We Commit To The Moon-Mars Mission - The True Spark for Changing the Culture - Page 9

Lunar Helium-3 for Fusion Propulsion
Develop advanced fusion propulsion spacecraft, fueled by the helium-3
resources on the Moon — enabling safe and rapid human travel to Mars and
other regions in the Solar System, with the goal of achieving constant onegravity acceleration/deceleration as the standard for human interplanetary
Rapid and safe human travel to other planets—such
as Mars—requires fusion propulsion. For example, using
today’s technologies based on chemical propulsion systems, a flight to Mars takes about 200 days—subjecting
prospective astronauts to an extended stay in the dangerous, high-radiation deep-space environment, and
the debilitating effects of prolonged zero-gravity on the
body. With advanced fusion propulsion, a trip from lunar orbit to Mars orbit could take two days to a week.
How can fusion get us to Mars 100 times faster? It
starts with energy density: fusion reactions provide millions of times more energy (per unit of weight) compared
to chemical reactions. With today’s chemical propulsion
systems, interplanetary spacecraft can only carry enough
fuel for short burns of thrust, sending the spacecraft on a
slow orbital trajectory for the majority of the flight (with
no ability to carry the additional heavy weight of the fuel
required for anything more than short burns). With fusion reactions, once spacecraft can be equipped with the
equivalent of 25 million times more fuel (owing to the
Colonizing Space Will Change Our Culture
higher energy density), an entirely new mode of space
travel becomes possible: constant high-thrust acceleration
spaceflight—with the ultimate goal of acceleration rates
that simulate Earth’s gravity (one Earth gravity) for the
crew during the entire trip.5
While constant-acceleration space flight at one gravity
is the gold standard we’ll strive for, earlier generations of
fusion propulsion systems will come first (along with fission systems), and important improvements will be provided along the way. Various designs for fusion-powered
spacecraft have been investigated for decades (including
proposals from NASA, the national laboratories, and ongoing studies by private companies), although the development of fusion propulsion in space has suffered from
the same problem as fusion power on Earth—a crippling
lack of funding. (See box: The Suppression of Fusion.)
However, the prospects of returning to the Moon
are now stimulating a new perspective on fusion, with
growing international interest in the helium-3 fusion
fuel resources available on the Moon. This rare isotope
of helium, helium-3, is far more abundant on the Moon
than on the to Earth, and is a superior fusion fuel (compared with the fusion fuels available on Earth).
Currently, fusion experiments largely focus on hydrogen isotope fuels, where most of the energy released
can’t be directed or controlled (and can only be captured
to generate heat). This is workable for first-generation
fusion power plants generating electricity, but the shift
to helium-3 fuels opens up an entirely new regime of
potential. With helium-3 fusion, nearly all of the energy
produced by the fusion reactions can be directed and
controlled. For power plants, this enables more efficient
modes of electricity generation (with far less energy lost
as heat, potentially doubling the electricity produced per
unit of energy).
For spacecraft propulsion, helium-3 ensures that near5. Technically, this would be constant acceleration for the first
half of the flight, rotating the spacecraft 180 degrees at the midpoint, and constant deceleration for the latter half of the trip.


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