STS-67

Astro-2 was the second dedicated Spacelab mission to conduct astronomical observations in the ultraviolet spectral regions (the first was the Astro-1 mission flown on STS-35). The Astro-2 Spacelab consisted of three unique instruments – the Hopkins Ultraviolet Telescope (HUT), the Ultraviolet Imaging Telescope (UIT) and the Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE). These took measurements from objects within the Solar System as well as individual stars, nebulae, supernova remnants, galaxies and active extragalactic objects. The data supplemented the data obtained from the Astro-1 mission.

The purpose of the UIT was to observe UV radiation from space (most UV radiation is absorbed by Earth's atmosphere and cannot be studied from the ground). The data collected from UIT Astro-1 mission provided the first accurate knowledge of UV data from the universe. The UIT in the Astro-2 Spacelab was capable of capturing almost twice the UV spectrum of its predecessor. As STS-67 launched at a different time of year from STS-35, data was collected from portions of the sky that Astro-1 was not able to view.

On the Middeck, science experiments included the Protein Crystal Growth Thermal Enclosure System Vapor Diffusion Apparatus-03 experiment (PCG-TES-03), the Protein Crystal Growth Single Thermal Enclosure System-02 (PCG-STES-02), the Shuttle Amateur Radio Experiment-II (SAREX-II), the Middeck Active Control Experiment (MACE), the Commercial Materials Dispersion Apparatus Instrumentation Technology Associates Experiments-03 (CMIX-03) and the Midcourse Space Experiment (MSX).

The Middeck Active Control Experiment (MACE) was a space engineering research payload and activity. It consisted of a rate gyro, reaction wheels, a precision pointing payload, and a scanning and pointing payload that produces motion disturbances. The goal of the experiment was to test a closed loop control system that could compensate for motion disturbances. On orbit, Commander Stephen S. Oswald and Pilot William G. Gregory used MACE to test about 200 different motion disturbance situations over 45 hours of testing during the mission. Information from MACE was to be used to design better control systems that compensate for motion in future spacecraft.