1032pearson.pdf

The Lunar Space Elevator

Jerome Pearson, Eugene Levin, John Oldson, and Harry Wykes NIAC Phase I Fellows Meeting Atlanta, GA, 16 Mar 2005

The Earth Space Elevator

An L2 Lunar Space Elevator

Types of Lunar Space Elevators

NIAC Study Phase I Goals •Develop LSE System Architecture •Coordinate with NASA Moon-Mars Initiative •Conceptual Design of all Components •Substantiate Revolutionary Impacts

System Architecture •A Revolutionary Cis-Lunar Transportation System •Low-Cost Transportation of Lunar Materials and Propellants to Earth orbits •Low-Cost Supply of Lunar Bases from LEO •Support for Moon and Mars Missions

Concept of Operations •The Lunar Space Elevator is an EarthMoon-L1“Hi ghway” •LSE Can Carry Traffic Throughout CisLunar Space, with Nodes in Earth Orbit, L1, Lunar Orbit, and the Lunar Surface •Robotic Vehicles Provide Redundancy, Reliability, and Low Cost Transportation

Transportation Architecture Earth

L1 Ballast

Payloads

Moon

Payloads

LSE to Earth Orbit Launches 300

250

Earth orbit radius, km

Apogee 200

150

Perigee 100

Synchronous orbit

50

0 60

90

120

150

180

210

Release height on L1 elevator, km

240

LSE Cis-Lunar Transportation Earth Orbit to Moon: –Ribbon to L1 –Supplies to Lunar Bases Moon to Earth Orbit: –Lunar Materials –Propellant to LEO –SSPS to GEO

System Components

•LSE Ribbon •Robotic Climbers •Catenary to Pole •Surface Robots •Mining Bases

Lunar SE Materials Material

Density ρ, kg/m3 2266

SWCN*

Stress Limit σ, GPa 50

Break Height σ/ρge, km 2200

T1000G†

1810

6.4

361

Zylon§ PBO

1560

5.8

379

970

3.0

316

M5**

1700

5.7

342

M5 Expected

1700

9.5

570

Kevlar††49

1440

3.6

255

Spectra¶ 2000

* Single-wall carbon nanotubes (lab measured) †Tor a yca r bonf i be r § Aramid, Ltd. Polybenzoxazole fiber

¶ Honeywell extended chain polyethylene fiber ** Magellan honeycomb-like 3-D polymer ††DuPontaramid fiber

Meteoroid-Safe Ribbons

Mean Time Between Meteor Cuts: T, yrs = 6 h2.6/L h = width, mm L = length, km

Strands

2

Safety Factor 4

3

4

5

6

3 2.7 2.5 2.4

LSE Ribbon and CW Mass 1.E+07

1.E+06 Mass, kg

ribbon counterweight Total Mass 1.E+05

1.E+04 60

120

180

240

He ight, thousands of k m

300

Spinning Tethers for Lunar Sling Launch (and Catch)

L1

Type

h, km r, km Vtip, km/s

atip,g’ s P, kW Tons/day

Low Orbit

4

118

1.68

2.4

100

3

Escape

4

236

2.38

2.4

100

3

Robotic Climber Design

•500-kg Climbers •100 Climbers on Ribbon •10-20 m/s Speed •340,000 kg/yr

Robotic Climber Design

•Articulated Solar Panels •10 kW at Surface, 100 W at 0.26 L1 •Big, Soft Drive Wheels •Ribbon Tracking Control •Full and Empty c.g. Control

Climber Components

Unloaded Climber Concept of Climber and LSE

c.g.

Polar Ice from Clementine Data

Curved LSE to Approach Poles Maxim um Latitude 90 Curved LSE

80 2

z/rm z/r

m

Latitude, Degrees

70

1

60 50 40 30 20

0

10 0

1

2

x/rm x/rm

3

4

0 0

1

2

3

4

5

6

2 2 ==vvt2/v02 Eta t /vo

7

8

9

10

“ Pol arExpr ess”Cat enar y

200 km crater, 4 km deep

Regolith Encapsulation

Truncated Octohedron Blocks

Unfilled Filled

Lunarcrete Blocks

Blocks Cast with Tension Wires

Tensegrity Towers 0.36 lb/foot on moon

Stations on the Polar Express

Equatorial: •Regolith mining •Factories •Habitats Catenary stops on the 2700km long Polar Express: •Mineral deposits •Water ice mining •Propellants

Two Man Catenary Crew Cab

Habitat Constructed with Regolith Blocks

Preliminary LSE Cost Analysis •LSE Construction: ~$10 B •(Assumes $5 M per Ton Launched to LEO) •Ion Propelled Payloads: 10-15% of mass, 6 mos. from LEO to Moon or Moon to LEO

Vision and Significance •Revolutionize Cis-Lunar Space •Drastically Reduce Cost of Propellants and Supplies in Earth Orbit •Provide Low Cost Support of Lunar Bases •Directly Support Moon-Mars Initiative

Potential Lunar Schedule

2008-15: 2015-20: 2020-25: 2025-35:

Robotic Missions Manned Missions LSE Construction Lunar Space Elevators Revolutionize Cis-Lunar Transportation

Phase II Objectives •Complete LSE architecture for future NASA missions •Create LSE roadmap with all enabling technologies •Evaluate benefits and cost vs. performance

Conclusions •Lunar space elevators and slings are new, revolutionary ideas with broad applications •The LSE is achievable, and provides a new architecture for lunar development •The lunar space elevator creates a new paradigm for lunar space transportation