moon exploration with the deep space gateway the lunar

PROJECT PAPER IN SD2905 - HUMAN SPACEFLIGHT, TEAM RED, THE LUNAR EXPLORATION ITSELF 1

Moon exploration with the Deep Space GatewayThe Lunar exploration itself.

Alexis Philippe, Kim Koponen, Maxime Astruc, Philipp Bonkoss

Abstract—Since the end of the Apollo program, no one has set foot on the Moon again. For decades, no humanmissions to the Moon have been prepared. Today, NASA launches its Deep Space Gateway project which consists ina space station in the vicinity of the Moon. This station is an ideal starting point for Lunar exploration by humans andfurther human space exploration. A conceptual study of this project is developed in this report.

F

1 INTRODUCTION

THE Moon is the closest celestial body tothe Earth and has fascinated centuries of

people. But it was not until 1969 when the firsthuman, Neil Armstrong, Mission Commanderof the Apollo 11 mission and Lunar ModulePilot, was able to step out on the Moon.

This project takes a closer look on thepossibility to live on the Moon by buildinga Lunar base and extracting water fromthe surrounding Lunar soil. The base isintended to house a crew of four people,and crew members would stay duringperiods of six months. This would providea great opportunity to examine and evaluatethe psychological and physical impacts onhumans during long-term stays on a differentcelestial body as well as provide a testingground for technologies for future missions.This would be a stepping stone towards Marsand even deeper space manned missions.

1.1 BackgroundThis Lunar base would be a first step towardsan even more desired and bold goal which isto send people to Mars, and eventually makethem live on the Martian soil. The thoughtbehind establishing a Lunar base first is theability to test out technologies and theories ina place where humans have been to before,and is closer to Earth. Here the crew couldexperience how it is to live on a foreign

celestial body for a longer period of time.Another thing that would be tested here iswater extraction, from the Lunar regolith sincethere is ice embedded in the soil. This processcould also be used on Mars, or to mine wateron asteroids as well.

Being able to mine water in larger quantitieson other planets or in space would providea big benefit for space missions, as therewould be no need to send water from theEarth anymore, assuming it is even possible.Hopefully this would make possible theexpansion of the Lunar station and in thefuture to start to produce liquid oxygen andliquid hydrogen as fuel to the Deep SpaceGateway. Water and fuel sources directlyin space would lower the launch masssignificantly for a Mars mission and wouldalso favor the setting up of missions towardsdeep space.

1.2 Aim of the project

This conceptual study of the Deep SpaceGateway (DSG) project focuses on the humanexploration of the Moon. It is divided into fouraxis : the DSG design, the transport systembetween DSG and the Lunar surface, the Lunarexploration itself and the overall coordinationof the previous axis. This document presentsto the reader the Lunar exploration itself, onwhich our study will focus on.

Our main objective is to make possible


for a four people crew to live on the Moonduring six months. This challenge raisesdifferent questions, as where to explore theMoon, the life support system for our crew,how to protect the crew from the spaceenvironment, what scientific experiments havebeen chosen to be conducted on the Lunar soil,the power required and so on. So as to fulfillthose requirements, our study will focus on theconstruction of a Lunar base and water mining.

1.3 Structure of the reportThe structure of this report is divided intoIntroduction, Construction of a Lunar base, Miningof regolith and Conclusion sections.

The Construction of a Lunar base section givesan insight of where the base will be built,as well as a description of the method used.Furthermore, a description of the Lunar soil isgiven, and the Water mining section describesand compares two methods of collecting water.Finally, in the Conclusion section, it is discussedwhat development is to expect for this base interms of autonomy and further studies.

2 CONSTRUCTION OF A LUNAR BASE

2.1 Location of the baseThe selection of the location of the base is ofgreat importance. It has indeed consequenceson what is possible to do there, and it hasalso an impact on the trajectory used fromthe DSG to the Lunar soil. Two main criteriafor the location of the Lunar base have beenstudied : concentration of ice in the soil andthe amount of sunlight. As water extraction isone of the goals of this project the concentrationof water is prioritized. This criterion puts thebase around one of the poles which are morerich in water [1].

However, the need for sunlight in order topower the base using solar power severelylimits the options for base locations aroundthe poles. The Shackleton crater is the bestoption for the Lunar base as a part of the ridgeof the crater is almost continuously lit. TheShackleton crater is almost in the center of the

south pole. Its exact location and shape canbe seen in Figure 1. The base can be built inthe crater, below its ridge, and the solar panelsfor the power generation can be placed on theridge so as to benefit from maximum sunshine.

Fig. 1. Shackleton Crater

2.2 RegolithRegolith is the thick layer that covers the entireLunar surface. It is composed of fragmentaland unconsolidated rock material. Its charac-teristics are the following [2] :• Regolith (fragments of meteorite impacts)

of the size of the ash• Average size about 19µm (40% smaller

than a hair)• Composition: SiO2 (44.72%) and Al2O3

(14.86%)• Properties: magnetic, very porous, ser-

rated, sharp, allergenic.• There is also iron, calcium and magnesium

bound in ores such as olivine and pyrox-ene.

NASA estimates to 0.01 kWh the electricalenergy needed to extract 1 kg of regolith andthat one percent of regolith is icy water. [3] Soas to extract the icy water from the regolith,the whole has to be heated to 100◦C abovethe ambient temperature to transform the icywater into gas. The water is then separatedfrom the regolith and can be collected andstocked after filtration.

2.3 The Lunar base itselfA station is indispensable for long stays onthe Moon. The crew as to be protected from


the harsh environment of space, that is to sayin our case vacuum, radiation and microme-teoroids or small debris. Therefore, knowingthe need, the Lunar base is designed. Eachbuilding is big enough to host a crew of fourastronauts and provides protection, housing,life support systems, as well as a work andrecreation areas. The housing, life support andrecreation systems are similar to the ones ofISS, and will then not be further detailed inthis report.

An inflatable dome is used to start buildingthe base. The advantage of this is that only arelatively small and lightweight capsule (1000kg) has to be brought to the Moon. The inflat-able dome is stored in the capsule and is theninflated on the Lunar surface. After that, thecapsule serves as airlock for the building.

The dome has an inner diameter of 12 m andthe exterior shell of the inflatable dome is tightand pressure resistant. However, this is notsufficient to protect the inside of the dome fromradiation and micrometeoroids. Therefore, anouter shell of Lunar regolith is build with a 3D-printing technology, as described in sections 2.5and 2.6. The printed wall has a thickness of 0.8m hollow closed cell structure, which providesbest mechanical properties at a minimum ofused material, and guaranties a shelter frommicro meteoroids. To get a sufficient protectionfrom radiation, another shell of 0.7 m of looseLunar regolith is put by the excavation roveron top of the printed shell. Not printing thewhole wall has the advantage that you have tobring less binder from the Earth to the Moon.[4] [5]

An overview of what the building wouldlook like is given below in the Figure 2.

Fig. 2. Lunar base [6].

2.4 Power supply of the Lunar baseSolar panels are chosen to power the base.Because of their cost to energy performance,they are a proven technology and also a saferchoice than nuclear energy since there is noneed for handling the radioactive waste.

The solar panels are placed around therim of the Shackleton Crater, since this areareceives sunlight around 85% of the time [7].Multijunction GaAs solar cells would be usedin the panels. These cells have an efficiencyof around 30% and even achieved higherefficiencies in laboratory settings [8]. A powerreserve consisting of lithium ion batteries alsoprovide power to the base when the solarpanels are not lit.

The power consumption of the base isestimated to be around 50 kW. This estimationis based on the power consumption of the ISSweighted for a crew of four people insteadof six and on the minimum requirement ofenergy for a small crew on a similar mission[9]. With a 30% efficiency, the solar panels areexpected to generate about 350 W/m2. Thesolar energy output for an Earth-like orbitaverages around 13650 W/m2 [10]. This resultsin an area of at least 143m2 of panels to powerthe base. However, an area of around 175 m2

has to be sent to the Moon for safety reasons,due to the need of recharging the batteriesafter a period of darkness (Lunar night) andsolar panel degradation.

2.5 3D-printingThe 3D-printing system is selected becauseit offers new possibilities and advantages.Compared with ready to use modules, it is notnecessary to bring large structures from theEarth to the Moon. As a result, maintenancecan be performed on site and walls canbe build as thick as needed to shield fromradiation and micrometeoroids. Furthermore,the amount of manipulated material is muchless important with this method than if onewants to build an underground shelter whichrequires a lot of drilling. This then also resultsin a positive energy aspect, since drilling is forinstance really energy demanding.


For all of these reasons, we orientate ourwork on the ESA research on 3D-printing onthe Lunar surface. The 3D-printing systemis installed on an independent movablerover. The printing process is detailed in thefollowing. 3D-printouts are built up layer bylayer. As printing material, Lunar regolithdust and a binding solution are used. Lunarregolith dust is composed of various typesof particles, such as rock fragments, mono-mineralic fragments and various kinds ofglasses. A more detailed description is givenin Section 2.2. The density is about 1.5 g/cm3[11]. To print one layer, regolith is mixed withthe binder, which is made out of magnesiumoxide and salt. Due to the environmentalconstraints, the nozzle to insert the binderinto the dust is placed under the surface ofthe regolith layer. This method permits toreduce the sublimation of the binder whichwe have in a limited amount brought fromthe Earth. With 3D-printing technology it ispossible to print various cross section designsof the wall. Aiming to decrease the amount ofbinder needed and to ensure good mechanicalproperties of the wall, a hollow closed cellstructure is used [4][5].

Two rovers are used to print one building,which permits to build the station within threemonths.

2.6 Lunar Rover

During the missions, we aim to explore theLunar surface, build the Lunar station, performgeological analyzes of the Lunar soil and col-lect large amounts of regolith for the waterextraction. A rover such as the one shown inFigure 3 is a perfect and versatile solution.The most important task of the rover once thebuilding is finished is to collect regolith fromthe Lunar surface. Therefore, the rover worksas an excavator with a shovel in its front, asseen in the Figure. The shovel is able to carrya 110 kg load.

Furthermore, the rover has a drilling unitto get soil samples. A further useful tool is aconnectible robot arm. With this arm, the rovercan plug a connecting expandable tube from

the Lunar station to the door of the crewedlanding module. This arm can also assist ina lot of operations. It is divided into fourmovable pieces, has a total length of 5 m andcan rotate around 6 axes.

Finally, the rover is powered by two radionuclid batteries as the one used on the Marsrover Curiosity [12]. It can then work andinteract absolutely independent from sunlightor recharging. The batteries provide 1.5 kWfor 6 months at a 50 % workload. The roverneeds 1.5 kW at a mass of 1250 kg [13]. Forvery power intensive tasks, such as breakingmaterial from the ground, it has an additionalLi-Ion battery. In long term thinking, the bat-teries can be exchanged with water fuel cellsif the water production from regolith workssufficiently well.

Fig. 3. 3D-printing and multipurpose rover [6].

3 MINING OF REGOLITH

3.1 Pre-study notions

3.1.1 Water management

The following Table 1 details the various needsof water for one person each day in space.

To be as close as possible to realistic tech-nologies, the values of the water recycledthrough the Sabatier Process and through theWater Recovery System are the ones providedby the NASA for the ISS. One can obtain theamount of fresh water per day by subtractingthe needs of water by the amount of waterrecycled, which gives 6.5 kg/day for a crew of4 persons.


TABLE 1Water cycle [14] [15] [16]

Need kg/day/personFood 1.2

Drinking 1.3Toilet flush 0.89

Laundry 0.5Dishes 0.89

Eva 0.08Creation of O2 1.41

Total 6.28Total H20 recycle (Sabatier process) -0.86

Total H20 recycle (Water Recovery System) -3.8Total of fresh water needed 1.62

3.1.2 Regolith ice content

One can assume that the Lunar soil is homo-geneous. This approximation will be largelyused in 3.2.3 so that to simplify the model, butsince the ice content varies depending on themining area, we wish to be able to determine atleast approximately the ice content of a regolithsample.

To do so, consider a container (dimensionsa, b and c) filled with regolith. Using a balancescale adapted to the Moon gravitational field(around gEarth

6), we then know both the volume

V = a.b.c and the mass mtot of the regolithsample.

Consider now the following data:

TABLE 2Density data ρ.

LDA ice [17] Lunar soil [11]Value [kg/m3] 940 1500

In this Table, LDA stands for Low DensityAmorphous, since we expect to find ice underthis state in the Moon environment.

Since we have: mtot = XρLDA + (V −X).ρsoilwhere X is the volume of ice in the sample, wethen have:

X =V.ρsoil −mtot

ρsoil − ρLDA

(1)

and:

content =X

V(2)

An example is given in Table 3:

TABLE 3Example of calculation of the ice content of a

sample.

Length*width*depth [cm3] mtot [kg] % ice content40*40*20 47 5.6

This method is nonetheless approximativesince it doesn’t take small rocks into accountfor example. It has then to be improved, butgives good basis to a new and more accuratemodel.

Moreover, the weight scale needs to be pre-cise enough to catch up with the weight varia-tions due to the ice content.

3.2 Methods of extraction3.2.1 The dish Stirling

Fig. 4. Photo of a solar dish Stirling [18].

The dish Stirling is the first technologicalproposition to heat the regolith and extractwater from it thanks to the thermal energy ofsunlight. Archimedes used the same type of


device to concentrate the solar rays to burnthe sails of the Romans in order to defendthe city of Syracuse in Sicily. As shown abovewith Figure 4, the solar energy shines onto thereflective concentrator and is focused throughthe aperture of a receiver localized at the focalpoint of the dish. Since, there is no atmosphereon the Moon, the radiations from the Sun arenot absorbed and could be fully used. Theregolith would be thus upon the collector, andthe heat transforms the icy water into gas. Cur-rently, the overall efficiency of such a devise is0.53 [19] and solar radiation provide a power of1366 W/m2 on the Moon. Moreover, 117 kW ofheat are needed to separate 1kg of water fromthe regolith. Therefore, a two meter diameterdish would provide 1476 W of heat, enoughto extract the 12 kg of water per day from theregolith.

3.2.2 Study of two types of microwavesAnother method to mine water is to use amicrowave to heat the regolith. The principle isthe same as for the parabolic mirror : thermicenergy is given to the regolith to increase itstemperature until the ice sublimates. Then, awater recovery system is used to collect thevapor and stock it under liquid or solid form.

From there, two options were studied :the first one is to use an open bell-shapeddevice which would be put on the floor tosend waves directly into the soil and collectthe water directly within the bell. The secondoption is to use a closed device which lookslike industrial microwaves already used onEarth. Both methods have pros and cons: anopen device requires to send waves in thedownwards direction. Since the waves areevanescent, the result is that the losses aregreat and a lot of energy has to be provided tocounterbalance these losses. It is not the case ina closed microwave where the electromagneticwaves are reflected on the walls of the device,however this method requires to carry regolithinto the device. Those considerations aresummed up in Table 4.

Given the results of this Table, a closedmicrowave is a better option for this mission,as it needs way less energy to heat the regolith.

TABLE 4Comparison between the open and closed

microwaving devices.

Device type Advantage Drawbackopen no need to collect high energy

regolithclosed lower energy need to collect

regolith

The closed device is then studied in 3.2.3.

3.2.3 Microwaving icy compoundsFor this study, the microwave is considered as ablack box whose input is electric energy (pro-vided by an external source), and the outputis heating energy (given to the regolith in thedevice). As announced in section 3.1.2, we willfrom now on consider that the lunar soil ishomogeneous, constituted of regolith withoutsmall rocks and containing 1% mass of ice,content given by the NASA report [3].

So as to calculate the heating energy whichhas to be provided to the frozen regolith, onecan proceed to a thermodynamic reasoning.Considering that our system is the the frozenregolith, we can determine the variation ofenergy due to the heating from a temperatureT1 to a temperature T2 (temperature of sub-limation of ice water in vacuum [20]) of theentire system, and then calculate the variationof energy due to the sublimation of the LDA iceonly (first to sublimate). The heating processis assumed to be isobaric, which permits toestablish that:

Q = ∆H = ∆HT1→T2 + ∆Hsublimation (3)

where ∆H is the variation of enthalpy andQ the heat received by our system. Then:

∆HT1→T2 = (mLDA.cp−LDA+mregolith.cp−regolith).∆T(4)

and, for the ice only:

∆Hsublimation = (∆hfusion + ∆hvaporization).nLDA

(5)


where nLDA = mLDA

MLDAis the number of moles

of ice in the sample, MLDA = 18 g.mol−1 is themolecular mass of the LDA (frozen water), ∆his its molar latent heat of change of state, cp isthe isobaric mass heat capacity of a body and∆T = T2 − T1.

If one wants to produce 12L of water per daywith this process (3L per person of the crew fora daily food and water drinking consumption,with a margin compared to Table 1), the needin regolith is of mtot = mLDA

icecontent= 12 tons. As

a reminder, 1L of water has a mass of 1kg,and 1kg of ice provides 1kg of water. In thefollowing calculations, cp−regolith is replacedby cp−sand which corresponds to a much moreknown silicate compound.

For the calculations, the following values willbe used:

TABLE 5Comparison between the open and closed

microwaving devices.

Parameter Valuemtot [kg] 12000

MLDA [g.mol−1] 18T1 [K] 100T2 [K] 150

cp−sand [J.kg−1.K−1] [21] 800cp−LDA [J.kg−1.K−1] [21] 2090∆hfusion [J.mol−1] [22] 6010

∆hvaporization [J.mol−1] [22] 44000

Given those figures, we calculate an energyneeded of 36.4 kWh. This energy, for 12L ofwater, can also be expressed for one liter : 3.0kWh. This result is consistent with the onegiven by NASA in its report (2.8 kWh.kg−1)[3]. The variation might be due to differencesin data, such as the heat capacity of regolithreplaced by the one of sand. The thermalpower needed to provide such an amountversus time is then given by the curve ofFigure 5, obtained with Excel.

As one can see in Figure 5, the shorterthe time, the higher the power. The powerincreases drastically below five hours ofproduction. The trend curve permits to obtaina direct formula to calculate the power for a

Fig. 5. Power required to produce 12L of waterversus time.

given time : P = 363.58t

, where P is in kW andthe time t in hours.

3.2.4 Comparison of the methodsTwo methods to extract water from regolithhave been developed in 3.2.1 and 3.2.3. Bothmethods heat the icy regolith to do so, andthen require to collect it from the ground(thanks to a nuclear powered rover as detailedin the 3D-printing section). The two methodsalso require a system to collect, filter andstock the water. But there are still differentaspects on which these methods are completelydifferent.

TABLE 6Comparison between the dish Stirling and the

microwave devices.

Device type Advantage DrawbackDish Stirling low energy quite large

several devices light dependentMicrowave light independent quite large

modular production high energy

Table 6 details the advantages anddrawbacks of both methods. A commondrawback is the size of the devices. Even if notknown precisely, we expect them to be ableto carry and heat up big amounts of regolith.Concerning the energy consumption, the dishStirling shows all its efficiency : since it isonly reflecting the solar rays (and maybe track


the Sun), the device does not need energywhereas the microwave is all the time turnedon to work. However, the microwave is muchmore practical since it is not dependent onthe Sun, whereas the dish Stirling cannotwork during the Moon nights (around twoterrestrial weeks). This can be counterbalancedby the fact that, since the dish Stirling doesnot need energy, one can build several ofthem in different areas so that we are able toensure a constant production. Nevertheless,the microwave has another advantage : itsproduction is modular, which means one canproduce more water in less time if necessary.

A typical off-nominal case would be atemporal breakdown of the device or pollutedwater. In the case of the dish Stirling, we haveno possibility to fasten the water extraction.With the microwave, this is feasible byincreasing the power input. Thanks to themodel given in 3.2.3, a member of the crewcan easily determine the quantity of regolithhe needs to collect and the power requiredjust by entering the quantity of water neededand the time available.

All of these reasons lead us, for the beginningof the mission, to choose the solution of themicrowave which is more modular. Duringa crisis scenario, extra batteries could beused to supply the extra power required(mechanical batteries for instance). One mighthowever be aware that this solution is morerisky since we may have only one microwavefor energetic reasons (power supply is limited).

3.3 A step forward : extraction of fuel andoxygen from regolith

The production of hydrogen and oxygenfrom asteroids, moons or others planets thanthe Earth is a crucial step for deep spaceexploration and for the self-reliance of a spacecrew. This part is to be considered for ourmission only if the phase of water productionis a success. Moreover, the aim would be toprovide enough fuel to do a round-trip fromthe Moon to the DSG with the spacecraft.

3.3.1 First solutionThe first solution is to extract the regolith, thenthe water from it and finally do an electrolysisto obtain pure hydrogen and pure oxygen.Table 7 below gives in details the amountof energy required to produce hydrogen andoxygen with this solution.

TABLE 7Solution 1 [23][24]

EnergyExtraction of regolith then water 3.8 kWh/kg of H2O

(electric + thermal)Production of H2 electrolysis 45 kWh/kg H2 (electric)

Production of O2 from electrolysis 5 kWh/kg O2 (electric)Total energy required 83 kWh/kg H2

9.2 kWh/kg O2

3.3.2 Second solutionThe second solution is to extract the fueldirectly from the regolith, through diversereactions. Since oxygen represents at least 40%of the Lunar soil (in mass), one can understandthe interest of this method. Dioxygen wouldbe produced thanks to the reduction of silicondioxide SiO2:

SiO2 −→ Si + O2

Moreover, the grains of the Lunar regolithabsorb the hydrogen of the solar winds andcan release it when it is heated to 700◦C. Theconcentration of hydrogen is estimated to 100ppm in the Lunar soil. Table 8 below givesin details the amount of energy required toproduce hydrogen and oxygen with this secondsolution.

TABLE 8Solution 2 [23]

EnergyExtraction of regolith 0.01 kWh/kg regolith (electric)

Extraction of H2 2,25 kWh/kg H2 (thermal)Reduction of SiO2 9.31 kWh/kg O2 (electric)

Total energy required 2,35 kWh/kg H2

9.85 kWh/kg O2


3.3.3 Comparison and selection of a solutionOne can notice that both solutions requireroughly the same amount of energy to produce1kg of oxygen. However, the second solutionrequires much less energy than the first one toextract 1kg of hydrogen (2.35 kWh/kg of H2

against 83 kWh/kg respectively, that is to say35 times less). This can be explained by theimportant amount of energy that is requiredto heat the regolith to release the hydrogen.Furthermore, the concentration of hydrogen issignificantly lower than icy water in regoltih.All in all, the second solution is the mostefficient solution to produce fuel.

3.3.4 Estimation of powerAssuming that a one round-trip with the cargois done every three months, we can find thepower needed to extract the necessary amountof fuel. According to the transport group, 8700kg of hydrogen and 34800 kg of oxygen areneeded to achieve the round-trip. The powerneeded to produce the fuel is equal to thepower to produce both hydrogen and oxygen.If we assume that the fuel production operates24 hours per day during 3 months, thus thetotal power needed is 169 kW. One can noticethat this is just an estimation but such anamount clearly emphasizes the need to changefrom solar electricity to a new major source ofelectricity to produce fuel, for instance nuclearelectricity.

4 CONCLUSION

The Shackleton crater has been chosen to printour building due to the high probability to findbig quantities of icy regolith there. Moreover,this crater offers a maximum sunlight on itsrim where the solar panels, which power thebase, are located. Thanks to the 3D-printingrovers, the setup of the base will be entirelyautonomous before the crew arrives, and thendirectly provides a protective shell. The hous-ing module provides every necessity for thecrew, including life support system with recy-cling of water and oxygen. Nuclide batteriesare the main source of energy for the rovers for

independence and mobility. Extracting water isof major importance during this mission andis done by microwaving the regolith, whichrequires a lot of energy but has the advantageto be independent from sunshine.

All of this constitutes the main objectivesof the mission. However, many improvementscan still be made: wastes could also be mi-crowaved instead of being just stocked away,so as to extract even more water and reducethe losses. Since the microwave already runs allday long, a new one should be built to fulfillthis purpose, but this is a way to increase thereliability of this system thanks to redundancy.

Concerning the base itself, a new buildingcould be built, either at the same location, ormore possibly in a new area of the Moon.More research could then be made, for examplein space farming which is another key pointof deep space exploration, and this new areawould be explored as well. The major needfor this is to bring a new crew of astronautsfrom Earth, but exploring different areas of ournatural satellite is the best way to learn about it,and might provide us new tools to understandthe formation of our Solar system and universe.


REFERENCES

[1] W.C. Feldman, Evidence for Water Near the Lunar Poleshttps://www.nasa.gov/pdf/230733main Lunar Water

Ice all.pdf [Accessed 19 Feb. 2018][2] Le problme de la poussire lunaire

http://www.de-la-terre-a-la-lune.com/apollo.php?page=regolithe [Accessed 22 Feb. 2018]

[3] Lunar architectureNASA, https://www.nasa.gov/pdf/140635main ESAS 04.pdf,Table 4-26.

[4] Lunar stationESA, http://www.esa.int/Our Activities/Space EngineeringTechnology/Building a lunar base with 3D printing.

[Accessed 20 Feb. 2018][5] 3D Printing

ESA, https://gsp.esa.int/documents/10192/43064675/C22835ExS.pdf/ce5dca46-e4c9-4980-a9d3-918decd24bd0. [Accessed11 Mar. 2018]

[6] ESA, http://www.esa.int/Highlights/Lunar 3D printing.[Accessed 20 Feb. 2018]

[7] Michiel Kruijff, Peaks of Eternal Sunlight on the Lunar SouthPole http://adsabs.harvard.edu/full/2000ESASP.462..333K[Accessed 19 Feb. 2018]

[8] Katsuaki Tanabe, A Review of Ultrahigh Efficiency III-V Semiconductor Compound Solar Cells : MultijunctionTandem, Lower Dimensional, Photonic Up/DownConversion and Plasmonic Nanometallic Structureslehttp://www.mdpi.com/1996-1073/2/3/504/pdf[Accessed 22 Feb. 2018]

[9] Lunar Architecturehttps://www.nasa.gov/pdf/140635main ESAS 04.pdf[Accessed 23 Feb. 2018]

[10] Greg Kopp & Judith L. Lean, A new, lower value of totalsolar irradiance: Evidence and climate significance http://onlinelibrary.wiley.com/doi/10.1029/2010GL045777/pdf[Accessed 22 Feb. 2018]

[11] C. Meyer, Lunar regolithNASA Lunar Petrographic Educational Thin Section Set,2003.

[12] Radio Nuclid Batteryhttps://en.wikipedia.org/wiki/Curiosity (rover).[Accessed 11 Mar. 2018]

[13] Rover SherpaSherpa, http://www.sherpaminiloaders.com/eng/models/sherpa-100-eco/. [Accessed 11 Mar. 2018]

[14] Layne Carter, Status of the Regenerative ECLS Water Recov-ery System. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100033089.pdf

[15] Michael Curie, International Space Station Water Sys-tem Successfully Activated. https://www.nasa.gov/home/hqnews/2010/oct/HQ 10-275 Sabatier.html

[16] Colorado University, MARS OR BUST, LLC https://www.colorado.edu/ASEN/project/mob/MOBFinalReport.5.pdf

[17] Amorphous iceWikipedia, https://en.wikipedia.org/wiki/Amorphous ice.[Accessed 20 Feb. 2018]

[18] SBP https://www.sbp.de/en/project/10-kw-dishstirling-eurodish-country-reference-unit-2/

[19] E. Gholamalizadeh ID and J.D. Chung, Exergy Analysis ofa Pilot Parabolic Solar Dish-Stirling System www.mdpi.com/1099-4300/19/10/509/pdf

[20] https://www.physicsforums.com/threads/sublimation-temperature-of-water-in-vacuum-150k.798322/ [Accessed20 Feb. 2018]

[21] P. Dellouve, Cours de thermodynamiqueCPGE Blaise Pascal

[22] Water (data page)https://en.wikipedia.org/wiki/Water (data page)[Accessed 20 Feb. 2018]

[23] NASA, NASA’s Exploration Systems Architecture Studyhttps://www.nasa.gov/pdf/140649main ESAS full.pdf

[24] D. Rapp, Human Missions to Mars: Enabling Technologiesfor Exploring the Red Planet New York : Springer BerlinHeideberg

moon exploration with the deep space gateway the lunar

Documents