Author Topic: Monday 15 April 2013 - Martian double craters  (Read 5892 times)

jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Monday 15 April 2013 - Martian double craters
« on: April 15, 2013, 07:44:20 pm »
Over on Planet Four Talk moderator wassock found this Martian double crater in the HiRise images:



which can only have been created by 2 simultaneous impacts.

He messaged me to ask if we had found anything similar on the Moon and also sent a further image of a laboratory test of a high velocity simultaneous impact by 2 objects:

http://www.lroc.asu.edu/news/


Here are some lunar doubles:

Messier A (on the left - most likely created by separate events)
Fauth
Tres Amicis

None of these examples has the distinctive "equatorial" ejecta pattern of first 2 images which I have never seen on the Moon. Why might that be? Well, we know that Mars and the Moon differ geologically so maybe the type of impacted surface and bedrock plays a role. Did the impact take place when Mars was much wetter/ muddier than it is now? Mars also has a more dynamic atmosphere. Would any of these differences account for the distinctive formation of the Martian doubles and ejecta pattern? Maybe the angle and velocity of impact is relevant here too and these double craters form only from high velocity overhead impacts. Wassock says he has found more Martian examples. On a quick look at ACT-REACT quick map I can't find any lunar equivalents. Can you?
« Last Edit: April 16, 2013, 10:29:29 am by jules »

JJ

  • Sr. Member
  • ****
  • Posts: 317
Re: Monday 15 April 2013 - Martian double craters
« Reply #1 on: April 15, 2013, 08:32:13 pm »
Catalan A and B
http://target.lroc.asu.edu/q3/?proj=eqc&center=-1388481.900079,-2693500.145205&zoom=8&lt=LocationOverlays=llgrid,F,70;moonsunlit,F,40;satview,F,;lroc_feat_images,T,;moon_ft,T,;=InstrumentFootprints=m3_fprints,F,50;nac_fprints,F,100;=SpecialProducts=lndtmcs,F,100;lndtms,F,100;lnpole,F,100;l_lro_mrf,F,100;l_ch1_mrf,F,100;lpjnac,F,100;=M3GlobalMosaics=m3_mosaic_op2c3,F,100;m3_mosaic_op2c2,F,100;m3_mosaic_op2c1,F,100;m3_mosaic_op2b,F,100;m3_mosaic_op2a,F,100;m3_mosaic_op1b,F,100;m3_mosaic_op1a,F,100;=M3SphModelGlobalMosaics=m3_mosaic_sph_op2c3,F,100;m3_mosaic_sph_op2c2,F,100;m3_mosaic_sph_op2c1,F,100;m3_mosaic_sph_op2b,F,100;m3_mosaic_sph_op2a,F,100;m3_mosaic_sph_op1b,F,100;m3_mosaic_sph_op1a,F,100;=Basemaps=lclem_mr,F,100;wac_demclrshd2_128ppd,F,30;lnbrowse,F,100;wac_bw_v1_par,F,100;wac_bw_v1_plus_nacs,T,100;=


http://target.lroc.asu.edu/q3/?proj=eqc&center=-1384474.572993,-1713770.928126&zoom=11&lt=LocationOverlays=llgrid,F,70;moonsunlit,F,40;satview,F,;lroc_feat_images,T,;moon_ft,T,;=InstrumentFootprints=m3_fprints,F,50;nac_fprints,F,100;=SpecialProducts=lndtmcs,F,100;lndtms,F,100;lnpole,F,100;l_lro_mrf,F,100;l_ch1_mrf,F,100;lpjnac,F,100;=M3GlobalMosaics=m3_mosaic_op2c3,F,100;m3_mosaic_op2c2,F,100;m3_mosaic_op2c1,F,100;m3_mosaic_op2b,F,100;m3_mosaic_op2a,F,100;m3_mosaic_op1b,F,100;m3_mosaic_op1a,F,100;=M3SphModelGlobalMosaics=m3_mosaic_sph_op2c3,F,100;m3_mosaic_sph_op2c2,F,100;m3_mosaic_sph_op2c1,F,100;m3_mosaic_sph_op2b,F,100;m3_mosaic_sph_op2a,F,100;m3_mosaic_sph_op1b,F,100;m3_mosaic_sph_op1a,F,100;=Basemaps=lclem_mr,F,100;wac_demclrshd2_128ppd,F,30;lnbrowse,F,100;wac_bw_v1_par,F,100;wac_bw_v1_plus_nacs,T,100;=
« Last Edit: April 15, 2013, 08:38:30 pm by JJ »

jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #2 on: April 15, 2013, 08:37:19 pm »
Nice find! (Why are those ACT-REACT permalinks so long? :-\ ) That's a good double. Could do with different illumination to see the rays properly.


jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #4 on: April 15, 2013, 08:52:58 pm »
Another good one. I suppose we need a fairly recent one to get a good view of any ray system too.

JJ

  • Sr. Member
  • ****
  • Posts: 317
Re: Monday 15 April 2013 - Martian double craters
« Reply #5 on: April 15, 2013, 08:57:24 pm »
It would have to be small, because the last one is split up between about 14 NAC's.


jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #6 on: April 15, 2013, 09:25:43 pm »
...and many WACs - which are a bit of a faff to process.

JJ

  • Sr. Member
  • ****
  • Posts: 317
Re: Monday 15 April 2013 - Martian double craters
« Reply #7 on: April 15, 2013, 10:34:07 pm »
...and many WACs - which are a bit of a faff to process.


faff, that's British for a pain in the butt isn't it? ::)

jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #8 on: April 16, 2013, 10:26:03 am »
 ;D ;D
Yes!

jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #9 on: April 16, 2013, 10:47:58 am »
Update - from Planet Four Talk.

Science team member Meg Schwamb said that these craters reminded her of the snowman, a double crater on Vesta, and linked to a blog by Emily Lakdawalla who considers how the snowman mighty have formed.

The lab experiment image in the first post:



is from the LROC article on one of the lunar double crater examples I gave (Tres Amicis) and I take this to imply that there are more lunar examples. The article highlights the septum between the craters rather than the more distinctive ejecta but if this is how the craters form then there should be doubles with this ejecta pattern on the Moon.





jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #10 on: April 16, 2013, 11:33:51 am »
Another maybe - in the farside Mare Moscoviense. Neither crater seems to overlap the other and there appears to be the required septum dividing the 2 craters.

jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #11 on: April 16, 2013, 11:45:58 am »
Possibly just a hint of equatorial ejecta in this double? (attachment - you need to be logged in to see it!)
« Last Edit: April 16, 2013, 12:14:02 pm by jules »

kodemunkey

  • IOTW posters
  • Hero Member
  • *
  • Posts: 1650
Re: Monday 15 April 2013 - Martian double craters
« Reply #12 on: April 17, 2013, 06:32:32 am »
I've not seen Tres Amicles before, is it a 'new' find? looks like i have something new to look for, are they only interested in the larger impacts because presumably the smaller versions of these are more common?

jules

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3478
Re: Monday 15 April 2013 - Martian double craters
« Reply #13 on: April 17, 2013, 10:24:47 am »
It's just an interesting feature that was found over on Planet Four and they wondered if the same pattern could be found on the Moon. I think double lunar craters are fairly common but these simultaneous impacts are a little different and seem to have their own type of morphology. So it's up to us. I haven't seen a really good example yet on the Moon (with both septum and ejecta.) I don't know if this is of any scientific value but I can ask! At the moment it's just an interesting exercise for the reader...

kodemunkey

  • IOTW posters
  • Hero Member
  • *
  • Posts: 1650
Re: Monday 15 April 2013 - Martian double craters
« Reply #14 on: April 17, 2013, 05:01:59 pm »
something new for the summer for me then.