perpetual power on the moon - nasa
TRANSCRIPT
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