1 AIAA Space 2013

Lunar Lander Designs for Crewed Surface Sortie Missions

in a Cost-Constrained Environment

12 September 2013 | San Diego, CA | Revision A

Mark Schaffer Senior Aerospace Engineer, Advanced Concepts Group

mark.schaffer@sei.aero | +1.770.379.8013

2 AIAA Space 2013

Compare the performance, cost, and reliability of lunar

lander vehicle designs based on different propellant

combinations and vehicle configurations.

1. Introduction

2. Trade Study Definition

3. Assumptions

4. Results

5. Conclusions

Objective

Contents

3 AIAA Space 2013

Introduction

4 AIAA Space 2013

Introduction to SpaceWorks

SpaceWorks is a responsive and nimble multidisciplinary aerospace engineering team

focused on independent concept design and systems analysis at fidelity levels suitable for

concept initiation through PDR.

We have over a decade of experience supporting advanced design and long range

planning activities for customers in private industry, NASA, DoD, and entrepreneurial

space organizations.

SpaceWorks is a privately held S-corporation. We are a small-business concern, are a

GSA PES schedule holder, and have a DCAA-approved accounting system.

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Rationale for Cislunar Space

SpaceWorks believes that cislunar space, i.e. the region of space surrounding the Earth and the Moon, is the next

logical step for NASA’s human space exploration program, with benefits in three areas:

Commerce – Development of a cislunar infrastructure will ensure continued U.S. leadership in the international

community, allow the U.S. to extend its economic influence beyond LEO, and enable the utilization of the

Moon’s material and energy resources.

Exploration – Cislunar space and the lunar surface provide a nearby proving grounds for new exploration

technologies and hardware; cislunar space is also a natural basing point for deep space missions.

Science – The study of the Moon’s surface and interior will be useful to the fields of planetary science and

solar system formation, and the lunar far side is of great interest to the astronomy community.

*Average distances based on mean Earth-Moon positions

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Trade Study Definition

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Propellant Options

Option Propellants Advantages Disadvantages

A LOX/LH2

• High performance

• Commonality with SLS upper

stage

• Hydrogen boil-off

• Low fuel density

B LOX/LCH4

• Low boil-off fuel and oxidizer

• Good fuel density

• Few heritage engines

• Low performance (compared

to LOX/LH2)

C LOX/RP

• Storable fuel,

• Low boil-off oxidizer

• Great fuel density

• Low performance (compared

to LOX/LH2 or LOX/LCH4)

D NTO/MMH

• Storable propellants

• Great propellant densities

• Lowest performance of all

options

• Toxicity necessitates special

handling

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Configuration Options

Option Configurations Advantages Disadvantages

1 Ascent + Descent

Stage

• Single shared propulsion

system

• Descent stage not reusable

2 In-Space + Lander

Stage

• Fully reusable

• Common propulsive elements

• LLO rendezvous

• Orbit plane change DV

3 Single Stage

Lander

• Fully reusable

• No LLO rendezvous

maneuver

• Single vehicle design

• Highest launch mass

• Largest physical lander size

9 AIAA Space 2013

Assumptions

10 AIAA Space 2013

Design Assumptions

Habitat Element

2 crew for 20 days

20 m3 pressurized volume

Interfaces

• Two NASA suitlocks with spacesuits

• NASA docking system

Electrical power generated from ASRG

Open loop life support system

• Waste CO2 collected with LiOH canisters

• Waste water collected and tanked

Propulsive Elements

Existing or near-term technologies for structures, propulsion,

and subsystems

Passive thermal control for cryogenic propellants

Power provided by Habitat

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Liquid Rocket Engines

Parameter Option A Option B Option C Option D

Propellants LOX/LH2 LOX/LCH4 LOX/RP NTO/MMH

Engine Name CECE CECE RD-58M Aestus

Manufacturer Aerojet Rocketdyne Aerojet Rocketdyne RSC Energia EADS Astrium

Number per Stage 1 1 1 3

Cycle Expander Expander Gas Generator Pressure Fed

Vacuum Thrust 66.7 kN (15.0 klbf) 66.7 kN (15.0 klbf) 83.4 kN (18.5 klbf) 29.6 kN (6.6 klbf)

Vacuum Isp 460 sec 360 sec 349 sec 324 sec

Mixture Ratio (O/F) 5.8 3.6 2.5 1.9

Mass 210 kg 210 kg 300 kg 111 kg

Design / Modify Cost $260M $310M $77M $77M

Acquisition Cost $30M $31M $9.4M $16M

Mean Failure Rate 0.575% 0.575% 0.379% 0.097%

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Earth-Moon L1/L2

Configuration 1: Ascent + Descent Stage

3. L1/L2 to Lunar Surface

Transit Time = 3 days

6. Lunar Ascent

Ascent Stage

ΔV = 2,540 m/s

1. L1/L2 Loiter

Wait Time = 90 days

(before crew arrives)

Descent Stage

is Discarded

Moon

5. Lunar Surface

Stay Time = 14 days

2. L1/L2 Departure

Descent Stage

ΔV = 240 m/s

4. Lunar Descent

Descent Stage

ΔV = 2,790 m/s

7. Lunar Surface to L1/L2

Transit Time = 3 days

8. L1/L2 Arrival

Ascent Stage

ΔV = 240 m/s

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In-Space Stage

remains in LLO

LLO

Configuration 2: In-Space + Lander Stage

Earth-Moon L1/L2

3. L1/L2 to LLO

Transit Time = 3 days

9. Lunar Ascent

Lander Stage

ΔV = 1,900 m/s

1. L1/L2 Loiter

Wait Time = 90 days

(before crew arrives)

Moon

7. Lunar Surface

Stay Time = 14 days

2. L1/L2 Departure

In-Space Stage

ΔV = 240 m/s

6. Lunar Descent

Lander Stage

ΔV = 2,150 m/s

12. Lunar Surface to L1/L2

Transit Time = 3 days

13. L1/L2 Arrival

In-Space Stage

ΔV = 240 m/s

4. LLO Arrival

In-Space Stage

ΔV = 640 m/s

5. Separation 8. Plane Change

In-Space Propulsion

ΔV = 2,300 m/s

10. Rendezvous

11. LLO Departure

In-Space Stage

ΔV = 640 m/s

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Configuration 3: Single Stage

Earth-Moon L1/L2

3. L1/L2 to Lunar Surface

Transit Time = 3 days

6. Lunar Ascent

ΔV = 2,540 m/s

1. L1/L2 Loiter

Wait Time = 90 days

(before crew arrives)

Descent Stage

is Discarded

Moon

5. Lunar Surface

Stay Time = 14 days

2. L1/L2 Departure

ΔV = 240 m/s

4. Lunar Descent

ΔV = 2,790 m/s

7. Lunar Surface to L1/L2

Transit Time = 3 days

8. L1/L2 Arrival

ΔV = 240 m/s

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Results

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Vehicle Scale

1B 1C 1D

3A 3B 3C 3D

2A 2B 2C 2D

1A

Ascent + Descent Stage LOX/LH2 Ascent + Descent Stage LOX/RP Ascent + Descent Stage LOX/LCH4 Ascent + Descent Stage NTO/MMH

In-Space + Lander Stage LOX/LH2 In-Space + Lander Stage LOX/LCH4 In-Space + Lander Stage LOX/RP In-Space + Lander Stage NTO/MMH

Single Stage LOX/LH2 Single Stage LOX/LCH4 Single Stage LOX/RP Single Stage NTO/MMH

5.0m

Asc

ent

+ D

esce

nt

Sta

ge

In-S

pac

e +

Lan

der

Sta

ge

Sin

gle

Sta

ge

LOX/LH2 LOX/LCH4 LOX/RP NTO/MMH

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Vehicle Masses

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Mas

s (t

)

Habitat Dry Stage 1 Dry Stage 2 Dry

Consumables* Stage 1 Propellant Stage 2 Propellant

* Includes crew, suits, crew consumables, vehicle fluids, and ACS propellant

Ascent + Descent Stage Lander + In-Space Stage Single Stage

1A 1B 1C 1D 2A 2B 2C 2D 3A 3B 3C 3D

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Non-recurring Cost

$0.0

$1.0

$2.0

$3.0

$4.0

$5.0

$6.0

$7.0

$8.0

$9.0

$10.0

Co

st (

$B F

Y13

)

Design, Development, Test, and Evaluation (DDT&E) Theoretical First Unit (TFU)

Ascent + Descent Stage Lander + In-Space Stage Single Stage

1A 1B 1C 1D 2A 2B 2C 2D 3A 3B 3C 3D

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Vehicle Reliability

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

Co

ntr

ibu

tio

n t

o P

rob

abili

ty o

f L

oss

of

Mis

sio

n

Habitat Lunar Landing Engine Rendezvous Separation

Ascent + Descent Stage Lander + In-Space Stage Single Stage

1A 1B 1C 1D 2A 2B 2C 2D 3A 3B 3C 3D

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Comparison to Other Designs

Apollo ESAS Altair Option 1A

Number of Crew 2 4 4 2

Mission Duration 3 days 7 days 7 days 20 days

Number of Stages 2 2 2 2

Propellants NTO / UDMH LOX / LH2 LOX / LH2 LOX / LH2

Lander Mass 14.7 t 27.9 t 45.6 t 31.8 t

Vehicle Height 5.5 m 9.5 m 10.5 m 6.4 m

Airlock Height 3.0 m 5.5 m 7.0 m 4.0 m

Diameter 4.3 m 7.5 m 7.5 m 8.4 m

Maneuvers

(1) Descent from LLO

(2) Ascent to LLO

(1) Descent from LLO

(2) Ascent to LLO

(1) LOI

(2) Descent from LLO

(3) Ascent to LLO

(1) Descent from

L1/L2

(2) Ascent to L1/L2

10 m

0 m

5 m

ESAS and Altair Lander Images Credit NASA

21 AIAA Space 2013

Results Summary and Ranks

Configuration Metric LOX/LH2 (A) LOX/CH4 (B) LOX/RP (C) NTO/MMH (D)

Ascent +

Descent Stage

(1)

Mass

(Initial in L1/L2)

31.8 t

2

36.7 t

3

39.5 t

5

47.4 t

9

Cost (DDT&E+TFU) $8,030

10

$7,520

6

$6,720

1

$7,400

4

Reliability

(LOM)

2.61%

8

2.58%

7

2.36%

4

2.18%

2

In-Space +

Lander Stage

(2)

Mass

(Initial in L1/L2)

29.0 t

1

37.4 t

4

42.0 t

7

55.3 t

11

Cost (DDT&E+TFU) $8,150

12

$7,530

7

$7,190

3

$7,670

9

Reliability

(LOM)

3.10%

12

3.08%

11

2.85%

10

2.66%

9

Single Stage

Lander

(3)

Mass

(Initial in L1/L2)

41.3 t

6

46.0 t

8

49.2 t

10

62.8 t

12

Cost (DDT&E+TFU) $8,150

11

$7,640

8

$6,760

2

$7,480

5

Reliability

(LOM)

2.43%

5

2.40%

6

2.18%

3

1.99%

1

22 AIAA Space 2013

Conclusions

23 AIAA Space 2013

Observations

By taking advantage of the large fairing diameter available on SLS, the overall height of a lunar

lander can be reduced significantly compared to other designs

Compared to hydrogen, hydrocarbon or fully storable propellants can reduce vehicle size

significantly at the expense of increased mass

In-space + lander stage configurations are both less reliable and more expensive than the

ascent + descent stage configurations, but are fully reusable

Single stage options are likely infeasible due to high launch masses

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Conclusions

Option 1C, the RP two-stage ascent + descent vehicle, is the best overall performer

• The low cost and high reliability of the flight-proven RD-58M

• High density and zero boil-off properties of RP

Option 1B, the CH4 two-stage ascent + descent vehicle, is strong alternative to the RP vehicle

• Methane is synergistic with Mars exploration using ISRU

• LOX/LCH4 offers an appreciable performance advantage over LOX/RP

Differences in cost and reliability between RP and CH4 vehicles driven solely by engine: flight-

proven RD-58M engine vs. prototype CECE engine

Recommendation: Further development of exploration-focused CH4 engines would make

these options competitive in cost and reliability and benefit other exploration missions

25 AIAA Space 2013

SPACEWORKS ENTERPRISES, INC. (SEI) | www.sei.aero | info@sei.aero

1040 Crown Pointe Parkway, Suite 950 | Atlanta, GA 30338 USA | +1-770-379-8000

26 AIAA Space 2013

Appendix

27 AIAA Space 2013

Mass Details

Element Item LOX/LH2 (A) LOX/LCH4 (B) LOX/RP (C) NTO/MMH (D)

Habitat (Common) Inert 3.0 t 3.0 t 3.0 t 3.0 t

Crew/Consumables 1.0 t 1.0 t 1.0 t 1.0 t

Configuration 1: Ascent + Descent Stage

Ascent Stage Inert 2.6 t 2.2 t 2.3 t 2.6 t

Usable Propellant 6.3 t 7.5 t 8.0 t 9.4 t

Descent Stage Inert 2.6 t 1.8 t 1.8 t 2.1 t

Usable Propellant 16.3 t 21.2 t 23.3 t 29.3 t

Total System 31.8 t 36.7 t 39.5 t 47.4 t

Configuration 2: In-Space + Lander Stage

In-Space Stage Inert 2.0 t 1.9 t 2.0 t 2.5 t

Usable Propellant 10.1 t 14.6 t 16.6 t 23.2 t

Lander Stage Inert 2.6 t 2.6 t 2.9 t 4.2 t

Usable Propellant 10.2 t 14.3 t 16.5 t 21.4 t

Total System 29.0 t 37.4 t 42.0 t 55.3 t

Configuration 3: Single Stage

Lander Inert 6.7 t 4.8 t 4.9 t 6.0 t

Usable Propellant 30.7 t 37.2 t 40.3 t 52.8 t

Total System 41.3 t 46.0 t 49.2 t 62.8 t

28 AIAA Space 2013

Cost Details

Configuration Cost LOX/LH2 (A) LOX/CH4 (B) LOX/RP (C) NTO/MMH (D)

Ascent + Descent

Stage (1)

DDT&E $7,390 $6,930 $6,210 $6,770

TFU $640 $590 $510 $630

Total $8,030 $7,520 $6,720 $7,400

In-Space +

Lander Stage (2)

DDT&E $7,430 $6,840 $6,560 $6,910

TFU $720 $690 $630 $760

Total $8,150 $7,530 $7,190 $7,670

Single Stage

Lander

(3)

DDT&E $7,460 $7,030 $6,190 $6,820

TFU $690 $610 $570 $660

Total $8,150 $7,640 $6,760 $7,480

29 AIAA Space 2013

Reliability Details

Item LOX/LH2 (A) LOX/LCH4 (B) LOX/RP (C) NTO/MMH (D)

Configuration 1: Ascent + Descent Stage

Propulsive Maneuvers 0.68% 0.65% 0.43% 0.24%

Habitat 0.63% 0.63% 0.63% 0.63%

Lunar Landing 0.66% 0.66% 0.67% 0.67%

Rendezvous 0.45% 0.45% 0.45% 0.45%

Separations 0.18% 0.18% 0.18% 0.18%

Total LOM 2.61% 2.58% 2.36% 2.18%

Configuration 2: In-Space + Lander Stage

Propulsive Maneuvers 0.67% 0.65% 0.43% 0.24%

Habitat 0.63% 0.63% 0.63% 0.63%

Lunar Landing 0.66% 0.66% 0.66% 0.66%

Rendezvous 0.90% 0.90% 0.90% 0.91%

Separations 0.23% 0.23% 0.22% 0.22%

Total LOM 3.10% 3.08% 2.85% 2.66%

Configuration 3: Single Stage

Propulsive Maneuvers 0.68% 0.65% 0.43% 0.24%

Habitat 0.63% 0.63% 0.63% 0.63%

Lunar Landing 0.66% 0.66% 0.67% 0.67%

Rendezvous 0.45% 0.45% 0.45% 0.46%

Separations 0.00% 0.00% 0.00% 0.00%

Total LOM 2.43% 2.40% 2.18% 1.99%