The NASA Radiation Belt Storm Probes (RBSP) mission addresses how populations of high energy charged particles are created, vary, and evolve in space environments, and specifically within Earth’s magnetically trapped radiation belts. RBSP, with a nominal launch date of August 2012, comprises two spacecraft making in situ measurements for at least 2 years in nearly the same highly elliptical, low inclination orbits (1.1×5.8 RE, 10∘). The orbits are slightly different so that 1 spacecraft laps the other spacecraft about every 2.5 months, allowing separation of spatial from temporal effects over spatial scales ranging from ∼0.1 to 5 RE. The uniquely comprehensive suite of instruments, identical on the two spacecraft, measures all of the particle (electrons, ions, ion composition), fields (E and B), and wave distributions (d E and d B) that are needed to resolve the most critical science questions. Here we summarize the high level science objectives for the RBSP mission, provide historical background on studies of Earth and planetary radiation belts, present examples of the most compelling scientific mysteries of the radiation belts, present the mission design of the RBSP mission that targets these mysteries and objectives, present the observation and measurement requirements for the mission, and introduce the instrumentation that will deliver these measurements. This paper references and is followed by a number of companion papers that describe the details of the RBSP mission, spacecraft, and instruments.

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Science Objectives and Rationale for the Radiation Belt Storm Probes Mission

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment: Editorial

Lunar sourcebook. A user's guide to the moon

1. Introduction 2. Radial velocities 3. Astrometry 4. Timing 5. Microlensing 6. Transits 7. Imaging 8. Host stars 9. Brown dwarfs and free-floating planets 10. Formation and evolution 11. Interiors and atmospheres 12. The Solar System Appendixes References Index.

/pdf/the-exoplanet-handbook-3g3nzlvc20.pdf

The Exoplanet Handbook

In May of 2011, NASA selected the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) asteroid sample return mission as the third mission in the New Frontiers program. The other two New Frontiers missions are New Horizons, which explored Pluto during a flyby in July 2015 and is on its way for a flyby of Kuiper Belt object 2014 MU69 on January 1, 2019, and Juno, an orbiting mission that is studying the origin, evolution, and internal structure of Jupiter. The spacecraft departed for near-Earth asteroid (101955) Bennu aboard an United Launch Alliance Atlas V 411 evolved expendable launch vehicle at 7:05 p.m. EDT on September 8, 2016, on a seven-year journey to return samples from Bennu. The spacecraft is on an outbound-cruise trajectory that will result in a rendezvous with Bennu in November 2018. The science instruments on the spacecraft will survey Bennu to measure its physical, geological, and chemical properties, and the team will use these data to select a site on the surface to collect at least 60 g of asteroid regolith. The team will also analyze the remote-sensing data to perform a detailed study of the sample site for context, assess Bennu’s resource potential, refine estimates of its impact probability with Earth, and provide ground-truth data for the extensive astronomical data set collected on this asteroid. The spacecraft will leave Bennu in 2021 and return the sample to the Utah Test and Training Range (UTTR) on September 24, 2023.

OSIRIS-REx: Sample Return from Asteroid (101955) Bennu

GeMini is a high-resolution gamma-ray spectrometer designed for planetary-science exploration. GeMini serves as the basis for instruments being flown on three upcoming deep-space missions: NASA’s mission to the M-class asteroid (16) Psyche, the Japan Aerospace Exploration Agency sample-return mission to the moons of Mars, and NASA’s Dragonfly mission that will land on Saturn’s largest moon, Titan. These science missions require high-resolution spectroscopy in a low-power, low-mass, rugged design that can survive in a variety of environments. GeMini addresses these needs by providing a cryogenically cooled crystal of high-purity germanium that can operate with as little as 10 to 20 watts, depending on the implementation and mission, and has a mass of less than 2 kg. GeMini helps determine the elemental composition of planetary bodies by measuring gamma rays emitted from the surface. This paper describes the mechanical, thermal, and electrical design of GeMini as well as its performance. It also describes testing that was performed to validate the design with respect to launch loads and radiation damage. Although the basic design of GeMini is common to all three missions, each planetary body has unique environmental conditions and mission specifications. This paper concludes by describing these upcoming missions and how GeMini is customized for each.

GeMini: A High-Resolution, Low-Resource, Gamma-Ray Spectrometer for Planetary Science Applications

Olivine or Impact Melt

Brett W. Denevi (1), Mark S. Robinson (2), Scott L. Murchie (1), Carolyn M. Ernst (1), Paul K. Byrne (3), Sean C. Solomon, (3) Patrick. N. Peplowski (1). (1) The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA, (2) School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA, (3) Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA. Corresponding author’s email address: Brett.Denevi@jhuapl.edu.

The Distribution of Young Plains on Mercury

Introduction: Knowing the elemental composition of a planetary surface is key to understanding its formation and evolution. Planetary gamma-ray spectroscopy is a well-established technique for remotely measuring planetary elemental concentrations for the following elements: H, C, O, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, Fe, Ni, Th, and U. It is unique among the available techniques in that it measures bulk concentrations to depths of tens of cm (in contrast to techniques sensitive only to the top tens of microns), and can quantify compositional layering within this range. Orbital gamma-ray measurements have resulted in significant discoveries from the Moon, Mars, Mercury, and asteroids [1–4]. A Gamma-Ray and Neutron Spectrometer (GRNS) is part of the recently selected Psyche mission, which will orbit the M-class asteroid 16 Psyche [5]. Surface-based, in situ gamma-ray spectroscopy has been relatively limited and not fully realized because the laboratory quality spectrometers needed to achieve full elemental sensitivitity require more resources (e.g., mass, power) than are available for landed missions. In addition, orbital missions increasingly require lower resource instruments, and new instruments need to incorporate lessons learned from prior flight instruments. Here we discuss a new instrument called GeMini Plus, which is a high-purity Ge (HPGe) Gamma-Ray Spectrometer (GRS) that can accomplish laboratory quality, high-precision gamma-ray measurements with the type of low resources needed for landed platforms as well as resource-constrained orbital missions. This abstract provides an overview of the GeMini Plus instrument, including improvements made to prior instruments, as well as future science applications for the use of GeMini-Plus technology. A complementary abstract provides additional information about GeMini Plus, including details of initial performance and expected future tests [6]. GeMini Plus Gamma-Ray Spectrometer: GeMini Plus is based on the MESSENGER GRS [7] and a miniature HPGe instrument known as GeMini (Fig. 1). GeMini was developed by Lawrence Livermore National Laboratory for national security applications [8]. GeMini Plus uses the same HPGe sensor as the MESSENGER GRS and so achieves the same sensitivety. Depending on mission scenario, GeMini Plus may or may not need a plastic scintillator anticoincidence shield (ACS) to reduce background from galactic cosmic rays. An ACS is generally not needed for surface-based measurements, whereas an ACS can significantly increase signal-to-background for many types of orbital measurements [9].

The GeMini Plus High-Purity Ge Gamma-Ray Spectrometer: Instrument Overview and Science Applications

Abstract We present results from a statistical analysis of Mercury's energetic electron (EE) events as observed by the gamma‐ray and neutron spectrometer instrument onboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The main objective of this study is to investigate possible anisotropic behavior of EE events using multiple data sets from MESSENGER instruments. We study the data from the neutron spectrometer (NS) and the gamma‐ray spectrometer anticoincidence shield (ACS) because they use the same type of borated plastic scintillator and, hence, they have very similar response functions, and their large surface areas make them more sensitive to low‐intensity EE events than MESSENGER's particle instrumentation. The combined analysis of NS and ACS data reveals two different classes of energetic electrons: “Standard” events and “ACS‐enhanced” events. Standard events, which comprise over 90% of all events, have signal sizes that are the same in both the ACS and NS. They are likely gyrating particles about Mercury's magnetic field following a 90° pitch angle distribution and are located in well‐defined latitude and altitude regions within Mercury's magnetosphere. ACS‐enhanced events, which comprise less than 10% of all events, have signal sizes in the ACS that are 10 to 100 times larger than those observed by the NS. They follow a beam‐like distribution and are observed both inside and outside Mercury's magnetosphere with a wider range of latitudes and altitudes than Standard events. The difference between the Standard and ACS‐enhanced event characteristics suggests distinct underyling acceleration mechanisms.

Patrick N. Peplowski

Papers

GeMini: A High-Resolution, Low-Resource, Gamma-Ray Spectrometer for Planetary Science Applications

Olivine or Impact Melt

The Distribution of Young Plains on Mercury

The GeMini Plus High-Purity Ge Gamma-Ray Spectrometer: Instrument Overview and Science Applications

Statistical Study of Mercury's Energetic Electron Events as Observed by the Gamma-Ray and Neutron Spectrometer Instrument onboard MESSENGER