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When Nova/Post Saturn were A Thing, landing Apollo on the moon was simply the first step. It was entirely expected that Apollo would be followed not only by larger missions to the moon - bases and such - but also manned missions to Mars and Venus flybys. These required *giant* vehicles with *vast* amounts of liquid hydrogen. That's why most of the payloads you see on Nova/Post-Saturn vehicles tend to be tanks of liquid hydrogen, up to one million pounds. You can't really plan on giant spacecraft that need to be tanked up with many individual launches of small LH2 tanks; boiloff in Earth orbit would be horrendous. Once the ship is on the way to Mars, it would be straightforward to orient the ship to keep sunlight heating to a minimum, but while orbiting Earth, orienting towards the sun becomes virtually impossible... and Earth itself is constantly irradiating you with IR. So you need to minimize the time you spend with LH2 in Earth orbit, and that means a minimum number of maximum payload launches.

<blockquote data-quote="Orionblamblam" data-source="post: 519592" data-attributes="member: 90"><p>When Nova/Post Saturn were A Thing, landing Apollo on the moon was simply the first step. It was entirely expected that Apollo would be followed not only by larger missions to the moon - bases and such - but also manned missions to Mars and Venus flybys. These required *giant* vehicles with *vast* amounts of liquid hydrogen. That's why most of the payloads you see on Nova/Post-Saturn vehicles tend to be tanks of liquid hydrogen, up to one million pounds. You can't really plan on giant spacecraft that need to be tanked up with many individual launches of small LH2 tanks; boiloff in Earth orbit would be horrendous. Once the ship is on the way to Mars, it would be straightforward to orient the ship to keep sunlight heating to a minimum, but while orbiting Earth, orienting towards the sun becomes virtually impossible... and Earth itself is constantly irradiating you with IR. So you need to minimize the time you spend with LH2 in Earth orbit, and that means a minimum number of maximum payload launches.</p></blockquote><p></p>

[QUOTE="Orionblamblam, post: 519592, member: 90"] When Nova/Post Saturn were A Thing, landing Apollo on the moon was simply the first step. It was entirely expected that Apollo would be followed not only by larger missions to the moon - bases and such - but also manned missions to Mars and Venus flybys. These required *giant* vehicles with *vast* amounts of liquid hydrogen. That's why most of the payloads you see on Nova/Post-Saturn vehicles tend to be tanks of liquid hydrogen, up to one million pounds. You can't really plan on giant spacecraft that need to be tanked up with many individual launches of small LH2 tanks; boiloff in Earth orbit would be horrendous. Once the ship is on the way to Mars, it would be straightforward to orient the ship to keep sunlight heating to a minimum, but while orbiting Earth, orienting towards the sun becomes virtually impossible... and Earth itself is constantly irradiating you with IR. So you need to minimize the time you spend with LH2 in Earth orbit, and that means a minimum number of maximum payload launches. [/QUOTE]

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