The Neurolab life sciences mission aboard the Space Shuttle Columbia will focus on one of the most complex and least understood parts of the human body – the nervous system.

The goals of Neurolab on Mission STS-90 will be to conduct basic research in the neurosciences and to expand understanding of how the nervous system develops and functions in space. The scheduled 16-day mission is expected to provide useful information for overcoming some of the physiological challenges of long-duration stay aboard the International Space Station, as well as in the treatment of diseases and improvement of life back on Earth.

The neurological system includes the brain, spinal cord, peripheral nerves and sensory organs. It controls blood pressure, maintains balance, coordinates movements and regulates sleep – all areas that are particularly affected by space flight.

Crew members will serve as operators and subjects of the 26 life sciences experiments. Other test subjects include rats, mice, crickets, fish and snails.

Most of the experiments will be conducted inside the Spacelab long module, a pressurized laboratory carried in Columbia's payload bay.

Neurolab is a cooperative effort of the National Aeronautics and Space Administration (NASA) and five other space agencies as well as a number of domestic partners. The international partners include the space agencies of Canada (CSA), France (CNES) and Germany (DARA), as well as the European Space Agency (ESA) and the National Space Development Agency of Japan (NASDA). Domestic partners include several institutes of the National Institutes of Health, the National Science Foundation and the Office of Naval Research.

The Neurolab mission will serve as a model of the international partnership in life sciences research aboard the International Space Station.

The 90th Space Shuttle launch and 25th flight of Columbia (OV-102) will begin with liftoff from Launch Pad 39B. Columbia will ascend at a 39-degree inclination to the equator for direct insertion to a 173-statute-mile (150-nautical-mile/278-kilometer) orbit.

Landing is planned at Kennedy Space Center's Shuttle Landing Facility.

Leading the seven-member flight crew as mission commander will be two-time Shuttle flier Richard A. "Rick" Searfoss, an Air Force lieutenant colonel. He was selected as an astronaut candidate in 1990 while serving as a flight instructor at the U.S. Air Force Test Pilot School at Edwards Air Force Base, CA. This will be his first Shuttle flight as mission commander. He was the pilot on STS-58 in 1993 and STS-76 in 1996.

Scott D. Altman, a commander in the Navy, will make his first space flight. A Naval officer since 1981, he held a variety of positions, including test pilot, fighter pilot and strike leader flying over southern Iraq. He was selected for the astronaut program in 1994.

Mission Specialist Richard M. "Rick" Linnehan, a veterinarian, will serve as payload commander. He flew once before, as a mission specialist on STS-78 in 1996. He was the chief clinical veterinarian for the U.S. Navy Marine Mammal Project in California before being chosen by NASA in 1992.

Mission Specialist Kathryn "Kay" P. Hire, a commander in the U.S. Naval Reserve, also will be the flight engineer on her first space flight. In 1993, she became the first female in America assigned to a combat air crew. She was an engineer and supervisor with Lockheed Space Operations Co. at Kennedy Space Center (KSC) in 1995 when she became KSC's first employee to be chosen as an astronaut candidate.

Mission Specialist Dafydd "Dave" Rhys Williams, a medical doctor and Canadian Space Agency (CSA) astronaut, also will fly for the first time. He was selected as an astronaut by the CSA in 1992 and later joined the 1995 NASA astronaut class. The experienced neuroscientist and physician is assistant professor of surgery at McGill University.

Serving as payload specialists will be rookie space fliers Jay Clark Buckey Jr., a medical doctor; and James A. "Jim" Pawelczyk, who has a doctor of philosophy degree in biology (physiology) and completed a post-doctoral fellowship in cardiovascular neurophysiology. They were chosen for their expertise in the Neurolab experiments. Buckey was co-investigator and project manager for an investigation which flew on the Spacelab Life Sciences-1 (SLS-1) and SLS-2 missions. He also served as an alternate payload specialist on SLS-2. He is an associate professor of medicine at Dartmouth-Hitchcock Medical School. Pawelczyk is a co-investigator for experiments on Neurolab and two Shuttle-Mir flights. He is an assistant professor of physiology and kinesiology at Pennsylvania State University.

Also training for STS-90 as alternate payload specialists are Alexander William Dunlap, a medical doctor and a veterinarian; and Chiaki Mukai, a medical doctor who also has a doctorate in physiology. Dunlap is on leave from his residency at the University of Tennessee Department of Family Medicine. Mukai, a NASDA astronaut, was an alternate payload specialist on STS-47 in 1992, and flew on STS-65 in 1994. During the mission, the alternates will work with the payload flight crew members.

Neurolab is NASA's contribution to a national research effort in the 1990s, which was designated by President George Bush as the "Decade of the Brain."

Eight scientific teams are responsible for the 26 experiments on Neurolab. Four of the teams will oversee a combined total of 11 experiments with the crew as human subjects. The other four teams will conduct 15 investigations using mice, rats, crickets, snails and fish.

The four teams using human test subjects are:

• The Autonomic (Involuntary) Nervous System Team will examine the effects of microgravity on the regulatory systems in humans, as well as the problems of autonomic system adaptation following space flight. The control of blood pressure is the major focus of these experiments.
• The Sensory Motor and Performance Team will investigate the effects of adaptation to microgravity on human perception and motor functions. Using virtual reality headgear for the first time in space, the team will study how astronauts use vision, the vestibular organs of the inner ear, and pressure cues to perceive their own orientation and the identity of objects around them. Other experiments will test eye-hand coordination, and the ability of the human central nervous system to accept and interpret new stimuli in space.
• The Sleep Team will evaluate the sleep patterns of crew members before, during and after the mission to identify the factors in sleep disturbances which may be associated with space flight. One study will focus on the hormone melatonin to determine its value as a sleep aid and its effects on daytime performance. Another experiment will examine how changes in respiration alter sleep and how sleep disturbances alter breathing.
• The Vestibular Team will study the balance organs in the inner ear and all the connections they make to the eyes, brain and muscles. Using the techniques of centrifugation and eye movement measurement, the team will examine the human vestibular system.

The four teams with non-human subjects are:

• The Neurobiology Team will investigate the effects of microgravity on development of gravity receptors in the domestic cricket. The experiment will attempt to answer the question of how much of normal development is preprogrammed genetically and how much can be modified by environment and experiences.
• The Aquatic Team will examine the effects of microgravity on the development and activation of vestibular gravity-sensing organs in fish and snails. Vestibular nerve impulse data will be collected and measured for the first time using a new wireless telemetry system devised by NASDA. Data from the aquatic experiments may help to pinpoint the mechanisms at work in various forms of motion sickness.
• The Mammalian Development Team will study the effects of space flight on normal development of the nervous system in rats and mice. In one investigation, young rats will take their first steps in space, helping scientists to determine whether "walking" develops the same way in space as on Earth.
• The Adult Neuronal Plasticity Team will investigate the neural and physiological changes in rats during space flight. For example, scientists will look for changes in the rodents' circadian rhythms of body temperature, heart rate, and activity when exposed to different light cycles.

STS-90 will be the 16th and last planned flight of the ESA-developed Spacelab pressurized module which first flew on the Space Shuttle in 1983.

The Spacelab modules are being phased out because future microgravity research will be conducted in space station laboratories. Spacelab pallets will continue to be used on the International Space Station.

Additional payloads include the Shuttle Vibration Forces experiment to provide flight measurements of the vibratory forces between an aerospace payload and its mounting structure; the Bioreactor Demonstration System-04, a tissue culture apparatus; and three Get-Away Special (GAS) canister investigations. The GAS can experiments include a prototype instrument cooler for planetary missions, a test of the collision of dust particles in space, and ultraviolet measurements of the Earth's upper atmosphere.