During IML-2, a team of scientists and engineers from 15 countries worked together to study basic scientific issues unique to space flight. Through the mission?s global approach to space science, the international partners shared the costs of development of equipment and support of investigators, thus reducing the expenses to any one space agency. Scientists from around the world used the IML-2 equipment to conduct complementary investigations and focus efforts on fundamental questions of interest to the worldwide scientific community. Overall, 77 experiments were flown aboard IML-2, studying materials science, fluid science, life sciences and bioprocessing, and the microgravity quality on board the spacecraft.
The IML-2 payload was managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. The IML-2 mission laid the groundwork for broader international partnerships and scientific alliances that will continue during future global endeavors. Five other space agencies joined NASA on this mission: the Canadian Space Agency (CSA), French Space Agency (CNES), German Space Agency (DARA), European Space Agency (ESA) and National Space Development Agency of Japan (NASDA).
The 37 life sciences experiments flown aboard the Spacelab IML-2 studied space biology, human physiology and radiation biology. Twenty-eight experiments focused on biology. Four of them investigated early development of the vestibular organ in aquatic vertebrates, such as Medaka fish and Japanese newt. Eight experiments investigated the gravisensitivity of plants, algae and jellyfish, using a slow-rotating centrifuge. Also, cell functions and responses were of great interest, especially bone resorption and the function of the immune system. A group of three experiments studied the effects of radiation on different biological specimens. One investigation measured radiation with the Real-Time Radiation Monitoring Device. Three human physiology experiments investigated cardiovascular deconditioning after space flight, the changes in the spinal cord during the stay in microgravity and the air quality inside of the Spacelab module.
Specific human physiology investigations on IML-2 included the Extended Duration Orbiter Medical Project developed by NASA, a series of investigations designed to assess the medical status of the crewmembers and the environment in which they work and live in during long-duration Shuttle flights. The Lower Body Negative Pressure (LBNP) study investigated whether the LBNP device can be used as a countermeasure for postflight orthostatic intolerance, a condition of low blood pressure after space flight. The Microbial Air Sampler investigation used a hand-held, battery-powered, centrifugal air sampler to collect samples of airborne bacteria and fungi during the IML-2 mission to help keep future long-duration missions like the Space Station free of potentially troublesome microbes.
Three investigations sponsored by NASA studied non-human life sciences. The Early Development of a Gravity-Receptor Organ in Microgravity experiment examined the development of otolith organs (gravity sensors) in newts from an early stage of growth (3-5 days after fertilization) under microgravity conditions. The Effects of Microgravity on Aurelia ephyra (jellyfish) Behavior and Development experiment was the continuation of an investigation flown on the Spacelab mission SLS-1. The IML-2 investigation examined the development and behavior of the jellyfish in varying levels of gravity. The Gravity and the Stability of the Differentiated State of Plant Embryos experiments examined how plant embryos grow and develop without the influence of gravity; it specifically examined the process of mitosis (cell division) and chromosome behavior.
Other life sciences experiments performed during the STS-65 mission, but not as a part of the IML-2 payload, were those classified as Detailed Supplementary Objectives (DSOs). A DSO is a NASA-sponsored investigation performed by Space Shuttle crewmembers, who serve as the test subjects. These studies are designed to require minimal crew time, power and stowage. Biomedical DSOs focus on operational concerns, including space motion sickness, cardiovascular deconditioning, muscle loss, changes in coordination and balance strategies, radiation exposure, pharmacokinetics and changes in the body's biochemistry.
The IML-2 materials science investigations studied a variety of questions concerning the structure of alloys after melting and solidification under microgravity conditions. Also, crystals were grown from different mediums to analyze their structure later on the ground, a process that can only be successful with large crystals grown in space. Other experiments examined how bubble formation and migration, surface-tension forces, thermal gradients and other parameters affect material development in microgravity. Samples produced in space were compared with similar samples made on Earth during and after the mission. Scientists studied fluid physics, such as thermocapillary flows and critical-point phase transitions, that are masked or distorted on Earth. Nearly every physical science depends on an understanding of these basic mechanisms, and this knowledge helps scientists to develop the next generation of materials needed for high-tech applications.
IML-2 was an international success for space life sciences and microgravity research. Many promising results were obtained and much study still remains to be performed on data acquired from the IML-2 experiments.