[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/7407\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n 1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n 2) Linking back to our original story\u003Cbr \/\u003E\n 3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n \n\u003Cdiv\u003E\n \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003E\u2018The line is getting fuzzier\u2019: asteroids and comets may be more similar than we think\u003C\/h2\u003E\u003Cp\u003EWhile specimens may not be large, it turns out such dust particles are reforming scientists\u2019 conception of asteroids and comets and are enough to reconstruct entire scenes in the history of the solar system.\u003C\/p\u003E\u003Cp\u003EAsteroids and comets are primitive bodies left over from early in solar system formation, so the more we can know about their composition, the more we know about where they formed. Those asteroids that formed in the same neighbourhood as comets tend to be closer in composition to them.\u003C\/p\u003E\u003Cp\u003ETrying to break down the asteroid-comet continuum and categorise how similar asteroids could be to comets\u0026nbsp;is what Dr Pierre Beck is doing in the \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/771691\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003ESOLARYS\u003C\/a\u003E\u0026nbsp;project at France\u2019s University of Grenoble Alpes.\u003C\/p\u003E\u003Cp\u003EThere are about a million asteroids registered officially and there should be many more, he explains.\u003C\/p\u003E\u003Cp\u003E\u2018Traditionally, these objects have been thought of as the most primitive in the solar system. You can look at the ingredients and see what was there, how they were accreted and how they were formed a long time ago.\u2019\u003C\/p\u003E\u003Cp\u003ESimilar primordial material that formed Earth or Mars has experienced geological activity and been fundamentally changed by conditions like heat, pressure and erosion.\u003C\/p\u003E\u003Cp\u003E\u2018The most primitive objects therefore don\u2019t come to Earth in the form of rocks, but in the form of dust,\u2019 he said. \u2018While the expected (amount) of meteorites that come to Earth in a year may be 5-6 tonnes \u2013 for dust it is 40,000 tonnes.\u2019\u003C\/p\u003E\u003Cp\u003EUsing samples of interplanetary dust collected from high in our stratosphere and micrometeorites from pristine locations like Antarctica, Dr Beck is using a new method of infrared spectroscopy combined with atomic force microscopes to examine their spectra and properties on the micrometre-scale.\u003C\/p\u003E\u003Cp\u003ELike an archaeologist placing artefacts from a dig site, he can then compare those results to existing data from asteroids in space. \u2018When you\u2019re a geologist and you find a rock, you have an outcropping and try see the rock in its context,\u2019 Dr Beck said.\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003E\u2018In the past we thought asteroids are rocks, comets are icy. But now we see that there are comets that are almost inactive\u2026and there are asteroids that are active.\u2019\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EDr Jessica Agarwal, Technical University of Braunschweig, Germany\u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECompounds\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EUsing changes in infrared laser light on samples that are just 10-20 micrometres, his team can for the first time pick out silicate minerals and organic compounds without using harsh chemicals that would disturb the material. They also construct bigger models of the samples in the lab to refine what to look for to identify and categorise asteroids and comets with ground-based telescopes.\u003C\/p\u003E\u003Cp\u003EWhat they have found in the dust are complex organic polymers, rich in hydrocarbons and elements like nitrogen and oxygen or sometimes deuterium (heavy water).\u003C\/p\u003E\u003Cp\u003E\u2018There is a big debate on how these extra-terrestrial organics were formed. One hypothesis is that ice mixtures were irradiated, but in that case different types of ice mixtures should yield different types of organics,\u2019 said Dr Beck.\u003C\/p\u003E\u003Cp\u003EStudying the chemical composition of these samples should help him to learn more about asteroids\u2019 origins as well as the difference between D-type asteroids, dark and difficult to detect bodies, some with icy interiors, which originate around Jupiter and beyond, and icy comets.\u003C\/p\u003E\u003Cp\u003E\u2018If we understand that, it will tell us what the outer solar system is made of and more about the initial stuff that came into the solar system.\u2019\u003C\/p\u003E\u003Cp\u003EKnowing where certain organic dust types can be found could even help future space probes.\u003C\/p\u003E\u003Cp\u003E\u2018You could view some of these asteroids as a fuel source,\u2019 he said. If there are reduced organic compounds, he says, they could be used as a source of energy.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EComets\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe presence of such compounds in interplanetary dust is just one thing making scientists wonder if asteroids and comets aren\u2019t necessarily so different after all. Dr Jessica Agarwal at the \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/757390\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003ECASTRA\u003C\/a\u003E project thinks there may be overlap for other reasons, too.\u003C\/p\u003E\u003Cp\u003EUsing data from the European Space Agency\u2019s Rosetta probe that studied Comet 67P\/Churyumov\u2013Gerasimenko and from astronomical telescopes, Dr Agarwal and her team at the Technical University of Braunschweig in Germany looked at how comets and asteroids actively emit material into space.\u003C\/p\u003E\u003Cp\u003E\u2018We aim to better understand the processes that lead to changes in the surfaces and interiors of comets and asteroids,\u2019 she said. \u2018We also hope to better understand their primitive nature, or how they were 4.5 billion years ago.\u2019\u003C\/p\u003E\u003Cp\u003EUsing data from several instruments onboard Rosetta, Dr Agarwal\u2019s team has been able to model the properties of cometary dust in the environment of Comet 67P. They found that the dust particles could be loose aggregates of micron-sized silicate and sub-micron-sized carbonaceous components.\u003C\/p\u003E\u003Cp\u003E\u2018We are also observing huge boulder-size materials coming out from Comet 67P, coming from certain specific places on the surface...a fountain of boulders,\u2019 Dr Agarwal explained.\u003C\/p\u003E\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022@alignleft@\u0022\u003E\n\u003Cimg alt=\u0022COSIMA is the in-situ dust analyzing instrument on board space probe Rosetta to comet 67P\/Churyumov-Gerasimenko. Image credit - DLR German Aerospace Center, licensed under CC BY 2.0\u0022 height=\u0022533\u0022 src=\u0022\/sites\/default\/files\/hm\/IMCEUpload\/14237329074_c63fc88832_c.jpg\u0022 title=\u0022COSIMA is the in-situ dust analyzing instrument on board space probe Rosetta to comet 67P\/Churyumov-Gerasimenko. Image credit - DLR German Aerospace Center, licensed under CC BY 2.0\u0022 width=\u0022799\u0022\u003E\n\u003Cfigcaption class=\u0022tw-italic tw-mb-4\u0022\u003ECOSIMA is the in-situ dust analyzing instrument on board space probe Rosetta to comet 67P\/Churyumov-Gerasimenko. Image credit - DLR German Aerospace Center, licensed under CC BY 2.0\u003C\/figcaption\u003E\n\u003C\/figure\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EActive asteroid\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EComets are not the only bodies to\u0026nbsp;emit material. Take the case of asteroid 288P. A so-called active asteroid that emits dust, from a distance it looks like a comet with a dusty tail.\u003C\/p\u003E\u003Cp\u003E\u2018The weird thing about 288P was that its nucleus looked double\u2026and in the end, I thought, well maybe it\u2019s a binary?\u2019 Dr Agarwal said. \u2018We had to wait a couple of years to reobserve it from close up, and then in 2016 we got more Hubble time and really saw that it was two components.\u0027\u003C\/p\u003E\u003Cp\u003ETheir measurements determined that this first-of-its-kind asteroid to be observed is comprised of two similarly-sized pieces, orbiting each other 100 kilometres apart.\u003C\/p\u003E\u003Cp\u003E\u2018We found it by chance. We don\u2019t know if there are more systems like it that we don\u2019t see,\u2019 Dr Agarwal said.\u003C\/p\u003E\u003Cp\u003EThey theorise that the asteroids were irradiated by the sun and begin to rotate, splitting in two when they spun too fast to hold together. The distance between the pair may be due to a jet of gas vaporising from the surface that propelled one rock away like a rocket. They are still trying to figure out what causes the tail.\u003C\/p\u003E\u003Cp\u003EScientists have long thought that asteroids mainly evolved through collisions, but it\u2019s possible that for smaller asteroids, fast rotation plays just as much of a role.\u003C\/p\u003E\u003Cp\u003ETheir research has revealed a range of active asteroids, from those which have a one-off burst of activity (as if from an impact), to those that emit bursts of dust repeatedly.\u003C\/p\u003E\u003Cp\u003E\u2018There is some process happening more or less randomly that triggers the eruption of dust clouds,\u2019 Dr Agarwal said, referring to asteroids which emit the repeated dust bursts. \u2018We think maybe it is fast rotation that triggers landslides or something like that.\u2019\u003C\/p\u003E\u003Cp\u003EThe upshot of all of this is that the distinction between comets and asteroids may be more of a spectrum than a hard divide.\u003C\/p\u003E\u003Cp\u003E\u2018The line is getting fuzzier. In the past we thought asteroids are rocks, comets are icy. But now we see that there are comets that are almost inactive\u2026and there are asteroids that are active. There is more of a transition between those two populations than we thought in the past,\u2019 Dr Agarwal said.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU\u0027s European Research Council. 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