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

Science Goals of the Mars-moon Exploration with GAmma rays and NEutrons (MEGANE) Investigation for the MMX Mission

Global Distribution and Spectral Properties of Low-Reflectance Material on Mercury

Many lines of evidence (e.g. common geochemistry, chronology, O-isotope trends, and the presence of different HED rock types in polymict breccias) indicate that the howardite, eucrite, and diogenite (HED) meteorites originated from a single parent body. Meteorite studies show that this protoplanet underwent igneous differentiation to form a metallic core, an ultramafic mantle, and a basaltic crust. A spectroscopic match between the HEDs and 4 Vesta along with a plausible mechanism for their transfer to Earth, perhaps as chips off V-type asteroids ejected from Vesta's southern impact basin, supports the consensus view that many of these achondritic meteorites are samples of Vesta's crust and upper mantle. The HED-Vesta connection was put to the test by the NASA Dawn mission, which spent a year in close proximity to Vesta. Measurements by Dawn's three instruments, redundant Framing Cameras (FC), a Visible-InfraRed (VIR) spectrometer, and a Gamma Ray and Neutron Detector (GRaND), along with radio science have strengthened the link. Gravity measurements by Dawn are consistent with a differentiated, silicate body, with a dense Fe-rich core. The range of pyroxene compositions determined by VIR overlaps that of the howardites. Elemental abundances determined by nuclear spectroscopy are also consistent with HED-compositions. Observations by GRaND provided a new view of Vesta inaccessible by telescopic observations. Here, we summarize the results of Dawn's geochemical investigation of Vesta and their implications.

https://ntrs.nasa.gov/api/citations/20140012596/downloads/20140012596.pdf

Vesta's Elemental Composition

Introduction: Distinctive low-reflectance material (LRM) was first observed on Mercury in Mariner 10 flyby images [1]. Visible to near-infrared reflectance spectra of LRM are flatter than the average reflectance spectrum of Mercury, which is strongly red sloped (increasing in reflectance with wavelength). From Mariner 10 and early MErcury, Surface, Space, ENvironment, GEochemistry, and Ranging (MESSENGER) flyby observations, it was suggested that a higher content of ilmenite, ulvöspinel, carbon, or iron metal could cause both the characteristic dark, flat spectrum of LRM and the globally low reflectance of Mercury [1,2]. Once MESSENGER entered orbit, low Fe and Ti abundances measured by the X-Ray and Gamma-Ray Spectrometers ruled out ilmenite and ulvöspinel as important surface constituents [3,4] and implied that LRM was darkened by a different phase, such as carbon or small amounts of microor nanophase iron or iron sulfide dispersed in a silicate matrix. Low-altitude thermal neutron measurements of three LRM-rich regions confirmed an enhancement of 1–3 wt% carbon over the global abundance, supporting the hypothesis that the darkening agent in LRM is carbon [5]. Here, using the final calibration of the Mercury Dual Imaging System (MDIS) 8-color global mosaic, we examine the distribution and spectral properties of LRM on a global scale, and extrapolate the results of Peplowski et al. [5] to place bounds on the carbon abundance of different LRM deposits across Mercury. Distribution of Low Reflectance Material: LRM is distributed across Mercury, typically having been excavated from depth by craters and basins. In contrast to the brighter high reflectance plains (HRP) and smooth plains deposits, which exhibit morphological evidence of volcanism [e.g., 6-8], LRM is not associated with flow features or other evidence of a volcanic origin. Older LRM boundaries are generally diffuse, and grade into low-reflectance blue plains (LBP). Because of the common lack of sharp geologic boundaries, LRM has been defined primarily based on albedo and spectral shape, isolated through principal components (PC) analyses of MDIS color images [9]. LRM is the darkest material on Mercury, with an albedo of 4–5% at 560 nm (compared to a global 560-nm albedo of ~6%), and it exhibits a spectral slope that is substantially less red than the rest of Mercury. The low iron content of Mercury’s surface results in a lack of the spectral absorption bands typically used to map mafic minerals on planets and asteroids. Thus, mathematical transformations such as PC analysis are required to map subtle spectral differences. For example, the second principal component (PC2), captures a combination of spectral slope and curvature, isolating LRM and hollows as one endmember, with red material and HRP as the other end member. LBP and intermediate plains (IP) are transitional from LRM to HRP [10]. In [5], concentrated LRM exposures were defined as regions with a photometrically corrected reflectance of <5% (at 560 nm wavelength) and a PC2 value of <0.023. This value corresponds with the lower ~25% of the range of PC2 values for the whole planet. The resulting LRM map, overlain on the global color mosaic, is shown in Fig. 1a. There are some regional concentrations where many moderate sized craters or several larger basins excavated LRM in close proximity to one another. LRM is most immediately recognizable visually when excavated by craters and deposited onto high-reflectance red plains (HRP, as in Caloris basin), due to the contrasting reflectance and spectral slopes of the different stratigraphic layers. However, it is also abundant throughout the oldest, rough terrains, where its boundaries are more difficult to delineate as they grade into LBP. In these older terrains LRM is still apparently associated with crater ejecta, but the high density of craters excavating LRM results in a patchy distribution of low-reflectance, low-PC2 material.

Patrick N. Peplowski

Papers

Science Goals of the Mars-moon Exploration with GAmma rays and NEutrons (MEGANE) Investigation for the MMX Mission

Global Distribution and Spectral Properties of Low-Reflectance Material on Mercury

Vesta's Elemental Composition

Examining the Distribution and Concentration of Carbon on Mercury

GeMini Plus: A Versatile Gamma-Ray Spectrometer for Planetary Composition Measurements