{"id":11806,"date":"2024-05-14T10:00:00","date_gmt":"2024-05-14T10:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=11806"},"modified":"2024-05-17T05:16:22","modified_gmt":"2024-05-17T05:16:22","slug":"venus-is-losing-water-faster-than-previously-thought-heres-what-that-could-mean-for-the-early-planets-habitability","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/venus-is-losing-water-faster-than-previously-thought-heres-what-that-could-mean-for-the-early-planets-habitability\/","title":{"rendered":"Venus is losing water faster than previously thought \u2013 here\u2019s what that could mean for the early planet\u2019s habitability"},"content":{"rendered":"\n
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\n \n
\n An artist\u2019s illustration of hydrogen disappearing from Venus.\n Aurore Simonnet\/ Laboratory for Atmospheric and Space Physics\/ University of Colorado Boulder<\/span><\/span>\n <\/figcaption>\n <\/figure>\n\n Eryn Cangi<\/a>, University of Colorado Boulder<\/a><\/em><\/span>\n\n

Today, the atmosphere of our neighbor planet Venus is as hot as a pizza oven<\/a> and drier than the driest desert on Earth<\/a> \u2013 but it wasn\u2019t always that way. <\/p>\n\n

Billions of years ago, Venus had as much water as Earth does today<\/a>. If that water was ever liquid, Venus may have once been habitable<\/a>.<\/p>\n\n

Over time, that water has nearly all been lost. Figuring out how, when and why Venus lost its water helps planetary scientists like me<\/a> understand what makes a planet habitable \u2014 or what can make a habitable planet transform into an uninhabitable world. <\/p>\n\n

\n \"Venus,<\/a>\n
\n Venus, Earth\u2019s solar system neighbor.<\/span>\n JAXA\/ISAS\/DARTS\/Kevin M. Gill<\/a>, CC BY<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

Scientists have theories explaining why most of that water disappeared, but more water has disappeared than they predicted.<\/p>\n\n

In a May 2024 study<\/a>, my colleagues and I revealed a new water removal process that has gone unnoticed for decades, but could explain this water loss mystery.<\/p>\n\n

Energy balance and early loss of water<\/h2>\n\n

The solar system has a habitable zone<\/a> \u2013 a narrow ring around the Sun in which planets can have liquid water on their surface. Earth is in the middle, Mars is outside on the too-cold side, and Venus is outside on the too-hot side. Where a planet sits on this habitability spectrum depends on how much energy the planet gets from the Sun, as well as how much energy the planet radiates away.<\/p>\n\n

The theory of how most of Venus\u2019 water loss occurred is tied to this energy balance. On early Venus, sunlight broke up water in its atmosphere into hydrogen and oxygen. Atmospheric hydrogen heats up a planet \u2014 like having too many blankets on the bed in summer. <\/p>\n\n

When the planet gets too hot, it throws off the blanket: the hydrogen escapes in a flow out to space, a process called hydrodynamic escape<\/a>. This process removed one of the key ingredients for water from Venus. It\u2019s not known exactly<\/a> when<\/a> this process occurred, but it was likely within the first billion years or so.<\/p>\n\n

Hydrodynamic escape stopped after most hydrogen was removed, but a little bit of hydrogen was left behind. It\u2019s like dumping out a water bottle \u2013 there will still be a few drops left at the bottom. These leftover drops can\u2019t escape in the same way. There must be some other process still at work on Venus that continues to remove hydrogen.<\/p>\n\n

Little reactions can make a big difference<\/h2>\n\n

Our new study reveals<\/a> that an overlooked chemical reaction in Venus\u2019 atmosphere can produce enough escaping hydrogen to close the gap between the expected and observed water loss. <\/p>\n\n

Here\u2019s how it works. In the atmosphere, gaseous HCO\u207a molecules, which are made up of one atom each of hydrogen, carbon and oxygen and have a positive charge, combine with negatively charged electrons, since opposites attract. <\/p>\n\n

But when the HCO\u207a and the electrons react, the HCO\u207a breaks up into a neutral carbon monoxide molecule, CO, and a hydrogen atom, H. This process energizes the hydrogen atom, which can then exceed the planet\u2019s escape velocity and escape to space. The whole reaction is called HCO\u207a dissociative recombination, but we like to call it DR for short. <\/p>\n\n

Water is the original source of hydrogen on Venus, so DR effectively dries out the planet. DR has likely happened throughout the history of Venus, and our work shows it probably still continues into the present day. It doubles the amount of hydrogen escape previously calculated<\/a> by planetary scientists, upending our understanding of present-day hydrogen escape on Venus.<\/p>\n\n

Understanding Venus with data, models and Mars<\/h2>\n\n

To study DR on Venus we used both computer modeling and data analysis.<\/p>\n\n

The modeling actually began as a Mars project. My Ph.D. research involved exploring what sort of conditions made planets habitable for life. Mars also used to have water<\/a>, though less than Venus, and also lost most of it to space. <\/p>\n\n

To understand martian hydrogen escape, I developed a computational model of the Mars atmosphere<\/a> that simulates Mars\u2019 atmospheric chemistry. Despite being very different planets, Mars and Venus actually have similar upper atmospheres, so my colleagues and I were able to extend the model to Venus. <\/p>\n\n

We found that HCO\u207a dissociative recombination produces lots of escaping hydrogen in both planets\u2019 atmospheres, which agreed with measurements taken by the Mars Atmosphere and Volatile EvolutioN, or MAVEN, mission<\/a>, a satellite orbiting Mars.<\/p>\n\n

\n \"A<\/a>\n
\n An illustration of the MAVEN mission orbiting Mars.<\/span>\n NASA\u2019s Goddard Space Flight Center<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

Having data collected in Venus\u2019 atmosphere to back up the model would be valuable, but previous missions to Venus haven\u2019t measured HCO\u207a \u2013 not because it\u2019s not there, but because they weren\u2019t designed to detect it. They did, however, measure the reactants that produce HCO\u207a in Venus\u2019 atmosphere. <\/p>\n\n

By analyzing measurements<\/a> made by Pioneer Venus<\/a>, a combination orbiter and probe mission that studied Venus from 1978-1992, and using our knowledge of chemistry, we demonstrated that HCO\u207a should be present in the atmosphere in similar amounts to our model.<\/p>\n\n

Follow the water<\/h2>\n\n

Our work<\/a> has filled in a piece of the puzzle of how water is lost from planets, which affects how habitable a planet is for life. We\u2019ve learned that water loss happens not just in one fell swoop, but over time through a combination of methods.<\/p>\n\n

Faster hydrogen loss today via DR means that less time is required overall to remove the remaining water from Venus. This means that if oceans were ever present on early Venus, they could have been present for longer than scientists thought before water loss through hydrodynamic escape and DR started. This would provide more time for possible life to arise. Our results don\u2019t mean oceans or life were definitely present, though \u2013 answering that question will require lots more science over many years.<\/p>\n\n

There is also a need for new Venus missions and observations. Future<\/a> Venus<\/a> missions<\/a> will provide some atmospheric measurements, but they won\u2019t focus on the upper atmosphere where most HCO\u207a dissociative recombination takes place. A future Venus upper atmosphere mission, similar to the MAVEN mission at Mars, could vastly expand everyone\u2019s knowledge of how terrestrial planets\u2019 atmospheres form and evolve over time. <\/p>\n\n

With the technological advancements of recent decades and a flourishing new interest in Venus, now is an excellent time to turn our eyes toward Earth\u2019s sister planet.\"The<\/p>\n\n

Eryn Cangi<\/a>, Research Scientist in Astrophysical & Planetary Sciences, University of Colorado Boulder<\/a><\/em><\/span><\/p>\n\n

This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n<\/div>\n\n","protected":false},"excerpt":{"rendered":"An artist\u2019s illustration of hydrogen disappearing from Venus. Aurore Simonnet\/ Laboratory for Atmospheric and Space Physics\/ University of…\n","protected":false},"author":816,"featured_media":11884,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","fifu_image_url":"https:\/\/drive.google.com\/uc?id=1V0C72fJxWeXdVNhpif9-j83o3WAGV4-t","fifu_image_alt":"","footnotes":""},"categories":[14],"tags":[474,492],"class_list":{"0":"post-11806","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-the-conversation","9":"tag-venus","10":"cs-entry","11":"cs-video-wrap"},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/11806","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/users\/816"}],"replies":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/comments?post=11806"}],"version-history":[{"count":1,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/11806\/revisions"}],"predecessor-version":[{"id":11807,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/11806\/revisions\/11807"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media\/11884"}],"wp:attachment":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media?parent=11806"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/categories?post=11806"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/tags?post=11806"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}