All planetary materials sampled thus far vary in their relative abundance of the major isotope of oxygen, (16)O, such that it has not been possible to define a primordial solar system composition. We measured the oxygen isotopic composition of solar wind captured and returned to Earth by NASA's Genesis mission. Our results demonstrate that the Sun is highly enriched in (16)O relative to the Earth, Moon, Mars, and bulk meteorites. Because the solar photosphere preserves the average isotopic composition of the solar system for elements heavier than lithium, we conclude that essentially all rocky materials in the inner solar system were enriched in (17)O and (18)O, relative to (16)O, by ~7%, probably via non-mass-dependent chemistry before accretion of the first planetesimals.

Plasma outflows, escaping from Earth through the high-altitude polar caps into the tail of the magnetosphere, have been observed with a xenon plasma source instrument to reduce the floating potential of the POLAR spacecraft. The largest component of H + flow, along the local magnetic field (30 to 60 kilometers per second), is faster than predicted by theory. The flows contain more O + than predicted by theories of thermal polar wind but also have elevated ion temperatures. These plasma outflows contribute to the plasmas energized in the elongated nightside tail of the magnetosphere, creating auroras, substorms, and storms. They also constitute an appreciable loss of terrestrial water dissociation products into space.

The Plasma Experiment for Planetary Exploration (PEPE) flown on Deep Space 1 combines an ion mass spectrometer and an electron spectrometer in a single, low-resource instrument. Among its novel features PEPE incorporates an electrostatically swept field-ofview and a linear electric field time-of-flight mass spectrometer. A significant amount of effort went into developing six novel technologies that helped reduce instrument mass to 5.5 kg and average power to 9.6 W. PEPE's performance was demonstrated successfully by extensive measurements made in the solar wind and during the DS1 encounter with Comet 19P/Borrelly in September 2001.

No abstract

This paper reviews recent advances in the detection of single photons at visible and near-infrared wavelengths, focusing on detectors based on superconducting and semiconducting technologies. * Contribution of NIST, an agency of the U.S. government, not subject to copyright. OCIS codes: (230.5160) Photodetectors; (270.5570) Quantum detectors IntroductionDetectors that are sensitive to single photons have applications in a wide variety of fields, such as biomedical imaging, astronomy, quantum cryptography, and quantum computing. Here we review various superconducting and semiconducting technologies for the detection of single photons, including avalanche photodiodes, visible light photon counters, quantum-dot-gated field-effect transistors, superconducting single photon detectors, and superconducting transition-edge sensors. Although all of the detectors discussed here are single-photon sensitive, some have the additional ability to resolve the number of photons in a pulse of light.Different applications have varying detector requirements. Quantum key distribution (QKD), for example, generally requires detectors with high efficiency and low dark count rate. If the QKD system is fiber-based, the detectors must operate at the telecommunication wavelengths, 1310 nm and 1550 nm. Energy-resolving detectors can also be used to verify that the source used creates the expected distribution of photon-number, an important determination because the ultimate security of many QKD systems rests on the transmission of single photons. Linear-optics quantum computing requires very high detection efficiency, low dark count rate, and photon-number-resolving detectors.