{"679654":{"#nid":"679654","#data":{"type":"news","title":"Why Does a Rocket Have to go 25,000 mph to Escape Earth?","body":[{"value":"\u003Cdiv class=\u0022theconversation-article-body\u0022\u003E\u003Cp\u003E\u003Cem\u003E\u003Cstrong\u003EWhy does a rocket have to go 25,000 mph (about 40,000 kilometers per hour) to escape Earth? \u2013 Bo H., age 10, Durham, New Hampshire\u003C\/strong\u003E\u003C\/em\u003E\u003C\/p\u003E\u003Chr\u003E\u003Cp\u003EThere\u2019s a reason why a rocket has to go so fast to escape Earth. It\u2019s about gravity \u2013 something all of us \u003Ca href=\u0022https:\/\/www1.grc.nasa.gov\/beginners-guide-to-aeronautics\/weight-equation\/\u0022\u003Eexperience every moment of every day\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003EGravity is the force that pulls you toward the ground. And that\u2019s a good thing. Gravity keeps you on Earth; otherwise, you would float away into space.\u003C\/p\u003E\u003Cp\u003EBut gravity also makes it difficult to leave Earth if you\u2019re a rocket heading for space. Escaping our planet\u2019s gravitational pull is hard \u2013 not only is gravity strong, but it also \u003Ca href=\u0022https:\/\/www.uu.edu\/dept\/physics\/scienceguys\/2004oct.cfm\u0022\u003Eextends far away from Earth\u003C\/a\u003E.\u003C\/p\u003E\u003Ch2\u003ELike a Balloon\u003C\/h2\u003E\u003Cp\u003EAs \u003Ca href=\u0022https:\/\/ae.gatech.edu\/directory\/person\/benjamin-lee-emerson-ii\u0022\u003Ea rocket scientist\u003C\/a\u003E, one of the things I do is teach students how rockets overcome gravity. Here\u2019s how it works:\u003C\/p\u003E\u003Cp\u003EEssentially, the rocket has to make thrust \u2013 that is, create force \u2013 by \u003Ca href=\u0022https:\/\/www.grc.nasa.gov\/www\/k-12\/airplane\/rocket.html\u0022\u003Eburning propellant to make hot gases\u003C\/a\u003E. Then it shoots those hot gases out of a nozzle. It\u2019s sort of like blowing up a balloon, letting go of it and watching it fly away as the air rushes out.\u003C\/p\u003E\u003Cp\u003EMore specifically, the rocket propellant \u003Ca href=\u0022https:\/\/blogs.nasa.gov\/Rocketology\/tag\/propellant\/#:%7E\u0022\u003Econsists of both fuel and oxidizer\u003C\/a\u003E. The fuel is typically something flammable, usually hydrogen, methane or kerosene. The oxidizer is usually liquid oxygen, which reacts with the fuel and allows it to burn.\u003C\/p\u003E\u003Cp\u003EWhen going into space and escaping from Earth, rockets need lots of force, so they consume propellant very quickly. That\u2019s a problem, because the rocket can\u2019t carry enough propellant to keep thrusting forever; the amount of propellant needed would make the rocket too heavy to get off the ground.\u003C\/p\u003E\u003Cp\u003ESo what happens when the propellant runs out? The thrust stops, and gravity slows the rocket down until it gradually begins to fall back to Earth.\u003C\/p\u003E\u003Cp\u003EFortunately, scientists can launch the rocket with some sideways momentum so that it misses the Earth when it returns. They can even do this so it continuously falls around the Earth forever. In other words, \u003Ca href=\u0022https:\/\/spaceplace.nasa.gov\/orbits\/en\/\u0022\u003Eit goes into orbit\u003C\/a\u003E, and begins to circle the planet.\u003C\/p\u003E\u003Cp\u003EMany launches intentionally don\u2019t completely leave Earth behind. Thousands of satellites are orbiting our planet right now, and they help phones and TVs work, display weather patterns for meteorologists, and even let you use a credit card to pay for things at the store or gas at the pump. You can sometimes see these satellites in the night sky, \u003Ca href=\u0022https:\/\/lompocrecord.com\/ask-the-weather-guys-can-we-see-satellites-at-night\/article_b67eeaa9-f7c5-56df-9646-5a0187c9eb53.html#:%7E\u0022\u003Eincluding the International Space Station\u003C\/a\u003E.\u003C\/p\u003E\u003Cfigure\u003E\u003Cp\u003E\u003Ciframe width=\u0022440\u0022 height=\u0022260\u0022 src=\u0022https:\/\/www.youtube.com\/embed\/Lti6a_YYQl0?wmode=transparent\u0026amp;start=0\u0022 frameborder=\u00220\u0022 allowfullscreen=\u0022\u0022\u003E\u003C\/iframe\u003E\u003C\/p\u003E\u003Cfigcaption\u003E\u003Cspan class=\u0022caption\u0022\u003EAn Atlas V rocket took NASA\u2019s Perseverance rover to Mars.\u003C\/span\u003E\u003C\/figcaption\u003E\u003C\/figure\u003E\u003Ch2\u003EEscaping Earth\u003C\/h2\u003E\u003Cp\u003EBut suppose the goal is to let the rocket escape from Earth\u2019s gravity forever so it can fly off into the depths of space. That\u2019s when scientists do \u003Ca href=\u0022https:\/\/www.discovermagazine.com\/the-sciences\/the-how-and-why-of-rockets-staging\u0022\u003Ea neat trick called staging\u003C\/a\u003E. They launch with a big rocket, and then, once in space, discard it to use a smaller rocket. That way, the journey can continue without the weight of the bigger rocket, and less propellant is needed.\u003C\/p\u003E\u003Cp\u003EBut even staging is not enough; eventually the rocket will run out of propellant. But if the rocket goes fast enough, it can run out of propellant and still continue to coast away from Earth forever, without gravity pulling it back. It\u2019s like riding a bike: build up enough speed and eventually you can coast up a hill without pedaling.\u003C\/p\u003E\u003Cp\u003EAnd just like there\u2019s a minimum speed required to coast the bike, there\u2019s a minimum speed a rocket needs to coast away into space: \u003Ca href=\u0022https:\/\/letstalkscience.ca\/educational-resources\/stem-explained\/escape-velocity\u0022\u003E25,020 mph\u003C\/a\u003E (about 40,000 kilometers per hour).\u003C\/p\u003E\u003Cp\u003EScientists call that speed the \u003Ca href=\u0022https:\/\/www.britannica.com\/science\/escape-velocity\u0022\u003Eescape velocity\u003C\/a\u003E. A rocket needs to go that fast so that the momentum propelling it away from Earth is stronger than the force of gravity pulling it back. Any slower, and you\u2019ll go into an orbit of Earth.\u003C\/p\u003E\u003Ch2\u003EEscaping Jupiter\u003C\/h2\u003E\u003Cp\u003EBigger, or more massive, objects have stronger gravitational pull. A rocket launching from a planet bigger than Earth would need to achieve a higher escape speed.\u003C\/p\u003E\u003Cp\u003EFor example, Jupiter is the most massive planet in our solar system. It\u2019s so big, \u003Ca href=\u0022https:\/\/theconversation.com\/how-can-jupiter-have-no-surface-a-dive-into-a-planet-so-big-it-could-swallow-1-000-earths-231901\u0022\u003Eit could swallow 1,000 Earths\u003C\/a\u003E. So it requires a very high escape speed: 133,100 mph (about 214,000 kilometers per hour), more than five times the escape speed of Earth.\u003C\/p\u003E\u003Cp\u003EBut the extreme example is a \u003Ca href=\u0022https:\/\/www.nasa.gov\/universe\/what-are-black-holes\/#:%7E\u0022\u003Eblack hole\u003C\/a\u003E, an object so massive that its escape speed is extraordinarily high. So high, in fact, that even light \u2013 which has a speed of about 670 million mph (over a billion kilometers per hour) \u2013 is not fast enough to escape. That\u2019s why it\u2019s called a black hole.\u003C!-- Below is The Conversation\u0027s page counter tag. Please DO NOT REMOVE. --\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cimg style=\u0022border-color:!important;border-style:none;box-shadow:none !important;margin:0 !important;max-height:1px !important;max-width:1px !important;min-height:1px !important;min-width:1px !important;opacity:0 !important;outline:none !important;padding:0 !important;\u0022 src=\u0022https:\/\/counter.theconversation.com\/content\/243338\/count.gif?distributor=republish-lightbox-basic\u0022 alt=\u0022The Conversation\u0022 width=\u00221\u0022 height=\u00221\u0022 referrerpolicy=\u0022no-referrer-when-downgrade\u0022\u003E\u003C!-- End of code. If you don\u0027t see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: https:\/\/theconversation.com\/republishing-guidelines --\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis article is republished from \u003C\/em\u003E\u003Ca href=\u0022https:\/\/theconversation.com\u0022\u003E\u003Cem\u003EThe Conversation\u003C\/em\u003E\u003C\/a\u003E\u003Cem\u003E under a Creative Commons license. Read the \u003C\/em\u003E\u003Ca href=\u0022https:\/\/theconversation.com\/why-does-a-rocket-have-to-go-25-000-mph-to-escape-earth-243338\u0022\u003E\u003Cem\u003Eoriginal article\u003C\/em\u003E\u003C\/a\u003E\u003Cem\u003E.\u003C\/em\u003E\u003C\/p\u003E\u003C\/div\u003E","summary":"","format":"full_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EThere\u2019s a reason why a rocket has to go so fast to escape Earth. It\u2019s about gravity \u2013 something all of us experience every moment of every day.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"There\u2019s a reason why a rocket has to go so fast to escape Earth. It\u2019s about gravity \u2013 something all of us experience every moment of every day."}],"uid":"27469","created_gmt":"2025-01-14 14:36:30","changed_gmt":"2026-03-19 13:14:35","author":"Kristen Bailey","boilerplate_text":"","field_publication":"","field_article_url":"","location":"Atlanta, GA","dateline":{"date":"2025-01-14T00:00:00-05:00","iso_date":"2025-01-14T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"676051":{"id":"676051","type":"image","title":"falconrocket.jpg","body":"\u003Cp\u003EA SpaceX Falcon 9 rocket with its Crew Dragon capsule launches from Cape Canaveral, Fla., in January 2024. Chandan Khanna\/AFP via Getty Images\u003C\/p\u003E","created":"1737069110","gmt_created":"2025-01-16 23:11:50","changed":"1737069219","gmt_changed":"2025-01-16 23:13:39","alt":"A SpaceX Falcon 9 rocket ","file":{"fid":"259756","name":"falconrocket.jpg","image_path":"\/sites\/default\/files\/2025\/01\/16\/falconrocket.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2025\/01\/16\/falconrocket.jpg","mime":"image\/jpeg","size":128028,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2025\/01\/16\/falconrocket.jpg?itok=6JI7e8cL"}}},"media_ids":["676051"],"related_links":[{"url":"https:\/\/theconversation.com\/why-does-a-rocket-have-to-go-25-000-mph-to-escape-earth-243338","title":"Read This Story on The Conversation"}],"groups":[{"id":"660364","name":"Aerospace Engineering"},{"id":"1237","name":"College of Engineering"},{"id":"658168","name":"Experts"},{"id":"1316","name":"Green Buzz"},{"id":"1214","name":"News Room"},{"id":"1188","name":"Research Horizons"}],"categories":[],"keywords":[{"id":"479","name":"Green Buzz"},{"id":"187915","name":"go-researchnews"}],"core_research_areas":[],"news_room_topics":[{"id":"71911","name":"Earth and Environment"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Ch5\u003EAuthor:\u003C\/h5\u003E\u003Cp\u003E\u003Ca href=\u0022https:\/\/theconversation.com\/profiles\/benjamin-l-emerson-2255671\u0022\u003EBenjamin L. Emerson\u003C\/a\u003E, Principal Research Engineer, Daniel Guggenheim School of Aerospace Engineering, \u003Ca href=\u0022https:\/\/theconversation.com\/institutions\/georgia-institute-of-technology-1310\u0022\u003E\u003Cem\u003EGeorgia Institute of Technology\u003C\/em\u003E\u003C\/a\u003E\u003C\/p\u003E\u003Ch5\u003EMedia Contact:\u003C\/h5\u003E\u003Cp\u003EShelley Wunder-Smith\u003Cbr\u003E\u003Ca href=\u0022mailto:shelley.wunder-smith@research.gatech.edu\u0022\u003Eshelley.wunder-smith@research.gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}