If the goal is to build a Moon base, it should be built on the surface of the Moon. That is where the science is, that is where the shielding material is, and that is where the resources to make propellant and other useful things are to be found. The best place to build it would be at one of the poles, because there are spots at both of the Moon’s poles where sunlight is accessible all the time, as well as permanently shadowed craters where water ice has accumulated. Such ice could be electrolyzed to make hydrogen-oxygen rocket propellant, to fuel both Earth-return vehicles as well as ballistic hoppers that would provide the base’s crew with exploratory access to most of the rest of the Moon. Other places on the Moon might also work as the base’s location, because while there is no water in nonpolar latitudes, there is iron oxide. This can be reduced to produce iron and oxygen, with the latter composing 75 percent or more of the most advantageous propellant combinations.
around the 3 minute mark, he says that if you can refuel a vehicle in orbit it's a very valuable thing to do.
Quote from: QuantumG on 05/17/2017 12:14 amaround the 3 minute mark, he says that if you can refuel a vehicle in orbit it's a very valuable thing to do. Okay, but so refueling in orbit doesn't really contradict the idea of having your base and propellant manufacturing on the lunar surface, does it? You'd manufacture on the surface, and then send it up to an orbiting depot (lagrange point?) for others to dock with and refuel off of.
This isn't about Zubrin all of a sudden saying we should go to the Moon first. It's Zubrin doing his usual space station bashing. He hates space stations. Cislunar gateway is a space station.
Yeah. My point was that Zubrin used to be hard line Mars Direct and anything else was "Battlestar Galactica". Mars Semi-Direct used to be as far as Zubrin would go in his softening of this. Now he's like, oh, if you can refuel in orbit I guess that's useful. In that video he even talks about staging at EML1. No really, watch it.
Quote from: QuantumG on 05/17/2017 10:28 pmYeah. My point was that Zubrin used to be hard line Mars Direct and anything else was "Battlestar Galactica". Mars Semi-Direct used to be as far as Zubrin would go in his softening of this. Now he's like, oh, if you can refuel in orbit I guess that's useful. In that video he even talks about staging at EML1. No really, watch it.Perhaps, like Musk, Zubrin sees which way the winds are blowing these days - ie. towards the Moon - and is willing to bend in that direction in the interest of furthering Mars goals. As the cost of spaceflight continues dropping, then building out around the Moon still helps to bring Mars closer ("a rising tide lifts all boats"). The whole "space economy" thing changes the rules of the game - wish more experts had seen that sooner.
I agree that the wind has changed. Mars guys like Zubrin, Musk and Aldrin are suddenly focusing on the Moon.But how do you mean that a Lunar program could facilitate a Mars program? They are totally different worlds that require totally different equipment and operations. What similarities do you imagine that they have?
Perhaps, like Musk, Zubrin sees which way the winds are blowing these days - ie. towards the Moon - and is willing to bend in that direction in the interest of furthering Mars goals. As the cost of spaceflight continues dropping, then building out around the Moon still helps to bring Mars closer ("a rising tide lifts all boats"). The whole "space economy" thing changes the rules of the game - wish more experts had seen that sooner.
Quote from: Robotbeat on 05/17/2017 12:59 pmThis isn't about Zubrin all of a sudden saying we should go to the Moon first. It's Zubrin doing his usual space station bashing. He hates space stations. Cislunar gateway is a space station.It really isn't though. Being roughly 40 mT, even if it had a modest 5 mT of Xenon, it would have enough maneuverability to move from a high energy Earth orbit to a high energy Mars orbit. Nothing stationary about it.
Quote from: ncb1397 on 05/17/2017 11:10 pmQuote from: Robotbeat on 05/17/2017 12:59 pmThis isn't about Zubrin all of a sudden saying we should go to the Moon first. It's Zubrin doing his usual space station bashing. He hates space stations. Cislunar gateway is a space station.It really isn't though. Being roughly 40 mT, even if it had a modest 5 mT of Xenon, it would have enough maneuverability to move from a high energy Earth orbit to a high energy Mars orbit. Nothing stationary about it.That's a lot of Xenon, and we have no reason to think it'll use SEP. And even if it did that, it'd be slow.One of the original ideas was for the gateway to be also used as the Mars transfer vehicle. But that's no longer the case. It's just a space station now. With about as much delta-V as ISS. Sure, it'll be able to change orbits (as ISS does), but energy-wise it's definitely not a Transfer Vehicle. (In my opinion, we shouldn't bother with the gateway unless it's a transfer vehicle and highly mobile as you suggest... Even able to get to asteroids and the dwarf planet Ceres.)And anyway, Zubrin doesn't like transfer vehicles, either.
The DSG component is slated to be the 8-9 metric tonne (mT) Power and Propulsion Bus – of the same design as the one that would have been used on the now-defunct Asteroid Robotic Redirect Mission – capable of generating 40 kW of power.The Power and Propulsion Bus will also have 12kW thrusters for maneuverability and will also have chemical propulsion capability as well, noted Mr. Gerstenmaier.
Yeah, 12kW is not enough SEP to make the gateway into a transfer vehicle. Off by 40 times (and even with 500kW, that's a little underpowered to function as transfer vehicle propulsion for the mass of the gateway they're proposing). Thanks for proving my point.