I Moon vs Earth for launch to Mars

[sophiecentaur]

Elon Musk is rich, but that doesn't make his "hope" impress me. I'm convinced he's going to crash and burn.

If people aren't careful, I can see Elon Musk becoming the 21st century version of Nicola Tesla in the minds of the public. I agree that he could very likely crash and burn because a space project would not be important enough or 'too big to fail'. Many of Musk's competitors would just be laughing up their sleeves (or out loud).

 

[nikkkom]

What are you talking about? With his prices and accelerating launch rate, Musk is already killing Proton and ULA. Arianespace is next to the chopping block. What "crash and burn"?

 

[stefan r]

Stefan @55 - those are not pic of technology that are economically viable and in every day use. The technologies to get people to Mars...

I was hoping this thread could include more orbital dynamics. We have samples of rocks that got here from Mars.

Of over 61,000 meteorites that have been found on Earth, 132 were identified as Martian as of 3 March 2014.

During the late heavy bombardment both the Earth and the moon were hit by many asteroids. There must be both terrestrial and lunar meteorites on Mars. Can we estimate the ratio? Most of this happened 3 to 4 billion years ago. It is nice that we are not likely to see a major comet impact in out lifetimes. We can still talk hypothetically about the relative probability of a surface chunk making the trip instead of falling back down.

 

[sophiecentaur]

What "crash and burn"?

Have they actually launched a Mars Project yet? Crash and burn doesn't only imply a financial fail. How many fails (or lost lives) will regular investors fund? The market doesn't have the same attitude to projects that JFK managed to instil into a whole nation.

 

[nikkkom]

Have they actually launched a Mars Project yet? Crash and burn doesn't only imply a financial fail.

That was not my point. You said "many of Musk's competitors would just be laughing".

As things go now, there *won't be* "many Musk competitors". At best, a few foreign launch providers will be surviving by subsisting on launching their governments' payloads. In US, NASA and ULA are becoming not viable as launch providers - the price gap is scary. Also, SpaceX success spurred a few private copycats, notably Bezos' Blue Origin looks technically promising (and it is backed by Bezos' $80B!). Even if SpaceX somehow fails, it already have shown the way how to make space much more accessible. Someone else will succeed.

 

[sophiecentaur]

That was not my point. You said "many of Musk's competitors would just be laughing".

As things go now, there *won't be* "many Musk competitors". At best, a few foreign launch providers will be surviving by subsisting on launching their governments' payloads. In US, NASA and ULA are becoming not viable as launch providers - the price gap is scary. Also, SpaceX success spurred a few private copycats, notably Bezos' Blue Origin looks technically promising (and it is backed by Bezos' $80B!). Even if SpaceX somehow fails, it already have shown the way how to make space much more accessible. Someone else will succeed.

You are making the assumption that Space X will actually succeed. Fact is, to most people, it makes little difference whether or not it succeeds and the "competitors" I referred to will not necessarily cease to exist. They may have failed or just withdrawn from the field when they see they are not going to get any immediate returns

 

[nikkkom]

You are making the assumption that Space X will actually succeed.

They succeeded (wildly) as a launch provider. And fingers crossed, they may launch their first 64ton-to-LEO Falcon Heavy this month, making their rocket the largest, by the factor of 2.5, operational launcher in the world. For the price of one Ariane-5 launch!

Cost of launch was the largest obstacle for all of humanity's space efforts, Moon/Mars programs included. SpaceX dramatically lowered that. Now, even if SpaceX magically disappears right this day, it would not matter: now we _know_ how to make launch much cheaper.

I'm not emotionally attached to SpaceX per se. If someone else builds the Mars base, it's fine with me.

 

[sophiecentaur]

I think the big difference between a Launch and an Expedition is who would pay for it. Customers will be queuing up for their satellites to be taken into orbit at a good price. Who is prepared to invest private funds in a project with a totally unknown return? How long term do investors, other than nations, work?

 

[Chronos]

Looking at it from a purely physics standpoint, a launch from the moon is much easier than a launch from earth. The escape velocity from the moon is just over 2 km/sec whereas from Earth you need over 11 km/sec The problem is in getting all the llaunch resources from Earth to the moon. If the raw materials needed are already present on the moon. problem solved. [mostly].

 

[mfb]

Launch technology has essentially stagnated for 50 years after fully maturing in 10. What is needed isn't "advances", but a totally new and radically better launch technology materializing out of thin air.

There are two companies working on this radically better launch technology, and two more are looking into it. Or should I say "landing technology"?

Don't get me wrong; I don't think robotic lunar mining is on the foreseeable horizon as something we WILL do, but it at least it is foreseeable as something we CAN. do.

Reusing rocket components is something we do now. SpaceX recovered the first booster just two years ago, now they have reflown a couple of them, reflown two Dragon spacecraft , and they seem to recover the fairings at least partially. Reusing the full rocket is something we can do in maybe 5-10 years. That is a leap as large as from expendable aircraft to reusable aircraft.
Exactly: There were never expendable aircraft. No one built them because they would have been ridiculously expensive. With rockets there was a market even for expendable rocket. Imagine how large the market can be if we can use the rockets like airplanes.

SpaceX has not built a BFR yet. But the schedule will either be on time in 2022 or get delayed. The rockets will either work or fail. If we assume that BFR works then we can talk about the best source for the LOx. We can also contemplate which orbit would be best for the rendezvous.

BFR can go to the Moon and back with a lot of in-orbit refueling - with something like 2000-3000 tons of fuel launched from Earth. It can bring back something like 200 tons of payload from the Moon, maybe twice that amount if it gets refueled on the surface. Using that payload for fuel wouldn't make any sense even if we would have free and unlimited tanks on the Moon.From LEO you need 4.3 km/s to reach Mars. From the surface of the Moon you need about 3.5 km/s. If you want to mate a rocket from Earth with fuel from the Moon the fuel from the Moon needs 5.7 km/s delta_v just to reach LEO (3.2 of it can be done with aerobraking) and 5.7 km/s more if you want the system back on the Moon for the next trip - for a sum of 8.2 km/s for a Moon<->LEO shuttle. That is nearly what you need from Earth to LEO. And producing 1 ton of oxygen on Earth is much easier than producing it on the Moon. With chemical rockets, as long as you build the rocket on Earth and don't have a lunar space elevator or similar, it makes no sense to bring fuel from the Moon.
If we consider lunar space elevators, we can also consider concepts like the StarTram which can potentially launch things to space at basically the electricity costs once it runs. If LEO launches are as cheap as an airplane flight, there is no point in a Moon-based propellant production, you just launch more from Earth.

What are you talking about? With his prices and accelerating launch rate, Musk is already killing Proton and ULA. Arianespace is next to the chopping block. What "crash and burn"?

None of them will cease to exist. The US government wants to have two launch providers, Russia and the EU want to have their own rocket for government satellites. SpaceX will probably get an even larger share of the commercial market.

 

[stefan r]

From LEO you need 4.3 km/s to reach Mars. From the surface of the Moon you need about 3.5 km/s. If you want to mate a rocket from Earth with fuel from the Moon the fuel from the Moon needs 5.7 km/s delta_v just to reach LEO (3.2 of it can be done with aerobraking) and 5.7 km/s more if you want the system back on the Moon for the next trip - for a sum of 8.2 km/s for a Moon<->LEO shuttle.

The rendevous in LEO might work poorly. Earth-moon Lagrange 1 looks a lot better. From EML1 it takes 1.2 km/s to reach mars. The launch from lunar surface to EML1 needs 2.5 km/s. Getting to EML 1 from LEO requires 3.8 km/s. So the astronauts, rocket, and luggage (and methane?) lose 0.7 km/s when they make a detour to EML1.
The worst part would be landing the methane needed to lift oxygen.

If we consider lunar space elevators, we can also consider concepts like the StarTram which can potentially launch things to space at basically the electricity costs once it runs. If LEO launches are as cheap as an airplane flight, there is no point in a Moon-based propellant production, you just launch more from Earth.

If we go solar the electricity costs are lower on the moon. No clouds or atmosphere to block sunlight. The StarTram itself would work much better on the moon. The magnetic sled does not need to leave the surface so magnetic breaks can recycle the electricity. There is no need for a heat shield. The cargo does not hit an atmosphere. The ship does not have to fit into a tube. A lunar StarTram would not need to be elevated so there is no active support structure. Refrigerating kilometers of niobium-titanium conductor drains a lot of power. I have not seen a suggestion for magnetic launch Earth direct to Mars would likely be thousands of km.

Anything that makes launch to LEO cheap or easier will also make establishing lunar colonies/depots cheaper or easier.

 

[sophiecentaur]

There were never expendable aircraft.

Actually, there were several occasions during WW2 when troops and equipment were landed by (non-reusable) gliders. It made sense at the time, on an Engineering basis. Link.
There can always be a use for a non-reusable craft.

 

[Al_]

Why do you say Phobos instead of Deimos?

Interestingly, Deimos has a 30hr rotation. This means that people and plants might be able to adapt to the day-night cycle.
Plenty of dust for shielding. A spacecraft that rotates for simulated gravity on the journey to Deimos would be able to continue rotating there, even with added shielding. Super low gravity means takeoff might be possible even with ion drives! Possibility that the interior contains water ice, and the low-g makes digging easier. From Diemos, it would be possible to control robots exploring the surface of Mars in real-time, virtual realty style.

 

[Al_]

I can see Elon Musk becoming the 21st century version of Nicola Tesla

I think not. Elon Musk seems much more hard-headed than Tesla. His degree, if I recall, was Economics and Physics.

 

[Vanadium 50]

Elon Musk seems much more hard-headed than Tesla.

That's not setting the bar all that high.

 

[sophiecentaur]

I think not. Elon Musk seems much more hard-headed than Tesla. His degree, if I recall, was Economics and Physics.

I wasn't comparing the men so much as comparing the public reaction to them. I reckon Musk would stand every chance of the post of POTUS and would have members of both parties vote for him.

 

[Al_]

constructing The Gateway, a spaceport through the method of "Block Construction."

Nice video!
But, it looks like all the materials have to be launched from Earth. That's a lotta launches, and a load of money, even at Musk prices.
It mentions using extraterrestrial materials, but only after the gateway is built.
I think if we put 5% of the effort into Lunar mining, we'd reduce the costs of this station greatly.
Then, once it's built, with Lunar materials and robots controlled from Earth by virtual reality telemetry, this would be a great construction location and launch location for any Mars mission or further out. Although, as said, the Lagrange points might make more sense in terms of delta-V

 

[Al_]

The worst part would be landing the methane needed to lift oxygen.

Can't wait to see prospecting on the Moon. What if there are Lunar hydrocarbon deposits? Well, why not, there are primordial hydrocarbons on Earth?
Looks like there are - https://www.lpi.usra.edu/meetings/lpsc2011/pdf/1425.pdf
And if not, well, we can use a H2 / O2 rocket.

 

[sophiecentaur]

Can't wait to see prospecting on the Moon.

Very different from prospecting (and refining) on Earth. Getting there could be a minor problem, in comparison I think.

 

[mfb]

The rendevous in LEO might work poorly. Earth-moon Lagrange 1 looks a lot better. From EML1 it takes 1.2 km/s to reach mars. The launch from lunar surface to EML1 needs 2.5 km/s. Getting to EML 1 from LEO requires 3.8 km/s. So the astronauts, rocket, and luggage (and methane?) lose 0.7 km/s when they make a detour to EML1.
The worst part would be landing the methane needed to lift oxygen.

They lose 0.5 km/s when they are nearly there. You need about 9 km/s to go to LEO and 3.8 km/s more to go to EML 1. At that point you are nearly at TMI already. Refueling at EML saves your rocket the last 0.7 km/s only.

If we go solar the electricity costs are lower on the moon.

Installation costs are orders of magnitude higher. Yes, that is a plural.
The same applies to all fixed launch installations.

 

[mheslep]

What "crash and burn"?...

Musk has four kids, several ongoing business concerns where thousands depend on him, and yet says things like

There have to be reasons that you get up in the morning and you want to live. Why do you want to live? What's the point? What inspires you? What do you love about the future? If the future does not include being out there among the stars and being a multi-planet species, I find that incredibly depressing

He increasingly sounds more like the alienated kid who went to live in the Alaska wilderness (never seen alive again) than, say, Neil Armstrong.

 

[stefan r]

saves your rocket the last 0.7 km/s only.

That increases the payload ~25%. That removes the infra-structure for 20% of the rockets. Some parts of the "payload" would not be delivered (controls, frame etc). So passengers and cargo arriving and remaining at Mars would increase more than 25%.

Shuttles should be traveling back and forth from Mars. The launch to EML1 does not need food production, waste recycling or exercise spaces. You could pack people in tight.

I think methane is coming back from Mars. The Delta-v for Sending it to EML1 is only slightly higher than sending it to LEO. Maybe send it to both?

 

[mfb]

That increases the payload ~25%. That removes the infra-structure for 20% of the rockets.

So we can spend 20% of the project cost on the Moon if it delivers enough fuel. I don't see what you would save elsewhere - you would just put fuel in the now empty last stage. The filling hardware might lead to additional mass.

I think methane is coming back from Mars.

I don't think using more than the absolute minimum to get back from Mars makes sense. It is so much easier to send it to space from Earth.

 

[stefan r]

So we can spend 20% of the project cost on the Moon if it delivers enough fuel.

Somehow we got that backwards. The astronauts need an extra 0.7 km/s to stop off in L1. See post #71.

Is hard to make it work without non-rocket assist.

 

[mfb]

The astronauts need extra fuel but that fuel was supposed to come from the Moon. The rocket that launches from Earth can be smaller as it only has to go to EML 1. Unless we refuel in LEO with fuel from Earth, in that case we don't save rocket mass, we only save a bit of LEO refueling.

 

[ISamson]

In terms of my concern of my own safety... Definitely the Moon!
I don't want to be blown up by 'a bunch of crazy "experimental" scientists doing "important development work" next door or in my city'.
No thank you!

 

[mfb]

All rocket launches are done in safe distances from everything not related to the spaceflight.

 

[Ilythiiri]

First, about fuel part. I thought "why O₂ must mean oxidation, why not oxygen ion thruster?".
Then i googled this paper:
"OXYGEN-PROPELLANT PLASMA THRUSTERS FOR CIS-LUNAR ELECTRIC PROPULSION MISSIONS"
https://deepblue.lib.umich.edu/bitstream/handle/2027.42/76753/AIAA-1998-3994-519.pdf?sequence=1Anyway, it's still discussion about Moon base for space travel facilitation.
Including assumption that humanity needs to become spacefaring in the long run, all that with supervolcanoes, asteroids and whatnot.
Considering current political dynamics, "long run" may be a teeny bit misleading term - read up on https://en.wikipedia.org/wiki/Bronze_Age_Collapse, then http://www.sciencedirect.com/science/article/pii/S0921800914000615?via=ihub

Again, what Moon is and space station isn't - raw materials.
(Also, a point with stationkeeping costs for low mass/high surface area orbital structures like solar, mirror or EM funnels.)

The Earth has readily available raw materials on or near the surface

Yup, we need products, not raw mats.

So yes - a (business) plan for making usable products out of regolith/craters. Products with a discount of >6km/s deltaV.
https://i.stack.imgur.com/ZLpuN.png - cislunar orbits and deltaV budgets in 1 pic.
>6km/s discount, because fuel used to get to GEO is not wasted, spacecraft within the scope of this discussion is going to NEO and beyond.
>6km/s discount, because getting to LLO from Moon is not just smaller gravity well. It's also no drag = no impulse loss over time.

People seem to ignore just how totally different every aspect of life would be away from Earth.

We're not talking about "life" - living there, we're talking about industry.
1.25s lag is not significant for remote operation.
Robotic assemby chambers are way beyond prototype phase.

For industry, vacuum is beneficial - no convective heat loss(more problems with cooling but Mr.Stirling may help in more than 1 way), no pesky oxidation for materials and machines.
I also consider vacuum as a "product". Deep vacuum is expensive to make and maintain; it's necessary for quite a number of industrial applications, and desirable but not cost effective for a lot more(including 3D metal printing). Distilling with "free" vacuum and "cheap" heat/insulation would look different. Quotes because deltaV tax.

What products?
Structural materials, shielding, tanks, wiring.
https://www.sawe.org/papers/3662 - "...Most spacecraft structures represent approximately 20% of the total spacecraft mass..."
3D printing is way beyond prototype phase.
And yes, fuel - it needs not be oxygen. No drag = high I_SP low thrust shines.
Ion thrusters are way beyond prototype phase.

Drone ion tug(solar powered), shuttling LEO - EML1.
Modular engineering, 3 drones, 2 teleoperated assembly chamber, 2 3D printers(using lunar dust to print more drone frame parts, for starters).
Hi-tech parts for more drones/printers/chambers.
Plus, almost insignificant moment of power/heat supply infrastructure for all this (:
1 Falcon9 lifts 8300kg to GTO.
Unspecified amount of years and failed attempts later - our first Moonshine distillery/melt separator is up and running!

If we need to lift only hi-tech from Earth - electronics, drives, batteries, sensors, coatings, specialized alloy parts - the price of spacecraft , industrial machinery and drones in situ drops. Mass (relative) abundance would change a number of considerations in design stage.

I am obviously aware of multitude of technical challenges - material properties in vacuum like outgassing and sticking and ablation, moon dust, statics, solar wind, etc. And challenges bring opportunities(ex. sticking = welding things together).
Also I am obviously aware of multitude of technical challenges we're not aware of (: - because we're not there to look.

Huge pile of know-how is needed to make it all feasible and afterwards profitable.
Yet, there is no other way to get this know-how - only testing engineering solutions in practice works.

 

[sophiecentaur]

https://lunarvolatiles.nasa.gov/wp-content/uploads/sites/6/2015/10/Lunar-Prospecting-Overview_Colaprete.pdfwhich shows people have been thinking about the problem of prospecting on the Moon. It makes quite good reading but it is a shame that there is no mention of timescale. At least, none that I could find. As timescale is a 'known unknown', I would have expected it to be discussed.

 

[Al_]

1.25s lag is not significant for remote operation.

Erm, I wouldn't go that far.
It is very hard to control things consistently without collisions etc. with that degree of lag.
But, combining recent driverless car collision avoidance, and robotic manipulation skills that exist today, with human oversight and slow control where needed, I think we could have lunar robots controlled from Earth doing pretty much anything in the fields of prospecting, mining, refining, manufacturing and construction. That is, without a huge leap in the technology from where it is today.

Furthermore, a lag like that can be simulated on Earth. Is there a lab somewhere that has simulated lunar soil, vacuum, the lag, smart robots, VR, AI, and some prospecting tools? Surely not too expensive to do?