(pauses to allow time for killjoy Vulcan "A fascinating theory Captain, but unfortunately the orbital parameters of the bodies involved means such a collison could not happen" posts to flood in...)
Full Version: Asteroid on track for possible Mars hit
Hey, look on the bright side... if it misses Mars then maybe it'll hit Phobos or Deimos instead, then shower Mars with enough debris to make dozens of new craters...!
(pauses to allow time for killjoy Vulcan "A fascinating theory Captain, but unfortunately the orbital parameters of the bodies involved means such a collison could not happen" posts to flood in...)
(pauses to allow time for killjoy Vulcan "A fascinating theory Captain, but unfortunately the orbital parameters of the bodies involved means such a collison could not happen" posts to flood in...)
QUOTE (Stu @ Dec 23 2007, 10:32 AM) 
Hey, look on the bright side... if it misses Mars then maybe it'll hit Phobos or Deimos instead, then shower Mars with enough debris to make dozens of new craters...!
LOL
..and don't forget the rings that would then take shape around Mars.
Well, I guess that is one way we could finally get a closer look at Phobos or Deimos!
This maybe a scary thought...despite logic, Captain Kirk tended to be correct with his intuition.
This maybe a scary thought...despite logic, Captain Kirk tended to be correct with his intuition.
QUOTE (Del Palmer @ Dec 22 2007, 11:24 PM)
The MERs use the popular LN-200 IMU.
Thanks, Del. That's a nice little unit: FOGs & SSAs, only uses 12W. Still think that it would sense an impact of reasonable energy not TOO far away (say within a few hundred km, or more depending on the kinetic energy conductance of Mars' crust).
To add some pessimism (but, yeah, here's still hopin'), unless MRO can track it inbound I wonder if we'll even know if it hits until it can't be found zooming around anymore. The uncertainty will remain pretty large until shortly before the encounter, and well before that it will become almost unobservable from Earth-based scopes due to growing Marslight washout...hell, it's hard enough to pick up Phobos & Deimos, much less a 50m rock.
Here's the latest Horizon observational ephemeris for Opportunity -- apparently based on the new observations. The asteroid really tears across the sky and is brighter at closest approach (ninth magnitude) in this revised version. It's interesting how the asteroid sets at about 11:40 UT and rises again about 4 hours later at 15:40. But all the interesting stuff happens in daylight.
On Spirit's side there's a much more interesting picture with almost everything happening at night. The asteroid rises about 11:40 UT, has closest approach around 12:00, transits around 12:20, and sets around 15:40. I imagine the batteries will be in no condition to even try to observe this.
Steve M
CODE
Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC Azi_(a-appr)_Elev APmag delta deldot
2008-Jan-30 08:00 *x 19 14 29.75 -26 06 47.0 44.2763 77.4146 n.a. .001119758994332 -12.4773173
2008-Jan-30 08:20 *x 19 11 04.19 -26 12 38.5 20.3823 80.7437 n.a. .001019834490894 -12.4346540
2008-Jan-30 08:40 *t 19 06 53.38 -26 19 25.0 343.2271 81.3518 n.a. .000920283052273 -12.3838495
2008-Jan-30 09:00 *x 19 01 41.25 -26 27 16.7 312.7583 78.5229 n.a. .000821184099440 -12.3210520
2008-Jan-30 09:20 *x 18 55 03.14 -26 36 22.6 296.0594 73.6897 n.a. .000722658243020 -12.2395393
2008-Jan-30 09:40 *x 18 46 19.28 -26 46 43.5 286.5309 67.7772 n.a. .000624900148017 -12.1268977
2008-Jan-30 10:00 *x 18 34 21.72 -26 57 50.2 280.1632 60.9379 n.a. .000528246662206 -11.9584635
2008-Jan-30 10:20 *x 18 17 05.69 -27 07 29.1 275.1185 52.8907 n.a. .000433331866382 -11.6803905
2008-Jan-30 10:40 *x 17 50 22.63 -27 07 14.3 270.3355 42.8424 n.a. .000341482965162 -11.1601933
2008-Jan-30 11:00 *x 17 05 19.88 -26 24 26.3 264.8198 28.9251 n.a. .000255874104730 -10.0236624
2008-Jan-30 11:20 *x 15 44 06.07 -22 50 37.3 256.9104 6.9177 n.a. .000185204194490 -7.1356436
2008-Jan-30 11:40 *s 13 35 09.46 -11 20 33.4 242.3044 -27.4819 9.68 .000151851190861 -0.5295519
2008-Jan-30 12:00 *x 11 31 52.61 +03 57 57.7 208.3976 -58.0619 8.78 .000178023916770 6.4910393
2008-Jan-30 12:20 *x 10 17 23.64 +12 49 43.0 157.4809 -63.1501 8.90 .000245131156386 9.7235864
2008-Ja-30 12:40 * 09 35 47.43 +17 02 46.4 130.7972 -55.7115 9.23 .000328828851257 10.9623996
2008-Jan-30 13:00 * 09 10 42.46 +19 15 12.6 119.4228 -47.4719 9.57 .000419183472640 11.5004648
2008-Jan-30 13:20 * 08 54 15.03 +20 33 00.3 113.5219 -39.9903 9.88 .000512617446795 11.7689937
2008-Jan-30 13:40 * 08 42 41.91 +21 23 00.6 109.9647 -33.1694 10.16 .000607668173096 11.9182664
2008-Jan-30 14:00 * 08 34 09.47 +21 57 22.6 107.6089 -26.8158 10.41 .000703653878681 12.0084555
2008-Jan-30 14:20 * 08 27 35.06 +22 22 12.4 105.9547 -20.7885 10.63 .000800223304134 12.0668511
2008-Jan-30 14:40 * 08 22 21.66 +22 40 51.2 104.7517 -14.9941 10.84 .000897182111537 12.1071307
2008-Jan-30 15:00 08 18 06.13 +22 55 17.0 103.8622 -9.3707 11.02 .000994417559616 12.1367131
2008-Jan-30 15:20 08 14 33.33 +23 06 43.5 103.2054 -3.8763 11.19 .001091862492983 12.1598826
2008-Jan-30 15:40 r 08 11 32.94 +23 15 58.9 102.7318 1.5184 11.35 .001189476710756 12.1792388
2008-Jan-30 16:00 08 08 57.72 +23 23 35.7 102.4110 6.8339 11.50 .001287236672609 12.1964205
2008-Jan-30 08:00 *x 19 14 29.75 -26 06 47.0 44.2763 77.4146 n.a. .001119758994332 -12.4773173
2008-Jan-30 08:20 *x 19 11 04.19 -26 12 38.5 20.3823 80.7437 n.a. .001019834490894 -12.4346540
2008-Jan-30 08:40 *t 19 06 53.38 -26 19 25.0 343.2271 81.3518 n.a. .000920283052273 -12.3838495
2008-Jan-30 09:00 *x 19 01 41.25 -26 27 16.7 312.7583 78.5229 n.a. .000821184099440 -12.3210520
2008-Jan-30 09:20 *x 18 55 03.14 -26 36 22.6 296.0594 73.6897 n.a. .000722658243020 -12.2395393
2008-Jan-30 09:40 *x 18 46 19.28 -26 46 43.5 286.5309 67.7772 n.a. .000624900148017 -12.1268977
2008-Jan-30 10:00 *x 18 34 21.72 -26 57 50.2 280.1632 60.9379 n.a. .000528246662206 -11.9584635
2008-Jan-30 10:20 *x 18 17 05.69 -27 07 29.1 275.1185 52.8907 n.a. .000433331866382 -11.6803905
2008-Jan-30 10:40 *x 17 50 22.63 -27 07 14.3 270.3355 42.8424 n.a. .000341482965162 -11.1601933
2008-Jan-30 11:00 *x 17 05 19.88 -26 24 26.3 264.8198 28.9251 n.a. .000255874104730 -10.0236624
2008-Jan-30 11:20 *x 15 44 06.07 -22 50 37.3 256.9104 6.9177 n.a. .000185204194490 -7.1356436
2008-Jan-30 11:40 *s 13 35 09.46 -11 20 33.4 242.3044 -27.4819 9.68 .000151851190861 -0.5295519
2008-Jan-30 12:00 *x 11 31 52.61 +03 57 57.7 208.3976 -58.0619 8.78 .000178023916770 6.4910393
2008-Jan-30 12:20 *x 10 17 23.64 +12 49 43.0 157.4809 -63.1501 8.90 .000245131156386 9.7235864
2008-Ja-30 12:40 * 09 35 47.43 +17 02 46.4 130.7972 -55.7115 9.23 .000328828851257 10.9623996
2008-Jan-30 13:00 * 09 10 42.46 +19 15 12.6 119.4228 -47.4719 9.57 .000419183472640 11.5004648
2008-Jan-30 13:20 * 08 54 15.03 +20 33 00.3 113.5219 -39.9903 9.88 .000512617446795 11.7689937
2008-Jan-30 13:40 * 08 42 41.91 +21 23 00.6 109.9647 -33.1694 10.16 .000607668173096 11.9182664
2008-Jan-30 14:00 * 08 34 09.47 +21 57 22.6 107.6089 -26.8158 10.41 .000703653878681 12.0084555
2008-Jan-30 14:20 * 08 27 35.06 +22 22 12.4 105.9547 -20.7885 10.63 .000800223304134 12.0668511
2008-Jan-30 14:40 * 08 22 21.66 +22 40 51.2 104.7517 -14.9941 10.84 .000897182111537 12.1071307
2008-Jan-30 15:00 08 18 06.13 +22 55 17.0 103.8622 -9.3707 11.02 .000994417559616 12.1367131
2008-Jan-30 15:20 08 14 33.33 +23 06 43.5 103.2054 -3.8763 11.19 .001091862492983 12.1598826
2008-Jan-30 15:40 r 08 11 32.94 +23 15 58.9 102.7318 1.5184 11.35 .001189476710756 12.1792388
2008-Jan-30 16:00 08 08 57.72 +23 23 35.7 102.4110 6.8339 11.50 .001287236672609 12.1964205
On Spirit's side there's a much more interesting picture with almost everything happening at night. The asteroid rises about 11:40 UT, has closest approach around 12:00, transits around 12:20, and sets around 15:40. I imagine the batteries will be in no condition to even try to observe this.
CODE
Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC Azi_(a-appr)_Elev APmag delta deldot
2008-Jan-30 08:00 19 13 06.32 -26 02 45.7 224.9959 -79.4715 n.a. .001164254698455 -12.4026555
2008-Jan-30 08:20 19 10 33.31 -26 11 43.3 194.9275 -81.8718 n.a. .001064733299115 -12.4093869
2008-Jan-30 08:40 19 07 28.40 -26 22 14.8 157.7088 -81.1152 n.a. .000965173885920 -12.4118425
2008-Jan-30 09:00 19 03 40.14 -26 34 46.4 133.6262 -77.5867 n.a. .000865619649547 -12.4076223
2008-Jan-30 09:20 18 58 51.03 -26 49 54.6 121.0385 -72.7149 n.a. .000766138710915 -12.3927472
2008-Jan-30 09:40 18 52 33.09 -27 08 29.9 113.9679 -67.0866 n.a. .000666842063599 -12.3601497
2008-Jan-30 10:00 18 43 58.67 -27 31 42.3 109.6459 -60.7735 n.a. .000567920270459 -12.2962015
2008-Jan-30 10:20 18 31 40.23 -28 00 58.3 106.9251 -53.5624 n.a. .000469725981687 -12.1718068
2008-Jan-30 10:40 18 12 40.34 -28 37 09.8 105.3570 -44.8778 n.a. .000372983558084 -11.9161452
2008-Jan-30 11:00 17 40 12.18 -29 14 39.7 104.9137 -33.3296 n.a. .000279413463162 -11.3244140
2008-Jan-30 11:20 16 36 49.03 -29 01 36.3 106.1210 -15.2233 n.a. .000193994449112 -9.6676512
2008-Jan-30 11:40 r 14 26 31.32 -22 34 28.8 111.2722 18.5189 10.23 .000133978614495 -4.3040660
2008-Jan-30 12:00 11 41 10.05 -03 28 50.7 135.2281 64.1958 8.40 .000138479769320 5.2727558
2008-Jan-30 12:20 t 10 04 52.40 +09 49 52.2 227.1653 72.0648 8.45 .000203411381899 10.0159916
2008-Jan-30 12:40 09 18 26.72 +15 32 21.1 252.3810 58.5211 8.86 .000290755177909 11.5007828
2008-Jan-30 13:00 08 53 11.66 +18 18 08.3 258.0637 48.1010 9.28 .000385569297056 12.0626098
2008-Jan-30 13:20 x 08 37 42.57 +19 52 00.2 259.9560 39.8333 9.64 .000483491658287 12.3248579
2008-Jan-30 13:40 x 08 27 21.54 +20 51 31.5 260.5320 32.7525 9.95 .000582970674857 12.4668322
2008-Jan-30 14:00 x 08 20 00.16 +21 32 24.8 260.4956 26.3734 10.23 .000683334761876 12.5518423
2008-Jan-30 14:20 x 08 14 32.09 +22 02 10.9 260.1155 20.4411 10.48 .000784246676696 12.6062504
2008-Jan-30 14:40 x 08 10 19.84 +22 24 49.4 259.5117 14.8120 10.70 .000885516500293 12.6424829
2008-Jan-30 15:00 x 08 07 00.73 +22 42 38.3 258.7417 9.4001 10.91 .000987026877464 12.6669807
2008-Jan-30 15:20 *x 08 04 20.26 +22 57 02.3 257.8330 4.1518 11.09 .001088699408410 12.6833433
2008-Jan-30 15:40 *s 08 02 08.75 +23 08 56.0 256.7959 -0.9675 11.26 .001190478107995 12.6937114
2008-Jan-30 16:00 *x 08 00 19.47 +23 18 56.3 255.6302 -5.9802 11.42 .001292320664677 12.6994289
2008-Jan-30 08:00 19 13 06.32 -26 02 45.7 224.9959 -79.4715 n.a. .001164254698455 -12.4026555
2008-Jan-30 08:20 19 10 33.31 -26 11 43.3 194.9275 -81.8718 n.a. .001064733299115 -12.4093869
2008-Jan-30 08:40 19 07 28.40 -26 22 14.8 157.7088 -81.1152 n.a. .000965173885920 -12.4118425
2008-Jan-30 09:00 19 03 40.14 -26 34 46.4 133.6262 -77.5867 n.a. .000865619649547 -12.4076223
2008-Jan-30 09:20 18 58 51.03 -26 49 54.6 121.0385 -72.7149 n.a. .000766138710915 -12.3927472
2008-Jan-30 09:40 18 52 33.09 -27 08 29.9 113.9679 -67.0866 n.a. .000666842063599 -12.3601497
2008-Jan-30 10:00 18 43 58.67 -27 31 42.3 109.6459 -60.7735 n.a. .000567920270459 -12.2962015
2008-Jan-30 10:20 18 31 40.23 -28 00 58.3 106.9251 -53.5624 n.a. .000469725981687 -12.1718068
2008-Jan-30 10:40 18 12 40.34 -28 37 09.8 105.3570 -44.8778 n.a. .000372983558084 -11.9161452
2008-Jan-30 11:00 17 40 12.18 -29 14 39.7 104.9137 -33.3296 n.a. .000279413463162 -11.3244140
2008-Jan-30 11:20 16 36 49.03 -29 01 36.3 106.1210 -15.2233 n.a. .000193994449112 -9.6676512
2008-Jan-30 11:40 r 14 26 31.32 -22 34 28.8 111.2722 18.5189 10.23 .000133978614495 -4.3040660
2008-Jan-30 12:00 11 41 10.05 -03 28 50.7 135.2281 64.1958 8.40 .000138479769320 5.2727558
2008-Jan-30 12:20 t 10 04 52.40 +09 49 52.2 227.1653 72.0648 8.45 .000203411381899 10.0159916
2008-Jan-30 12:40 09 18 26.72 +15 32 21.1 252.3810 58.5211 8.86 .000290755177909 11.5007828
2008-Jan-30 13:00 08 53 11.66 +18 18 08.3 258.0637 48.1010 9.28 .000385569297056 12.0626098
2008-Jan-30 13:20 x 08 37 42.57 +19 52 00.2 259.9560 39.8333 9.64 .000483491658287 12.3248579
2008-Jan-30 13:40 x 08 27 21.54 +20 51 31.5 260.5320 32.7525 9.95 .000582970674857 12.4668322
2008-Jan-30 14:00 x 08 20 00.16 +21 32 24.8 260.4956 26.3734 10.23 .000683334761876 12.5518423
2008-Jan-30 14:20 x 08 14 32.09 +22 02 10.9 260.1155 20.4411 10.48 .000784246676696 12.6062504
2008-Jan-30 14:40 x 08 10 19.84 +22 24 49.4 259.5117 14.8120 10.70 .000885516500293 12.6424829
2008-Jan-30 15:00 x 08 07 00.73 +22 42 38.3 258.7417 9.4001 10.91 .000987026877464 12.6669807
2008-Jan-30 15:20 *x 08 04 20.26 +22 57 02.3 257.8330 4.1518 11.09 .001088699408410 12.6833433
2008-Jan-30 15:40 *s 08 02 08.75 +23 08 56.0 256.7959 -0.9675 11.26 .001190478107995 12.6937114
2008-Jan-30 16:00 *x 08 00 19.47 +23 18 56.3 255.6302 -5.9802 11.42 .001292320664677 12.6994289
Steve M
There is no reason not to try. Remember, these things have been through a lot of what I like to call 'cruel punishment'. What I think they can do(the mission team) is to try and devote an entire day for recharging the batteries or even 2 days (maybe Im asking for too much) then release that energy for a short time in the form of a late night astronomical observation.
When it comes to Spirit Im willing to expose her to the elements. One thing I've noticed about her is that she tends to be the toughest girl in the fleet when you look at her technical record.Need I say more?
By the way, can any body give me extra info/data on the rover batteries?
When it comes to Spirit Im willing to expose her to the elements. One thing I've noticed about her is that she tends to be the toughest girl in the fleet when you look at her technical record.Need I say more?
By the way, can any body give me extra info/data on the rover batteries?
QUOTE (Doc @ Dec 24 2007, 09:41 AM)
an entire day for recharging the batteries or even 2 days (maybe Im asking for too much) then release that energy for a short time in the form of a late night astronomical observation.
Lets combine the lessons from the dust storm, with current Whrs. The batteries are roughly 600 Whrs in total when new - and running at something like 80% capacity now, 480 whrs.. The current power is 291 whrs (and decreasing) per Sol
We established that something like 150 Whrs was the minimum survival power when doing nothing ( no comms, no science - nothing ) So currently - the most you could put back in the battery is about 140 Whrs. It would take 4 days to recharge it fully.
To do late night obs ( 0240 AM and on for 2 hours) now would require enormous amounts of actuator heating, put joints and cables thru some nasty stresses and for what? Maybe, a small white streak in an image. Honestly, this is something I'm more than happy for Spirit to pass on.
More info :
http://trs-new.jpl.nasa.gov/dspace/handle/2014/39912
http://trs-new.jpl.nasa.gov/dspace/handle/2014/39793
Doug
Assuming that the asteroid hits the planet not too far away from Opportunity, I am curious to know what we would see.
A humongous plume of dust and rock in the horizon?
Personally, I'd be overjoyed to see the rover get a very unlikely photo of the little speck screaming down to the surface. Just like in the impact scene in the movie 'Deep Impact'. That will probably cause a sensation in the entire human community.
And it will probably cause governments around the world to literally pour their resources into the NEO projects :-)
A humongous plume of dust and rock in the horizon?
Personally, I'd be overjoyed to see the rover get a very unlikely photo of the little speck screaming down to the surface. Just like in the impact scene in the movie 'Deep Impact'. That will probably cause a sensation in the entire human community.
And it will probably cause governments around the world to literally pour their resources into the NEO projects :-)
Welcome to UMSF by the way Doc! 
I know what you mean, but I think the cultural impact of an image showing a streak across the martian sky would be somewhere between nothing and absolutely nothing. After all, that very famous (mid 70s?) footage of the asteroid streaking across a clear blue sky above some mountains and a lake (oh come on, you know the one I mean, we've all seen it a gazillion times!) before skipping off the atmosphere and heading back didn't lead people to worry about asteroid impacts, nor has the classic "Peekskill" footage either. And actually, if the footage from Deep Impact and Armageddon hasn't been enough for Govts to take the problem seriously then there's no way on Earth - or Mars - that a grainy image of a streaky...something... taken by one of the rovers will have Govts reaching for their chequebooks...
Like you I'm very curious to know what we'd see if an impact occurred, but unless WD comes down very close to Oppy (which we don't want!) I'm sure we won't see a "humongous plume". Maybe just a vague puff on the horizon? I don't know, we're all just speculating here. But it's fun!
Anyway, I'm sure one of our little rover buddies will get fantastic shots of debris spraying away from either Phobos or Deimos when WD hits it... then the sky will be so full of shooting stars it'll be more like the end of INdependance Day than Deep Impact!
(that was a joke by the way... )
I know what you mean, but I think the cultural impact of an image showing a streak across the martian sky would be somewhere between nothing and absolutely nothing. After all, that very famous (mid 70s?) footage of the asteroid streaking across a clear blue sky above some mountains and a lake (oh come on, you know the one I mean, we've all seen it a gazillion times!) before skipping off the atmosphere and heading back didn't lead people to worry about asteroid impacts, nor has the classic "Peekskill" footage either. And actually, if the footage from Deep Impact and Armageddon hasn't been enough for Govts to take the problem seriously then there's no way on Earth - or Mars - that a grainy image of a streaky...something... taken by one of the rovers will have Govts reaching for their chequebooks...
Like you I'm very curious to know what we'd see if an impact occurred, but unless WD comes down very close to Oppy (which we don't want!) I'm sure we won't see a "humongous plume". Maybe just a vague puff on the horizon? I don't know, we're all just speculating here. But it's fun!
Anyway, I'm sure one of our little rover buddies will get fantastic shots of debris spraying away from either Phobos or Deimos when WD hits it... then the sky will be so full of shooting stars it'll be more like the end of INdependance Day than Deep Impact!
(that was a joke by the way...
)
For all those people wanting a "Roving Mars" sequel...
Click to view attachment
Seriously tho, when will we have a better idea of what's actually going to happen? Will it literally be on the day? If so, that'll be a "don't stray too far from the computer" day, won't it?
Click to view attachment
Seriously tho, when will we have a better idea of what's actually going to happen? Will it literally be on the day? If so, that'll be a "don't stray too far from the computer" day, won't it?
It'll get more and more accurate as time goes on - I'm sure we'll have a firm hit/miss in plenty of time.
Doug
Doug
My money's on a miss... it would be just too greedy to expect an impact as well as everything else we've enjoyed on or around Mars recently. I'll be happy to see it hit, of course, but equally happy to see it sail by harmlessly.
Would be sooooo funny if it hit a certain face-shaped mesa in Cydonia tho... wow, imagine those conspiracy theories!
Would be sooooo funny if it hit a certain face-shaped mesa in Cydonia tho... wow, imagine those conspiracy theories!
QUOTE (Stu @ Dec 24 2007, 05:11 AM)
Would be sooooo funny if it hit a certain face-shaped mesa in Cydonia tho... wow, imagine those conspiracy theories!
..."The Great Acne Scar on the <Bleep> on Mars!"
Thanks, Phil.
Gotta say that these NEO searches really are paying off serendipitous dividends, here. Really did not expect that we'd ever pick up a potential Mars impactor (fantasized about it once or twice, though). For sheer SFX, would love to find a good-sized body slamming into Venus, preferably near inferior conjunction, preferably on the night side (hey, it's Christmas...I can ask for stuff!!! )
Gotta say that these NEO searches really are paying off serendipitous dividends, here. Really did not expect that we'd ever pick up a potential Mars impactor (fantasized about it once or twice, though). For sheer SFX, would love to find a good-sized body slamming into Venus, preferably near inferior conjunction, preferably on the night side (hey, it's Christmas...I can ask for stuff!!!
)
If this asteroid did impact Mars on its sunward side, how easily would the impact be visible from earth?
Here are some back-of-the envelope calculations (they may be WAY off):
A similar-sized impactor hitting the moon would probably release energy in the kiloton range (at least?) and would probably be easily visible and even spectacular on earth with the naked eye... let’s be optimistic and say a magnitude of -10.
Mars is currently roughly 250 times farther than the moon, so all things being equal the magnitude of a similar-sized impact on Mars would be about 250 squared = 62,500 times fainter, that’s a 12 magnitude difference down to +2.
That would contribute only a few percent increase to Mars’ current brightness (and then for only a few seconds).
Bottom line (if these VERY rough calculations are in the ballpark): here on earth, the impact would not be visible to the naked eye, nor directly in a 6” reflector like mine; but might be recordable by advanced amateur scopes and more than likely visible to Hubble.
Another question: Would having an atmosphere (like Mars) make the impact brighter than if it impacted the airless moon? Or would a Mars impact be “instantaneously” dimmer, but with a longer “afterglow” due to ionized gases in its atmosphere (energy being conserved and all)?
Here are some back-of-the envelope calculations (they may be WAY off):
A similar-sized impactor hitting the moon would probably release energy in the kiloton range (at least?) and would probably be easily visible and even spectacular on earth with the naked eye... let’s be optimistic and say a magnitude of -10.
Mars is currently roughly 250 times farther than the moon, so all things being equal the magnitude of a similar-sized impact on Mars would be about 250 squared = 62,500 times fainter, that’s a 12 magnitude difference down to +2.
That would contribute only a few percent increase to Mars’ current brightness (and then for only a few seconds).
Bottom line (if these VERY rough calculations are in the ballpark): here on earth, the impact would not be visible to the naked eye, nor directly in a 6” reflector like mine; but might be recordable by advanced amateur scopes and more than likely visible to Hubble.
Another question: Would having an atmosphere (like Mars) make the impact brighter than if it impacted the airless moon? Or would a Mars impact be “instantaneously” dimmer, but with a longer “afterglow” due to ionized gases in its atmosphere (energy being conserved and all)?
QUOTE (ElkGroveDan @ Dec 21 2007, 08:50 PM)
Not until we witnessed freshly created hematite spheres raining from your impact surge cloud. 
Sorry, I haven't been monitoring this speculative thread over the weekend. But hey, EGD, the blue-gray hematitic spherules are the Meridiani exception, not the martian rule - you don't find them everywhere on Mars, even though Mars was virtually saturated with impact craters. To form the hematitic spherules via impact, there must have been something unusual about the target, or something unusual about the impactor, or both. So you can't very well expect hematitic spherules from every martian impact. Also, keep in mind that Mars at the time of the Meridiani-forming impacts (if that's what formed Meridiani's uppermost layers and blueberries) presumably had a somewhat thicker atmosphere (although by then, about 3.8 billion years ago, Mars may have already lost 99 per cent of its atmosphere owing to erosion by the Late Heavy Bombardment). And, if not formed by impact (or other high temperature process), why are the spherules apparently the blue-gray or high temperature (specular) form of hematite (i.e., why aren't they the same color as the rest of Mars)? And if they're indeed sedimentary concretions, why do the blueberries so little resemble actual sedimentary concretions in terms of their distribution, size, shape, degree of aggegation (clumping), and host rocks?
BTW, I much enjoyed the two competing artistic impressions of distant meteorite impacts as seen from Victoria. One, the nuclear bomb-type "mushroom cloud" looks like what I would expect of a small impact on any planet with an atmosphere (i.e., Earth or Mars). The other looks like virtually all textbook illustrations of impacts, and shows the early-formed ballistic ejecta curtain only. It is what I might expect for impacts on the Moon or other planet with no atmosphere (although even there the rocks themselves are vaporized, at least ephemerally). Keep in mind that, AFAIK, there are absolutely no photos of actual large impacts to use as a basis for comparison (and that any such photos might well be the photographer's last ever). All the more reason to wish for Oppy to supply such an actual impact image, and survive.
-- HDP Don
QUOTE (dburt @ Dec 24 2007, 10:32 PM)
One, the nuclear bomb-type "mushroom cloud" looks like what I would expect of a small impact on any planet with an atmosphere (i.e., Earth or Mars). The other looks like virtually all textbook illustrations of impacts, and shows the early-formed ballistic ejecta curtain only. It is what I might expect for impacts on the Moon or other planet with no atmosphere (although even there the rocks themselves are vaporized, at least ephemerally).
I myself am very interested in how a convective updraft cloud would behave in a low-density atmosphere. On Titan I'd expect a mushroom cloud very similar to one on Earth, varying in head/stem dimension, but it would be interesting to see how one would look on Mars. For one, the buoyancy would be greaty reduced, also reducing the updraft which creates the characteristic mushroom stem. The two artistic views could be regarded as the same scenario - mine would be the initial impact (I was actually aiming at that) throwing ejecta up and Stu's would be the aftermath several minutes later when ejecta has settled down and the dusty "fireball" rose up and cooled down.
I believe the initial moments of an impact that couples energy to the ground well (something surface-detonated nuclear weapons don't do well, in addition to releasing over 50% energy as thermal, not kinetic) would be dominated by the ejecta blanket, screening the (small) incandescent fireball at the point of impact.
Here's a not-so-good analogy with ground penetrating weapons: http://www.youtube.com/watch?v=KF8gnokHrWw (Caution: VERY LOUD!)
There are better videos out there, but I can't seem to dig them up now.
Would you really like Opportunity to be anywhere near this shower of debris (and note Mars' thin atmosphere would basically allow ballistic emplacement of debris)? I know I wouldn't...
Here's a more classical fireball on the other hand, typical of atmospheric nukes, not resulting in large excavation as much as a large fireball and atmospheric shockwave: http://www.youtube.com/watch?v=PwuMdNg9oWQ (ignore the F-words)
My latest entry for the "I know it would look nothing like this, but just imagine...!" Martian Asteroid Impact Gallery...
Click to view attachment
Christmas Day now here in the UK and I'm off to work... have a great day everyone, wherever you are!
Click to view attachment
Christmas Day now here in the UK and I'm off to work... have a great day everyone, wherever you are!
Honestly, I don't think the stem of the mushroom cloud on Mars would be that tall. The air is too thin, so it would probably spread horizontally much quicker than on Earth. In fact, the mushroom like cloud might not even have a stem on Mars. Most or All the energy might go toward forming the cap almost immediately. The cap itself might simply grow larger as the blast wave expands.
I don't know. I'd like to see one in action on Mars for real.
I don't know. I'd like to see one in action on Mars for real.
Indeed, the impact would be a 'minor' one...
Please check this video of an impact on the Moon:
http://science.nasa.gov/headlines/y2006/13...narsporadic.htm
Please check this video of an impact on the Moon:
http://science.nasa.gov/headlines/y2006/13...narsporadic.htm
QUOTE (MarsIsImportant @ Dec 25 2007, 06:58 AM)
Honestly, I don't think the stem of the mushroom cloud on Mars would be that tall.
... which is probably why I said...
"I know it would look nothing like this..."
One thing puzzles me. JPL is saying that if it does hit, the impact area would be in northern Meridiani. Given the fact that the margin of error is still about five times the diameter of Mars itself, how can they make such a statement?
Seems much more reasonable to assume that if (a damn big if) it hits, the location at this point would be defined as a huge ellipse projected on Mars spanning almost 180 deg of longitude. I'm sure that JPL's statement has something to do with the output of one or more models, but I can't really lend it any credence. Anybody have better info?
Seems much more reasonable to assume that if (a damn big if) it hits, the location at this point would be defined as a huge ellipse projected on Mars spanning almost 180 deg of longitude. I'm sure that JPL's statement has something to do with the output of one or more models, but I can't really lend it any credence. Anybody have better info?
QUOTE (nprev @ Dec 25 2007, 04:17 PM)
One thing puzzles me. JPL is saying that if it does hit, the impact area would be in northern Meridiani. Given the fact that the margin of error is still about five times the diameter of Mars itself, how can they make such a statement?
I'm curious, where did you come up with such a small margin of error? As I understand it, the uncertainty ellipse is very stretched out with the semimajor axis still probably some 100 000 km (a guess out of thin air), but the semiminor axis is much, much smaller so the point where it intersects Mars is just a band covering a portion of Martian surface. In other words, we know the trajectory with enough certainty even now to rule out for example near-polar hits.
I'm puzzled as well, Gordan; here's a quote from the JPL press release (21 Dec):
"If this unlikely event were to occur, it would be somewhere within a broad swath across the planet north of where the Opportunity rover is located."
Full article: http://www.jpl.nasa.gov/news/news.cfm?release=2007-152
I think that I mis-stated Meridiani as the stated potential impact area, though pretty sure I've seen that in other articles (derived from this press release, no doubt). This may be getting out of control.
EDIT: Whups, didn't answer your question. The last published uncertainty I saw for a miss distance was around 21,000 miles, so rounding Mars' diameter to 4000 miles gave a bit more than 5 Mars diameters. Very simplistic, uniplanar, manifestly inaccurate; I withdraw the comment.
"If this unlikely event were to occur, it would be somewhere within a broad swath across the planet north of where the Opportunity rover is located."
Full article: http://www.jpl.nasa.gov/news/news.cfm?release=2007-152
I think that I mis-stated Meridiani as the stated potential impact area, though pretty sure I've seen that in other articles (derived from this press release, no doubt). This may be getting out of control.
EDIT: Whups, didn't answer your question. The last published uncertainty I saw for a miss distance was around 21,000 miles, so rounding Mars' diameter to 4000 miles gave a bit more than 5 Mars diameters. Very simplistic, uniplanar, manifestly inaccurate; I withdraw the comment.
QUOTE (Stu @ Dec 24 2007, 12:47 PM)
Seriously tho, when will we have a better idea of what's actually going to happen? Will it literally be on the day? If so, that'll be a "don't stray too far from the computer" day, won't it?
It might become easier to observe as the bright moon gets out of the way...
QUOTE (ugordan @ Dec 24 2007, 02:58 PM)
...The two artistic views could be regarded as the same scenario - mine would be the initial impact (I was actually aiming at that) throwing ejecta up and Stu's would be the aftermath several minutes later when ejecta has settled down and the dusty "fireball" rose up and cooled down...
Agreed, and agree that, in principle, the mushroom cloud might be reduced by the relative thinness of the atmosphere and weakness of the fireball. Of course, what interests me is the ground-hugging, ground-scouring, dust storm-like impact surge cloud and the distance of its effects would be felt from the impact site - probably at least 10 crater diameters (judging from recent imagery), implying that Oppy wouldn't want to be there.
-- HDP Don
I guess even if it missed, that would still be a great opportunity for the orbiters - they will be within thousands of kilometers from the asteroid - any guesses on imaging it from orbit just like other asteroid-imaging spacecraft did?
Well, if the time of the asteroid breaking the plane is fairly well known, then the possible impact points could be narrowed down to one hemisphere (probably longitudinally constrained, if the asteroid is near the ecliptic). And if the expected trajectory is to one side of Mars, then an impact would be more likely on that half of Mars than the other half. (Eg, if it is expected to pass north of Mars's north pole, then an impact in the northern hemisphere of Mars would be more likely than an impact in the southern hemisphere.) But I would expect the latter constraint to be very loose until it is determined if the asteroid hits at all. So maybe there would be a 55% probability for the one hemisphere vs. the other. But as the time draws closer, that would presumably collapse to 100%-0% (assuming there is a hit at all).
The Near Earth Object Program at
http://neo.jpl.nasa.gov/news/
has/will have the latest news....
here is an animated gif I lifted off their website:
Click to view attachment
The animation shows the motion of the uncertainty region of 2007 WD5 as it approaches Mars.
The thin white line is the orbit of Mars.
The vertical fuzzy line is the current uncertainty region of the asteroid
The blue line traces the motion of the center of the uncertainty region, which is the most likely position of the asteroid.
cheers
http://neo.jpl.nasa.gov/news/
has/will have the latest news....
here is an animated gif I lifted off their website:
Click to view attachment
The animation shows the motion of the uncertainty region of 2007 WD5 as it approaches Mars.
The thin white line is the orbit of Mars.
The vertical fuzzy line is the current uncertainty region of the asteroid
The blue line traces the motion of the center of the uncertainty region, which is the most likely position of the asteroid.
cheers
QUOTE (PDP8E @ Dec 27 2007, 07:18 PM)
here is an animated gif I lifted off their website:
That's apparently an old animation, already posted in post #32 of this thread and does not take into account the 3 "precovery" observations which reduced the projected miss distance to the current 21 000 km. I'm most interested in seeing how that translates to the uncertainty ellipse.
If I'm reading Emily's latest blog entry correctly, the odds of an impact have now possibly shrunk to 1 in 25...?
"Possibly" is the keyword here, Stu; they may have also increased to 1 in 300 based on 'precovery' observations. Looks like we're still awhile from dialing in on a good range of odds, although personally I doubt they'll ever drop below 1 in 50 (if we're lucky.)
Since I have a spectacular record of guessing wrong...please please please let me be wrong here!!!
Since I have a spectacular record of guessing wrong...please please please let me be wrong here!!!
QUOTE (Stu @ Dec 28 2007, 01:31 PM)
If I'm reading Emily's latest blog entry correctly, the odds of an impact have now possibly shrunk to 1 in 25...?
Emily quotes the Minor Planet Mailing List which is here.
The latest post there from Aldo Vitagliano explains the discrepancy between the two results Emily reported:
QUOTE
The reason for the discrepancy between these results and those I gave in my previous post is that (perhaps arbitrarily) I discarded the following two observations having residuals substantially larger than the average, while JPL did not.
2007 12 04.22377
2007 12 05.2261
If I include the above observations in my MonteCarlo runs, I get nearly the same results as JPL.
I am not expert in probability and statistics, but I would say that a probability estimate which is so crucially dependent on two
observations lying among others in the middle of the observational arc is in itself very uncertain. In other words, it seems to me that even the error estimate is affected by a large error ... :-)
Regards
Aldo Vitagliano
2007 12 04.22377
2007 12 05.2261
If I include the above observations in my MonteCarlo runs, I get nearly the same results as JPL.
I am not expert in probability and statistics, but I would say that a probability estimate which is so crucially dependent on two
observations lying among others in the middle of the observational arc is in itself very uncertain. In other words, it seems to me that even the error estimate is affected by a large error ... :-)
Regards
Aldo Vitagliano
It sounds like it's still very much a gamble, with the current odds 1/25, and we won't know more until the astronomers get some more observations.
Steve M
JPL has now published the new odds on Mars impact.
The new image shows that the most probable path passes on the other side of Mars (compared to the earlier prediction).
Steve M
QUOTE
The impact probability for a collision of asteroid 2007 WD5 with Mars on January 30 has increased from 1.3% to 3.9%.
Pre-discovery observations of asteroid 2007 WD5, taken on November 8, 2007 have allowed its orbit to be refined and the uncertainties for the late January Mars encounter have been improved. The impact probability resulting from the recent orbit refinement has increased to a surprising 3.9% (about 1 in 25 odds). The uncertainty region during the Mars encounter now extends over 400,000 km along a very narrow ellipsoid that is only 600 km wide. Since the uncertainty region intersects Mars itself, a Mars impact is still possible. However, the most likely scenario is that additional observations of the asteroid will allow the uncertainty region to shrink so that a Mars impact is ruled out. In the unlikely event of an impact, the time would be 2008 January 30 at 10:56 UT (2:56 a.m. PST) with an uncertainty of a few minutes.
Pre-discovery observations of asteroid 2007 WD5, taken on November 8, 2007 have allowed its orbit to be refined and the uncertainties for the late January Mars encounter have been improved. The impact probability resulting from the recent orbit refinement has increased to a surprising 3.9% (about 1 in 25 odds). The uncertainty region during the Mars encounter now extends over 400,000 km along a very narrow ellipsoid that is only 600 km wide. Since the uncertainty region intersects Mars itself, a Mars impact is still possible. However, the most likely scenario is that additional observations of the asteroid will allow the uncertainty region to shrink so that a Mars impact is ruled out. In the unlikely event of an impact, the time would be 2008 January 30 at 10:56 UT (2:56 a.m. PST) with an uncertainty of a few minutes.
The new image shows that the most probable path passes on the other side of Mars (compared to the earlier prediction).
Steve M
I hope the MER are old enough to remember how to "duck and cover". 
I don't think you have to worry about that just yet.
I have a feeling we're all lining up for a big disappointment here. Suppose the impact odds come up to 1/10 and then be completely ruled out. Talk about an anticlimax...
Still, Shaka's observation raises an interesting question: how many (if any) of you would be willing to sacrifice (or, rather, consciously put at risk of destruction) one of the rovers in exchange for being able to witness an event this rare (and not necessarily witness it by the rover itself)?
I have a feeling we're all lining up for a big disappointment here. Suppose the impact odds come up to 1/10 and then be completely ruled out. Talk about an anticlimax...
Still, Shaka's observation raises an interesting question: how many (if any) of you would be willing to sacrifice (or, rather, consciously put at risk of destruction) one of the rovers in exchange for being able to witness an event this rare (and not necessarily witness it by the rover itself)?
QUOTE (ugordan @ Dec 28 2007, 09:29 PM)
how many (if any) of you would be willing to sacrifice (or, rather, consciously put at risk of destruction) one of the rovers in exchange for being able to witness an event this rare (and not necessarily witness it by the rover itself)?
Not me, no way. Even if an impact was absolutely guaranteed there's no guarantee that the asteroid would make a "useful" crater; it might not show us anything dramatically new. The rovers could die tomorrow, yes, but there might still be another good couple of years left in these most amazing of resources yet, so it would be foolish to put one at them of risk of destruction for anything less than a potentially paradigm-shifting discovery - trying to reach a "green patch" half-way down a dangerously steep slope, or attempting to investigate a strange flickering glint of what might just possibly be ice on the underside of a big boulder that could only be reached by crossing a veritable minefield of jagged, dangerous rocks...
An impact would be cool, definitely, and I'm hoping we all get to see one, but if we don't then I won't lose any sleep over it; the best we could hope for from one of the rovers far enough outside the impact zone to have a good chance of surviving the event would be a shuddery image or two of a dust cloud above the horizon. WHatever happens, happens.
QUOTE (Stu @ Dec 28 2007, 11:10 PM)
Even if an impact was absolutely guaranteed there's no guarantee that the asteroid would make a "useful" crater; it might not show us anything dramatically new.
I was thinking the same thing, actually. To me the most exciting prospects would be actually recording the moment of impact (chances of which are second to none - both from Mars/Earth ground or orbital assets; this would not be SL9 by far) and maybe detecting various volatiles (MEX PFS?) released to the atmosphere by the excavation event. The crater itself would end up being at a remote location and all we'd get would be CRISM mineralogy and HiRISE imagery. How different than Victoria can a crater without dust and erosion look anyway?
The question is if a known (big) impact would add significant knowledge to what we already know about Mars. It might actually do more to raise the awareness about NEOs here on Earth and the importance of detecting them on time.
QUOTE (Stu @ Dec 28 2007, 05:10 PM)
Even if an impact was absolutely guaranteed there's no guarantee that the asteroid would make a "useful" crater; it might not show us anything dramatically new.
I totally beg to differ.
We'd learn volumes about how dust clouds disperse and affect the atmospheric layers during impact events. Sure, we've got theoretical models, but backing them up with observations would be really useful. Heck, even watching the dust cloud drift around would give us even more information about meteorology and local wind fields on Mars.
(I agree strongly with ugordan. Showing (eventually) a new crater on Mars would drive home the "This could be you" message.)
Just checked my sources on the asteroid (Ron Baalke).
The chances of the asteroid impacting Mars have increased from 1 in 75 to 1 in 25.
The chances of the asteroid impacting Mars have increased from 1 in 75 to 1 in 25.
QUOTE (ugordan @ Dec 28 2007, 02:22 PM)
To me the most exciting prospects would be actually recording the moment of impact...
Agreed, even if it's beyond visual range of either of the MERs. I'm convinced that the rover IMUs are sensitive enough to detect the impact shock. The beauty here is that even if they're not, that would set some constraints on Martian crustal properties based on the distance from the rovers, the IMU performance characteristics, and the calculated impact energy...we'd learn something about Mars' crust either way.
Re elevated expectations: If it happens, aren't we lucky...
...if not, no biggie. I'm actually excited by the fact that we've achieved the ability to even detect such potential events on Mars!
Remember, slump effects can be enhanced by seismic shocks. Mass wasting downslope is often driven by seismic activity.
So, one way to observe seismic events is to look at how much change we end up seeing in materials on slopes.
Seems to me Opportunity and Spirit are both sitting on slopes right now...
-the other Doug
So, one way to observe seismic events is to look at how much change we end up seeing in materials on slopes.
Seems to me Opportunity and Spirit are both sitting on slopes right now...
-the other Doug
QUOTE (Juramike @ Dec 29 2007, 12:14 AM)
I totally beg to differ.
We'd learn volumes about how dust clouds disperse and affect the atmospheric layers during impact events. Sure, we've got theoretical models, but backing them up with observations would be really useful. Heck, even watching the dust cloud drift around would give us even more information about meteorology and local wind fields on Mars.
We'd learn volumes about how dust clouds disperse and affect the atmospheric layers during impact events. Sure, we've got theoretical models, but backing them up with observations would be really useful. Heck, even watching the dust cloud drift around would give us even more information about meteorology and local wind fields on Mars.
I see what you mean. To be honest, I wasn't talking (or even thinking) about those things you refer to, I was thinking more geologically - newly exposed rock, etc. I see your point.
Still wouldn't risk a fairly healthy, still a'roving rover for a possible chance to see a drifting dust cloud tho
"2:55 am PST" 
Dam' I'll have to stay awake 'til 1:00 in the morning.
Dam' I'll have to stay awake 'til 1:00 in the morning.
An asteroid hit would be even better if something like METNET was in place.
QUOTE (Shaka @ Dec 29 2007, 12:21 PM)
"2:55 am PST"
Dam' I'll have to stay awake 'til 1:00 in the morning.
Dam' I'll have to stay awake 'til 1:00 in the morning.
You think that's bad, I just did the complex time-zone conversion calculations for PST-to-Hawaii and back again (subtract 22 hours and add 1 day) . So it looks like I'll have to stay awake until 2:55 am PST if my figures are correct.
Guys...dunno if I'd bother. How would we get real-time coverage of the (probably non-)event? Doubt that if it hits we'd even know about it until several hours--if not a full day or more--later. Stay in the sack, get your Zzzs!
QUOTE (nprev @ Dec 30 2007, 12:24 AM)
Doubt that if it hits we'd even know about it until several hours--if not a full day or more--later.
The following segment of Science Friday, a National Public Radio show, gives a good summary of everything mention in this thread, and also mention how faint the object is. They hope to get a "big" telescope, like one on Mauna Kea, to track it.
8 min : mp3
file size: 4 MB
Asteroid May Cross Path of Red Planet
NASA astronomers are monitoring a 164-foot wide asteroid that is headed in the direction of Mars at about 28,000 miles per hour. Scientists say that the space rock has a 1-in-25 chance of colliding with the Red Planet.
Guest: Donald Yeomans
Manager, Near Earth Object Program
NASA's Jet Propulsion Laboratory
Pasadena, California
Alternate link for mp3 plus rm and wm streaming.
http://www.sciencefriday.com/program/archives/200712281
Jack
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