Starship Asterisk*

http://www.cometcampaign.org/karl/exciting-times
Mon, 10/06/2014 - 08:37 — Karl Battams
We're now less than two weeks away from Comet Siding Spring buzzing ridiculously close to Mars, and the excitement is building - in both good and bad ways...

Of course we're all tremendously thrilled at the prospect of the comet flying so close to so many wonderful spacecraft at Mars. ... pretty much the entire Martian fleet of spacecraft and rovers are going to be attempting to take observations of the comet.

... All of the comet nuclei we've observed so far have been periodic comets - objects that stay relatively close to our solar system and swing predictably past the Sun every few or few dozen years. They've been doing this for centuries or millennia, which means their surface has undergone substantial changes since their formation a few billion years ago.

Comet Siding Spring is different - it's an Oort Cloud comet, dynamically new, and on its first ever foray into our solar system. This means it is largely pristine and will likely not have undergone any major changes since it formed. We've never seen one of these comets up close. Never. We don't know exactly what to expect.
... the bottom line is that we are more-or-less clueless right now on what it will do over the next couple of weeks. It could dramatically brighten, it could stay the same, it could fade rapidly, or it could even completely fall apart!
...

NASA Science Fleet Prepares for Mars Comet

Oct. 9, 2014: NASA’s extensive fleet of science assets, particularly those orbiting and roving Mars, have front row seats to image and study a once-in-a-lifetime comet flyby on Sunday, Oct. 19.
Comet C/2013 A1, also known as comet Siding Spring, will pass within about 87,000 miles (139,500 kilometers) of the Red Planet -- less than half the distance between Earth and our moon and less than one-tenth the distance of any known comet flyby of Earth.

Click to view full size image

...
Images and updates will be posted online before and after the comet flyby. Several pre-flyby images of Siding Spring, as well as information about the comet and NASA’s planned observations of the event, are available online at http://mars.nasa.gov/comets/sidingspring

Click to play embedded YouTube video.

Comet Siding Spring Approaches Mars
The Planetary Society
Published on 13 Oct 2014

On October 19, 2014, Comet Siding Spring will fly very close to Mars. Here’s an introduction from The Planetary Society (http://planetary.org) to get you up to speed on this planetary near miss, and some suggestions on how to find out more now, during, and after the encounter.

Karl Battams wrote on October 18, 2014

...As I write, we're only just over 24-hours away from the comet's gassy coma engulfing Mars as the comet roars past the Red Planet at 56km/s (126,000mph). Does this brightness drop jeopardize all of the Mars-based observations we've been hearing about? Is the comet still even active? Could it fall apart? Would it change the situation and threaten Mars if it did fall apart now? They're good questions that I've been asked in recent days in media interviews and via email and Twitter. So again, just like I did last year with ISON, let me try and calm a few of these last minute nerves, and be explicit on what we do and don't know.
read more at: http://www.cometcampaign.org/karl/drawing-parallels

Click to view full size image

http://blogs.esa.int/mex/2014/10/20/spa ... continues/
Posted on 20/10/2014 by Daniel

Update from Spacecraft Operations Manager Michel Denis at ESOC:

Comet Siding Spring has flown by Mars .

Thanks to the DSN radio-science receiver at Madrid (then Goldstone) we could follow the Mars Express S-Band beacon practically all the time, including closest approach and comet plane crossing. Despite the very low level of concern, this was quite good to have.
...

ISRO's Mars Orbiter Mission is in good health past the exit of comet ‪#‎SidingSpring‬.

Planetary Society: Seven Mars spacecraft attempted observations of comet Siding Spring. How did they go?
Posted by Emily Lakdawalla
2014/11/03 22:03 UTC

It's been two weeks since comet Siding Spring passed close by Mars, and six of the seven Mars spacecraft have now checked in with quick looks at their images of the encounter. None of the spacecraft photos of the comet is visually spectacular -- there are no enormous fireballs streaking across Martian skies. What the released images do show us is that this is a terrific data set taken from very close range on an Oort cloud comet; over the coming months and years, we'll enjoy the fruits of careful scientific investigation of a unique data set.

And it's worth taking a moment to appreciate how we got these photos. A year ago, we discovered a teeny tiny object that had never visited the inner solar system before; we predicted that it would pass by another planet; we already had five spacecraft at that planet, and two more preparing to launch; and we commanded all these autonomous robots to catch the comet as it flashed by at 55 kilometers per second
...

[i]Artist’s concept of Comet Siding Spring approaching Mars, shown with NASA’s orbiters preparing to make science observations of this unique encounter. [b](Image Credit: NASA/JPL)[/b][/i]

---

Two NASA and one European spacecraft that obtained the first up-close observations of a comet flyby of Mars on Oct. 19, have gathered new information about the basic properties of the comet's nucleus and directly detected the effects on the Martian atmosphere.

Data from observations carried out by NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission, NASA's Mars Reconnaissance Orbiter (MRO), and a radar instrument on the European Space Agency's (ESA's) Mars Express spacecraft have revealed that debris from the comet added a temporary and very strong layer of ions to the ionosphere, the electrically charged layer high above Mars. In these observations, scientists were able to make a direct connection from the input of debris from a specific meteor shower to the formation of this kind of transient layer in response; that is a first on any planet, including Earth.

Comet C/2013 A1 Siding Spring traveled from the most distant region of our solar system, called the Oort Cloud, and made a close approach around 2:27 p.m. EDT within about 87,000 miles (139,500 kilometers) of the Red Planet. This is less than half the distance between Earth and our moon and less than one-tenth the distance of any known comet flyby of Earth.

Dust from the comet impacted Mars and was vaporized high in the atmosphere, producing what was likely an impressive meteor shower. This debris resulted in significant temporary changes to the planet's upper atmosphere and possible longer-term perturbations. Earth-based and a host of space telescopes also observed the unique celestial object. ...

[url=http://www.psi.edu/news/sidingspringimages][i]Images of Comet Siding Spring from the Hubble Space Telescope.[/i][/url] [b][i]Credit: NASA, ESA, PSI, J.-Y. Li et al.[/i][/b]

---

Data from the Hubble Space Telescope gathered on Comet C/2013 A1 (Siding Spring) as it approached and closely passed Mars could offer insights on the formation of our Solar System, a Planetary Science Institute researcher said.

“The HST images reveal how the comet looked as it raced towards Mars, not only helping us understand its composition and physical properties, but also, more critically, providing a wealth of unique information to understand the dust coma of the comet that Mars and the spacecraft around it had to pass through,” said Jian-Yang Li, a research scientist at the Planetary Science Institute.

Li is lead author on a paper, “Constraining the Dust Coma Properties of Comet C/Siding Spring (2013 A1) at Large Heliocentric Distances” that will appear in Astrophysical Journal Letters. Li gave a presentation on this research today, and will discuss his findings at a press conference Tuesday, at the 46th Annual Division for Planetary Science conference held in Tucson Nov. 9-14. He will also present at the meeting the preliminary results from the Hubble Space Telescope observations of the comet during its close encounter with Mars that occurred on October 19.

“The color of this comet suggests the existence of water ice in its coma, when it was observed more than 3 AU from the Sun. At this distance, the bulk of comet activity is driven by the sublimation of CO and CO2. Water ice is like rock,” Li said. “This is similar to our results for C/ISON, and may indicate a common phenomenon among dynamically new comets. Comets like C/Siding Spring visit the Sun’s vicinity only once every million of years or even once in their lifetimes.”

“This work provides important insight into the nature of comet nuclei. It suggests that ice in the comet nucleus may be mechanically similar to its rocky components – separate chunks capable of being lofted by outgassing, instead of being welded to surrounding ice,” said PSI Director Mark Sykes, who participated in a separate study on the potential hazard of this dust to orbiting spacecraft at Mars.

• arXiv.org > astro-ph > arXiv:1411.0027 > 31 Oct 2014

CIOC:Comet Dust in Mars' Atmosphere: How Do the Orbiter Observations Relate to the Siding Spring Dust Models?

November 9, 2014 - 00:01 — Tony Farnham

NASA held a telecon/press conference on November 7 to announce the results from the MAVEN, Mars Express (MEX) and Mars Reconnaissance Orbiter (MRO) observations that were obtained during the encounter between Mars and comet Siding Spring. The broadcast can be found here: (http://www.ustream.tv/nasajpl2). During this event, there were presentations that showed three fascinating pieces of evidence indicating that a significant amount of comet dust was deposited into Mars' atmosphere during the encounter. ...