Perpetual Power on the Moon

Peter C. Chen,

Catholic U. of America and Code 671, NASA Goddard Space Flight Center

Douglas M. Rabin

Code 670, NASA Goddard Space Flight Center

Phillip C. Chamberlin

code 671, NASA Goddard Space Flight Center

© P. Chen 2013

Introduction – What’s the problem?

• There are many scientific, technological, and space

exploration advantages for placing hardware on the

near side of the moon

• But• The lunar night is long (~350 hours) and extremely

cold*, so providing power reliably and continuously

is a major challenge

• RTGs (radio-isotope thermal generators) are limited

in availability. They are hazardous to produce, and

difficult to transport and operate on the Moon

* ~100K on surface, ~30K in permanently shadowed craters

The Earth is the brightest object in the lunar sky*.

The Sun-Earth-Moon geometry is unique:

From any point on the near side of the Moon, the

Earth is always visible

The Earth stays at the same spot in the sky**

The Earth is bright when the Moon is

dark - see next slide

* During an early Apollo mission, the astronauts remarked that the

Earthshine was bright enough to land a spacecraft by

** There is a little wobble due to libration

Our Idea - Use Light from the Earth (Earthshine)

The Earth-Moon Orbit

On the Moon, as it goes from dusk –> midnight –> dawn (last Q to new to 1st Q as

seen from Earth), the Earth goes from 1st quarter –> full –> last quarter. Therefore

Earthshine is always available during the lunar night.

The Earth is the brightest object in the lunar sky.It is estimated that full Earth is about 50-100x brighter than full Moon

The Sun is about a million times brighter than full Moon

Hence, Full Earth is about 1/10000 (10**-4) as bright as the Sun

Earth Irradiance at the Lunar Surface. Approx. 1 kW is

available with a 200m diameter solar concentrator.

Power Generation From Earthshine 1

Using a large thin reflector in space is not a new idea. The Russian Space

Agency orbited a 20m mylar dish from the ISS in 1993 (Znamya 2). It briefly lit

up areas of Siberia at night. Source http://src.space.ru/aro3.gif

Power Generation From Earthshine 2

Power Generation From Earthshine 3

Cryogenic photo-voltaic panels, such as would be required for lunar night time

power generation, can use units similar to those already developed for deep space

missions. The above image shows the solar panels for the Juno mission.

Earthshine is collected by a large thin reflector which sends the light to a cryogenic

photo-voltaic array to generate power. (Artist’s concept).

Moon Telescope Powered by Earthshine

© P. Chen 2013

Potential Applications

• Science - Environmental monitoring of solar and

cosmic radiation, lunar seismic motion, lunar dust

charging, densities, and motion; telescopes for Earth

science, heliophysics, astrophysics, and planetary

protection (e.g. Near Earth Objects surveillance and

detection)

• Exploration - navigational beacons, emergency

communications power, emergency shelter power

• Technology – resource mining and processing

Just For Fun!

The following are some of the ideas that

came up while we were pursuing this line

of thought.

Daytime Power and Regolith Processing

During daytime, a 200m diameter reflector can generate ~10s of megawatts of solar

power. The energy can be used to melt regolith for material processing and

extraction of oxygen and other minerals.

© P.. Chen 2013

Daytime Dust Repellence

Protective Halo For A Lunar

Telescope. Another potential

application Is that solar power

can be used in a large

(superconducting?)

magnetic coil surrounding the

telescope. The magnetic field

keeps away charged dust

particles (if any) lofted by the

solar wind.

Lines of force around a

magnet coil.

Source: https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTMIS8iVfU6d0QhTU5tGqYuRHBtwzEh4wTtnrRtEqgfP7USFc1S

© P. Chen 2013

The topic of this presentation is ‘Moon Telescope Powered by Earthshine’. We thought it’d

be fun to make a picture where the terms ‘Earth’ and ‘Moon’ are reversed.

Earth Telescope Powered by Moonshine

© P. Chen 2013

We thank G. Canter, P. Cursey, J. Friedlander,

G. Gliba, P. Mirel, M. Perry, T. Perry, T. Plummer,

and M. Saulino (NASA GSFC) for advice and

assistance.

This work was supported under grant

NNA09DB30A from the Lunar University Network

for Astrophysics Research (LUNAR), a consortium

of research institutions led by the University of

Colorado, Dr. J. Burns, PI.

Acknowledgements