Biological Clocks For Space Travel
Future Human Mars Missions To Carry Circadian Knowledge
February 10, 2003 --
George W. 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.
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
of spaceship earth.
at the University of Virginia have begun looking for ways to
help the human body adapt to months,
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
the routine of day and night during space travel, astronauts
must create an artificial wake/sleep cycle to override their
clocks, which are set to Earth time cycles.
Menaker, U.Va. professor of biology, and colleagues, including
Gene Block, U.Va. vice
president and provost and professor of biology,
to explore ways to adapt circadian rhythms to space by manipulating the
timing of meals, hormone administration, exercise and light conditions.
learn may be used to adjust the environments and schedules of astronauts
their performance in space.
are part of a team that is trying to understand what is likely
to happen to circadian organization during prolonged space travel,” Menaker
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
must remain alert while performing complex activities under the
unusual physical and environmental
conditions of space. To perform
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
day/night cycles on Earth.
astronauts reach Mars, about 64 to 105 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 day.
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.
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.
also have shown that organs such as the lung and liver contain
their own biological
clocks, which are regulated by
timer in the
a complex system, but these circadian rhythms help mammals
sleep and stay active, controlling energy levels, growth, moods
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
by ‘jet lag’ and
better understanding of biological timing will enable the development
and help astronauts
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
Menaker’s space-related research is
sponsored by the National Biomedical Research Institute,
a NASA-affiliated consortium of 12 institutions working
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.
Fariss Samarrai, (434) 924-3778