Comet observation from Mars, comets close encounters to Mars in 2013 and 2014 |
Comet observation from Mars, comets close encounters to Mars in 2013 and 2014 |
Feb 25 2013, 10:07 PM
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Newbie Group: Members Posts: 18 Joined: 20-April 05 From: Czech Republic Member No.: 300 |
Is there is any possibility to observe comets in near future from surface of Mars and/or from Mars orbiters. Which types of instruments are possible to use?
For example (http://ssd.jpl.nasa.gov/horizons.cgi - position Mars 0deg Longitude, 5deg south Latitude, time UTC): 1) Comet C/2012 S1 (ISON) 2013-Oct-01 17:19UTC RA 23 07 44.73 DE +69 27 46.0 MAG 2.93 r 1.637007919902 delta 0.07246306543080 So there is relativly very close encounter in October 2013, about 11 million km from Mars.. 2) Comet C/2013 A1 (Sidding Spring) 2014-Oct-19 20:59UTC RA 10 49 50.64 DE -60 38 09.5 MAG -8.29 r 1.401218071277 delta 0.00070643344409 There is still maybe not so precise orbit BUT, there is ONLY about 105 000 km (65 000 miles) encounter from Mars. Especially the second comet, if this orbit will be OK, is very interesting target to observe. -------------------- |
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Mar 4 2013, 10:22 PM
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Senior Member Group: Admin Posts: 3108 Joined: 21-December 05 From: Canberra, Australia Member No.: 615 |
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Mar 5 2013, 03:17 PM
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Member Group: Members Posts: 267 Joined: 5-February 06 Member No.: 675 |
Checked the flyby on NASA's Horizons and found that the elongation of the comet from the Sun remains in the range 84° to 90° throughout the encounter.
According to the current model, Mars will never be "downstream" from the comet so won't be as strongly impacted by the outflow of the coma as it would be if it passed directly through the tail. Steve M |
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Mar 5 2013, 06:57 PM
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#4
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Senior Member Group: Members Posts: 4256 Joined: 17-January 05 Member No.: 152 |
The jpl database now lists the "nominal" close-approach distance at a bit over 50 000 km. But they list the "maximum" distance as over 300 000 km. I can see no definition for the "maximum" distance, but elsewhere they refer to 1-sigma uncertainties. So if that "maximum" distance corresponds to the 1-sigma upper limit, then it will be a much better indication of the likely close-approach distance than the "nominal" value, if the errors used in the calculations aren't overestimated. In fact, for a gaussian error distribution, the odds are something like 32% that the actual value will be greater than 300 000 km!
The "minimum" distance is listed as zero, which presumably means the error ellipse still intersects Mars. But the area of Mars is an incredibly tiny fraction of the area of a 300 000 km (or 600 000 km?) error ellipse, so the chance of collision is extremely small. the elongation of the comet from the Sun remains in the range 84° to 90° That's interesting - it would mean that the comet would be viewed perpendicularly to the tail throughout the encounter, which is great news for getting good tail views (or at least views that aren't very foreshortened). But if the error ellipse still includes Mars, the comet could as easily be on one side of the planet as the other during encounter. It could also be sunwards or outwards, presumably by as much as something like the 1-sigma value, 300 000 km. So all options still seem to be open. It looks like we'll need lots more observations before we can pin down the encounter specifics. |
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