Hosted by Steve Nerlich. We are still out there. Dear Cheap Astronomy – Why do some space missions last so long? So, we're all familiar with the stories of the Mars rovers, Spirit and Opportunity, landing with mission lifespans of 90 days, that then went on to rove the surface of Mars for 15 years. And the Voyager probes, launched in 1977, were supposed to have five-year missions, which are now going on 47 years and counting. So, what's going on? Is NASA just crap at predicting mission lifetimes? Dear Cheap Astronomy – How much faster is nuclear thermal propulsion? The idea behind nuclear thermal propulsion or NTP is that you have a nuclear fission core, which is probably uranium-based. This can generate a lot of heat over long periods and you then feed in a propellant that will expand on heating, for example liquid hydrogen. The expanded gas then shoots out a rocket nozzle and pushes your spacecraft forward on the basis of Newton's actions produce opposite reactions. We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs. Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too! Every bit helps! Thank you! ------------------------------------ Do go visit http://www.redbubble.com/people/CosmoQuestX/shop for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations. Thank you! (Haven't donated? It's not too late! Just click!) ------------------------------------ The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. http://www.psi.edu Visit us on the web at 365DaysOfAstronomy.org or email us at [email protected].

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“What did the council decide on item 42?” — answered with the speaker and the moment.

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