S. Pope

The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons

Abstract The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the solar wind and ions created by atmospheric loss from Pluto. These measurements provide a characterization of the total loss rate and allow us to examine the complex plasma interactions at Pluto for the first time. Constrained to fit within minimal resources, SWAP is optimized to make plasma-ion measurements at all rotation angles as the New Horizons spacecraft scans to image Pluto and Charon during the flyby. To meet these unique requirements, we combined a cylindrically symmetric retarding potential analyzer with small deflectors, a top-hat analyzer, and a redundant/coincidence detection scheme. This configuration allows for highly sensitive measurements and a controllable energy passband at all scan angles of the spacecraft.

The interstellar boundary explorer (IBEX): Update at the end of phase B

The Interstellar Boundary Explorer (IBEX) mission will make the first global observations of the heliosphere’s interaction with the interstellar medium. IBEX achieves these breakthrough observations by traveling outside of the Earth’s magnetosphere in a highly elliptical orbit and taking global Energetic Neutral Atoms (ENA) images over energies from ∼10 eV to 6 keV. IBEX’s high‐apogee (∼50 RE) orbit enables heliospheric ENA measurements by providing viewing from far above the Earth’s relatively bright magnetospheric ENA emissions. This high energy orbit is achieved from a Pegasus XL launch vehicle by adding the propulsion from an IBEX‐supplied solid rocket motor and the spacecraft’s hydrazine propulsion system. IBEX carries two very large‐aperture, single‐pixel ENA cameras that view perpendicular to the spacecraft’s Sun‐pointed spin axis. Each six months, the continuous spinning of the spacecraft and periodic re‐pointing to maintain the sun‐pointing spin axis naturally lead to global, all‐sky images. Over the course of our NASA Phase B program, the IBEX team optimized the designs of all subsystems. In this paper we summarize several significant advances in both IBEX sensors, our expected signal to noise (and background), and our groundbreaking approach to achieve a very high‐altitude orbit from a Pegasus launch vehicle for the first time. IBEX is in full scale development and on track for launch in June of 2008.The Interstellar Boundary Explorer (IBEX) mission will make the first global observations of the heliosphere’s interaction with the interstellar medium. IBEX achieves these breakthrough observations by traveling outside of the Earth’s magnetosphere in a highly elliptical orbit and taking global Energetic Neutral Atoms (ENA) images over energies from ∼10 eV to 6 keV. IBEX’s high‐apogee (∼50 RE) orbit enables heliospheric ENA measurements by providing viewing from far above the Earth’s relatively bright magnetospheric ENA emissions. This high energy orbit is achieved from a Pegasus XL launch vehicle by adding the propulsion from an IBEX‐supplied solid rocket motor and the spacecraft’s hydrazine propulsion system. IBEX carries two very large‐aperture, single‐pixel ENA cameras that view perpendicular to the spacecraft’s Sun‐pointed spin axis. Each six months, the continuous spinning of the spacecraft and periodic re‐pointing to maintain the sun‐pointing spin axis naturally lead to global, all‐sky images. Over...

Technique for increasing dynamic range of space-borne ion composition instruments

The dynamic range of ion composition spectrometers is limited by several factors, including saturation of particle counters and spillover of signals from highly dominant species into channels tuned to minor species. Instruments designed for composition measurements of hot plasmas in space can suffer greatly from both of these problems because of the wide energy range required and the wide disparity in fluxes encountered in various regions of interest. In order to detect minor ions in regions of very weak fluxes, geometry factors need to be as large as possible within the mass and volume resources available. As a result, problems with saturation by the dominant fluxes and spillover to minor-ion channels in plasma regions with intense fluxes become especially acute. This article reports on a technique for solving the dynamic-range problem in the few eV to several keV energy/charge range that is of central importance for space physics research where the dominant ion is of low mass/charge (typically H+), and ...