Author Topic: Zubrin writes piece advocating mining the moon for propellant  (Read 2231 times)

Online Nilof

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http://www.nationalreview.com/article/447644/nasa-lunar-orbit-space-station-terrible-idea

Well, really he's just attacking any plan for a cislunar outpost, and does that by comparing it with a lunar surface base, but this still surprised me.

Relevant segment:
Quote
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.
« Last Edit: 05/16/2017 04:12 PM by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline space_dreamer

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I agree with Zubrin, Nasa needs to dust off plans for Altair lunar lander, build it and go to the F**king Moon!

Offline QuantumG

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In this video



around the 3 minute mark, he says that if you can refuel a vehicle in orbit it's a very valuable thing to do.

!!!

Let no-one say that age isn't mellowing Bob Zubrin.

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Offline sanman

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around 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.

Online AncientU

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around 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.

Refueling in orbit (at the Lagrange points plus LLO) is a principal reason to have a Lunar base, as well as an essential link in the infrastructure to make it viable.  (Both Lunar landers and vehicles heading outbound would refuel there.)  A sustained presence on the Moon is impossible without it.

Also, we need to stop talking about depot -- singular.  Depots are part of a distributed architecture that allows space travel to be broken into legs... just like road trips require a series of service stations/charging stations. (Try that with just a gas station -- singular.)  LEO, EML-1/2, LLO is the chain that makes for a sustained presence on the Lunar surface.  And none of this requires a heavy lift vehicle, BTW.
« Last Edit: 05/17/2017 11:31 AM by AncientU »
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Offline TakeOff

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Robert Zubrin is as usual a sane voice in the pretty much crazy public "debate" about space flight.

Lunar resources should be used on the Moon. To fuel ballistic hoppers for example. Exporting fuel from the Moon won't happen until we have a several orders of magnitude larger space program, and hardly even then. Satellites do not use H/LOX fuels for station keeping. It leaks, it is voluminous. And what's the demand for fuel for a Mars mission every 26 months? 100 tons? Well, that can be launched from Earth for a fraction of a billion dollar. How much would it cost to set up a fuel producing industry on the Moon? The Curiosity rover has a total budget of about $3 billion and it has drilled two inches deeps a few times. And it's jammed and out of operation since a year or so. A caterpillar on the Moon would be seriously expensive in the near term.

The Lunar poles remain great places to go regardless if there's profitable water mining potential there, because they enjoy more insolation. Half a month long nights on batteries is a big problem.

There's no reason to have a permanently crewed space station outside of the protection of LEO. It would be a "gateway" if it was a component of a Lunar landing program, but it is not. It will replace the ISS with a dangerous space station that will be uncrewed most of the time, probably for many years in a row, because it is too expensive and dangerous and completely pointless anyway.
« Last Edit: 05/17/2017 12:57 PM by TakeOff »

Online Robotbeat

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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.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline jabe

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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.
my 2 cents..
eventually both are needed but getting a base started first can help supply the gateway.  So it will lower overall cost of the whole  cislunar/moon base setup.  So have to lean toward base first.. not that that means anything :)
jb

Offline QuantumG

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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.
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Offline jabe

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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.

i have some free time to kill.. will have to do that :)
so he  is mellowing?? wow!!!

Online ncb1397

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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.

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.
« Last Edit: 05/17/2017 11:12 PM by ncb1397 »

Offline sanman

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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.

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.
« Last Edit: 05/17/2017 11:44 PM by sanman »

Offline TakeOff

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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.

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?
« Last Edit: 05/18/2017 12:33 AM by TakeOff »

Offline sanman

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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?

While they may be distinct environments with different respective characteristics, both are part of humanity's journey outward. It's the same pool of engineering talent which can bring both within reach. In today's new reinvigorated world of commercial spaceflight, there's no reason why both can't be possible as goals. The Moon may seem like safer, lower-hanging fruit, but returning there could help to create more momentum in the public imagination for reaching farther out to Mars.

I think that in the past, Dr Zubrin has been more firmly in favor of Mars-first, because it was a question of where finite/scarce space budget dollars would go. But the private sector doesn't impose similarly hard limits on capital - if you can drum up the interest, make a plausible business case, and keep selling more conservative flights as your day job, then you can dream of bigger things by night. Launch satellites to LEO, while dreaming of flights to the Moon. Launch flights to the Moon, while dreaming of flights to Mars. Etc, etc.

Offline Jimmy Murdok

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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 think he sees SpaceX better positioned and focused than NASA for Mars. He don't want to see NASA dying as it has a very important role besides it's crewed waving. If they invest in the moon, do it meaningfully. If they make a station for a deep space habitat we will see nothing cool neither meaningful in the next 10 years and NASA need to do cool things to impress taxpayers.

Bottom line: finish the SLS-Orion, get the privates to make a lander without breaking the bank and focus. You almost have the giant rocket and lunar spaceship. Demonstrate that you still matter or you might be killed.

Edit: and no, Elon is not specially interested in the moon, but if it is in the capacity of his hardware, part of tourism and commercialisation then is welcomed. The ITS was not shown landed in our moon in its presentation.
« Last Edit: 05/18/2017 07:25 AM by Jimmy Murdok »

Online Robotbeat

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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.

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.
« Last Edit: 05/18/2017 12:08 PM by Robotbeat »
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Offline LM13

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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.

Not always.  Even in "The Case for Mars" he remarks that, if fully-reusable SSTO is available, then refueling an SSTO in LEO to fly to Mars and back is the smartest thing to do.  He has not mellowed with age--rather, the game has changed enough from 1993 that Mars Direct is no longer the best way to get to Mars (according to his general principles of "do it fast and do it cheap, while maximizing ISRU").  His opposition to refueling came from the fact that, when Mars Direct was written, the US had no experience with it or with orbital construction (and, as he wrote, cooperation with Russia was not proven), which mean that the entire program could hinge on a technology development effort that may not bear fruit soon enough.  Now, things have changed--rendezvous and docking is routine, and launch costs are dropping, so the case for integrating this new technique is better. 

Similarly, he wasn't always opposed to the Moon in principle--he simply did not think it was a useful or necessary first step toward Mars.  The Case for Mars also mentions using Mars Direct hardware for lunar missions.  And this interview is just along the lines of "if you're going to go to the Moon, do it right and don't mess around in high lunar orbit." 

In other words, this isn't a case of age mellowing him out.  Rather, to borrow his own analogy of "if Columbus had waited for ironclad steam ships, he'd still be waiting," he's redrawing his transatlantic scheme to use clipper ships rather than carracks, since they've become available while he waited. 

Online ncb1397

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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.

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.

Quote
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.
https://www.nasaspaceflight.com/2017/04/nasa-goals-missions-sls-eyes-multi-step-mars/

Online Robotbeat

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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.
« Last Edit: 05/19/2017 02:09 AM by Robotbeat »
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Online ncb1397

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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.

The concept that was shown shows 4 thrusters I believe(see image below). So, the thrusters would use all the power that the solar panels could provide at 1 AU from sunlight. The DST presumably would use the same solar panels and thrusters or derivatives thereof(just roughly an order of magnitude more panels and thrusters). Anyways, it will stay in cislunar space but is closer to a vehicle than a station IMO as it can do inclination changes and orbital maneuvers that stations like Mir/ISS never could. The transfers could either be done unmanned or with multiple crews if they are too long. I've seen various commentary on the internet that the DSG wouldn't be in the right place for this mission or that mission, and just wanted to clear up any confusion that might be out there when it is labeled with the "station" moniker.

« Last Edit: 05/19/2017 03:32 AM by ncb1397 »

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