House bill seeks to gut NASA’s Artemis plan, resurrect Journey to Mars

Lawmakers also appear to like cost-plus contracts.

Read the whole story

 

[Bobsleigh]

Oxygen and hydrogen are great and all, but their engine runs on methane.

Aerodynamic damage? how about the cost of dealing with a second propulsion system because the base system cant handle hydrolox?

I assume you're both referring to Starship, which is an awe-inspiring system that I really hope comes to fruition (even if a little later than Musk-time predicts). But Mr Musk would I believe be among the first to agree that humanity having several horses in the race is a good thing.

Hydrolox vacuum engines are proven tech and electric propulsion is progressing, there's no reason they can't operate alongside and in competition to Starship.

 

[Barleyman]

Are you maybe somehow building those rockets out of Lunar regolith?

You see, to lift the water from the Moon you first need to get the rockets there somehow, meaning you launch them from Earth anyway, packed with fuel instead of water. Might need to refuel on LEO anyway. Then you use some of that fuel to land on the Moon and the rest of it launching again with the water, flying back to LEO and parking there. How is that supposed to be less costly than just lifting the water from Earth to LEO in the first place?

Reusability is key here. Clearly doing this once you're better off launching fuel direct from the surface. But 10x, 100x, more for a single launch of the flotilla from Earth and it could start to be worthwhile. Add in potential mining of regolith and/or asteroids for heavy materials needed in orbital construction, using similar infrastructure.

As in other posts, I recognise this is many decades away, but the issue here is the baby steps with a view to long-term exploitation, so a decades-long return on investment is part of the package.

Quite so. It doesn't make any sense for small scale but this is Elon Musk and his ideas about a sizeable fleet in regular operation. For not-fuel parts you're likely to be better off just hauling it from Earth.

 

[Bobsleigh]

Not sure how great hydrogen is, for prop transfer type work, it doesn't like to stay liquid and it leaks through almost anything.

The materials science and systems research necessary for long-term orbital storage of fuels is another area where NASA has been woefully underfunded.

A skeptic might note - as many have - that such advancements would undermine the case for large rocket systems such as SLS.

 

[blackhawk887]

Why would you take lunar ice to LEO, it is far less costly in money and delta v to launch the prop from Earth where it is far cheaper and you have more useful options.

Getting it to LEO from Earth isn't less costly, if you need five launches to refuel Starship, you're spending vast majority of your fuel for lift, not payload.

You do realize you don't have to process the water in the moon? Just ship it as it is, you can do the electrolysis in LEO as needed, as a bonus you don't have a 2 week night to deal with. Space(X) orbital gas station now open for business with low low cost on water, oxygen and hydrogen..

The whole point of Starship is to make launch cheap, cost of a launch is just fuel (couple million) and operations (another few million) plus whatever margin SpaceX wants on it,

One of those new maintenance free rockets? SpaceX can manage low double digit launches right now, if they need six launches for one flight, to keep similar cadence for Starship it'd need substantial increase in stock, new launch sites and so on. I know Elon has visions of < 1 day turnaround but I think we can agree that one is not going to happen anytime soon.

The whole concept rotates around the fact that from Earth to LEO you have around 5% effective payload vs rocket mass (Falcon Heavy) and that's if you throw away the boosters.

The round-trip delta-v from the lunar surface to LEO and back is not much better than from Earth to LEO and back. With aerobraking for both, it's ~9.1 km/s vs ~9.3 km/s, and the lunar trip wears on your heatshield more because you enter at 11 km/s instead of 7.5 km/s

 

[Barleyman]

Oxygen and hydrogen are great and all, but their engine runs on methane.

My OP said its a shame there's no methane on the moon..

And hey, come on, if we're talking about something that would take decades to set up, it's pretty meaningless to consider today's engines as a showstopper. You'd obviously need entirely different set of of hardware.

In 2020s I'd be impressed to see Starship working in anger with the repeated orbital (methane) refuelling in operation.

 

[Barleyman]

Why would you take lunar ice to LEO, it is far less costly in money and delta v to launch the prop from Earth where it is far cheaper and you have more useful options.

Getting it to LEO from Earth isn't less costly, if you need five launches to refuel Starship, you're spending vast majority of your fuel for lift, not payload.

You do realize you don't have to process the water in the moon? Just ship it as it is, you can do the electrolysis in LEO as needed, as a bonus you don't have a 2 week night to deal with. Space(X) orbital gas station now open for business with low low cost on water, oxygen and hydrogen..

The whole point of Starship is to make launch cheap, cost of a launch is just fuel (couple million) and operations (another few million) plus whatever margin SpaceX wants on it,

One of those new maintenance free rockets? SpaceX can manage low double digit launches right now, if they need six launches for one flight, to keep similar cadence for Starship it'd need substantial increase in stock, new launch sites and so on. I know Elon has visions of < 1 day turnaround but I think we can agree that one is not going to happen anytime soon.

The whole concept rotates around the fact that from Earth to LEO you have around 5% effective payload vs rocket mass (Falcon Heavy) and that's if you throw away the boosters.

The round-trip delta-v from the lunar surface to LEO and back is not much better than from Earth to LEO and back. With aerobraking for both, it's ~9.1 km/s vs ~9.3 km/s, and the lunar trip wears on your heatshield more because you enter at 11 km/s instead of 7.5 km/s

You're hauling a lot less mass to the Moon than the other way around however and you shed mass all the way to the surface.

Someone with too much time on their hands could figure how the numbers would work for Starship but in reality an ice freighter would be rather different design as its operating on low gravity and no atmosphere.

 

[mhalpern]

Are you maybe somehow building those rockets out of Lunar regolith?

You see, to lift the water from the Moon you first need to get the rockets there somehow, meaning you launch them from Earth anyway, packed with fuel instead of water. Might need to refuel on LEO anyway. Then you use some of that fuel to land on the Moon and the rest of it launching again with the water, flying back to LEO and parking there. How is that supposed to be less costly than just lifting the water from Earth to LEO in the first place?

Reusability is key here. Clearly doing this once you're better off launching fuel direct from the surface. But 10x, 100x, more for a single launch of the flotilla from Earth and it could start to be worthwhile. Add in potential mining of regolith and/or asteroids for heavy materials needed in orbital construction, using similar infrastructure.

As in other posts, I recognise this is many decades away, but the issue here is the baby steps with a view to long-term exploitation, so a decades-long return on investment is part of the package.

If you are at the point where you are trying to get more to Mars with fewer launches, you basically have 2 primary options an Aldrin cycler (yes that Aldrin) which would allow you to comfortably pack more people into each ship because they will be spending most of the time in a large habitat that is in an orbit that passes near Earth and Mars regularly, same delta v cost but you could probably double or triple the number of people on each ship, or a likely electric propelled orbit to orbit vehicle this costs more delta v and it will take longer, but the propulsion is largely ion which gets you much higher isp, recommended reaction mass- argon, as it is available in abundance both on Earth and on Mars, benefit of this over a cycler is that you have time to stock and maintain the orbit to orbit transfer vehicle between synods you could lower delta v requirements with aerocapture, but I generally assume you wouldnt as if you are relying on it you have a small margin of error between too much deceleration leading to lithobraking and not enough and overshooting both of which are fatal.

If your space activities reach such a scale chances are you would only use cryogenics and chemical propulsion in general to escape and land on gravitational bodies, almost everything else save for high thrust maneuvering would be electric propulsion so that you arent lugging around huge masses of propellant you dont need to be.

 

[mhalpern]

Why would you take lunar ice to LEO, it is far less costly in money and delta v to launch the prop from Earth where it is far cheaper and you have more useful options.

Getting it to LEO from Earth isn't less costly, if you need five launches to refuel Starship, you're spending vast majority of your fuel for lift, not payload.

You do realize you don't have to process the water in the moon? Just ship it as it is, you can do the electrolysis in LEO as needed, as a bonus you don't have a 2 week night to deal with. Space(X) orbital gas station now open for business with low low cost on water, oxygen and hydrogen..

The whole point of Starship is to make launch cheap, cost of a launch is just fuel (couple million) and operations (another few million) plus whatever margin SpaceX wants on it,

One of those new maintenance free rockets? SpaceX can manage low double digit launches right now, if they need six launches for one flight, to keep similar cadence for Starship it'd need substantial increase in stock, new launch sites and so on. I know Elon has visions of < 1 day turnaround but I think we can agree that one is not going to happen anytime soon.

The whole concept rotates around the fact that from Earth to LEO you have around 5% effective payload vs rocket mass (Falcon Heavy) and that's if you throw away the boosters.

Maintenance is part of "operations" the SH booster itself is supposed to be able to fly 3x in 24hrs, (design goal) the SS has a reusable heat-shield made of almost entirely identical tiles (stronger than STS had) that are attached mechanically and likely by robot, you also dont have to worry about ice falling on them only occasional debris strikes and burn out,

 

[1Zach1]

In other news, looks like SN01 is full steam ahead after the latest pressure tests.

https://mobile.twitter.com/Teslarati/st ... 3462289408

 

[mhalpern]

Not sure how great hydrogen is, for prop transfer type work, it doesn't like to stay liquid and it leaks through almost anything.

The materials science and systems research necessary for long-term orbital storage of fuels is another areas where NASA has been woefully underfunded.

A skeptic might note - as many have - that such advancements would undermine the case for large rocket systems such as SLS.

I wont disagree, however LCH4 is much easier to store than LH2 regardless, it is far denser and it is liquid in a similar temperature range to LOX in addition to not leaking as easily as hydrogen, with LOX and LCH4 at similar temps you dont have to worry about as many temperature regimes in your spacecraft, or your oxidizer boiling your fuel.

 

[Faanchou]

Why would you take lunar ice to LEO, it is far less costly in money and delta v to launch the prop from Earth where it is far cheaper and you have more useful options.

Getting it to LEO from Earth isn't less costly, if you need five launches to refuel Starship, you're spending vast majority of your fuel for lift, not payload.

You do realize you don't have to process the water in the moon? Just ship it as it is, you can do the electrolysis in LEO as needed, as a bonus you don't have a 2 week night to deal with. Space(X) orbital gas station now open for business with low low cost on water, oxygen and hydrogen..

The whole point of Starship is to make launch cheap, cost of a launch is just fuel (couple million) and operations (another few million) plus whatever margin SpaceX wants on it,

One of those new maintenance free rockets? SpaceX can manage low double digit launches right now, if they need six launches for one flight, to keep similar cadence for Starship it'd need substantial increase in stock, new launch sites and so on. I know Elon has visions of < 1 day turnaround but I think we can agree that one is not going to happen anytime soon.

The whole concept rotates around the fact that from Earth to LEO you have around 5% effective payload vs rocket mass (Falcon Heavy) and that's if you throw away the boosters.

The round-trip delta-v from the lunar surface to LEO and back is not much better than from Earth to LEO and back. With aerobraking for both, it's ~9.1 km/s vs ~9.3 km/s, and the lunar trip wears on your heatshield more because you enter at 11 km/s instead of 7.5 km/s

You're hauling a lot less mass to the Moon than the other way around however and you shed mass all the way to the surface.

Someone with too much time on their hands could figure how the numbers would work for Starship but in reality an ice freighter would be rather different design as its operating on low gravity and no atmosphere.

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

 

[Azure_Sentry]

So, what do we imagine Bridenstine's choice of whiskey is, and how much is he consuming right now?

Maybe we should all pitch in for a bottle of the good stuff and a condolences card.

 

[mhalpern]

Why would you take lunar ice to LEO, it is far less costly in money and delta v to launch the prop from Earth where it is far cheaper and you have more useful options.

Getting it to LEO from Earth isn't less costly, if you need five launches to refuel Starship, you're spending vast majority of your fuel for lift, not payload.

You do realize you don't have to process the water in the moon? Just ship it as it is, you can do the electrolysis in LEO as needed, as a bonus you don't have a 2 week night to deal with. Space(X) orbital gas station now open for business with low low cost on water, oxygen and hydrogen..

The whole point of Starship is to make launch cheap, cost of a launch is just fuel (couple million) and operations (another few million) plus whatever margin SpaceX wants on it,

One of those new maintenance free rockets? SpaceX can manage low double digit launches right now, if they need six launches for one flight, to keep similar cadence for Starship it'd need substantial increase in stock, new launch sites and so on. I know Elon has visions of < 1 day turnaround but I think we can agree that one is not going to happen anytime soon.

The whole concept rotates around the fact that from Earth to LEO you have around 5% effective payload vs rocket mass (Falcon Heavy) and that's if you throw away the boosters.

The round-trip delta-v from the lunar surface to LEO and back is not much better than from Earth to LEO and back. With aerobraking for both, it's ~9.1 km/s vs ~9.3 km/s, and the lunar trip wears on your heatshield more because you enter at 11 km/s instead of 7.5 km/s

You're hauling a lot less mass to the Moon than the other way around however and you shed mass all the way to the surface.

Someone with too much time on their hands could figure how the numbers would work for Starship but in reality an ice freighter would be rather different design as its operating on low gravity and no atmosphere.

You are adding additional steps that dont necessarily need to be added, this costs money, if for some reason the lunar ice infrastructure serves other activities that pay for it most of the time, there can maybe be gains but even if there were sats in Earth orbit that can be refueled, most of them would be looking for either complex chemical prop or ion prop, there is some interest in water based propulsion, but it is a niche.

 

[compgeek89]

With the expectation, that they sell lot of A380s and recoup that money with profit on top. What is the recoup and profit on SpaceX spending say 50 billion OF THEIR OWN MONEY in developing and launching mission to Mars.

Airbus has sold 6 A380s since 2015 and has had 72 order cancellations in that time. Production will end at 251 with the last delivery in 2021. They basically broke even on production, but the $25 billion development cost was a near total loss. Had Emirates not bought 123 of them, it would have been a complete flop.

EXPECTATION. What happens later, happens later. Also eh..... Airbus taking massive loss on 25 billion on complex expensive aerospace project.... That should be re-assuring to SpaceX, that these complex and costly aerospace projects always return profit..... Also Airbus is way bigger conglomerate, that can handle 25 billion of unexpected loss. what are SpaceXs cash reserves to write down to accounting (just lost 50 billion dollars on a Mars mission, no body seem to be willing to buy extra missions. Might have something to do with tens of billions per mission price tag.)

So come the real hard part of actually starting to prep mission gear and not just generic heavy lift rocket, they bean counters in SpaceX most likely will tell Elon: Boss this is a bad bad idea and will bankrupt the company, unless you can secure as a sure customer willing to pay tens of billions before we even start the mission hardware development. Elon is ofcourse free to ignore that, but then will most likely bankrupt the company way before them being anywhere near complete space mission.

Also I would like to see the crew willing to embark on 2 year mission to Mars, backed by entity that might go bankrupt during those 2 years. Ground support? hello yeah, what is up on Earth? Yeah we all got fired, company is bankrupt. This is our last call.

First, where do you get $50B for a spaceX mars mission? They are talking about launching Starship, which is already under development and, for which I have seen estimates ranging between $2B and $10B for development costs (with the higher ones being before they switched to steel). Even giving you the $10B for developing the ship, where is the other $40B going? Remember, this is SpaceX, not NASA or Boeing. They don't blow $2B on a few engines.

There are, of course, other costs for the initial mission. A habitat, a tricked out Cybertruck, lots and lots of solar panels, ISRU plant, etc. But, most of these will be nowhere near the costs you are quoting for development. Starship should be the largest cost in this endeavor and once they complete that, I don't see the other items as being major inhibiting factors.

Now, if you are talking about costs for colonizing mars and developing the tech to be fully self-reliant, then the costs balloon, but that is a very different phase of this project.

 

[Statistical]

If you want to go to the moon then go to the moon. Coming up with rube goldberg solutions for going to the moon to get prop to LEO to use it to go places other than the moon is silly.

Maybe lunar propellant delivered to LEO will be economical in a decade or a century compared to propellant delivered from Earth or maybe it never will be. Cheaper rockets make lunar infrastructure cheaper but they also make deliveries of propellant to LEO cheaper as well. It is a dubious justification of unknown economics for going to the moon.

I mean it sounds silly to say the reverse. We need to go the Mars to build propellant factories to ship the propellant to Earth orbit to use for missions to go to the moon. If anyone claimed that about Mars they would get laughed at however it seems to be THE go to rationale for some lunar proponents.

Now SpaceX does want to build propellant factories on Mars but only to get ships on Mars back to the Earth. The key thing there is those factories don't need to compete 1:1 with cheap LEO propellant (they never could). By refueling on Mars (as part of Martian missions) it improves the cost effectiveness of each spacecraft sent to Mars and back because the spacecraft only needs enough propellant to go one way. That massive improves payload to prop ratio for the spacecrafts. Likewise someday building propellant factories on the moon to refuel ships returning to Earth from the moon might make sense. They wouldn't need to compete 1:1 with cheap LEO prop. You would still use cheap LEO prop to get TO the moon you would use local prop to get back meaning each spacecraft requires less overall prop and can carry more payloads. Of course that just improves the economics of flights to and from the moon you still need a reason to be there to begin with.

If the only reason you can think of going to the moon involves getting prop and shipping it to LEO to use for places other than the moon well that is another way of saying "I can't think of any good reason to go to the moon". There are plenty of good reasons to go to the moon but going to the moon to get prop to go to Mars is not one of them. If you want to go to Mars then just go to Mars.

Hell I don't even care which destination we pick as long as we pick one and go.

 

[wagnerrp]

Oxygen and hydrogen are great and all, but their engine runs on methane.

Aerodynamic damage? how about the cost of dealing with a second propulsion system because the base system cant handle hydrolox?

I assume you're both referring to Starship, which is awe-inspiring system that I really hope comes to fruition (even if a little later than Musk-time predicts). But Mr Musk would I believe be among the first to agree that humanity having several horses in the race is a good thing.

Hydrolox vacuum engines are proven tech and electric propulsion is progressing, there's no reason they can't operate alongside and in competition to Starship.

Starship is the only proposed vehicle which could actually bootstrap such a large scale Lunar mining operation. Nothing else on the horizon has the throw weight for it, including dedicated orbital tugs and landers.

 

[mhalpern]

First, where do you get $50B for a spaceX mars mission? They are talking about launching Starship, which is already under development and, for which I have seen estimates ranging between $2B and $10B for development costs (with the higher ones being before they switched to steel). Even giving you the $10B for developing the ship, where is the other $40B going? Remember, this is SpaceX, not NASA or Boeing. They don't blow $2B on a few engines.

There are, of course, other costs for the initial mission. A habitat, a tricked out Cybertruck, lots and lots of solar panels, ISRU plant, etc. But, most of these will be nowhere near the costs you are quoting for development. Starship should be the largest cost in this endeavor and once they complete that, I don't see the other items as being major inhibiting factors.

Now, if you are talking about costs for colonizing mars and developing the tech to be fully self-reliant, then the costs balloon, but that is a very different phase of this project.

I wouldn't even count all of Starship's dev costs towards the Mars mission, most of its activities will be Earth orbit commercial, one of the benefits of on orbit prop xfer is your BEO rocket is useful for Earth Orbit activities,

 

[mhalpern]

If you want to go to the moon then go to the moon. Coming up with rube goldberg solutions for going to the moon to get prop to LEO to use it to go places other than the moon is just dumb it really is.

Maybe lunar propellant delivered to LEO will be economical in a decade or a century compared to propellant delivered from Earth or maybe it never will be. It is a dubious justification of unknown economics for going to the moon.

If the only reason you can think of going to the moon involves getting prop and shipping it to LEO to use for places other than the moon well that is another way of saying "I can't think of any good reason to go to the moon". There are actually plenty of good reasons to go to the moon but going to the moon to get prop to go to Mars is not one of them. If you want to go to Mars then just go to Mars.

I mean it sounds silly to say the reverse. We need to go the Mars to build propellant factories to ship the propellant to Earth orbit to use for missions to the moon. Now SpaceX does want to build propellant factories but only to get ships on Mars back to the Earth. Likewise someday building propellant factories on the moon to refuel ships returning from the moon to Earth might make sense. Of course that just improves the economics of flights to and from the moon you still need a reason to be there to begin with.

Hell I don't even care which destination we pick as long as we pick one and go.

A principle that applies to both engineering and economics, and I am sure many other things, the more steps you take the less efficient it is, if infrastructure exists that serves more than just you, then using it isn't taking extra steps (from your perspective), its using established infrastructure, but if you are creating the infrastructure just for your purposes, it is extra steps and it is inefficient.

 

[ivekadi]

For propellants/raw material deliveries to LEO there are better sources than Luna.

There is plenty of NEO asteroids. And their small gravity field means that the entire trip can be done using high ISP solar electric propulsion. Zero human intervention.

Yes, it would require infrastructure and automation and additional R&D into solar panels and plasma engines, and processing equipment.

I'm not certain whether it would actually be cheaper on $/kg to LEO in the long term (30-50 years from now) but it most certainly could be cheaper to deliver it to GEO or other (orbital) locations of interest. Such as L points.

What about propellant deliveries to High Jupiter Orbit? ( HJO )
Doing it from Earth is pretty damn expensive. Not to mention the shear mass ratios involved. (kg prop/kg delivered to HJO)

Unfortunately there is much research to be done in this area. Our technology readiness levels (TRL) are abysmal (on this)

NASA is forced to focus on the wrong stuff.

 

[Wickwick]

If you want to go to the moon then go to the moon. Coming up with rube goldberg solutions for going to the moon to get prop to LEO to use it to go places other than the moon is just dumb it really is.

Maybe lunar propellant delivered to LEO will be economical in a decade or a century compared to propellant delivered from Earth or maybe it never will be. It is a dubious justification of unknown economics for going to the moon.

I mean it sounds silly to say the reverse. We need to go the Mars to build propellant factories to ship the propellant to Earth orbit to use for missions to the moon. If anyone claimed that about Mars they would get laughed at however it seems to be THE go to rationale for some lunar proponents.

Now SpaceX does want to build propellant factories on Mars but only to get ships on Mars back to the Earth. The key thing there is those factories don't need to compete 1:1 with cheap LEO propellant (they never could). By refueling on Mars (as part of Martian missions) it improves the cost effectiveness of each spacecraft sent to Mars and back. Likewise someday building propellant factories on the moon to refuel ships returning to Earth from the moon might make sense. They wouldn't need to compete 1:1 with cheap LEO prop. You would still use cheap LEO prop to get TO the moon you would use local prop to get back meaning each spacecraft requires less overall prop and can carry more payloads. Of course that just improves the economics of flights to and from the moon you still need a reason to be there to begin with.

If the only reason you can think of going to the moon involves getting prop and shipping it to LEO to use for places other than the moon well that is another way of saying "I can't think of any good reason to go to the moon". There are plenty of good reasons to go to the moon but going to the moon to get prop to go to Mars is not one of them. If you want to go to Mars then just go to Mars.

Hell I don't even care which destination we pick as long as we pick one and go.

Propellant factories on asteroids probably makes as much sense for fuel to-from Mars as on the moon. Actually, it might make more sense.

 

[mhalpern]

For propellants/raw material deliveries to LEO there are better sources than Luna.

There is plenty of NEO asteroids. And their small gravity field means that the entire trip can be done using high ISP solar electric propulsion. Zero human intervention.

Yes, it would require infrastructure and automation and additional R&D into solar panels and plasma engines, and processing equipment.

I'm not certain whether it would actually be cheaper on $/kg to LEO in the long term (30-50 years from now) but it most certainly could be cheaper to deliver it to GEO or other (orbital) locations of interest. Such as L points.

What about propellant deliveries to High Jupiter Orbit? ( HJO )
Doing it from Earth is pretty damn expensive. Not to mention the shear mass ratios involved. (kg prop/kg delivered to HJO)

Unfortunately there is much research to be done in this area. Our technology readiness levels (TRL) are abysmal (on this)

NASA is forced to focus on the wrong stuff.

for prop/reaction mass deliveries to GEO or other Earth Orbits most spacecraft are ion or hypergol, and GEO's continued usefulness depends on impact of cheaper launch and payloads. There aren't enough spacecraft in orbit of other planetary bodies to consider refueling infrastructure for them right now.

 

[ars reader 1]

This is absolutely insane. I smell Senator Shelby all over this trying to pull strings.

I smell Trump being told by Putin to stay away from the Moon. This, of course, leaves the Moon open to Russia, China and India.

Putin>Bannon>Trump

 

[mhalpern]

If you want to go to the moon then go to the moon. Coming up with rube goldberg solutions for going to the moon to get prop to LEO to use it to go places other than the moon is just dumb it really is.

Maybe lunar propellant delivered to LEO will be economical in a decade or a century compared to propellant delivered from Earth or maybe it never will be. It is a dubious justification of unknown economics for going to the moon.

I mean it sounds silly to say the reverse. We need to go the Mars to build propellant factories to ship the propellant to Earth orbit to use for missions to the moon. If anyone claimed that about Mars they would get laughed at however it seems to be THE go to rationale for some lunar proponents.

Now SpaceX does want to build propellant factories on Mars but only to get ships on Mars back to the Earth. The key thing there is those factories don't need to compete 1:1 with cheap LEO propellant (they never could). By refueling on Mars (as part of Martian missions) it improves the cost effectiveness of each spacecraft sent to Mars and back. Likewise someday building propellant factories on the moon to refuel ships returning to Earth from the moon might make sense. They wouldn't need to compete 1:1 with cheap LEO prop. You would still use cheap LEO prop to get TO the moon you would use local prop to get back meaning each spacecraft requires less overall prop and can carry more payloads. Of course that just improves the economics of flights to and from the moon you still need a reason to be there to begin with.

If the only reason you can think of going to the moon involves getting prop and shipping it to LEO to use for places other than the moon well that is another way of saying "I can't think of any good reason to go to the moon". There are plenty of good reasons to go to the moon but going to the moon to get prop to go to Mars is not one of them. If you want to go to Mars then just go to Mars.

Hell I don't even care which destination we pick as long as we pick one and go.

Propellant factories on asteroids probably makes as much sense for fuel to-from Mars as on the moon. Actually, it might make more sense.

Energy wise perhaps, but there is also scheduling to consider,

 

[Statistical]

This is absolutely insane. I smell Senator Shelby all over this trying to pull strings.

I smell Trump being told by Putin to stay away from the Moon. This, of course, leaves the Moon open to Russia, China and India.

Putin>Bannon>Trump

Russia isn't doing anything with the moon. China has plans for a flags and footprints mission in the early 2030s.

I wish Russia, China, and India were making big moves regarding the moon. A second space race might jolt NASA out of its Congressional imposed doldrums when it comes to HSF.

 

[blackhawk887]

Why would you take lunar ice to LEO, it is far less costly in money and delta v to launch the prop from Earth where it is far cheaper and you have more useful options.

Getting it to LEO from Earth isn't less costly, if you need five launches to refuel Starship, you're spending vast majority of your fuel for lift, not payload.

You do realize you don't have to process the water in the moon? Just ship it as it is, you can do the electrolysis in LEO as needed, as a bonus you don't have a 2 week night to deal with. Space(X) orbital gas station now open for business with low low cost on water, oxygen and hydrogen..

The whole point of Starship is to make launch cheap, cost of a launch is just fuel (couple million) and operations (another few million) plus whatever margin SpaceX wants on it,

One of those new maintenance free rockets? SpaceX can manage low double digit launches right now, if they need six launches for one flight, to keep similar cadence for Starship it'd need substantial increase in stock, new launch sites and so on. I know Elon has visions of < 1 day turnaround but I think we can agree that one is not going to happen anytime soon.

The whole concept rotates around the fact that from Earth to LEO you have around 5% effective payload vs rocket mass (Falcon Heavy) and that's if you throw away the boosters.

The round-trip delta-v from the lunar surface to LEO and back is not much better than from Earth to LEO and back. With aerobraking for both, it's ~9.1 km/s vs ~9.3 km/s, and the lunar trip wears on your heatshield more because you enter at 11 km/s instead of 7.5 km/s

You're hauling a lot less mass to the Moon than the other way around however and you shed mass all the way to the surface.

Someone with too much time on their hands could figure how the numbers would work for Starship but in reality an ice freighter would be rather different design as its operating on low gravity and no atmosphere.

If you want to use aerobraking, you have to design it for at least some of the same atmospheric issues as Starship. You can get away from some of the issues by doing multiple passes, but that adds a lot of time to the trip, with most of it spent in the van Allen belts, so you're need to trade out delivery rate and ship lifetimes.

Solar-electric and solar-thermal are both viable propulsion options, though. Solar-thermal can be relatively high thrust, and can use straight water as reaction mass with better than hydrolox specific impulse.

 

[mhalpern]

A couple things to consider are that the long duration life support and ISRU prop production can be essentially the same tech at different scales, life support may add additional steps to separate the hydrogen from the carbon in CH4, to make water supply last longer, but same principles. there are also different stages of self sufficiency, the costs for basic food self sufficiency aren't that much because the tech isn't complicated, as you colonize you gradually add more and more self sufficiency which will also free up payload mass for more equipment.

 

[blackhawk887]

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

Aerobraking actually doesn't require diving straight into the thick stuff. Several Mars orbiters have circularized their orbits even with solar arrays deployed. A vehicle with a large area to mass ratio can get significant deceleration even with rather low temperatures.

 

[compgeek89]

Propellant factories on asteroids probably makes as much sense for fuel to-from Mars as on the moon. Actually, it might make more sense.

If we get to fully reusable architectures, launching propellant from earth will be a few million $ for about 100+ tons, right? That is about $20-30/kg.

At that price, I can't see it being economical to pull an asteroid into earth orbit, develop and set up mining, process mining, etc until we have a need for many thousands of tons of fuel/year.

Think about it, with full reusability, we could launch 1000 refueling ships, carrying 100,000 tons of fuel for about $2-3B (even double that is still dirt cheap). I seriously doubt you could capture and build an asteriod gas station for anywhere near that.

 

[mhalpern]

If you want to use aerobraking, you have to design it for at least some of the same atmospheric issues as Starship. You can get away from some of the issues by doing multiple passes, but that adds a lot of time to the trip, with most of it spent in the van Allen belts, so you're need to trade out delivery rate and ship lifetimes.

Solar-electric and solar-thermal are both viable propulsion options, though. Solar-thermal can be relatively high thrust, and can use straight water as reaction mass with better than hydrolox specific impulse.

Of course solar-thermal trades off spacecraft lifetime or at least propulsion unit lifetime as the materials that transfer that heat efficiently to the reaction mass tend to degrade at such high temps. of course all engineering is trades. There are some SEP options that can take straight water as well as most other fluids, basically they are electric steam/ water plasma rockets.

 

[prime1987]

I chuckled a little at the woebegone support for asteroid mining ... i confess I still fancy the idea. Maybe too much Clarke or Doc Smith as boy.

An 'early' problem would seem to be knowing whether the cost-benefit makes it even worth trying. There's reason to suppose that some of the really dense, valuable heavy metals will be more common in asteroid stuff than on Earth (where most of the denser metals have 'sunk'; iridium being the notorious example, viz iridium-rich layers deposited on Earth after asteroid impacts), but (a) in what concentrations would they need to be, and (b) how to even find the richest nuggets floating out there?

I suspect I'm being a little optimistic, but I do like the idea of a survey programme, whereby a small fleet of automated probes skulks around the Belt and eventually shortlists candidate asteroids: exceptional density, within a certain mass range, occupying suitable orbits, probably older, more cohesive ones. Followed up by another robot, which can harpoon an engine and fuel supply to one of the candidates, so that over the course of a few of years it could be brought into lunar orbit. (Perhaps a multi-national project, for all sorts of good reasons including the reassurance that the rock won't 'accidentally' be dropped on anyone's capital.)

I can imagine—and maybe that's all this will ever be, admitted—that having any asteroid to study in close detail would be hugely informative, and perhaps offer clues about what to look for in future. It's hard to believe that a million-tonne rock in lunar orbit wouldn't be useful for something, even if it's not full of platinum. With an optimistic density of perhaps twice Earth, that's maybe as much as 200 feet across: big enough to attach things to, providing it is, as I said earlier, 'cohesive'.

(Heck, the Lunar Gateway could become the Lunar Boulder.)

Perhaps such ideas always come back to: how cheaply could it be done?

 

[mhalpern]

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

Aerobraking actually doesn't require diving straight into the thick stuff. Several Mars orbiters have circularized their orbits even with solar arrays deployed. A vehicle with a large area to mass ratio can get significant deceleration even with rather low temperatures.

a large area to mass ratio is harder to achieve when the spacecraft is higher volume, even if you have wide solar arrays to power everything inside, that eventually means more structure on the arrays to handle such a maneuver, cubed square law is not your friend here.

 

[Barleyman]

You're hauling a lot less mass to the Moon than the other way around however and you shed mass all the way to the surface.

Someone with too much time on their hands could figure how the numbers would work for Starship but in reality an ice freighter would be rather different design as its operating on low gravity and no atmosphere.

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

Hence the call for someone to do the math on it. Where did that 11km/s come from, moon surface to LEO is about 2.8km/s?

https://en.m.wikipedia.org/wiki/Delta-v_budget

There's not really anything to stop you from doing aerobrake, it was mentioned that using it for rounding out an elliptical orbit is actually something that's done IRL.

 

[Statistical]

Propellant factories on asteroids probably makes as much sense for fuel to-from Mars as on the moon. Actually, it might make more sense.

If we get to fully reusable architectures, launching propellant from earth will be a few million $ for about 100+ tons, right? That is about $20-30/kg.

At that price, I can't see it being economical to pull an asteroid into earth orbit, develop and set up mining, process mining, etc until we have a need for many thousands of tons of fuel/year.

Think about it, with full reusability, we could launch 1000 refueling ships, carrying 100,000 tons of fuel for about $2-3B (even double that is still dirt cheap). I seriously doubt you could capture and build an asteriod gas station for anywhere near that.

Well SpaceX has only said less than $10M and that would be THEIR COST not the price to customers. So your numbers probably are low by an order of magnitude.

Lets say SpaceX sells Starship flights for $20M for 100t. That is $200K per ton or $200 per kg. Methalox itself (3.8:1 O/F) is dirt cheap around $700 per ton (<$1 per kg). Even if pricing is higher say $50M per flight we are still talking about $500 per kg of methalox delivered to orbit.

In comparison
Space Shuttle (full lifecycle costs): $75,000 per kg
Space Shuttle (flyaway cost near end of program): $20,000 per kg
Falcon 9 (retail price): $3,000 per kg
Falcon 9 (spacex internal cost w/ very high reuse lower bound): $750 per kg
Starship (initial retail $50M per flight 100t): $500 per kg
Starship (future retail $20M per flight 150t): $130 per kg
Starship (spacex internal flyaway cost $9M per flight, 150t): $60 per kg

 

[Faanchou]

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

Aerobraking actually doesn't require diving straight into the thick stuff. Several Mars orbiters have circularized their orbits even with solar arrays deployed. A vehicle with a large area to mass ratio can get significant deceleration even with rather low temperatures.

Indeed, but wannabe orbiters do need to get down to an orbital speed with the first pass, because otherwise the next pass won't be until after going around the Sun at least once.

 

[AverageDutchGuy]

"The United States should retain "full ownership" of the Human Landing System, and unfettered insight into its design and development. In other words, it must be let under a cost-plus contract."

Those are not mutually exclusive! It's called "white box" (as opposed to black box where the buyer doesn't know or own any IP about the product or build-to-print where the buyer owns the IP and gives only the drawings of exactly what to build to the manufacturer) and it's done under fixed price contracts in the commercial world all the freaking time!

This is just a blatant attempt to get Boeing a new cost-plus contract.

 

[mhalpern]

You're hauling a lot less mass to the Moon than the other way around however and you shed mass all the way to the surface.

Someone with too much time on their hands could figure how the numbers would work for Starship but in reality an ice freighter would be rather different design as its operating on low gravity and no atmosphere.

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

Hence the call for someone to do the math on it. Where did that 11km/s come from, moon surface to LEO is about 2.8km/s?

https://en.m.wikipedia.org/wiki/Delta-v_budget

There's not really anything to stop you from doing aerobrake, it was mentioned that using it for rounding out an elliptical orbit is actually something that's done IRL.

we also haven't done it with anything much larger than a small refrigerator, there are lots of unknowns for scaling.

 

[Barleyman]

for prop/reaction mass deliveries to GEO or other Earth Orbits most spacecraft are ion or hypergol, and GEO's continued usefulness depends on impact of cheaper launch and payloads. There aren't enough spacecraft in orbit of other planetary bodies to consider refueling infrastructure for them right now.

As if ice mining operation with regular freight shipments had anything whatsoever to do with "right now". In our lifetime? Well depends on how old you are..

 

[Agitation]

Can someone please explain this to me?

The United States should retain "full ownership" of the Human Landing System, and unfettered insight into its design and development. In other words, it must be let under a cost-plus contract

How does the US retaining full ownership = cost-plus?

If I understand contracts & IP... I am not a lawyer.

Cost plus means the US Gov is paying for all research, and acquires ownership of any IP thereby generated.

Fixed cost means the contractor does the research, acquires ownership of the IP, to which the government gets to license at a pre-negotiated rate.

That's not necessarily correct. The IP can remain the possession of the company doing the work or the government as contracted. For the SLS core, NASA is doing the engineering and Boeing the construction. The IP remains with the government. However, no sane private enterprise would agree to manufacture someone else's not-yet-complete design at a fixed price. Cost-plus contracts were developed so the government could shoulder the risks for uncertain endeavors. Which is why buying the next round of SLS cores on a cost-plus basis is so ironic. Said manufacturing shouldn't be uncertain after you've already built two or three.

Thank you. That makes sense. This was possibly explained in an article I missed, but "cost-plus" seems to have been framed here at Ars as little more than a handout, and while that may be the case in this instance --or in many instances -- it's good to know that it does have a legitimate function in allowing the government to own the IP.

 

[mhalpern]

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

Aerobraking actually doesn't require diving straight into the thick stuff. Several Mars orbiters have circularized their orbits even with solar arrays deployed. A vehicle with a large area to mass ratio can get significant deceleration even with rather low temperatures.

Indeed, but wannabe orbiters do need to get down to an orbital speed with the first pass, because otherwise the next pass won't be until after going around the Sun at least once.

which is why for larger spacecraft I dont assume areocapture, at least not until we start getting really good at it.

 

[Statistical]

But then you won't be using aerobraking for lunar surface to LEO and will instead pay for that delta-v from 11 km/s to orbital entirely in propellant. And that's with a full water load on board.

Aerobraking actually doesn't require diving straight into the thick stuff. Several Mars orbiters have circularized their orbits even with solar arrays deployed. A vehicle with a large area to mass ratio can get significant deceleration even with rather low temperatures.

Indeed, but wannabe orbiters do need to get down to an orbital speed with the first pass, because otherwise the next pass won't be until after going around the Sun at least once.

100% aerobraking maybe but with a small amount of propulsive DeltaV before and after that with aerobreaking pass you can convert from a heliocentric orbit to a geocentric or aerocentric orbit. Now you would still have a long period so the next pass might take a month or more but you are in orbit around the target body after the first pass.