Leonid Elenin in which he states he has made new calculations including a further 6 days of observation arc.

These have not been published at the MPC yet, which is where the JPL data comes from.

Carl
Carl,

from JPL I get:

Code:
 EC= 1.000076483324882E+00 QR= 1.399572296215722E+00 IN= 1.290158988346881E+02
 OM= 3.009529751244577E+02 W = 2.438725831780988E+00 Tp=  2456956.205760196317
Using find_orb with all the observations in MPEC (last entries are in K13D50) I get mag 5.9 and:

Code:
 EC= 1.0001012017          QR= 1.3995560557          IN= 129.01549809
 OM= 300.95223725          W = 2.43718722            Tp=  2456956.189119
From 133 observations 2012 Dec. 8-2013 Feb. 20; RMS error 0.519 arcseconds.

Unfortunately find_orb won't generate an ephemeris with the necessary number of digits of precision to generate the graph. Trying those MPEC numbers in Starry Night it generates closest approach at 2014-10-19 23:21 UTC and 348526 km.
Attached Thumbnails
Click for full-size image (K13A010-Mars-MPEC.jpg)
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  #25  
Old 28-02-2013, 08:41 PM
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Lets hope it doesn't impact, wow what a sight it would be to see observing it from mars

Last edited by Forgey; 28-02-2013 at 10:57 PM.
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  #26  
Old 01-03-2013, 04:21 AM
wowlfie (Vincent)
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Quote:
Originally Posted by Scopie View Post
Would be interesting if it hit Phobos- I think that would shatter the moon...

A recently discovered comet will make an uncomfortably close planetary flyby next year — but this time it’s not Earth that’s in the crosshairs.
According to preliminary orbital prediction models, comet C/2013 A1 will buzz by Mars on Oct. 19, 2014. The icy interloper is thought to originate from the Oort Cloud — a hypothetical region surrounding the solar system containing countless billions of cometary nuclei that were outcast from the primordial solar system billions of years ago.
We know that comets have hit the planets before (re: the massive Comet Shoemaker–Levy 9 that crashed into Jupiter in 1994), Mars in particular.

C/2013 A1 was discovered by ace comet-hunter Robert McNaught at the Siding Spring Observatory in New South Wales, Australia, on Jan. 3. When the discovery was made, astronomers at the Catalina Sky Survey in Arizona looked back over their observations to find “prerecovery” images of the comet dating back to Dec. 8, 2012. These observations placed the orbital trajectory of comet C/2013 A1 through Mars orbit on Oct. 19, 2014.
Could the Red Planet be in for a potentially huge impact next year? Will Mars rovers Curiosity and Opportunity be in danger of becoming scrap metal?
It seems the likelihood of an awesome planetary impact is low — for now.

According to NASA’s Jet Propulsion Laboratory (JPL) calculations, close approach data suggests the comet is most likely to make a close pass of 0.0007 AU (that’s approximately 63,000 miles from the Martian surface). However, there’s one huge caveat.
Due to uncertainties in the observations — the comet has only been observed for 74 days (so far), so it’s difficult for astronomers to forecast the comet’s precise location in 20 months time — comet C/2013 A1 may fly past at a very safe distance of 0.008 AU (650,000 miles). But to the other extreme, its orbital pass could put Mars directly in its path. At time of Mars close approach (or impact), the comet will be barreling along at a breakneck speed of 35 miles per second (126,000 miles per hour). (~55km/s relative to Mars)
Also, we don’t yet know how big comet C/2013 A1 is, but comets typically aren’t small. If it did hit, the impact could be a huge, global event. But the comet’s likely location in 2014 is also highly uncertain, so this is by no means a “sure thing” for Mars impact (Curiosity, you can relax, for now).

A flyby of that distance will mean that should C3/2013 A1 erupt with a tail and coma around its nucleus (as it becomes heated by solar radiation), our Mars rovers and orbiting armada of planetary observation satellites will have a very intimate view of this historic moment. It has the potential to be a more impressive sight than Comet ISON’s inner-solar system trek later this year. But understanding the nature of comets is hard to predict; we won’t know if the sun’s heating will be sufficient enough for the comet nucleus to erupt and start out-gassing for some time to come.
The Comet is estimated at 30 miles in diameter based on it's luminosity index ("absolute magnitude of the nucleus M2 = 10.3, which might indicate the diameter up to 50 kilometers [30 miles], the energy of impact might reach the equivalent of staggering 2×10^10 megatons!"; source http://science.nbcnews.com/_news/201...s-in-2014?lite

This Comet if it impacted Mars would be nothing short of astounding and could cause substantial damage on Earth from a swarm of Martians chunks thrown out of orbit. The energy of a collision is estimated to be 400 times larger than the one which did in the dinosaurs on Earth 65 million years ago (based on a mass of 125 times larger from it's volume and speed which is 3.2 times larger; 126,000 mph versus 40,000 mph estimated for the dino killer).

This would create a layer of Dust on Mars so thick that navigating would be all but impossible by robotic surveyors in the future.

It also has the capability of literally splitting Mars into pieces because Mars has little atmosphere to heat up the comet and destroy it before it impacts-so it will dig a huge hole many miles deep and throw an immense amount of material out into space. And since it's coming at Mars from outside direction (towards the sun) it could conceivably throw a huge swarm of asteroids into the inner planets including Earth, Venus and Mercury.

This should be really interesting in the months ahead as they further refine the orbit with additional measurements.

JPL is great to include the orbits as calculated so far.

http://ssd.jpl.nasa.gov/sbdb.cgi?sst...ov=0;log=0#orb
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  #27  
Old 01-03-2013, 04:22 AM
wowlfie (Vincent)
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Quote:
Originally Posted by rustigsmed View Post
This is very interesting, could either be spectacular for the rovers on mars or destructive. I wonder if the event would be visible from earth?
A collision you'd think would pump some more funding into the system!
It should be clearly visible from Earth in broad daylight. Nearly as bright as the sun for a few moments. The energy released would be over 20 billion megatons.
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  #28  
Old 01-03-2013, 08:29 AM
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The comet don't have 50 km
Hale-Bopp has 60 km, but C/2013 A1 maybe 8-14 km
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  #29  
Old 01-03-2013, 09:59 AM
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This is something to put on my calendar definitely!! it is disturbing to think about it but at the same time simply awesome! I really hope the mars rover's aren't damaged, or even worse, destroyed in the process.
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  #30  
Old 01-03-2013, 11:02 AM
mamasinham
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The thing I find astonishing about this comet relates to the 500km wide, 2km deep crater, that'll result from a direct impact. People around me are cooing in wonder, and saying things like: "Ooh, Ahhh, hope it hits, won't it look pretty." I, however, am furrowing my brow, as deep as it'll go, at the thought of how much of Mars' surface, which used to occupy that crater, will be flung into the void, and sent tumbling through the inner solar system. We're surely in for a pummelling, too, if collision occurs. If not right away, then quite probably after from orbiting bits of it.
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  #31  
Old 01-03-2013, 09:09 PM
tonybarry (Tony)
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The seriousness of the impact cannot be overstated.

Estimates of velocity (>50km/sec) and size (> 50km diameter) along with the tenuous nature of Mar's atmosphere mean the inner solar system will likely be unfit for safe space travel for a very long time (in human reckoning).

The ejecta will spread far and wide, and there will be big lumps in it. The earth orbit debris caused by one Chinese satellite collision will be absolutely nothing compared to the mess C/2013 A1 will cause if it hits Mars.

I really hope that it does not impact. But if it does, our troubles have just begun.

Regards,
Tony Barry
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  #32  
Old 01-03-2013, 11:15 PM
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I tend to agree. As much as I'm curious to witness such an event I'm afraid we're very much in the splatter zone.

Cheers
Steffen.
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  #33  
Old 02-03-2013, 01:15 AM
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"Ejecta!" That's the word I was searching for.
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  #34  
Old 03-03-2013, 04:30 PM
Greg Bryant
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Today saw the publication of pre-discovery observations from last October, extending the arc quite significantly. The "miss" distance continues to move closer to Mars, and an impact (albeit extremely unlikely) still can't be ruled out.

I've been keeping an eye on the updates since January when the close approach was first identified, and it's been interesting to see the path keep getting closer.

The latest orbit has the comet's nominal miss distance at just 0.00036 au.

Greg
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  #35  
Old 04-03-2013, 04:27 PM
tonybarry (Tony)
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The Wiki page has an interesting table about the refinement of the orbit and the expected minimum separation distance.

http://en.wikipedia.org/wiki/C/2013_A1

I think this will be a comet to watch.

Regards,
Tony Barry
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  #36  
Old 05-03-2013, 07:14 PM
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I think all too many of you are getting carried away with "doom and gloom" hysteria here. Let's just get a little bit of perspective here.

Yes, if this comet does look like it will impact Mars, it doesn't matter what it is made out of, it will impact. Even if it comes in at a shallow angle, i.e. travels through a lot of atmosphere before it impacts. Mars' atmosphere is too thin to prevent bodies of a significant size from impacting (anything larger than about 1 metre in size, and of the right composition). It will also most likely be a significant impact, just given the kinetic energy derived from its orbital velocity. However, the final explosion equivalent will be predicated on just how large the comet's nucleus actually is. That's yet to be really determined. If it is 50km in size, the amount of energy imparted on impact will be a simple matter of its kinetic energy on impact...which will be large. As to its size compared to Chicxulub, that depends on its composition. Typical comets have a density of around 1.2-2.5 grams per cubic centimetre. That directly effects its mass and therefore the kinetic energy of the impact. The Chicxulub impactor was a stony-iron asteroid, which have densities around 3.2-5 grams per cubic centimetre (depending on iron content).

Now, for the ejecta from the impact...whether any of it heads towards our planet and collides with it will depend on so many extraneous factors that the only thing that can be said about this is that it is possible, but not probable. It depends on where the comet hits on the planet, the impact energy and how much debris is lofted out of the Martian gravity well. As for large pieces being blasted out that could cause significant damage to Earth, that is taking things a little too far. Any pieces which did come towards our planet would be on the order of the Chelyabinsk Meteorite at their largest, however it's the numbers of pieces which would be of concern. As for splitting Mars apart...there's no worries that this will happen. It would take many orders of magnitude a strike on a planet the size of Mars, than this object could deliver, to blast the planet into debris. There's no need for any apocalyptic nonsense to be spread around in this forum or any other.
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  #37  
Old 06-03-2013, 08:26 AM
tonybarry (Tony)
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Hi Carl,

I refer you to the following paper which may possibly answer your doubts.

http://www.gps.caltech.edu/~asimow/T...Seismo_958.pdf

The original speculation was that the inner solar system would be less safe for travel as a result of a >50km/sec impact on Mars by a >20km cometary body, primarily as a result of ejecta from the impact exceeding Martian escape velocity and entering into unpredictable orbits around the sun.

The question might be better posed as, "How much more likely is a micrometeoroid impact on a spacecraft in Martian or Earth orbit as a result of this (as yet uncertain) impact ?"

To that question I have no answer as yet. Gut feelings (always dubious as I am sure you are aware) tell me that it will significantly raise the risk. Hard numbers would be much more confidence building. To that end I continue to investigate.

Note that the paper by O'Keefe cited above is by an author who advocates the non-terrestrial origin of tektites. In this, the balance of opinion has shifted towards a terrestrial origin (i.e local impacts) rather than the lunar impacts suggested by O'Keefe.

Regards,
Tony Barry
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  #38  
Old 06-03-2013, 09:55 AM
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Hi Guys,

I'm inclined to think the chances of a hit is very small. Space is big.
Even if you take the projected bypass distance as roughly 100,000km and the radius of Mars as 3,400km the likelihood of a purely random hit would be about (3,400/100,000)^2 or roughly 1 in 865 as the error radius is 100,000km.
Of course, the chances of impact is not purely random as there would be certain confidence levels built into the calculated trajectory and these will build over time.

If the path of the comet is, as suggested in an earlier post, to be more or less normal to Mar's orbit the likelihood of Mars inflecting the comet, in my opinion, is pretty much zilch.

Regards, Rob
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  #39  
Old 06-03-2013, 10:21 AM
mccann73 (Andrew)
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If by some remote chance this comet does impact, as well any possible effects on earth, it would be interesting to see the long term effects on Mars, apart from the obvious destruction at the impact zone, wouldn’t the amount of dust and material thrown into the atmosphere have an impact on global temperature (atmosphere and land), depending on the location would the impact zone melt large amounts of permafrost, increasing the atmospheric pressure, possibly even enough for running water?


Cheers
Andrew
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  #40  
Old 06-03-2013, 10:22 AM
tonybarry (Tony)
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Hi Rob,

You are absolutely correct. Leonid Elenin has published a graph of Mote Carlo simulations of the impact probability - and it's probably not a lot better than winning Lotto.

http://spaceobs.org/en/

The most likely outcome is a close pass. And that's all.

As the comet sheds surface material during its time nearer the sun, we can expect that objects in Mars orbit may ***possibly*** experience micro impacts as a result. Phit Plait (of BadAstronomy fame) discusses this.

http://www.slate.com/blogs/bad_astro...ober_2014.html

Regards,
Tony Barry
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