SpaceChampion

SpaceX's Big Falcon Topic 2

190 posts in this topic

17 hours ago, Fall Bass said:

It's probably going to have to piggy-back off of a publicly-funded space infrastructure for those purposes (like if NASA and/or some other countries' space programs puts up a moon base down the line, with all that entails for infrastructure and technology). Either that, or they get the launch costs into space low enough that someone could design, launch, and operate a space capsule for only tens of millions of dollars (at which point you could get space missions funded by business, or by consortia of universities and private donors like with telescopes). 

But what's the business case for any public (govt) investment in the $billions that would be required to develop a moon or orbital platform that could be purposed for space-based / moon-based launches?

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17 hours ago, Erik of Hazelfield said:

Why do they need a third drone ship to land two boosters, if the center core is expended? What would the third drone ship be doing?

One ship ("Just Read The Instructions") stays on the west coast for launches to polar orbit out of Vandenburg Airforce Base in California.

They're probably aiming to rarely expend the centre core.  Best case would be to fly it 9 times and recover it but expend it on the 10th flight (while the side boosters fly a hundred times but refurbish them every 10th flight).  They could schedule their flights so expendable launches is the case for every 10 flights.  Theoretically for those orbits that require a lot of energy to get to, they could send a 4th drone ship way out in the Atlantic for the landing the centre core on, while two other drone ships are a bit closer to shore for the boosters to land on.  But that would be rare they'd need to do that, so with careful scheduling they could avoid having a 4th ship.

Edited by SpaceChampion

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8 hours ago, The Anti-Targ said:

But what's the business case for any public (govt) investment in the $billions that would be required to develop a moon or orbital platform that could be purposed for space-based / moon-based launches?

None. The base would be for scientific and technological research purposes, and paid for by NASA (and possibly other space agencies). The commercial activities would just grow off of the infrastructure already paid for for those purposes. 

Edited by Fall Bass

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14 hours ago, Fall Bass said:

None. The base would be for scientific and technological research purposes, and paid for by NASA (and possibly other space agencies). The commercial activities would just grow off of the infrastructure already paid for for those purposes. 

There still has to be a business case. NASA (and partner agencies) aren't going to build any space infrastructure unless there is a clear case that doing so is necessary (i.e. can't possibly be done on earth or at the ISS) for a sufficient number of research proposals over a sufficiently long time-frame that the investment (cost to the taxpayer in significant proportion) is justified.

Low gravity manufacturing of certain products may eventually have a business case, but only after the public has funded the base infrastructure. It's only going to get done "because we can" if people like Gates, Soros, Musk and a few other mega billionnaires decide to earmark the lions share of the $billions it would take to build the infrastructure, and then donate it to the international community, or at least share it quite openly.

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So one reason they overshot the heliocentric apogee for the Roadster is that during the 6-hour coast phase before firing the 2nd stage engine for the 3rd time to send it on it's final trajectory SpaceX expected some amount of boil off of the oxygen (and freeze of the kerosene), reducing the amount of propellant available for that final burn, but it apparently didn't.

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4 minutes ago, SpaceChampion said:

So one reason they overshot the heliocentric apogee for the Roadster is that during the 6-hour coast phase before firing the 2nd stage engine for the 3rd time to send it on it's final trajectory SpaceX expected some amount of boil off of the oxygen (and freeze of the kerosene), reducing the amount of propellant available for that final burn, but it apparently didn't.

Did they do something that can be repeated to protect the propellant?

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1 hour ago, Ser Scot A Ellison said:

Did they do something that can be repeated to protect the propellant?

It was obviously the playing of David Bowie.   

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1 hour ago, Ser Scot A Ellison said:

Did they do something that can be repeated to protect the propellant?

Without spending a lot on exotic materials, probably not.  Boil off is a problem for all rockets.  However SpaceX cools their propellants much lower than the condensation temperature, in order to squeeze more of it into the same volume, allowing for more lift capacity / larger payloads.  That might have been the beneficial factor.

For BFR they'll actually be putting the oxygen tank within the methane tank (a sphere within a sphere), so it'll be protected for the journey to Mars.  Falcon upper stage dimensions don't really allow for that strategy.

Edited by SpaceChampion

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