Onboard Space Shuttle Columbia (STS-73) Payload Commander Kathryn Thornton works with the Drop Physics Module (DPM) in the United States Microgravity Laboratory 2 (USML-2) Spacelab Science Module cleaning the experiment chamber of the DPM.

The first United States Microgravity Laboratory (USML-1) was one of NASA's science and technology programs that provided scientists an opportunity to research various scientific investigations in a weightlessness environment inside the Spacelab module. It also provided demonstrations of new equipment to help prepare for advanced microgravity research and processing aboard the Space Station. The USML-1 flew in orbit for extended periods, providing greater opportunities for research in materials science, fluid dynamics, biotechnology (crystal growth), and combustion science. This is a close-up view of the Drop Physics Module (DPM) in the USML science laboratory. The DPM was dedicated to the detailed study of the dynamics of fluid drops in microgravity: their equilibrium shapes, the dynamics of their flows, and their stable and chaotic behaviors. It also demonstrated a technique known as containerless processing. The DPM and microgravity combine to remove the effects of the container, such as chemical contamination and shape, on the sample being studied. Sound waves, generating acoustic forces, were used to suspend a sample in microgravity and to hold a sample of free drops away from the walls of the experiment chamber, which isolated the sample from potentially harmful external influences. The DPM gave scientists the opportunity to test theories of classical fluid physics, which have not been confirmed by experiments conducted on Earth. This image is a close-up view of the DPM. The USML-1 flew aboard the STS-50 mission on June 1992, and was managed by the Marshall Space Flight Center.

Astronaut Kathryn C. Thornton, payload commander, works at the Drop Physics Module (DPM) on the portside of the science module supporting the U.S. Microgravity Laboratory (USML-2). Astronaut Kerneth D. Bowersox, mission commander, looks on.

Astronaut Kathryn C. Thornton, payload commander for STS-73, works at the drop physics module (DPM) on the portside of the science module aboard the Space Shuttle Columbia in Earth orbit.

iss065e276849 (Aug. 16, 2021) --- NASA astronaut and Expedition 65 Flight Engineer Mark Vande Hei works inside the U.S. Destiny laboratory module's Microgravity Science Glovebox for the Ring Sheared Drop fluid physics study.

Onboard Space Shuttle Columbia (STS-73) Payload Commander Kathryn Thornton and Commander Ken Bowersox discuss the Drop Physics Module (DPM) experiment in the United States Microgravity Laboratory 2 (USML-2) spacelab science module.

STS073-225-036 (20 October-5 November 1995) --- Payload specialist Fred W. Leslie monitors the response of a liquid drop at the Drop Physics Module (DPM) in the U.S. Microgravity Laboratory (USML-2) science module aboard the Space Shuttle Columbia. Leslie joined another guest researcher and five NASA astronauts for almost 16-days of Earth-orbit research in support of the mission.

STS073-229-014 (20 October - 5 November 1995) --- Astronauts Kathryn C. Thornton, STS-73 payload commander, and Kenneth D. Bowersox, mission commander, observe a liquid drop's activity at the Drop Physics Module (DPM) in the science module aboard the Earth-orbiting Space Shuttle Columbia. The drop is partially visible at the center of the left edge of the frame. The two were joined by three other NASA astronauts and two guest researchers for almost 16-days of in-orbit research in support of the U.S. Microgravity Laboratory (USML-2) mission.

STS050-02-023 (25 June-9 July 1992) --- Astronaut Bonnie J. Dunbar, payload commander, unstows United States Microgravity Laboratory 1 (USML-1) experiment paraphernalia in early stages of the mission. The Multipurpose Glove Box (MPGB) is at upper left. And, at right center, is the Space Station design foot restraint, making its first flight aboard a Space Shuttle on the record-setting 14-day mission.

View showing Payload Specialists Bonnie Dunbar and Larry DeLucas in the aft section of the U. S. Microgravity Laboratory-1. Dunbar prepares to load a sample in the Crystal Growth Furnace (CGF) Integrated Furnace Experiment Assembly (IFEA) in rack 9 of the Microgravity Laboratory, while DeLucas checks out the multi-purpose Glovebox Facility.

Apfel's excellent match: This series of photos shows a water drop containing a surfactant (Triton-100) as it experiences a complete cycle of superoscillation on U.S. Microgravity Lab-2 (USML-2; October 1995). The time in seconds appears under the photos. The figures above the photos are the oscillation shapes predicted by a numerical model. The time shown with the predictions is nondimensional. Robert Apfel (Yale University) used the Drop Physics Module on USML-2 to explore the effect of surfactants on liquid drops. Apfel's research of surfactants may contribute to improvements in a variety of industrial processes, including oil recovery and environmental cleanup.

STS073-108-005 (20 October-5 November 1995) --- Two members of the crew perform an in-flight maintenance on the Drop Physics Module (DPM) in the science module aboard the Earth-orbiting Space Shuttle Columbia. Payload commander Kathryn C. Thornton and payload specialist Albert Sacco Jr. were part of a seven-member crew that spent 16 full days in space in support of the United States Microgravity Laboratory (USML-2) mission.

STS073-E-5311 (3 Nov. 1995) --- Astronaut Kathryn C. Thornton, STS-73 payload commander, works at the Drop Physics Module (DPM) on the portside of the science module supporting the U.S. Microgravity Laboratory (USML-2). Astronaut Kenneth D. Bowersox, mission commander, looks on. Five NASA astronauts and two payload specialists are in the last few days of a scheduled 16-day mission. This frame was exposed with the Electronic Still Camera (ESC).

STS073-E-5003 (23 Oct. 1995) --- Astronaut Kathryn C. Thornton, STS-73 payload commander, works at the Drop Physics Module (DPM) on the portside of the science module aboard the Space Shuttle Columbia in Earth orbit. Payload specialist Albert Sacco Jr. conducts an experiment at the Glovebox. This frame was exposed with the color Electronic Still Camera (ESC) assigned to the 16-day United States Microgravity Laboratory (USML-2) mission.

STS050-255-027 (25 June-9 July 1992) --- Payload specialist Eugene H. Trinh, left, and astronaut Carl J. Meade, mission specialist, go to work in the U.S. Microgravity Laboratory (USML-1) science module as the blue shift crew takes over from the red. Trinh is working with an experiment at the Drop Physics Module (DPM) and Meade prepares to monitor an experiment in the Glovebox. The two joined four other astronauts and a second scientist from the private sector for 14-days of scientific data-gathering.

STS050-301-001 (25 June-9July 1992) --- Astronaut Carl J. Meade, mission specialist, works with the Generic Bioprocessing Apparatus in the science module aboard the Earth-orbiting Space Shuttle Columbia. Payload specialist Eugene H. Trinh is partially visible (left), monitoring an experiment in the Drop Physics Module (DPM). The two joined four other astronauts and a second scientist from the private sector for 14-days of scientific data-gathering.

STS073-143-026 (20 October-5 November 1995) --- Astronaut Kathryn C. Thornton, STS-73 payload commander for the United States Microgravity Laboratory (USML-2), explores the inner workings of the Drop Physics Module (DPM). Thornton was joined by four other NASA astronauts and two guest researchers for almost 16 days of research aboard the Space Shuttle Columbia in Earth-orbit.

iss065e319336 (Aug. 27, 2021) --- Expedition 65 Flight Engineer Thomas Pesquet of ESA (European Space Agency) works on the Ring-Sheared Drop experiment inside the U.S. Destiny laboratory module's Microgravity Science Glovebox. Results from the fluid physics study could contribute to a better understanding of neurodegenerative diseases such as Alzheimer’s as well as the development of advanced materials.

iss073e0253842 (July 1, 2025) --- NASA astronaut and Expedition 73 Flight Engineer Nichole Ayers stows physics research hardware from inside the Microgravity Science Glovebox located inside the International Space Station's Destiny laboratory module. Ayers was completing operations with the Ring Sheared Drop investigation that may benefit pharmaceutical manufacturing techniques and 3D printing in space.

iss073e0253837 (July 1, 2025) --- NASA astronaut and Expedition 73 Flight Engineer Nichole Ayers poses for a portrait as she removes physics research hardware from inside the Microgravity Science Glovebox located inside the International Space Station's Destiny laboratory module. Ayers was completing operations with the Ring Sheared Drop investigation that may benefit pharmaceutical manufacturing techniques and 3D printing in space.

iss073e0253839 (July 1, 2025) --- NASA astronaut and Expedition 73 Flight Engineer Nichole Ayers removes physics research hardware from inside the Microgravity Science Glovebox located inside the International Space Station's Destiny laboratory module. Ayers was completing operations with the Ring Sheared Drop investigation that may benefit pharmaceutical manufacturing techniques and 3D printing in space.

In this photograph, astronaut Eugene Trinh, a payload specialist for this mission, is working at the Drop Physics Module (DPM), and mission specialist Carl Meade is working on the experiment at the Glovebox inside the first United States Microgravity Laboratory (USML-1) Science Module. The USML-1 was one of NASA's missions dedicated to scientific investigations in a microgravity environment inside the Spacelab module. Investigations aboard the USML-1 included: materials science, fluid dynamics, biotechnology (crystal growth), and combustion science. The DPM is dedicated to the detailed study of the dynamics of fluid drops in microgravity. The Glovebox offers experimenters new capabilities and technologies in microgravity with a clean working space and minimizes contamination risks to both Spacelab and experiment samples. Payload specialists are professional scientists or engineers whose only assignment on a space flight is to carry out scientific and technological experiments. Their specific training for a space flight is usually limited to a short period of learning how to live and work in weightlessness. Mission Specialists are both professional scientists and career astronauts. Thus they are a link or bridge between the other crew members, and combine the functions of resident maintenance engineers, in-space counterparts of flight engineers in aircraft, and fully qualified scientists. The USML-1 flew aboard the STS-50 mission on June 1992, and was managed by the Marshall Space Flight Center.