Earth to Mars: Planning a Manned Mission to the Red Planet
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Earth to Mars: Planning a Manned
Mission to the Red Planet
by Elizabeth Knapp
Introduction
On January 14, 2004, President George W. Bush unveiled an ambitious plan
to send astronauts back to the Moon, to create a permanent lunar colony, and to
launch the first manned mission to Mars. His plan calls for sending astronauts
back to the Moon by 2015 and to Mars by 2030. In his speech, Bush made the
following remarks:
Two centuries ago, Meriwether Lewis and William Clark left St. Louis to
explore the new lands acquired in the Louisiana Purchase. They made that
journey in the spirit of discovery, to learn the potential of vast new territory,
and to chart a way for others to follow.
America has ventured forth into space for the same reasons. We have
undertaken space travel because the desire to explore and understand is part
of our character. And that quest has brought tangible benefits that improve
our lives in countless ways. The exploration of space has led to advances in
weather forecasting, in communications, in computing, search and rescue
technology, robotics, and electronics. Our investment in space exploration
helped to create our satellite telecommunications network and the Global
Positioning System. Medical technologies that help prolong life—such as the
imaging processing used in CAT scanners and MRI machines—trace their
origins to technology engineered for. . . use in space. . . .
With the experience and knowledge gained on the moon, we will then be
ready to take the next steps of space exploration: human missions to Mars and
to worlds beyond. Robotic missions will serve as trailblazers—the advanced
guard to the unknown. Probes, landers and other vehicles of this kind
continue to prove their worth, sending spectacular images and vast amounts
of data back to Earth. Yet the human thirst for knowledge ultimately cannot be
satisfied by even the most vivid pictures, or the most detailed measurements.
We need to see and examine and touch for ourselves. And only human beings
are capable of adapting to the inevitable uncertainties posed by space travel.
1President Bush’s plan has generated widespread excitement and
anticipation. After the space shuttle Columbia accident in February 2003, the
possibility of further space exploration was shadowed by the reality of the risks of
space flight. Still, many experts feel that it is time we sent human beings to the
Red Planet. As former Apollo 11 astronaut Buzz Aldrin has said, “We went from
the Wright brothers to the Moon landing in 66 years. It shouldn’t take longer than
66 years between the Moon landing and [getting to] Mars.” But now that the
commitment has been made, exactly what are the preparations and risks involved
in a manned mission to Mars?
Harsh, but Habitable?
Of all the planets in our solar system, Mars is the most like Earth. It also has
the greatest potential to support human life. The climate is very cold and dry. Yet
Mars has four seasons, and surface temperatures at the equator can reach 80
degrees Fahrenheit in the summer. Like Earth, Mars has polar ice caps,
mountains, dormant volcanoes, and dry riverbeds. Based on data gathered from
recent missions, scientists believe that Mars once had a warmer, wetter climate,
with oceans, lakes, and rivers. It may have sustained life, and simple life forms
like bacteria may still exist there.
For 40 years, unmanned spacecraft and robots have sent back valuable data
from Mars. Scientists have learned much about the planet’s mass, shape, geology,
surface features, atmosphere, and climate. But many scientific tasks cannot be
performed by robots. Furthermore, sending humans to Mars is the only way
scientists can know for certain if the planet is habitable.
Getting There
The voyage to Mars will be far more dangerous and technically difficult
than the mission to the Moon was in 1969. While a trip to the Moon is only
240,000 miles, the journey to Mars is 47,000,000 miles. And while the mission to
the Moon lasted only eight days, the astronauts who leave Earth for Mars will not
be able to return for almost three years. The journey alone will take between four
and six months. Once there, they will have to remain on Mars for about 18
months, until Mars and Earth are aligned properly for their return.
2Rotation of Mars and Earth around the Sun During Astronauts’ Stay on Mars
Scientists at NASA have not yet determined the type of spacecraft that will
be used on a manned mission to Mars. But during the trip, the astronauts will
probably live in an inflatable modular housing unit similar to the design proposed
by NASA as a replacement for crew quarters on the International Space Station.
Their home would be a cylindrical structure 27 feet in diameter, with a 12-inch
protective shell made of a material stronger than steel. This material would have a
high hydrogen content in order to fragment and absorb the intense radiation to
which crew members would be exposed. A self-contained unit, the module would
consist of four levels, including work, health care, crew quarters, and galley areas.
Health Risks
There would be many health risks on a manned mission to Mars. One of the
greatest is radiation. Space radiation—energy and particles emitted from the Sun
and other stars—can harm or destroy strands of DNA in human cells and lead to
cancer. Other types of radiation, such as that from cosmic rays, can damage the
central nervous system and impair the ability of astronauts to perform their duties.
Due to radiation risks, NASA will not allow astronauts to spend more than
250 days at a time in space. The trip to Mars and back will take about a thousand
days. To combat the risks, scientists are developing the radiation-shielded module
described above.
3Another major concern is the effects of weak gravity or no gravity on the
human body, including bone loss and muscle atrophy. On long spaceflights,
astronauts’ bones thin at a rate of one to two percent a month, and they lose
muscle mass. By the end of a three-year Mars mission, astronauts could suffer
bone loss of up to 50 percent.
One solution is to create artificial gravity conditions through the use of a
centrifuge. Strapping themselves into one of the machine’s seats, the astronauts
would power the centrifuge by peddling. The spinning motion would create
artificial gravity. Like going to the gym, the astronauts would “go for a spin” for
an hour or so each day.
The last major health concern is the psychological effects of the long flight.
Long periods of confinement, coupled with isolation and loneliness, may cause
problems such as depression and friction among crew members. Scientists are
doing research to determine what kinds of problems can arise and what steps can
be taken to protect astronauts from them. The studies include personality testing
of potential crew members.
Survival on Mars
Upon landing, the astronauts would live in the same module they used to
make the trip to Mars. This habitat module, about 960 square feet, would contain
the life support systems and many of the supplies that the astronauts would need
during their 540-day stay on the planet.
It would be impossible to bring all the supplies the astronauts will need from
Earth. Therefore, they would have to live off the Martian land, using its natural
resources to create water, oxygen, food, and fuel for the return flight. Using
converters brought from Earth, the astronauts would combine liquid hydrogen
with carbon dioxide from the planet’s atmosphere. The two substances would
react to create water and methane for fuel. The astronauts would then use
electrolysis to break the water down into oxygen for breathing and hydrogen for
reuse. Throughout their stay, the astronauts’ survival would depend on the
equipment they have, their common expertise, and the skills of each crew
member.
Conclusion
All the risks of a manned trip to Mars cannot be known. Yet one thing is
clear: it would be one of the most dangerous and ambitious endeavors in history.
Dennis Pelaccio is an engineer who assesses the risks of planetary missions for
4NASA. He says that the probability of a safe return from the first mission could
be lower than 75 percent. Yet the odds were similar for the Apollo 11 mission to
the Moon. Ultimately, a Mars mission, with all its potential obstacles and risks,
illustrates the primary purpose of the space program—to take humans to worlds
where they’ve never been before.
Comparing Earth to Mars
Earth Mars
Gravity (g's) 1 0.38
Length of day 24 hours 37 minutes 24 hours
Length of year 365 days 687 days
Axis tilt (degrees) 23.5 25.2
Average sunlight reaching the planet
345 147
(watts per square meter)
Average surface temperature (degrees
15 -60
Celsius)
Surface pressure (atmospheres) 1 0.008
Most abundant gases in atmosphere Nitrogen, oxygen Carbon dioxide
5Life on Mars?
Just “Follow the Water”!
by Elizabeth Knapp
Introduction Mars in History
Throughout human history, In the 1600s, the Italian
Mars, the Red Planet, has astronomer Galileo was the first to
fascinated, mystified, and inspired focus his telescope on Mars. In the
us. Ancient civilizations believed same century, the Irish writer
Mars to be a deity. The Egyptians Jonathan Swift foretold the
referred to the planet as “Horus of discovery of Mars’s two rocky
the Horizon.” The Romans named moons in his book Gulliver’s
the glowing red light in the night Travels. Mars gained serious
sky after their god of war. public attention in the late 1870s
Centuries later, Mars when the Italian astronomer
continues to beckon the human Giovanni Schiaparelli claimed to
race with the possibility of life have seen canali, or channels, on
beyond our home planet. No longer the surface of the planet through a
the stuff of fiction—little green telescope.
men or rock formations in the A businessman named
shape of extraterrestrial faces—the Percival Lowell, who was also an
possibility that there was, or is, life amateur astronomer, is believed to
on Mars is now the subject of have wrongly translated canali as
serious scientific study. What have “canals.” From his telescopes in
scientists found? What do they Flagstaff, Arizona, Lowell
hope to discover? And how can it observed the Martian “canals.” He
help us to better understand the became convinced that only
nature of life on our own planet? intelligent life could have dug
them. Lowell maintained that
creatures on the planet dug the
canals to transport water from the
polar ice caps to regions near the
equator.
6By the turn of the century, Schiaparelli had said. Scientists
Lowell’s theory had inspired many who studied the images believe
popular tales. One of them was that the channels were probably
H. G. Wells’s 1898 novel The War formed by flowing water. They
of the Worlds. In this book, the also think that ancient Mars may
Martians leave their dying planet to have held a vast ocean in its
invade Earth, for its fertile lands northern hemisphere. Since water
and fresh water. Other authors soon is a key element for life, scientists
followed Wells’s example. They began to hope that if liquid water
included the science fiction writers once existed on Mars, microscopic
Edgar Rice Burroughs (A Princess life forms also could have existed
of Mars) and Ray Bradbury (The at some time in the planet’s
Martian Chronicles). history.
Modern Views of Mars Life in a Martian Meteorite?
Yet as public interest in the On August 7, 1996, in a
Red Planet grew, scientists became historic press conference, a team of
increasingly skeptical about the scientists from NASA and Stanford
possibility of finding life on Mars. University announced the
These doubts were reinforced by discovery of ancient, fossilized,
NASA’s Viking missions, which microscopic life in a Martian
were launched in 1975. The Viking meteorite that had penetrated
probes sent back pictures of a Earth’s atmosphere and landed in
desolate planet, whose pockmarked Antarctica 12 years earlier.
surface looked very similar to that Prefacing the announcement,
of the moon. Such images were a President Bill Clinton made these
major blow to NASA. And remarks:
renowned astronomer Carl Sagan This is the product of years of
was allegedly “never so depressed” exploration and months of
in his life as when he heard the intensive study by some of the
news. world’s most distinguished
Because of its harsh scientists. Like all discoveries, this
environment, scientists now knew one will and should continue to be
that they would not find intelligent reviewed, examined, and
life on Mars. Yet the Viking probes scrutinized. It must be confirmed
confirmed the existence of by other scientists. . . . I am
channels on Mars, just as determined that the American
7space program will put its full took on the planet, and perhaps
intellectual power and under its surface, may lead to
technological progress behind the evidence of past life, or even to
search for life on Mars. simple creatures like bacteria that
Although some scientists still live. These explorations will
disagreed with the team’s findings, almost certainly give scientists a
the meteorite, known as better understanding of what
ALH84001, reopened the issue of happened to Mars to make it the
life on Mars. harsh and barren planet it is today.
And since Mars and Earth are so
“Follow the Water” much alike, scientists also believe
The strategy of NASA’s that a glimpse into Mars’s past may
Mars Exploration Program is reveal clues about Earth’s future.
known as “Follow the Water.” In
current and future missions to The Future of Life on Mars
Mars, that is exactly what scientists Since the beginning of the
will do. We know that the building Mars Exploration Program,
blocks for life are liquid water, scientists have been challenged to
organic compounds (compounds think and collaborate in new and
that contain carbon), and energy. different ways. NASA’s
But beyond these basics, we do not Astrobiology Institute includes a
yet understand the environmental team of astronomers, physicists,
and chemical conditions under and biologists who work together
which life can begin. to study the data and images
Scientists have discovered collected from the various Mars
that microscopic life on Earth can missions. One of their main goals
survive in extreme environments. is to uncover evidence of life on
Therefore, they believe that it Mars. Another is to determine
could be found on the cold, dry whether people can live there.
surface of Mars, or even far below Whether there is, or ever was, life
it, in hot springs, hydrothermal on Mars is still uncertain. Either
vents, or water reserves. way, the Red Planet will continue
Mars today is too cold and its to fascinate us. And perhaps one
atmosphere too thin for liquid day a form of life will exist on
water to exist on its surface. Mars—human life.
However, scientists believe that
following the paths that water once
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