crystal position have been measured at −183°C. A new nozzle developed by Hakon Hope, which uses a heater element to produce a warm outer flow from the inner cold flow, is being tested.

Experiment Control. The status and operation of the various components of the XCF (the HDPCG, the visualization unit, the CPPI, and the X-ray diffraction system) on the ISS can be monitored on the ground through a Payload Operations Control Center. Current plans call for these centralized control capabilities to be situated at the Center for Macromolecular Crystallography at the University of Alabama at Birmingham.

Relevant Support Equipment

The apparatus listed here is not a part of the BTF or the XCF but is scheduled to be located elsewhere on the ISS. Like crew time for experimental activities, use of support equipment will be shared by many research projects on the ISS.

Minus Eighty Degree Laboratory Freezer for ISS (MELFI). This unit will provide cooling down and storage for reagents, samples, and perishable materials in four dewars with independently selectable temperatures of −80°C, −26°C, and +4°C during on-orbit ISS operations. It will also be used to transport samples to and from the ISS in a low-temperature controlled environment. The total capacity of MELFI is 300 liters; the system occupies a full rack. MELFI is currently in development by the European Space Agency; delivery is due late in 2000.

Cryofreezer System. This unit is designed to provide ultrarapid freezing and storage capacity for 3 liters of research specimens at −183°C. It is also under development by the European Space Agency for delivery in 2004.

Middeck Glovebox. This unit provides an enclosed space for experiment manipulation and observation for work in the several disciplines to be studied on ISS, including protein crystallization, fluid physics, combustion, and material science. Various modes of air circulation and pressurization are possible. Multipurpose filters are used to remove particles, liquids, and reaction gases from the circulated air. The glovebox, which occupies two MLEs, has a working volume of 35 liters and a door opening of 20.3 by 19.4 cm for sample and hardware transfer. Up to 60 W of 24, 12, and 5 V of direct current power is available for instruments to be used inside the glovebox.

Cell and Tissue Culture Hardware in Development for ISS

Biotechnology Temperature Controller (BTC). This unit is designed to provide refrigeration on-orbit as well as the capability of preserving and incubating multiple cell cultures simultaneously. The cell culture bags are transparent to allow visualization of the samples by light microscopy. While the BTC does not have the capability of automated medium exchange, the cultures can be fed using special needleless “penetration” connectors on the bags that provide for multiple aseptic connections. The BTC can be used as one large chamber or reconfigured into 2, 3, or 4 chambers with separate environmental controls (temperatures can range from 4°C to 40°C in 1°C increments). The unit occupies one MLE and can contain up to 120 7-ml culture bags, which are Teflon sample modules containing media and cells. This unit is in development at NASA, and its first flight is scheduled for late 2001. The BTC, with its combined refrigeration and incubation capabilities, was designed based on lessons learned from NASA's Biotechnology Specimen Temperature Controller (BSTC) and Biotechnology Refrigerator (BTR), which have been flown both for short-term space shuttle trips and for long-term experiments on Mir.

Cell Culture Unit (CCU). This unit is a modular cassette-style bioreactor that can accommodate multiple cell culture chambers (see Figure 2.2). The CCU provides control of temperature (between 4°C and 39°C) and pH (between 3.5 and 8.5) and allows for continual feeding and waste medium harvest from perfused stationary

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