The microgravity environment created by an orbiting spacecraft
allows people to float effortlessly and events to occur as if
there were no gravity present. Microgravity is not the absence
of gravity, but is a state where the effects of gravity have been
greatly reduced. It makes possible experiments that are normally
limited by gravitational effects on Earth. However, whereas gravity
is greatly reduced during orbit, vibrations and motions of the
shuttle can affect experiment results. For example, the shuttle
vibrates, accelerates, and decelerates when thrusters are fired,
experiments are operated, and the crew performs various operations
and exercises, among many other things. In microgravity, even
minute forces can affect experiments: therefore, investigators
need to know the precise strength of the gravitational levels
and vibrations affecting their experiments to interpret results
correctly and to develop an understanding of the effects caused
by these forces.
The Microgravity Measurement and Analysis Project (MMAP) at the
NASA Lewis Research Center was established to provide a single
source for measuring the microgravity environment on various orbiting
spacecraft, providing support for scientists, and microgravity
environment data. As part of this project, the Space Acceleration
Measurement System (SAMS) and the Orbital Acceleration Research
Experiment (OARE) have supported 15 shuttle missions. In addition,
one SAMS unit has been operated on Russia's Mir Space Station
since September 1994.
SAMS and OARE data were prepared and distributed to users after
each mission. Specialized analyses were performed by the Principal
Investigator Microgravity Services project in real time during
missions, as well as before and after the missions for principal
investigators. Reports summarizing the microgravity environment
of the mission were prepared by the Principal Investigator Microgravity
Services project and distributed to users after each shuttle mission
and periodically from Mir operations.
Future microgravity science research on the International Space
Station will be supported by a project called SAMS-II that will
measure the microgravity environment near each science experiment
and deliver the data to the investigators at their operations
center on the ground.
Other future microgravity science experiments that require an
extremely low level of microgravity may fly on a free flyer (unmanned)
carrier. SAMS-FF, another MMAP project under development, will
measure and record the microgravity environment encountered on
such a satellite during a typical 2-week mission.
For both International Space Station and free flyer operations,
the Principal Investigator Microgravity Services project will
continue to provide scientists with data interpretation and summary
reports.
For more information, see our MMAP homepage.
Rogers, M.J.B.; and DeLombard, R.: Summary Report of Mission Acceleration Measurements for STS-73. NASA TM-107269, 1996.
Ryaboukha, S., et al.: Further Analysis of the Microgravity Environment on Mir Space Station During Mir-16. NASA TM-107239, 1996.
DeLombard, R.: Compendium of Information for Interpreting the Microgravity Environment of the Orbiter Spacecraft. NASA TM-107032, 1996.
DeLombard, R., et al.: SAMS Acceleration Measurements on Mir From June to November 1995. NASA TM-107312, 1996.
Previous articleLast updated April 30, 1997
Responsible NASA Official:
Gynelle.C.Steele@nasa.gov
216-433-8258
Point of contact for NASA Glenn's Research & Technology reports:
Cynthia.L.Dreibelbis@nasa.gov
216-433-2912
SGT, Inc.
Web page curator:
Nancy.L.Obryan@nasa.gov
216-433-5793
Wyle Information Systems, LLC
