Mars Comet Encounter Observations, C/2013 A1 Siding Spring, 19 Oct 2014 Options

[Fran Ontanaya]

Will MEX's VMC be sensitive an wide angle enough to show both Mars and the comet?

They captured Earth two days ago with a 2-30 seconds exposures, so maybe they can expose separatedly to capture the coma and Mars; or if not, just do it when MEX is on Mars' night-side.

[Gerald]

NASA Holds Briefing About Comet Flyby of Mars

NASA will host a briefing at 11 a.m. PDT (2 p.m. EDT) Thursday, Oct. 9, to outline the space and Earth-based assets that will have extraordinary opportunities to image and study a comet from relatively close range to Mars on Sunday, Oct. 19...

[djellison]

Not a hard seartch to do....finding this took less time than typing it up.

http://lmgtfy.com/?q=mro+siding+spring

Third hit

http://cometcampaign.org/files/docs/sessio...CSS_CIOC_v3.pdf
Mars Reconnaissance Orbiter Observation Plan for Comet Siding Spring Encounter

Page 5 of which states....

There are 3 main science objectives for MRO during the encounter:
– Observations of the comet near closest approach
• Nucleus size, rotation, shape (estimate => 0.6-1.5 km diameter)
– HiRISE (best resolution ~131 m/pixel)
– CTX (> 3 km/pixel) and CRISM (>10 km/pixel) with also observe

[Explorer1]

Basically, we can expect something more like the radar pictures of 2012 DA14 last year than what we've gotten from close flybys. An identifiable shape, but not much else. Plenty of science can come from that alone.

T-minus 1 week....

[nprev]

I've been searching off & on for a couple of hours but no luck. Anybody know if there's a tau prediction for encounter time for each of the rovers yet? I hear that there are some pretty good localized sandstorms happening mostly in the southern hemisphere, dunno if any of those are expected to blow up into regional events that might affect surface observations on C-sol.

[scalbers]

The Minor Planet Center
http://scully.cfa.harvard.edu/cgi-bin/retu...&o=CK13A010
and
Visual Comets in the Future
http://www.aerith.net/comet/future-n.html

predict about magnitude +8 1/2, as seen from Earth, about the time of closest approach to Mars. Not that our view has much to do with the ability to see the comet from Mars.

The current estimate for the brightness seen from Earth on Seiichi Yoshida's site is about magnitude 10.8. A simple distance adjustment would then give magnitude -5.4 seen from Mars. This might change a bit depending on differences in phase angle and whether there is forward or backward scattering in the coma. If the magnitude of the nucleus is 5 magnitudes fainter it would show up as magnitude zero.

Recent images on the same site can be found here, taken from Earth: http://aerith.net/comet/catalog/2013A1/pictures.html. The coma diameter of roughly 1 arcminute seen from Earth would spread out to 28 degrees from Mars at closest approach.

Another good image is here: http://www.universetoday.com/114913/how-to...ncounters-mars/

[Deimos]

Earth-based observers have reported regional dust storms. This is seen at Opportunity's site as optical depths >1; the norm has been around 0.8 according to the MER weather page (http://www.lpl.arizona.edu/~lemmon/mars-tau-b.html). At the 8th Mars conference I saw that, as of that time, MSL and Opportunity optical depths had tracked each other fairly closely. This is pretty close to a time of year when larger (and sometimes much larger) dust storms can emerge.

[vikingmars]

Today's release is a ChemCam Siding-Spring imaging test : the scientists were to try Chemcam on Sirius (that can be observed in October before sunrise) and on Canopus (that can be observed for 4 hours before sunrise from August to September and which is low on the horizon)... But also at Archenar and at Spica... Do you know which stars they were pointing at ? Enjoy
http://mars.jpl.nasa.gov/msl/multimedia/ra...camera=CHEMCAM_

[Gerald]

ChemCam Vega imaging has been scheduled for Sol 777.

Finally, after sunset on Sol 777, Mastcam, and ChemCam will observe the bright star Vega to help refine plans to observe comet Siding Spring next weekend.

Here a stitch of four mostly cleaned images:

Some CR hits are visible, too. I didn't succeed in identifying other stars, yet.
(The pale spot about 188 pixels below Vega is a ghost/camera artifact of Vega.)

[jmknapp]

Trying to figure out a way to best show the viewing situation on sol 783, the sol of the closest approach, here's a cut at it:





Based on that, looks like the best opportunity is something like 7-10pm, range about one million km (vs. closest approach of 0.14 million km around 3:30pm, just as the comet is rising in the north). I don't suppose there's any chance it would be visible in the daytime? Sunset is 5:31pm.

[Gerald]

With an albedo of 0.04, a distance of 139,500 km from Mars, a diameter of 0.7 km, and a distance of 1.5 a.u. from the Sun as model assumptions, I get an apparent visual magnitude estimate for the nucleus during closest approach of about 5.6 m:
 VisualMagnitudeEstimate.pdf ( 41K ) Number of downloads: 595

For a distance of 1 million kilometers, the magnitude is 2.14 m fainter, hence about 7.8 m with the other assumptions kept the same.
Some Wikipedia links for the notions used:
Albedo, solid angle, magnitude, right triangle, Moon.

[fredk]

Trying to figure out a way to best show the viewing situation on sol 783, the sol of the closest approach, here's a cut at it

Thanks a lot, Joe, I was hoping someone would put together plots like that! Any chance you could repeat the elevation-azimuth plot for Oppy?

[jmknapp]

OK, had to hack that together real quick, hope this is right for Oppy's view of the comet:

[JohnVV]

for any that want to run the sim and do not already know about this

http://forum.celestialmatters.org/viewtopi...mp;t=578#p10789

i posted a celestia NAIF-spice add on for siding spring
using the HORIZONS database to make the position kernel
( i can not post images at this time - software error do to building VisionWorkbench and StereoPipline )

--- edited later -----
software fixed
Oct 19 at 18:27 UT
[attachment=33988:marsrise.jpg] [attachment=33989:marsrise1.jpg] [attachment=33990:ssm.jpg]

[Adam Hurcewicz]

for any that want to run the sim and do not already know about this

http://forum.celestialmatters.org/viewtopi...mp;t=578#p10789

i posted a celestia NAIF-spice add on for siding spring
using the HORIZONS database to make the position kernel
( i can not post images at this time - software error do to building VisionWorkbench and StereoPipline )

I'm made animation from SPICE orbital elements for MEX, Odyssey, MRO, MAVEN, and comet. Also xyzv for MOM from HORIZONS.
That's all in Celestia. I upload to Youtube soon, maybe tonight

I compared precision of simulation from HORIZONS/JPL ephemerides and (for MEX) http://blogs.esa.int/mex/2014/10/15/comet-flyby-timeline/