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Space NASA

Mars Orbiter Beams Back Images of Comet's Surprisingly Tiny Nucleus 47

astroengine writes The High-Resolution Imaging Science Experiment (HiRISE) camera on board NASA's Mars Reconnaissance Orbiter (MRO) has become the first instrument orbiting Mars to beam back images of comet Siding Spring's nucleus and coma. And by default, it has also become the first ever mission to photograph a long-period comet's pristine nucleus on its first foray into the inner solar system. Interestingly, through analysis of these first HiRISE observations, astronomers have determined that the icy nucleus at the comet's core is much smaller than originally thought. "Telescopic observers had modeled the size of the nucleus as about half a mile, or one kilometer, wide," writes a NASA Jet Propulsion Laboratory news release. "However, the best HiRISE images show only two to three pixels across the brightest feature, probably the nucleus, suggesting a size less than half that estimate."
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Mars Orbiter Beams Back Images of Comet's Surprisingly Tiny Nucleus

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  • by Anonymous Coward on Tuesday October 21, 2014 @07:59AM (#48194495)

    "Is your lady not impressed with your girth? Are other comets causing global cataclysms while you flame out in the atmosphere? Try Adamantice for 30 days, only $39.99!"

  • How long has it been unconscious?

  • by jeffb (2.718) ( 1189693 ) on Tuesday October 21, 2014 @08:12AM (#48194573)

    Well, I guess that takes a bit of the sting out of the missed impact opportunity.

    If the nucleus really had been 50km in diameter (original estimated maximum), and if it had hit Mars, it would've significantly increased Mars' atmosphere with one blow. I'll confess that I was a bit disappointed when we realized that wasn't going to happen.

    A comet this small would still have made an impressive boom, but it would have been perhaps a bit less world-changing.

    • If the nucleus really had been 50km in diameter (original estimated maximum), and if it had hit Mars, it would've significantly increased Mars' atmosphere with one blow.

      Some folks have recommended nabbing some passing asteroids and detonating them in the Martian atmosphere, just to create more atmosphere as they burn up. I still don't know how they deal with the lack of gravity, though.

      • Some folks have recommended nabbing some passing asteroids and detonating them in the Martian atmosphere, just to create more atmosphere as they burn up.

        Even if it didn't create more atmosphere, wouldn't that be a cool thing to do just for the hell of it?

    • by necro81 ( 917438 ) on Tuesday October 21, 2014 @09:33AM (#48195283) Journal
      So, what you are saying is...

      "Where's the kaboom [youtube.com]? There was supposed to be a Mars-shattering kaboom?"
    • Re: (Score:3, Informative)

      by aaron4801 ( 3007881 )
      Without a planetary magnetic field to speak of, any atmosphere created by comet or terraforming would be temporary. If humans are to colonize Mars someday, we would need a steady stream of comets to fire at the planet to replenish the atmosphere swept away by the solar winds. Somehow, dropping comets on a planet for the sole purpose of supporting a permanent settlement seems....odd?
      • by Anonymous Coward

        Without a planetary magnetic field to speak of, any atmosphere created by comet or terraforming would be temporary

        Temporary on what timescale though? If it were a million+ years, a second one might not be needed considering how much technology and needs might change by then. Even if it only lasted a thousand years, if the whole point was just to make landing and construction easier (as opposed to actually providing a breathable atmosphere), then a second one might not be needed anyway as construction and rocket tech advances.

      • True... but it's not like having a flat tire on a car. It would take centuries for the atmosphere to leak away. So they have to drop another commet every 100 years or so, that's not so bad.

      • The Oort cloud is supposed to be a veritable treasure trove of these things, all you have to do is tip them sunward (decrease their negligible orbital velocity just a little) and be precise enough about it to achieve Mars impact. The trick is getting a ship with any kind of delta V capability into the Oort cloud in the first place - solar power ain't gonna cut it out there, probably need a massive Thorium or Plutonium pile to make it go. Extra bonus, when you get there, the objects you are moving provide

        • What a perfect application for a truck-bed-sided fusion plant.

          Actually, scale it up a good bit from that. Cold side for heat-engine power cycle? You're sitting on a giant snowball! Boil off volatiles with the hot side of your exchanger, use some of your power to drive the deuterium separation plant you hauled along, and use the rest to accelerate some of the vapor out the back. It's the next best thing to rendezvousing with an already-filled fuel tank.*

          * some assembly required

  • ½mile == 1km? (Score:1, Insightful)

    by durin ( 72931 )

    "about half a mile or one kilometer"? Could they make up their mind? Or are they actually suggesting that ½mile == 1km?

    • by Anonymous Coward

      No, they're suggesting that 1 km is about half a mile. And that's correct.

    • 0.8 kilometer (1/2 mile) is about one kilometer. Claiming more precision ("1/2 mile, or 0.8 kilometer") would actually be misleading.

    • Within their measurement errors bounds, yes ½mile == 1km

    • by jrumney ( 197329 )
      They are extraterrestrial miles. Somewhere between a nautical mile and a terrestrial mile.
  • Can anyone explain what a "siding spring" is? It sounds like a Linux OS release.
    • by Anonymous Coward
      Sure, it is a USism. It is the spring that pops up the siding boards on the side of the house to open the gun ports. Some US RVs have these built in too. Here, http://forums.pelicanparts.com... [pelicanparts.com], you can see a US RV with the siding dropped down instead of sprung up to expose the gun ports. You know, in the US we love our guns...
    • Re:I don't get it (Score:5, Informative)

      by tomhath ( 637240 ) on Tuesday October 21, 2014 @08:53AM (#48194903)
      Comets are named after whoever spots it first. Siding Spring [wikipedia.org] is an observatory in Australia.
  • Please (Score:5, Informative)

    by hackertourist ( 2202674 ) on Tuesday October 21, 2014 @08:37AM (#48194741)

    don't link to Discovery.com for TFA. The last time I tried to load a page there, the NoScript menu got half a mile long. Every domain I enabled trying to get the site to display correctly, added 5 more script domains to the list. You end up downloading half the Internet just to display one page.

    • Who the heck modded up this FUD?

      Discovery.com tries to load lots of external resources.
      However, the text on the page is displayed without loading any of them (unlike some other sites, such as gawker).

      The images and the stylesheet are at ddmcdn.com, if you're using RequestPolicy. This is the only domain that needs to be allowed in RequestPolicy if you want it to "display correctly", but if you're only using NoScript, the page loads fine without allowing anything. The text is reasonably well-formatted and

  • I wonder why do they still write "icy comet nucleus" if no comet photographed up to today - and we have at least three close encounters with crafts - had displayed icy features. All of them are pretty much rocky.

    By now it should be obvious that the light-show given by comets is electric in nature, and has nothing to do with melting ice or snow.

    • by Anonymous Coward

      I wonder why do they still write "icy comet nucleus" if no comet photographed up to today - and we have at least three close encounters with crafts - had displayed icy features.

      They still write that because what you say is wrong, as seen by repeated spectroscopic measurements. The vast majority (90+%) of what comes out of a comet is water, and while there is some rock and dust on the surface, a lot of water ice has been observed on and below the surface of comets.

      • There is no water coming out of comets. What is detected are OH- ions, that are believed to be derived from water - which is not there - but can equally derive from ionized oxygen combined with protons (A.K.A. H+) from the solar wind.

        • Re:"Icy nucleus" (Score:4, Informative)

          by Anonymous Coward on Tuesday October 21, 2014 @01:02PM (#48197323)

          There is no water coming out of comets. What is detected are OH- ions, that are believed to be derived from water - which is not there

          This is flat out wrong in the sense that water, as opposed to OH-groups, have been confirmed. This includes the v2 bending mode and v3 asymmetric stretching mode ~1600 cm^1 and ~3750 cm^-1, plus other combination vibration modes such as v1+v3. These modes do not exist in just the OH ion, and involve frequencies specific to water (although some combination modes overlap with other detected vibration modes). This stuff has been seen since at least the 80s.

          • BTW, the grandparent post was written in a "trollish" wording on purpose - but I seriously consider the electric comet theory - and would advise anyone not tending to hold "the most accepted current theory" in science as if it were a religious fact. If anyone one is curious about it, give it a read.

            Now - I just got to this article and video depicting an explosion in Mars that fits quite well with the electric comet model - but which would get a hard time being explained by ice blocks: https://missiongala [wordpress.com]

  • by Anonymous Coward

    Is this the first instance of a scientifically important astronomical observation of an external body (besides the planet itself, its moons and rings) made from another planet? I know there have been look back shots of the Earth and Moon from Mars and Saturn, but AFIK they didn't add anything of significance to scientific knowledge.

  • who could increase the size of your nucleus. also he can get you viagra.

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