A low-temperature origin for the planetesimals that formed Jupiter

The four giant planets in the Solar System have abundances of 'metals' (elements heavier than helium), relative to hydrogen, that are much higher than observed in the Sun. In order to explain this, all models for the formation of these planets rely on an influx of solid planetesimals(17). It is generally assumed that these planetesimals were similar, if not identical, to the comets from the Oort cloud that we see today. Comets that formed in the region of the giant planets should not have contained much neon, argon and nitrogen, because the temperatures were too high for these volatile gases to be trapped effectively in ice. This means that the abundances of those elements on the giant planets should be approximately solar. Here we show that argon, krypton and xenon in Jupiter's atmosphere are enriched to the same extent as the other heavy elements, which suggests that the planetesimals carrying these elements must have formed at temperatures lower than predicted by present models of giant-planet formation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62913/1/402269a0.pd

Galileo Probe Mass Spectrometer experiment

The Galileo Probe Mass Spectrometer (GPMS) is a Probe instrument designed to measure the chemical and isotopic composition including vertical variations of the constituents in the atmosphere of Jupiter. The measurement will be performed by in situ sampling of the ambient atmosphere in the pressure range from approximately 150 mbar to 20 bar. In addition batch sampling will be performed for noble gas composition measurement and isotopic ratio determination and for sensitivity enhancement of non-reactive trace gases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43775/1/11214_2004_Article_BF00216852.pd

The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe

Saturn's largest moon, Titan, remains an enigma, explored only by remote sensing from Earth, and by the Voyager and Cassini spacecraft. The most puzzling aspects include the origin of the molecular nitrogen and methane in its atmosphere, and the mechanism(s) by which methane is maintained in the face of rapid destruction by photolysis. The Huygens probe, launched from the Cassini spacecraft, has made the first direct observations of the satellite's surface and lower atmosphere. Here we report direct atmospheric measurements from the Gas Chromatograph Mass Spectrometer (GCMS), including altitude profiles of the constituents, isotopic ratios and trace species ( including organic compounds). The primary constituents were confirmed to be nitrogen and methane. Noble gases other than argon were not detected. The argon includes primordial Ar-36, and the radiogenic isotope Ar-40, providing an important constraint on the outgassing history of Titan. Trace organic species, including cyanogen and ethane, were found in surface measurements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62703/1/nature04122.pd

Astrochemistry - Complex organic matter in Titan's aerosols? Reply

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62938/1/nature05418.pd

The Cassini Ion and Neutral Mass Spectrometer (INMS) Investigation

The Cassini Ion and Neutral Mass Spectrometer (INMS) investigation will determine the mass composition and number densities of neutral species and low-energy ions in key regions of the Saturn system. The primary focus of the INMS investigation is on the composition and structure of Titan’s upper atmosphere and its interaction with Saturn’s magnetospheric plasma. Of particular interest is the high-altitude region, between 900 and 1000 km, where the methane and nitrogen photochemistry is initiated that leads to the creation of complex hydrocarbons and nitriles that may eventually precipitate onto the moon’s surface to form hydrocarbon–nitrile lakes or oceans. The investigation is also focused on the neutral and plasma environments of Saturn’s ring system and icy moons and on the identification of positive ions and neutral species in Saturn’s inner magnetosphere. Measurement of material sputtered from the satellites and the rings by magnetospheric charged particle and micrometeorite bombardment is expected to provide information about the formation of the giant neutral cloud of water molecules and water products that surrounds Saturn out to a distance of ∼12 planetary radii and about the genesis and evolution of the rings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43764/1/11214_2004_Article_1408.pd

The Gas Chromatograph Mass Spectrometer for the Huygens Probe

The Gas Chromatograph Mass Spectrometer (GCMS) on the Huygens Probe will measure the chemical composition of Titan's atmosphere from 170 km altitude (∼1 hPa) to the surface (∼1500 hPa) and determine the isotope ratios of the major gaseous constituents. The GCMS will also analyze gas samples from the Aerosol Collector Pyrolyser (ACP) and may be able to investigate the composition (including isotope ratios) of several candidate surface materials.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43756/1/11214_2004_Article_5106930.pd

An atomic oxygen beam system for the investigation of mass spectrometer response in the upper atmosphere

http://deepblue.lib.umich.edu/bitstream/2027.42/6827/5/bac9749.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/6827/4/bac9749.0001.001.tx

An Atomic Oxygen Beam System for the Investigation of Mass Spectrometer Response in the Upper Atmosphere

An atomic oxygen beam system has been designed and tested for the laboratory evaluation of mass spectrometers used in upper atmospheric measurements. The atomic oxygen is generated by thermal dissociation of molecular oxygen on the surface of a tungsten filament heated to 2800 K. A symmetrical bidirectional beam is produced to permit simultaneous monitoring of the particle flux in the beam while target experiments are being conducted. Flux levels of 5×1014 particles cm−2 sec−1 over a cross‐sectional area of 1 cm2 have been produced with a relative atomic oxygen concentration of 70%. At flux levels below 1013 particles cm−2 sec−1, relative atomic oxygen concentrations of more than 90% were obtained. The oxygen beam is of high purity and free from chemically active contaminants. Strong chemical and low temperature pumping are used to reduce background gas contributions to less than 1%. Measurements of the relative atomic concentration in the beam were made with a quadrupole spectrometer using an open flowthrough ion source. The absolute flux of molecular oxygen was determined with the aid of an enclosed omegatron mass spectrometer. The combined use of both instruments permitted a determination of the magnitude of the atomic oxygen flux in the beam.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70929/2/RSINAK-43-8-1151-1.pd

Omegatron Mass Spectrometer for Partial Pressure Measurements in Upper Atmosphere

A simple Omegatron mass analyzer used for measuring density and temperature of nitrogen in the 100 to 350 km region of the upper atmosphere has been developed. The mechanical and electrical configurations have been designed for rocket flight application, and the operating parameters optimized for the upper atmosphere measurement. This Omegatron is calibrated and flown as part of a sounding rocket experiment known as the Thermosphere Probe, which also contains an electron temperature probe for determining electron temperature and density. Several successful flights have shown that the Omegatron is a reliable device for this application.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70446/2/RSINAK-37-6-722-1.pd

Application of a quasi-open ion source for neutral particle density measurements in the thermosphere

http://deepblue.lib.umich.edu/bitstream/2027.42/6826/5/bac9750.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/6826/4/bac9750.0001.001.tx