The Impact of Gravity on Life: Abstract
We are thrilled to share with you The Impact of Gravity on Life, a paper written by Dr. Emily R. Morey-Holton, NASA Ames Research Center, Moffett Field, California. It is published here in blog posts tagged Impact of Gravity on Life.
Gravity is a well-known, but little understood, physical force. Its intensity and direction have been constant throughout evolutionary history on Earth, making it difficult to understand what role, if any, this vector force may have on life as we know it. Only since the launch of Sputnik in October of 1957 has life left the planet Earth and ventured into space, so that we could begin to investigate what happens to life with minimal gravity. To date, we only have fascinating snapshots of life in space. Completion of the International Space Station should allow long-duration studies over multiple generations in multiple species.
This chapter explores four questions: What is gravity? What happens to life when gravity changes?Is gravity necessary for life as we know it? Did gravity play a role in evolution of life on Earth? Life from the cellular level through adult humans exposed to spaceflight is briefly examined and examples from spaceflight and ground-based experiments are discussed. The conclusion from these studies suggests that gravity is necessary for life as we know it, and that ‘gravity shapes life’.
GLOSSARY:
Centrifugal force or centrifugal acceleration: The apparent force in a rotating system, deflecting masses radially outward from the axis of rotation, with magnitude per unit mass ω²R, where ω is the angular speed of rotation and R is the radius of curvature of the path.
Centripetal acceleration: The acceleration on a particle moving in a curved path, directed toward the instantaneous center of curvature of the path, with magnitude v2/R, where v is the speed of the particle and R is the radius of curvature of the path.
Drosophila: A small fly of the genus Drosophila, especially the fruit fly D. melanogaster used extensively in genetic studies.
Escherichia coli: A member of the genus of schizomycetes that are gram-negative, rod-shaped bacteria found as normal inhabitants of the lower bowel of man and lower animals. Usually nonpathogenic, but pathogenic strains are common.
Gravity: The force imparted by any heavenly body to a mass which is at rest relative to the heavenly body viewed from a frame of reference fixed in the heavenly body. If the body is rotating, the force observed as gravity is the resultant of the force of gravitation and the centrifugal force arising from this rotation and the use of an body-bound rotating frame of reference. On Earth, it is directed normal to sea level and to its geopotential surfaces.
Nematodes: Worms of the phylum Nematoda that have unsegmented threadlike bodies. The best know nematode for research purposes is the roundworm C. Elegans.
Paramecium: Usually oval-shaped ciliate protozoans of the genus
Paramecium with an oral groove for feeding.
Protozoan: Single-celled, usually microscopic, organisms including the most primitive forms of animal life.
Sputnick: The first artificial Earth satellite which was launched by the former Soviet Union on October 4, 1957.
Weight: An object’s mass times the local value of gravitational acceleration (1G on Earth).