Discovery lifted off on 6 October 1990 at 7:47:15 am EDT. Liftoff occurred 12 minutes after a two-and-a-half-hour launch window opened that day at 7:35 am EDT. STS-41 featured the heaviest payload to date; Discovery weighed 259,593 lb (117 749 kg) .

The primary payload was the ESA-built Ulysses spacecraft to explore the polar regions of Sun. Attached to Ulysses were two upper stages, the Inertial Upper Stage (IUS) and a mission-specific Payload Assist Module-S (PAM-S), combined for first time to send Ulysses toward an out-of-ecliptic trajectory. Other payloads and experiments included the Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment, INTELSAT Solar Array Coupon (ISAC), Chromosome and Plant Cell Division Experiment (CHROMEX), Voice Command System (VCS), Solid Surface Combustion Experiment (SSCE), Investigations into Polymer Membrane Processing (IPMP), Physiological Systems Experiment (PSE), Radiation Monitoring Experiment III (RME III), Shuttle Student Involvement Program (SSIP) and Air Force Maui Optical Site (AMOS).

plant samples carried on Discovery, researchers hoped to determine how the genetic material in the root cells respond to microgravity. The information gained was of importance to future space travelers on long-term expeditions, researchers on the planned Space Station Freedom, and may contribute to advances in intensive farming practices on Earth.

Understanding fire behavior in microgravity was part of the continuing research to improve Space Shuttle safety. In a specially designed chamber, called the Solid Surface Combustion Experiment, a strip of paper was burned and filmed to gain an understanding of the development of flame and its movement in the absence of convection currents. This experiment was sponsored by the Lewis Research Center and Mississippi State University.

Atmospheric ozone depletion is an environmental problem of worldwide concern. At the time, NASA's NIMBUS-7 satellite and NOAA's TIROS satellites provided daily data to permit researchers to detect ozone trends. The Shuttle Solar Backscatter Ultraviolet Instrument, from the Goddard Space Flight Center, carried an ozone detector instrument identical to those on the satellites. By comparing Discovery's measurements with coordinated satellite observations, scientists were able to calibrate their satellite instruments to insure the most accurate readings possible.

In 1990, a commercial expendable launch vehicle stranded an INTELSAT VI communication satellite in low orbit. Before STS-41, NASA was evaluating a possible Shuttle rescue mission in 1992. In preparation for this rescue, solar arrays, similar to those on the satellite, were exposed to the conditions of low orbit to determine if they were in any way altered by the atomic oxygen present. When the returned arrays were closely examined, it was found that the arrays were not significantly damaged. Based on this finding, NASA went ahead and carried out STS-49 in 1992.

Until STS-41, previous research had shown that during the process of adapting to microgravity, animals and humans experienced loss of bone mass, cardiac deconditioning, and after prolonged periods (over 30 days), developed symptoms similar to that of terrestrial disuse osteoporosis. The goal of the STS-41 Physiological Systems Experiment, sponsored by the Ames Research Center and Pennsylvania State University's Center for Cell Research, was to determine if pharmacological treatments would be

effective in reducing or eliminating some of these disorders. Proteins, developed by Genentech of San Francisco, California, were administered to eight rats during the flight while another eight rats accompanying them on the flight did not receive the treatment.

The Investigations into Polymer Membrane Processing experiment was conducted to determine the role convection currents play in membrane formation. Membranes are used in commercial applications for purification of medicines, kidney dialysis, and water desalination. This experiment was sponsored in part by the Battelle Advanced Materials Center for the Commercial Development of Space in Columbus, OH.