The international space station X-ray crystallography facility

Abstract

This paper presents an overview of the X-ray Crystallography Facility (XCF) currently under development by UAB/CBSE with major support from three contractors. The XCF is to be used on the International Space Station (ISS) for analysis of macromolecular protein crystals grown on the ISS. A brief summary of protein crystal growth experience on the Space Shuttle Orbiter over nearly 15 years is presented, followed by an explanation of reasons for and advantages of a crystal analysis laboratory on the ISS to support protein crystal growth on that space vehicle. The major elements (called prime items) of the XCF are then described, with emphasis on the critical technologies which have been invented or adapted for the ISS and which could also have scientific and commercial applications outside the ISS arena. The crystal preparation prime item is the first of these major elements. The crystal preparation prime item harvests, prepares, and cryogenically preserves crystals by telerobotic techniques completely controlled by crystallographers on the ground. The X-ray diffraction prime item is the second of these major elements. An advanced X-ray source has been invented and developed for this single-crystal diffraction application. This source is described, together with an advanced goniometer and X-ray detector. The third of these major elements is the command, control, and data prime item which implements command, control and data acquisition from remote ground laboratories, as well as by the ISS crew. A realistic operational scenario is postulated for the XCF on the ISS. This scenario has been analyzed in detail to show that the resources required for the XCF operation are well within the bounds of resources to be available on the ISS. A full rack integrated prototype has been constructed, tested, and evaluated and demonstrates full feasibility of the XCF for the ISS application.