Development of a thin section device for space exploration: Overview and system performance estimates

In this paper we present a conceptual design of a spaceborne instrument for the in situ production of rock thin sections on planetary surfaces. The in situ Automated Rock Thin Section Instrument (IS-ARTS) conceptual design demonstrates that the in situ production of thin sections on a planetary body is a plausible new instrument capability for future planetary exploration. Thin section analysis would reduce much ambiguity in the geological history of a sampled site that is present with instruments currently flown. The technical challenge of producing a thin section device compatible with the spacecraft environment is formidable and has been thought too technically difficult to be practical. Terrestrial thin section preparation requires a skilled petrographist, several preparation instruments that individually exceed typical spacecraft mass and power limits, and consumable materials that are not easily compatible with spaceflight. In two companion papers we present research and development work used to constrain the capabilities of IS-ARTS in the technical space compatible with the spacecraft environment. For the design configuration shown we conclude that a device can be constructed that is capable of 50 sample preparations over a 2 year lifespan with mass, power, and volume constraints compatible with current landed Mars mission configurations. The technical requirements of IS-ARTS (mass, power and number of samples produced) depend strongly on the sample mechanical properties, sample processing rate, the sample size and number of samples to be produced.     

Free-Flight Models in Wind Tunnels

A radio telemetry system is described which permits the acquisition of aerodynamic data from free-flight models in wind tunnels. Small transistorized telemeters are used. The telemeters are frequency modulated by either variable-capacitance pressure transducers or by variable-resistance heat-transfer transducers. The models are generally recovered intact after tunnel runs, allowing repeated runs using a single model and permitting recalibrations to verify that no calibration changes have occurred. As many as four channels of data have been recorded simultaneously from a single model at Mach 20. These were base pressure and heat-transfer rate, and forebody surface pressure and heat-transfer rate on 9-deg half-angle, blunt cone models. Several single-channel, base-pressure measurements have been made on 10-deg half-angle, sharp cone models at Mach numbers of 4, 8, and 10. Sample aerodynamic data transmitted during these tests are presented to illustrate the performance of these telemetry systems.     

Rethinking and regrouping

This Washington Watch column briefly reviews spaceflight decisions to be made in Congress, improvements in air travel, and production of helicopters for the Marines which meet the new UH-1Y and AH-1Z standards.     

Fullerenes and interplanetary dust at the Permian-Triassic boundary

We recently presented new evidence that an impact occurred approximately 250 million years ago at the Permian-Triassic boundary (PTB), triggering the most severe mass extinction in the history of life on Earth. We used a new extraterrestrial tracer, fullerene, a third carbon carrier of noble gases besides diamond and graphite. By exploiting the unique properties of this molecule to trap noble gases inside of its caged structure (helium, neon, argon), the origin of the fullerenes can be determined. Here, we present new evidence for fullerenes with extraterrestrial noble gases in the PTB at Graphite Peak, Antarctica, similar to PTB fullerenes from Meishan, China and Sasayama, Japan. In addition, we isolated a (3)He-rich magnetic carrier phase in three fractions from the Graphite Peak section. The noble gases in this magnetic fraction were similar to zero-age deep-sea interplanetary dust particles (IDPs) and some magnetic grains isolated from the Cretaceous-Tertiary boundary. The helium and neon isotopic compositions for both the bulk Graphite Peak sediments and an isolated magnetic fraction from the bulk material are consistent with solar-type gases measured in zero-age deep-sea sediments and point to a common source, namely, the flux of IDPs to the Earth's surface. In this instance, the IDP noble gas signature for the bulk sediment can be uniquely decoupled from fullerene, demonstrating that two separate tracers are present (direct flux of IDPs for (3)He vs. giant impact for fullerene).     

The search for extraterrestrial artifacts (SETA)

The rationale for the use of interstellar artifacts by intelligent life in the universe is described. The advantages of using interstellar probes as a means of exploration and communication are presented and shown to be significant enough to counter the time, energy, and technology arguments generally raised against contact via extraterrestrial artifacts. Four classes of artifacts are defined: Those seeking contact, those seeking to avoid contact, those intended to provide a passive technological threshold for detection, and those for which detection is irrelevant. The Search for Extraterrestrial Artifacts (SETA) is based on the latter two classes. Under the assumption that an extraterrestrial probe will be interested in life in our solar system, a near-Earth search space is defined. This search space is accessible to us now with ground and satellite observing facilities. The current observational status of SETA is reviewed and contrasted with the achievable detection limits for the different parts of the search space.     

Possible effects of organelle charge and density on cell metabolism

To respond to gravity a biological system must: First, perceive the stimulus; and, second transduce the stimulus into an appropriate response. This laboratory has studied a system of perception and transduction involving the gravity-induced asymmetric distribution of a plant growth hormone. From these studies we have developed a working theory which states as its postulates that: a) The perception of the gravitational stimulus involved a perturbation of the plant's bio-electric field; and b) that the transduction of the stimulus involved voltage-gating of hormone movement from the plant's vascular tissue into the hormone responsive growing tissue. These studies may provide the simplest system for studing the mechanism whereby the gravity signal is translated into a biological response.     

Decisions, endings, and new beginnings

The Washington Watch column examines NASA shuttle developments, airline pilot age issues, development of a personnel recovery vehicle, and includes an obituary for retired Air Force General Bernard Schriever, remembered as an air and space pioneer. The discussion of NASA shuttle developments reports on the space shuttle flight schedule and NASA's ability to deliver hardware to the International Space Station, funding levels and equipment development schedules related to President Bush's mandate to visit Mars, a report on the space program by the American Academy of Arts and Sciences, and top-level management changes at NASA. The discussion of airline pilot age issues examines efforts to change mandatory retirement requirements. The discussion of personnel recovery vehicles reports on development of an aircraft designed to rescue survivors during combat search and rescue missions.