Manned Mars missions on the
The red planet, as viewed from its surface by Viking
I. A new initiative by NASA could put humans on Mars by the
year 2030. U.Va. researchers are looking for ways to help
the human body adapt to months or years of space travel. Michael
Menaker, below, leads the project.
Bush recently set two goals for the nation’s space program:
humans will return to the moon by 2020, and land on Mars by 2030.
But human biology is not designed for space travel. The Earth
is, in effect, a spaceship, with an atmosphere, gravity and light
cycles that allow us to thrive. Space, however, is inhospitable.
To travel across vast distances of space, humans must bring along
the conditions of spaceship Earth.
Researchers at U.Va. have begun looking for ways to help the human
body adapt to months, perhaps years, of space travel during a
Mars mission. Once astronauts leave Earth, there will be no day/night
cycles. And on the Martian surface, the days are slightly longer
than the 24-hour day on Earth, which likely will skew the natural
rhythms of the astronauts’ biological clocks.
Without the routine of day and night during space travel, astronauts
must create an artificial wake/sleep cycle to override their bodies’
natural clocks, which are set to Earth-time cycles.
Michael Menaker, professor of biology,
and colleagues, including Gene Block, vice
president and provost and professor of biology, are using
animal models to explore ways to adapt circadian rhythms to space
by manipulating the timing of meals, hormone administration, exercise
and light conditions. What they learn may be used to adjust the
environments and schedules of astronauts to maximize their performance
“We are part of a team that is trying to understand what
is likely to happen to circadian organization during prolonged
space travel,” Menaker said. “We want to know how
to make the circadian system behave normally under abnormal conditions.
Even small variations in environmental conditions can cause big
problems for biorhythms and for the important cognitive abilities
that depend on them.”
Astronauts must remain alert while performing complex activities
under the unusual physical and environmental conditions of space.
To perform well, they need at least six hours of sleep per day,
even as their daily activity and rest cycles are altered by both
their mission requirements and the loss of the normal day/night
cycles on Earth.
Once astronauts reach Mars, roughly 50 to 250 million miles from
Earth (it varies, owing to the nature of elliptical orbits), they
will have to “synchronize to Mars time,” Menaker said
— a day on Mars is nearly 40 minutes longer than an Earth
The light on Mars also is much redder than the light on Earth,
which may affect the astronauts’ biological clocks. Menaker
and colleagues are matching the intensity of wavelength differences
on their lab specimens to simulate the Martian light conditions.
Biological clocks are the body’s internal timekeepers that
regulate the functions and behaviors of organs. In recent years,
Menaker and his colleagues have shown that a central timer in
the brain sends signals to other organs and tissues, regulating
the body’s activity/rest cycle. They have demonstrated that
mammals have specialized light-sensing cells in the eyes that
synchronize the clock in the brain to day and night.
They also have shown that organs such as the lung and liver contain
their own biological clocks, which are regulated by the central
timer in the brain. It’s a complex system, but these circadian
rhythms help mammals sleep and stay active, controlling energy
levels, growth, moods and aging.
“Our basic goal is understanding how the multiple oscillators
in various organs of which the circadian system is composed are
organized and how this organization is maintained,” Menaker
said. “These are basic biological questions. Once this is
understood, countermeasures can be designed to compensate for
the circadian disorganization produced by space travel, and also
by ‘jet lag’ and shift work.”
A better understanding of biological timing will enable the development
of countermeasures, and help astronauts reduce mistakes and accidents
due to fatigue. Lack of sleep affects a person’s level of
alertness, eating cycles and can disrupt the metabolism. Sleeplessness
also can lead to declining cognitive abilities and possibly a
shortened lifespan. These are serious health concerns for the
average person and more so for astronauts who must perform at
their peak under stressful conditions.
Menaker’s space-related research is sponsored by the National
Biomedical Research Institute, a NASA-affiliated consortium of
12 institutions working to prevent or solve health problems related
to long-duration space travel and prolonged exposure to microgravity.
The group’s purpose is to help ensure safe and productive
human space flight.