Beyond earth's boundaries: Human exploration of the Solar System

The USA has adopted the long-term goal of exploring the space frontier, including establishing human settlements beyond Earth orbit. This article describes four candidate missions for developing pathways into the Solar System which have been identified by NASA's Office of Exploration: human expeditions to Phobos and Mars, a lunar observatory and a lunar outpost to assist Mars explorations. The requirements placed upon near-term programmes by each of these missions are outlined and the elements necessary for a long-term implementation strategy are analysed.     

A viable microbial community in a subglacial volcanic crater lake, Iceland

We describe a viable microbial community in a subglacial lake within the Grímsv?tn volcanic caldera, Iceland. We used a hot water drill to penetrate the 300-m ice shelf and retrieved lake water and volcanic tephra sediments. We also acquired samples of borehole water before and after penetration to the lake, overlying glacial ice and snow, and water from a nearby subaerial geothermal lake for comparative analyses. Lake water is at the freezing point and fresh (total dissolved solids = 260 mg L(-1)). Detectable numbers of cells were found in samples of the lake water column and tephra sediments: 2 x 10(4) ml(-1) and 4 x 10(7) g(-1), respectively. Plate counts document abundant cold-adapted cultivable organisms in the lake water, but not in the borehole (before penetration) or glacial ice. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from genomic DNA extracted from Grímsv?tn samples indicates that the lake community is distinct from the assemblages of organisms in borehole water (before penetration) and the overlying ice and snow. Sequencing of selected DGGE bands revealed that many sequences are highly similar to known psychrophilic organisms or cloned DNA from other cold environments. Significant uptake of 14C-labeled bicarbonate occurred in dark, low-temperature incubations of lake water samples, indicating the presence of autotrophs. Acetylene reduction assays under similar incubation conditions showed no significant nitrogen fixation potential by lake water samples. This may be a consequence of the inhibition of diazotrophy by nitrogen in the lake.     

CTACTS Charleston Tactical Aircrew Combat Training System

This paper presents an overview of the Ocean Engineering and Construction Project Office (FPO-1) of the Chesapeake Division, Naval Facilities Engineering Command design and construction of eight ocean towers. These towers are for the Charleston Tactical Aircrew Combat Training System (CTACTS). The offshore portion of the CTACTS provides the necessary facilities to accurately monitor and control the training of Navy, Marine Corps, and Air Force pilots, during aerial warfare training exercises. These offshore facilities are located 30 to 72 nautical miles east of northern Georgia in water depths ranging from 81 to 143 feet. In June, 1984, FPO-1 awarded the ocean tower design contract to Brown & Root Development, Inc. The final design was completed in August, 1985 and in January, 1986, FPO-1 awarded a contract to McDermott Marine Construction to fabricate and install the platforms. The installation is scheduled to be completed by mid-September, 1986.