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Lunar
Mission Scenarios |
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"I found myself flying through the
air...I had forgotten that on the moon, with only
an eighth part of the earth's mass and a quarter of
it's diameter, my weight was barely a sixth what it
was on earth. But now that fact insisted on
being remembered. "It seems to be deserted"
said Cavor, "absolutely desolate."
-H.G.Wells, The
First Men in the Moon, 1901
"Magnificent desolation."
-Buzz Aldrin, Apollo
11, 1969
Several mission scenarios
have been proposed over the years for a return to
the Moon. We will look at a few in this chapter.
In the fall of 1990, NASA completed a project to study
future Moon and Mars missions. The results of this
study were presented to the National Space Council
in the "Report of the 90-day Study on Human Exploration
of the Moon and Mars."
THE NASA 90-DAY STUDY
The goal of the 90-Day Study is to expand
human presence into the solar system, resulting in
human missions to Mars. The space station and
an established outpost on the lunar surface would
provide opportunities for significant research. A
lunar outpost would serve as a test-bed for validating
critical mission systems, hardware, technologies,
human capability, and operational techniques that
can be applied to the Mars missions. |
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The
exploration strategy in the 90-Day Study followed
a three-phase approach: space station, moon, and
Mars. Each step serves as a building-block to
the next step in human exploration of the solar
system.
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Space station is used as a zero-gravity
research facility to answer some of the fundamental
questions of missions to the moon and Mars, such as
the psychological and physiological effects of long-term
space travel. It supports fundamental research in
assembling and servicing vehicles in space, and serves
as a platform to perform unique technology demonstrations.
All of the knowledge gained at the space station will
support missions to the moon and a permanent lunar
base. Similarly, the moon will serve as a test-bed
for future missions to Mars. Complete end-to-end simulations
of the Mars missions (station to lunar outpost to
station) can be conducted on the Moon. |
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The
first step is the Robotic Phase, during which
important information data about the lunar surface
is gathered. This information supports the design
and development of the surface systems, and transportation
systems, and pre-planning activities prior to
the actual human missions.
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The information gained from the robotic
missions aids in site selection for the lunar outpost.
Several factors, including the scientific interest
of the site, potential resources that may be available,
and operations are considered. Robotic missions provide
an opportunity to demonstrate key technologies, such
as aerobraking, landing accuracy, hazard avoidance,
and autonomous rendezvous and docking. Demonstrations
of these technologies can reduce total program cost.
The next step is the Emplacement
phase. The objective of this phase is to establish
a permanent presence on the Moon and begin developing
ways to live and work there. Simple equipment and
instruments would lay the foundation for later more
complex surface operations. The space station supports
the initial test of the lunar transportation system
including vehicle integration, checkout, launch support,
and inspection after flight. |
The
Consolidation Phase expands the permanent presence
on the Moon and increases our knowledge about
how to live and work on other worlds. During this
phase, the outpost capabilities are expanded.
A habitation module is erected for habitation
and scientific research.
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The habitat provides the ability to
test long-duration exposure to low gravity in preparation
for missions to Mars. Reducing dependence on Earth
takes on great importance in reaching the capability
for Mars exploration, and developing confidence in
operational techniques and equipment. This is accomplished
by relying on more efficient systems, such as life
support and outpost operations, and by testing prototypes
of lunar resource production plants. Experience is
gained in day-to-day activities in the absence of
continual Earth guidance, thereby reducing operational
ties to Earth. |
Lunar Oxygen Production Plant |
The
final Operation Phase is focused on developing
further independence from Earth. Local resources,
such as lunar oxygen production at the outpost
are used to fuel the lunar excursion vehicles.
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| The space station facilities are expanded to support
the assembly and processing of the first Mars vehicles.
Further expansion of the lunar outpost infrastructure
would be scaled back at this time in order to open operational,
logistic, and funding to accomplish missions to Mars. |
Human Lunar Return Study
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In 1995, NASA began the Human Lunar
Return (HLR) study. HLR had three major
goals, to test technologies for developing
lunar resources, to consider the commercial development
of the moon and to test future Mars mission technologies.
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The first HLR mission was going to land
at Aristarchus
crater. This crater was shaped by volcanic activity
in the moon's distant past and is of interest to scientists.
The International Space station would be the staging
platform for the lunar vehicle. The space shuttle
would deliver some components for a two-person crew.
A Russian
Proton rocket would launch a habitat into Earth
orbit. The habitat uses an inflatable design and is
connected to a lander that houses science experiements.
The mission would last 18 days. |
Aristarchus crater landing site |
The astronauts would work for several
days on the surface of the moon. Science experiments
could include a telerobotically controlled rover
and a small lunar oxygen plant. Later mission
scenarios considered a robotic mission to look for
ice at the south pole, a larger lunar oxygen plant,
and a large crew rover vehicle similar to the one
used during the Apollo missions.
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Future missions would last up to 32
days and could include pressurized rovers for long
range expeditions. A full scale lunar oxygen
plant could produce up to 20 tons of oxygen each
year! Total cost of the first Human Lunar
Return mission was $2.5 billion dollars.
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Where to Land?
Dr. Spudis, a planetary scientist at the
Lunar
and Planetary Institute and a scientist with the
Defense Department's Clementine
lunar polar orbiter recommends the south pole of the
moon as a good candidate for a lunar outpost for a
variety of reasons. The possibility of water ice deposited
by comets in the moon's distant past was suggested
from findings aboard the Clementine and Lunar
Prospector missions. There could be as much water
ice as one billion metric tons located deep in the
craters that do not receive any sunlight due to their
location at the pole in a deep crater.
Spudis speculates that other ices
such as ammonia and methane could be mixed in with
the water ice. These are commonly found in comets.
The lunar south pole is inside the largest crater
in the solar system. The South
Pole-Aitken Basin is 2600 kilometers across and
12 kilometers deep.
Much of the bottom is permanently shadowed and temperatures
are as low as -230 degrees Celsius. This could
prove to be a problem for robotic equipment.
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The
moon has a two-week day followed by a two-week
night. Fortunately however at the south
pole there are some areas that receive sunlight
almost 90 percent of the time. These would
be good locations for solar power arrays to power
a lunar outpost.
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Finally, the temperatures at the south
pole do not change very much over time. Without
large increases in temperatures, engineering designs
will not have to take into account thermal fluxes.
For more on the South Pole-Aiken Basin, check out
the newest
slide show from the LPI. Alternative Lunar Mission Strategies
NASA Exploration engineer Bret
Drake recommends exploring both the Moon and Mars
before committing to any permanent outpost. This approach
relies on using local resources to reduce the re-supply
requirement from Earth. He suggests many alternatives
ranging from expeditions (similar to Apollo), to development
of research outposts, to colonization of the Moon
and Mars. Each alternative would provide differing
levels of scientific, educational, motivational, and
technological returns. |
These
alternate approaches are currently being studied
by NASA's Exploration Office at the Johnson Space
Center. Exploration Emphasis highlights continued
exploration of the Moon and Mars prior to building
an outpost, and Expanding Human Presence looks
at expanding human presence into the solar system.
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Exploration Emphasis
The goal of the Exploration Emphasis is
to gather knowledge of the Moon and Mars by developing
an understanding of these worlds before committing
to a permanent human outpost. Although
human and robotic missions have been sent to the Moon
and robotic vehicles have landed on the surface of
Mars, both planets still remain largely unexplored
from a scientific point of view.
In addition, the Apollo missions
have shown that there is a great diversity of lunar
terrains, and our knowledge of the Moon will remain
scarce until investigations are made on a global scale.
According to Drake, exploration of the Moon and Mars
should be phased together to increase the scientific
return and to reduce program cost. |
The
exploration strategy for both the Moon and Mars
relies on human and robotic missions. Telerobotic
explorers explore potential sites with human counterparts.
the robotic explorers extend the access of humans
by venturing into very remote regions and performing
geologic investigations, experiments, and bringing
samples back to study.
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Small unmanned robotic landers can deploy
rovers, sample return stages, in-situ resource utilization
units, and science experiments. These robotic missions
can survey potential exploration sites in advance
of the human missions.
Visit the Lunar
Rover Initiative at Carnegie Mellon University
- an ongoing project to create robots that can explore
unknown territory and do science experiments at interesting
locations. |
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Geologic
field work provides the opportunity for people
to investigate the lunar surface, so that we can
understand planetary processes, geologic
formations, and planetary history. Geologic field
work is a complex process, and will require some
human interaction.
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 Some
field work can be done by teleoperated robotic geologists
under the control of trained geologists at the landing
site (or possibly on Earth.) These robotic field
geologists, or Teleprospectors, are robotic
vehicles which imitate many functions of their human
counterparts including stereoscopic vision and manipulation
of arms. Teleprospectors provide humans access to
regions of the lunar surface without risking human
lives. Human missions to the lunar surface
are similar to the Apollo
missions, but are longer in duration in this
design. Extended surface stays, from two to six
weeks long would provide time for the crews to perform
geologic field work, deploy scientific experiments,
and perform technology demonstrations (such as utilizing
the local resources to manufacture usable products).
Pre-deployed scientific packages,
which may be in remote areas, can be routinely maintained,
adjusted, serviced, and re-supplied by humans in
conjunction with robots over a longer mission.
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This
particular strategy has specific requirements
for the transportation systems. The location for
the vehicles in orbit can impose significant constraints
on the missions depending on their location.
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For instance,
staging the missions from an equatorial orbit limits
the landing sites to a narrow band about the equator.
On the other hand, staging from polar lunar orbits
opens up access to any point on the lunar surface
(though launch opportunities are less frequent).
(Libration or LaGrange
points are fixed locations in the Earth-Moon
system where the gravitational attraction of the
Moon equals the gravitational attraction of the
Earth.) Staging from a location, such as a
lunar libration point, can remove some of these
constraints, by providing routine access to the
entire lunar surface.
Expanding Human Presence |
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The
goal of the Expanding Human Presence mission approach
is to expand human presence into the solar system,
leading to future human settlements. One of the
most important objectives of our national space
policy is this long-term goal of expanding human
activity beyond Earth orbit.
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A key objective of the expanding human
presence strategy is to reduce the support required
from Earth by developing the capability for self-sufficiency.
Emphasis is on research with application of this research
into practical use. Developing independence from Earth
will encourage expansion of any outpost and its capabilities.
Initial scientific research is focused on developing
self-sufficiency, with follow-on science experiments
occurring only once the outpost is in a stable mode.
The initial lunar outpost supports
research in self-sufficiency techniques and efficient
outpost operation. Becoming independent from Earth
takes time and the learning curve for the lunar pioneers
will include such questions as:
- How will the human body perform away from Earth
for long periods?
- How will plants thrive in a space environment?
- How will equipment function on the planetary
surfaces?
- What local resources exist and what can be
produced with them?
As these answers are gathered, the outpost will rely
on less support from Earth. |
A crew and equipment module; a lunar transport
vehicle (LTV) for landing and takeoff, and
two experiment/exploration payloads. |
This
approach begins with a Robotic Exploration Phase.
During this phase robotic spacecraft identifies
an outpost site. The location of the site is critical
to the future success of the outpost. It
must be easily accessible and capable of supporting
numerous surface activities.
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Resources contained in the lunar regolith
(soil) located near the outpost are critical for an
in-situ resource utilization program. This is the
most important requirement in order to develop the
outpost's self-sufficiency by utilizing the local
resources.
Data from orbiting spacecraft and
samples returned by robotic spacecraft will allow
scientists to characterize the surface features and
composition. A determination of the best areas
of lunar regolith to use for production plants can
be made.
Check out the NASA
Telerobotics plan!
The Emplacement
Phase, allows humans to build a permanent outpost
and continue learning how to "live off the land".
The initial lunar outpost is a small research facility.
Finally, check-out of the
ISRU plant is conducted on the lunar surface. ISRU
processes include production of ceramics for construction,
oxygen for use in rovers and life support system,
soils for growing plants, and gases for life support.
During the Emplacement Phase, science experiments
are limited and the focus is on developing outpost
self-sufficiency. Research is done in closed biosphere
environments and life science research is conducted
related to long-duration missions to Mars. |
The
outpost is expanded during the next phase, the
Expansion Phase. Pressurized facilities
including habitation areas, laboratories, and
maintenance rooms are built. Oxygen extracted
from the lunar surface is used in the life support
system and as propellants for transportation vehicles.
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As the outpost gains more experience,
control will shift from the Earth ('Mission control')
to the moon itself. During the Operation Phase
the emphasis is towards more complete self-sufficiency.
Scientific research in disciplines other than life
sciences, such as astrophysics
and planetary
geology begin. The growth of the facilities will
provide the confidence and technological experience
to initiate this process on far distant Mars. This
plan describes a small community heavily dependent
on the Earth evolving into a nearly self-supporting,
thriving community. |
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The
technologies developed for a lunar outpost can
be returned for use on Earth. Information gained
from experiments in small ecosystems (biospheres)
will improve our knowledge about the Earth's environment.
Products and specialized goods can be exported
from these settlements to Earth.
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Commercial Ventures
Shimizu Corporation, a Japan-based company,
in 1994 conceived of a Japanese lunar base. Costing
3 trillion yen, it could be built by 2025. Shimuzu
surmised that the lunar base could be funded if it
was presented to the people of Japan in various competitions. |
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These competitions included moving soil,
separating elements out of lunar soil, making and
stacking lunar bricks, rover races and astronaut
Olympics. These competitions would help develop
technologies needed for lunar exploration.
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LunaCorp is developing a series of lunar
adventures based on intelligent robots. Unlike previous
robots that only sent narrow-band science data back
to Earth, these robots will deliver live video and
wide-open interactivity to the public.
The excitement of real-time lunar exploration will
be features of participating Web sites, television
networks and large science centers that offer hands-on
access via remote control. |
Questions
to think about:
- Which of the above scenarios appeals to you?
Why?
- What other ways could we excite people about
going to the moon?
- What sports would be the most exciting on the
moon?
In the next lesson, you will take a closer look at
the types of operations that would take place on a
lunar base and what types of equipment and facilities
would be needed to accomplish them.
Next... Mining
and Manufacturing on the Moon
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