LIVE: Comet C/2013 A1 to make a close flyby of Mars - October 19, 2014

[Orbiter]

There is a chance that the comet C/2013 A1 (Siding Spring), discovered in the beginning of 2013, might collide with Mars. At the moment, based on the observation arc of 74 days, the nominal close approach distance between the red planet and the comet might be as little as 0.00073 AU, that is approximately 109,200 km! Distance to Mars’ natural satellite Deimos will be smaller by 6000 km, making it 103,000 km. On the 19th October 2014, the comet might reach apparent magnitude of -8…-8.5, as seen from Mars! Perhaps it will be possible to accuire high-resolution images from the Mars Reconnaissance Orbiter (MRO)...

... The current orbit uncertainty allows for a collision scenario, but the possibility of this is small. Astronomers keep watching this interesting comet, and I will keep you up to date with the news.

http://spaceobs.org/en/2013/02/25/comet-c2013-a1-siding-spring-a-possible-collision-with-mars/

[kevin-rf]

Cool!!! 2013 really is turning into the year of the comet!

I can just picture Curiosity looking up and going, Doh!

[Chris Bergin]

Also see:
http://forum.nasaspaceflight.com/index.php?topic=31201.0

[Orbiter]

Also see:
http://forum.nasaspaceflight.com/index.php?topic=31201.0

Interesting topic, but not necessarily related to the comet itself. I don't think it is wise to send massive comets into other planets solely for the purpose of seeing if it will at all change the planet's climate. 

What caught my attention was the fact that the comet would be coming in at over 50 km/s due to the retrograde orbit v. Mars's prograde orbit. The crater could be over 500km in size if an impact would occur. I'd imagine that would significantly disrupt NASA's currently ongoing missions to the red planet (Curiosity, Opportunity, MER, etc). Another thing is that the comet will be over a -8.0 magnitude from the surface of Mars, it would be great to get our first glimpse of a comet in another planet's night sky.

[kevin-rf]

With such a thin atmosphere and such a large potential crater I wonder if enough debris will be short term thrown into LMO (Low Mars Orbit) to pretty much end the assets in mars orbit. 

Edit: delete my question the crater estimate, it comes from the news article.

btw. Mars while five months past opposition will still be in a good position in the sky to watch the fireworks.

[Orbiter]

With such a thin atmosphere and such a large potential crater I wonder if enough debris will be short term thrown into LMO (Low Mars Orbit) to pretty much end the assets in mars orbit. 

btw. Where is this 500km crater number coming for? Do we have a nucleolus estimate that corresponds to a predicted 500 km crater?

Article says they've measured from the absolute magnitude of the nucleus that the comet is 50km in diameter moving at 56 km/s relative to Mars. That's certainly large enough to leave quite a dent on Mars.

[simonbp]

Article says they've measured from the absolute magnitude of the nucleus that the comet is 50km in diameter moving at 56 km/s relative to Mars. That's certainly large enough to leave quite a dent on Mars.

Yes, that's probably large enough to survive the atmosphere and make it down to the surface. There is going to be a lot of error, though, as comet nuclei are so dark that any jetting can throw off the absolute magnitude quite a bit. This being an Oort comet on probably its first passage through the inner solar system, it could start jetting pretty far out with low-temperature ices (nitrogen, methane, CO, O2, etc).

Now, the challenge: get MRO and/or Mars Express in position to watch the flyby/impact!

[Ben the Space Brit]

Let's look at the scenarios in the event of an impact. 

1) Would the impact temporarily rule out Mars as a destination for space exploration? I'm thinking about the low orbital region being filled with debris from both the impactor and the planet in unpredictable and decaying orbits.

2) Could the impact alter the Martian climate? A large amount of vaporised regolith plus water vapour in the atmosphere (plus possible impact-triggered volcanic eruptions) could trigger a greenhouse effect and make Mars warmer and wetter.  If there is a spacecraft still operational either on the surface or in orbit after the impact, then the next few decades would probably rewrite a few textbooks on atmospheric evolution.

[R7]

Now, the challenge: get MRO and/or Mars Express in position to watch the flyby/impact!

50km ball, assuming 0.6kg/L density (wiki's opinion for average comet density) at 56km/s gives yield of ... ~15 million gigatons of TNT. Unlikely that any asset in orbit or ground would survive. Might even send very nasty debris cloud crossing Earth orbit too.

[Robotbeat]

Now, the challenge: get MRO and/or Mars Express in position to watch the flyby/impact!

50km ball, assuming 0.6kg/L density (wiki's opinion for average comet density) at 56km/s gives yield of ... ~15 million gigatons of TNT. Unlikely that any asset in orbit or ground would survive. Might even send very nasty debris cloud crossing Earth orbit too.

It'd still be great for space exploration. Nothing like a dramatic dinosaur-killing impact on Mars to increase funding for doing /something/ about those asteroids...

Aned the effect on Mars' climate would be very significant, because the impact still couldn't dramatically reduce the mass of Mars' atmosphere (it can't blow off anything beyond the horizon) but it would add a heck of a lot of energy and volatiles (more than all of Mars' atmosphere!) to the planet, a combination of out-gassing and such that could dramatically increase the mass of the Martian atmosphere. Perhaps in some places, within half of the Armstrong limit!

[kevin-rf]

http://www.offworlddesigns.com/p-814-asteroids-t-shirt.aspx

[R7]

It'd still be great for space exploration. Nothing like a dramatic dinosaur-killing impact on Mars to increase funding for doing /something/ about those asteroids...

As long as Joe 6Pack's daily rythm isn't disturbed he would not be moved by hazy telescope imagery of distant bright flash that just indicated the death of Martian dinosaurs. 

Aned the effect on Mars' climate would be very significant, because the impact still couldn't dramatically reduce the mass of Mars' atmosphere (it can't blow off anything beyond the horizon) but it would add a heck of a lot of energy and volatiles (more than all of Mars' atmosphere!) to the planet, a combination of out-gassing and such that could dramatically increase the mass of the Martian atmosphere. Perhaps in some places, within half of the Armstrong limit!

That would be interesting prospect though .. but how long would outer space near Mars be a debris minefield? What if it isn't a clean hit but just scrapes the surface, could plow a lot of stuff into orbit. I'd protest if it would vaporize the ice from Elysium Planitia (assuming there is).

edit: given the thin atmosphere that would not stop this one much at all, right? Could it plunge through the crust to instigate longer lasting volcanic activity? That might add to the atmosphere too.

[Ben the Space Brit]

Now, the challenge: get MRO and/or Mars Express in position to watch the flyby/impact!

50km ball, assuming 0.6kg/L density (wiki's opinion for average comet density) at 56km/s gives yield of ... ~15 million gigatons of TNT. Unlikely that any asset in orbit or ground would survive. Might even send very nasty debris cloud crossing Earth orbit too.

It'd still be great for space exploration. Nothing like a dramatic dinosaur-killing impact on Mars to increase funding for doing /something/ about those asteroids...

Aned the effect on Mars' climate would be very significant, because the impact still couldn't dramatically reduce the mass of Mars' atmosphere (it can't blow off anything beyond the horizon) but it would add a heck of a lot of energy and volatiles (more than all of Mars' atmosphere!) to the planet, a combination of out-gassing and such that could dramatically increase the mass of the Martian atmosphere. Perhaps in some places, within half of the Armstrong limit!

Interestingly, in the medium-run, it might make Mars more settler-friendly.

Initially, there would be a lot of pressure to replace the lost planetary assets there.  If the data from these new probes indicates that the planet is settling down, even only temporarily, into a wet/temperate phase (and remember that 'temporary' in planetary evolution terms can be tens of thousands of years long), then the pressure to put a crew, maybe even a colony on the surface would become immense.

[MP99]

It'd still be great for space exploration. Nothing like a dramatic dinosaur-killing impact on Mars to increase funding for doing /something/ about those asteroids...

The OP article quotes the upper bound for the energy of a collision as around 200x what Wiki quotes as the energy of the Chixculub impact. [Edit: 2e16 vs 1e14 tons TNT.]

That would put it in a different league...

cheers, Martin

[ugordan]

Article says they've measured from the absolute magnitude of the nucleus that the comet is 50km in diameter moving at 56 km/s relative to Mars. That's certainly large enough to leave quite a dent on Mars.

Yes, that's probably large enough to survive the atmosphere and make it down to the surface.

Probably?

Unlikely that any asset in orbit or ground would survive.

Yes, I'd guess the huge debris cloud reaching up to orbital altitudes would be the primary killer.

Might even send very nasty debris cloud crossing Earth orbit too.

Great, we can cancel MSR, then?

[Ben the Space Brit]

It'd still be great for space exploration. Nothing like a dramatic dinosaur-killing impact on Mars to increase funding for doing /something/ about those asteroids...

The OP article quotes the upper bound for the energy of a collision as around 200x what Wiki quotes as the energy of the Chixculub impact. [Edit: 2e16 vs 1e14 tons TNT.]

That would put it in a different league...

Planet-cracker?

[kevin-rf]

That would be interesting prospect though .. but how long would outer space near Mars be a debris minefield?

Considering the point of impact is inside the atmosphere, that means the Perigees will be pretty low (as inside the thin atmosphere above the impact point), the bulk of the debris will not last very long. An orbit or two.

Now Debris hitting other debris and Mar's two Moons should produce debris that would have long lasting orbits.

It will be interesting to see how the debris field evolves. If any orbital assets survive.

[Archibald]

Once again reality (may) beat sci-fi.

The damn comet may kill many birds with a single stone (pun not intended)

- man vs robot on Mars ?  wipe the robots, terraform the planet for man.
Man: 1 robots: 0

- Mars sample return is too expensive ? let those rocks coming...

This is crazy.

[R7]

Considering the point of impact is inside the atmosphere, that means the Perigees will be pretty low (as inside the thin atmosphere above the impact point), the bulk of the debris will not last very long. An orbit or two.

This is actually what I keep failing to understand in Moon's giant impact hypothesis. What circularized enough ejecta beyond Roche-limit for Moon to form? What ever an impact throws into what ever (elliptical, hyperbolics would espace, no?) orbit don't those orbits have perigee at (or under) surface?  Apparently not, some other effect is in play, would it affect Mars case too, maybe create a ring or something?

[Ben the Space Brit]

Considering the point of impact is inside the atmosphere, that means the Perigees will be pretty low (as inside the thin atmosphere above the impact point), the bulk of the debris will not last very long. An orbit or two.

This is actually what I keep failing to understand in Moon's giant impact hypothesis. What circularized enough ejecta beyond Roche-limit for Moon to form? What ever an impact throws into what ever (elliptical, hyperbolics would espace, no?) orbit don't those orbits have perigee at (or under) surface?  Apparently not, some other effect is in play, would it affect Mars case too, maybe create a ring or something?

As I understand it, the impactor proposed by this theory was the size of Mars.  The impact was so powerful that both the impactor and the proto-Earth were both completely disintegrated into an asteroid field.  The relative motions of the impactor and proto-Earth were such that the lighter material coalesced into the Moon and the heavier material into the Earth.  The two were fairly close at first but the Moon receded to its current distance after a while.