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Old May 31st 17, 07:08 AM posted to sci.space.policy
William Mook[_2_]
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Default Mining the moon for rocket fuel to get us to Mars

On Wednesday, May 31, 2017 at 4:09:40 PM UTC+12, David Spain wrote:
On 5/28/2017 10:21 AM, Jeff Findley wrote:
First, this isn't my "subject", it's the title of this article:

Mining the moon for rocket fuel to get us to Mars
May 14, 2017 8.04pm EDT ?Updated May 18, 2017 9.01am EDT
http://theconversation.com/mining-th...-to-get-us-to-
mars-76123

I saw this article (or a variation of it from another online
publication) on Twitter. I replied something to the effect that this
article glosses over all of the hard stuff, like the fact that the lunar
soil and rock is horribly abrasive and that mining equipment isn't
anything like the lightweight rovers that NASA/JPL has flown in the
past. For crying out loud, JPL keeps using ALUMINUM for the rover
wheels to keep them light, even though they're wearing holes in the
things after less than 100 miles. Mining equipment can't be that weak!
Anyway, I replied that mining equipment is *really heavy* because it's
made of steel and hardened steel.

The response by one Twitter follower was along the lines of, "That's why
the mining equipment will be built on the moon from local materials".


At that point, "I couldn't even". I mean WTF?


There is quite a lot of "exercise for the student" type problems here.
There is a lot of work & study needed about lunar industrialization for
sure including mining.

One factor that may get some consideration down the road is the idea of
what I'd call incremental industrial "densification". The idea being
that lightweight gear is first sent up
that has limited capacity for manufacture of the "heavy gear". Heavy
feed stock ( steel, etc) would then be sent
up subsequently for lunar manufacture. Enabling a heavy mfg. capability
via bootstrapping. At this point my conjecture
is pretty much a total hand wave, but I could at least see it as a
possibility. Would need some math to determine if
this would be preferable to just shipping up the heavy equipment
directly. I suppose if the scale is massive enough
the bootstrap approach might be the only really feasible one. Further
study needed....

But no, we'll do it all with SLS. Why waste money on studies?

Dave


Composite Tank Studies

http://www.compositesworld.com/artic...-scores-firsts

Aerospike Engine Studies

https://www.youtube.com/watch?v=-0Y0FS8Z1Qk

If the studies are a pre-amble to doing a thing! They're essential to develop efficient tooling and procedures.

Electron facts:
• Lift off mass: 12,550kg
• Propellant mass: 11,300kg
• Propellants: Liquid oxygen and kerosene
• Length: 17m
• Diameter: 1.2m
• Top speed: 27,500kph
• First stage engines thrust (s.l./vac) : 153.5 / 184.6 kN (9 engines)
• Second stage engine thrust (vac) : 22.2 kN
• Nominal orbit: 500km circular sun synchronous
• Isp 353 sec
• Ve 3.46 km/sec.

12,396.69 kg Take Off Weight

9,959.04 kg propellant - First Stage
7,161,56 kg LOX
2,787.48 kg Kerosene

1,074.01 kg - Stage 1 Structure Weight

1,363.63 kg Total Stage 2 Weight

1,095.49 kg Propellant Weight
787.77 kg - LOX
307.72 kg - Kerosene

118.14 kg - Stage 2 Structure

150.00 kg - Payload

Using two First Stage Boosters as Liquid Strap-On Boosters, increases payload to 645 kg to the same orbits as the single unit.

Using four First Stage Boosters as Liquid Strap-On Boosters, increases payload to 1,625 kg to the same orbits as the previous launchers.

* * *

Increasing from 1.2 m diameter system to a 5.5 m diameter system and from 17 m length to 77.92 m length, increases launch weight from 12,400 kg to 1,194,000 kg and payload weight from 150 kg to 14,440 kg.

1,193,576.39 kg Take Off Weight
958,874.91 kg Propellant Weight
689,528.02 kg - LOX
269,346.88 kg - Kerosene
103,408.08 kg - Structure Stage 1

131,292.40 kg - Stage Two Total Weight
105,476.24 kg - Propellant Weight
75,848.08 kg - LOX
29,628.16 kg - Kerosene
11,375.89 kg - Structure Stage 2

14,442.27 kg - Payload

A three element common core booster of this size using these propellants lifts 62,100 kg into LEO.

A seven element common core booster of this size using these propellants lifts 156,450 kg into LEO.

A cost of $2,000 per kg for structure translates to $2.4 million for each of the smaller vehicles. Another $1.1 million to run each campaign, $3.5 million total out of pocket costs. Insurance and other costs add to this.

The larger vehicle costs $187 million to build, and $3.0 million to run each campaign.

* * *

Reusable systems, similar to SpaceX approach, using inflatable wings and tow planes, rather than floating launch platforms, to bring parts and pieces back to the launch center, and allowing them to land vertically like the tail sitter aircraft of the 1950s.

Highly reusable with 1,900 uses per airframe, a CAPEX of $100,000 per flight for the larger vehicle, $1,260 per flight for the smaller vehicle. Fast turn around with 100 flights per year, a 19 year life span for the vehicle. Total costs run $1.5 million for 150 kg - $10,000/kg and $3.1 million for 14,400 kg - $215/kg

The larger clustered vehicles are $3.3 million and $3.7 million respectively. This reduces cost to $53/kg and $24/kg respectively.

For the smaller clusterd vehicles prices are $2,500 per kg and 1,120 per kg respectively.

156.45 tonnes at 22 MW per tonne launches a power satellite capable of producing 3.44 GW continuously on orbit.