Living and Dying With a Comet

By Corey S. Powell | September 30, 2016 11:42 pm
Comet 67P on April 28, 2015, as it was nearing closest approach to the sun and starting to really cook. (Credit: ESA/Rosetta/NavCam)

Comet 67P on April 28, 2015, as it was nearing closest approach to the sun and starting to really cook. (Credit: ESA/Rosetta/NavCam)

Like many other space enthusiasts around the world, I woke up today in a bittersweet mood as I read the reports about the death of the European Space Agency’s Rosetta comet probe. Its demise was carefully planned and long foretold but was sad all the same, putting a period at the end of a story that rolling out for more than 12 years. During that time, Rosetta made three passes by Earth, one by Mars, visited a pair of asteroids, and spent more than two years scrutinizing Comet 67P/Churyumov–Gerasimenko (typically shorted to “Comet 67P” for obvious reasons). It was the first spacecraft to orbit a comet. It also deployed the first-ever comet lander, Philae.

Now all that is over. No way around it, the end of a great adventure is bitter.

The sweet part is the extraordinary science Rosetta has conducted along the way. Early results confirmed the presence of diverse organic compounds; showed that comets alone could not have provided the water that fills Earth’s oceans; mapped the surprisingly complex magnetic environment around Comet 67P; and catalogued enormous eruptions of gas and dust–roughly 100,000 kilos [200,000 pounds] at a time–that show how comets disintegrate under the force of solar heat. Much of Rosetta’s dataset has yet to be fully analyzed. Planetary scientists will be mining new insights from it for many years to come.

The time and effort that went into the Rosetta mission only intensify the bitter and the sweet. Planning for the mission began in 1985, when the mission was known as CNSR, for “Comet Nucleus Sample Return.” Many things changed along the way as budgets shrank, NASA dropped out as a partner with the European Space Agency (ESA), and the whole idea of bringing home samples of the comet had to be abandoned. (I discuss the mission’s twisted history in more detail here.) Even after launch in 2004, Rosetta needed more than 10 years to reach the comet. That is the longest gap ever between launch and arrival for a space probe, longer even than New Horizon’s 9-year journey to Pluto.

The payoff from this drawn-out timeline is that Rosetta saw remarkable sights along the way. Its two-year main mission lasted so long that the ESA described it as “living with a comet.” The agency created a series of affecting cartoon animations that anthropomorphized the spacecraft in a way that greatly amplified the “living” aspect. And then there are the astonishing images that Rosetta has returned. The spacecraft is dead, but the emotional power of these views, along with their perception-altering qualities, insure that they will live forever as milestones in the human exploration of the solar system.

For more space news and images, follow me on Twitter: @coreyspowell

On its second Earth flyby, Rosetta captured this poetic view of our planet's nightside, ringed by sunshine and dotted by city lights. (Credit: ESA/MPS/Osiris)

Above: On its second Earth flyby, Rosetta captured this poetic view of our planet’s nightside, ringed by sunshine and dotted by city lights. (Credit: ESA/MPS/Osiris)

 

While getting a gravity boost from Mars, Rosetta's lander snapped this unique shot of the probe silhouetted against the Red Planet. (Credit: ESA/Rosetta/Philae/CIVA)

Above: While getting a gravity boost from Mars, Rosetta’s lander snapped this unique shot of the probe silhouetted against the Red Planet. (Credit: ESA/Rosetta/Philae/CIVA)

 

Another stunning Rosetta selfie, with the probe's solar panel stretched out toward a crescent Comet 67P. (Credit: ESA/Rosetta/Philae/CIVA)

Above: Another stunning Rosetta selfie, with the probe’s solar panel stretched out toward a double-crescent Comet 67P. (Credit: ESA/Rosetta/Philae/CIVA)

 

Something no human has ever seen before: An eclipse of the sun by a comet. Note the streamers of dust escaping. (Credit: ESA/Rosetta/NavCam)

Above: Something no human has ever seen before: A comet backlit by the sun (which is just outside the frame of this image). Note the long streamers of dust escaping. (Credit: ESA/Rosetta/NavCam)

 

Despite its diminutive size (less than 4 miles across its longest dimension), Comet 67P displays a complex shape and diverse landforms. (Credit: ESA/Rosetta/MPS/Osiris)

Above: Despite its diminutive size (less than 7 kilometers/4 miles across its longest dimension), Comet 67P displays a complex shape and diverse landforms. (Credit: ESA/Rosetta/MPS/Osiris)

 

Dusty sky and craggy landscape of Comet 67P seem almost tactile in this shot. (Credit: ESA/Rosetta/MPS/OSIRIS)

Above: The dusty sky and craggy landscape of Comet 67P seem almost tactile in this Rosetta shot. (Credit: ESA/Rosetta/MPS/OSIRIS)

 

Enhanced color view of Comet 67P reveals hints of water (blue) beneath a ubiquitous layer of dust. Analysis of the diverse structure and composition indicates that the two lobes here began life as separate comets that merged in a low-speed impact. (Credit: ESA/Rosetta/MPS/OSIRIS)

Above: Enhanced color view of Comet 67P reveals hints of water (blue) beneath a ubiquitous layer of dust. Analysis of the diverse structure and composition on display here indicates that the two lobes here began life as separate comets that merged in an ancient, low-speed impact. (Credit: ESA/Rosetta/MPS/OSIRIS)

 

24 of the brightest outbursts observed while Comet 67P was at perihelion, its point closest to the sun. Such eruptions feed the comet's tail. (Credit: ESA/Rosetta/MPS/OSIRIS)

Above: 24 of the brightest outbursts observed while Comet 67P was at perihelion, its point closest to the sun. Rosetta revealed that comets are geologically complex, shedding material through many different processes depending on location. (Credit: ESA/Rosetta/MPS/OSIRIS)

 

Final images from Rosetta: a mosaic of views during descent to the comet, and the very last image ever transmitted by Rosetta at right. RIP, intrepid probe. (Credit: ESA/Rosetta/MPS/ OSIRIS)

Above: The final views sent back from Rosetta. At left, a mosaic of views during descent to the comet. At right, the very last image ever transmitted, from a distance of just 51 meters [167 feet]. RIP, intrepid probe. (Credit: ESA/Rosetta/MPS/ OSIRIS)

MORE ABOUT: ESA, Philae, Rosetta
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  • Yashgee Y’Assmen

    So it has all ended, I have been my lights modified to be used as telescopes for monitoring some of your missions, probes & satellites.

    Now I am happy, that I will not troubled anymore by those insects near my light. Please don’t ignore this message, and I have been scared since I started following your space news, even if you were doing some magic to teleport insects near our lights.

    It is true that some of your animate & inanimate objects & subjects did appear as little aliens near us. And some of the failures were seen by us in detail.

    I am just making this comments to be sent to the space news offices, and not to be discussed by other sane readers here. Thanks a lot for being kind & understanding…………

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    A most interesting tidbit is its average density being 0.533 g/cm^3. If that is general for comets – a largely fractal void icey dirtball – one “coming right at us” is overall insignificant other than its gigatonne thermal early re-entry pulse.

    • Paul

      “Hot-fudge Tuesday”

    • John C

      It has a mass of 9.9 x 10^12 kg

      Empire State Building 3.2 x 10^8

      So 30,000 Empire State Buildings roughly

      • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

        E = (mv²)/2
        E = ((10^13 kg)(~3.8×10^4 m/s)^2]/(2)(4.186×10^18 J/Gton) = 1700 gigatonnes

        OK, a big comet might leave a mark, re Jupiter and Comet Shoemaker-Levy. “8^>)

  • OWilson

    Don’t be too remorseful, Cory,

    There are “billions and billions” of rocks out there, and we will always find the money to send probes (and men) to boldly go where no man has ever been.

    This thing is just getting started! :)

  • Richard

    Regardless of what anyone says, Rosetta and Philae were one of the most ambitious missions ever devised. ESA is still new to the scene, and they’re learning. I for one think they did an amazing job!

    With that said, there are plenty of meteorites here on Earth to study, as well as in space. You can find meteorites (and even meteorite jewellery) here: http://thespacecollective.com/buy-meteorites and here: http://thespacecollective.com/meteorite-space-jewellery, so you’re never too far away from them. But when all is said and done, the only future we have it up there, and this was just a small stepping stone to making that happen.

    Come on space mining! 😀

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Notes from the far edge of space, astronomy, and physics.

About Corey S. Powell

Corey S. Powell is DISCOVER's Editor at Large and former Editor in Chief. Previously he has sat on the board of editors of Scientific American, taught science journalism at NYU, and been fired from NASA. Corey is the author of "20 Ways the World Could End," one of the first doomsday manuals, and "God in the Equation," an examination of the spiritual impulse in modern cosmology. He lives in Brooklyn, under nearly starless skies.

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