[{"command":"settings","settings":{"ajaxPageState":{"theme":"hm_theme","theme_token":"CRnGW1aqorR4dhhpVyltWhHWybvem7B2nZTANtTrbus","libraries":"eJwDAAAAAAE"},"ajaxTrustedUrl":{"form_action_p_pvdeGsVG5zNF_XLGPTvYSKCf43t8qZYSwcfZl2uzM":true},"pluralDelimiter":"\u0003","user":{"uid":0,"permissionsHash":"2af85631393b514cbde3779a1f71d92618d53b94b54ea1960d28b2e2d121ff12"}},"merge":true},{"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\/7220\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\u003EMaking satellites safer: the search for new propellants \u003C\/h2\u003E\u003Cp\u003EAs the number of satellites soars, so will the amount of fuel we use to launch them. And getting into orbit is only half of the equation. Once a satellite is in position above Earth it needs a method of propulsion to make sure it can move if needed, avoiding space debris, compensating for drag over time, and even de-orbiting itself at the end of its mission.\u003C\/p\u003E\u003Cp\u003EThe current standard propellant for satellites is hydrazine-based fuel, which is highly toxic. Exposure to high levels of hydrazine can cause a host of health problems, including \u003Ca href=\u0022https:\/\/echa.europa.eu\/fr\/registration-dossier\/-\/registered-dossier\/14983\/7\/11\/4\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Edamage to the liver, kidneys and central nervous system\u003C\/a\u003E. If hydrazine spills while a satellite is still on the ground, its violent and explosive nature can become \u003Ca href=\u0022https:\/\/www.google.com\/url?sa=t\u0026amp;rct=j\u0026amp;q=\u0026amp;esrc=s\u0026amp;source=web\u0026amp;cd=14\u0026amp;ved=2ahUKEwiVw-nYnZ_oAhXFQkEAHeirAPgQFjANegQIBxAB\u0026amp;url=https%3A%2F%2Fassets.publishing.service.gov.uk%2Fgovernment%2Fuploads%2Fsystem%2Fuploads%2Fattachment_data%2Ffile%2F566781%2Fhydrazine_incident_management.pdf\u0026amp;usg=AOvVaw3vdfR1FVfBECewcXlMYes9\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Ea public safety problem\u003C\/a\u003E.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EPreparing a hydrazine-fuelled satellite for space is a hazardous task requiring special precautions for anyone involved, including space suit-like clothing that makes sure, if something were to go wrong, the people handling the fuel wouldn\u2019t breathe in the gas itself. \u2018They look a bit like a Michelin Man,\u2019 said Dr Norbert Frischauf, a partner at space consultancy \u003Ca href=\u0022https:\/\/www.spacetec.partners\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003ESpaceTec Partners\u003C\/a\u003E in Belgium.\u003C\/p\u003E\u003Cp\u003ESo it\u2019s no surprise that engineers are looking for new, cleaner ways to launch and propel satellites that use non-toxic fuels instead. \u2018Hydrazine is pretty nasty to work with from a health and safety perspective, so we\u0027re seeing a lot more interest in these sorts of propellants,\u2019 said Erikas Knei\u017eys, Chief Design Officer at \u003Ca href=\u0022https:\/\/nanoavionics.com\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003ENanoAvionics\u003C\/a\u003E, a spacecraft equipment manufacturer based in Europe and the US.\u003C\/p\u003E\u003Cp\u003EIn 2011, the European Chemicals Agency added hydrazine to \u003Ca href=\u0022https:\/\/www.esa.int\/Safety_Security\/Clean_Space\/Green_propellants_need_to_match_performance_benchmarks_Ferran_Valencia_Bel_interview\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Eits list of \u2018substances of very high concern\u2019\u003C\/a\u003E, meaning its usage could soon be restricted.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECubeSats\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003ENanoAvionics specialises in technology for nanosatellites, including CubeSats, which are miniature satellites made of 10cm cube-shaped units, typically built using off-the-shelf components and weighing around 1kg each. As smaller satellites like these become more commonplace \u2013 NanoAvionics say there has been a 300% increase in small satellite launches between 2016 and 2020 \u2013 demand for clean propellants suited to them is likely to rise.\u003C\/p\u003E\u003Cp\u003E\u0027There were basically no products when looking at the CubeSat market and when looking especially at (chemical) propulsion using (clean fuel),\u0027 said Knei\u017eys. \u0027So we\u2019ve seen this niche and started working on it.\u0027\u003C\/p\u003E\u003Cp\u003EThrough a project titled \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/768434\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EEPSS\u003C\/a\u003E, NanoAvionics has developed a \u003Ca href=\u0022https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1033\u0026amp;context=smallsat\u0022\u003Eless harmful\u003C\/a\u003E\u003Ca href=\u0022https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1033\u0026amp;context=smallsat\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003E propellant based on ammonium dinitramide\u003C\/a\u003E, or ADN, a compound made up of nitrogen, oxygen, and hydrogen, especially for small satellites. The system has been integrated into a pilot satellite and has undergone a demonstration in orbit.\u003C\/p\u003E\u003Cp\u003EThe new system is what\u2019s known as a monopropellant, which works by passing the fuel over a catalyst that causes it to decompose, producing heat and gases that propel the spacecraft. Other systems use a bipropellant, in which two liquids are kept separate and typically ignite on mixing.\u003C\/p\u003E\u003Cp\u003EUsing a bipropellant ups the risk during manufacturing, says Knei\u017eys, as the two substances could accidentally come into contact and ignite before they are supposed to. \u2018In our monopropellant you have to go miles to make sure it burns, so it\u2019s relatively benign and stable compared to (most) bipropellant systems,\u2019 said Knei\u017eys.\u003C\/p\u003E\u003Cp\u003EBut it\u2019s not just smaller satellites that could benefit from non-toxic propellant.\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\u2018Hydrazine is pretty nasty to work with from a health and safety perspective.\u2019\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EErikas Knei\u017eys, Chief Design Officer, NanoAvionics\u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/634534\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EHyproGEO\u003C\/a\u003E, a project coordinated by aerospace company Airbus, has also developed a non-toxic propulsion system, this time focussing on satellites in geostationary orbit around Earth. Orbiting at 36,000 km, these satellites appear to stay at a fixed point above Earth\u2019s surface and are typically used for things like communications and broadcasting.\u003C\/p\u003E\u003Cp\u003E\u0027To get up there, it takes quite a lot of energy,\u2019 says Dr Frischauf of SpaceTec Partners, a member of the HyproGEO consortium.\u003C\/p\u003E\u003Cp\u003ERight now, that energy is provided mostly by hydrazine-based propellants. But HyproGEO has developed a hybrid propulsion system that uses hydrogen peroxide instead. The fuel, which is 98% hydrogen peroxide \u2013 compared to the 6% or so solution you\u2019d use for bleaching your hair \u2013\u0026nbsp; is highly acidic, but still \u003Ca href=\u0022https:\/\/digitalcommons.usu.edu\/smallsat\/1998\/all1998\/44\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Eless risky to work with than hydrazine\u003C\/a\u003E. It also breaks down to oxygen and water, avoiding the release of fumes that are harmful to humans.\u003C\/p\u003E\u003Cp\u003EGeostationary satellites are designed to last a decade or longer, so the propellant, which is also used to manoeuvre them once they\u2019re in orbit, must be similarly robust. \u2018You have to make sure that it will still be running after 15 years, so it should be a simple system, because if it\u0027s complicated there\u0027s always a risk that something breaks,\u2019 said Dr Frischauf.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EHybrid\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe solution HyproGEO came up with was to use hybrid propulsion, which involves passing the hydrogen peroxide over a catalyser to produce very hot oxygen as well as water vapour. That oxygen can provide the propulsion by itself, or it can be used to ignite another substance for an extra boost. \u2018When you control the flow of the oxygen, you can control the thrust of the engine,\u2019 said Dr Frischauf.\u003C\/p\u003E\u003Cp\u003EThe team successfully developed a test engine to store the new propellant, showed that it decomposed as expected, and then designed a rocket engine using the fuel. Since that work was completed in 2018, Norwegian defence company Nammo have \u003Ca href=\u0022https:\/\/www.esa.int\/Enabling_Support\/Space_Transportation\/Norway_takes_the_lead_in_hybrid_propulsion\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Eused the HyproGEO hybrid engine to launch a rocket 107km from Earth\u2019s surface in just three minutes\u003Cu\u003E,\u003C\/u\u003E a timescale typical of suborbital rockets using traditional propulsion systems\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003EUsing these new propellants doesn\u2019t just benefit the people working with the current toxic fuels, it makes the whole infrastructure more efficient and cheaper too. Knei\u017eys says the EPSS system designed by NanoAvionics costs roughly a third of similar products that use traditional propellants.\u003C\/p\u003E\u003Cp\u003EWith all those benefits, what\u2019s holding these new propellants back? For one, hybrid propulsion systems traditionally haven\u2019t been capable of the long-duration firing needed to put satellites into geostationary orbit, a problem that HyproGEO managed to overcome.\u003C\/p\u003E\u003Cp\u003EAnd the industry already has procedures set up to deal with traditional fuels like hydrazine \u2013 transitioning to something new requires disrupting those systems, said Dr Frischauf. \u2018It always takes a bit of an impetus, a bit of a push to make sure the new technology can prevail.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU. 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