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The successful operation of spacecraft requires careful planning. Each mission comes with a unique set of challenges that must be met by tools and techniques developed on a mission-specific basis. In the past, these tools have been created as Command Line Interfaces (CLIs), Remote Command Line Interfaces (Remote CLIs), or Graphical User Interfaces (GUIs). This paper presents a method for the development of these custom tools implemented for the mission planning of the CYGNSS (Cyclone Global Navigation Space System) mission: using the Django web framework to act as a remote Graphical User Interface. CYGNSS, the NASA Earth Venture Class mission which launched in late 2016, is a constellation of eight microsatellites in low Earth orbit which perform ocean wind speed measurements using reflected GPS signals to aid in weather modeling. Several tools have been developed to aid in the extensive and ongoing workload in mission planning. Now operating in the extended mission phase, the CYGNSS team is small. However, each team-member works on several projects aside from CYGNSS and performs the necessary mission planning and operations from their individual computer. Since, when using traditional tools, each operator's computer generally has a different combination of hardware, software, and operating system, developers are often required to perform custom installation and debugging for each new user of the system. This results in a system which is prone to user-specific bugs, and is not suitable for the low-cost environment in which CYGNSS operates. We present a method which alleviates these problems. We use Django, a Python-based website framework, to host a suite of mission planning tools on a local website. This framework is split into three components: the Object Relational Mapping (ORM), the Template, and the View. The Django ORM is used to access the backend database from Python. Django Templates are used to control how the tool is displayed to the end user. Django Views tie the previous two components together by taking a request from the user, retrieving data from the database, rendering a template using that data, and returning the rendered template to the user where it is displayed by a web browser. We show how each of these components is used and the benefits of using such a web based system over a traditional tool.

The Kuiper Belt is a distant region of the Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU69, a Cold Classical Kuiper Belt Object, a class of objects that have never been heated by the Sun and are therefore well preserved since their formation. Here we describe initial results from these encounter observations. MU69 is a bi-lobed contact binary with a flattened shape, discrete geological units, and noticeable albedo heterogeneity. However, there is little surface color and compositional heterogeneity. No evidence for satellites, ring or dust structures, gas coma, or solar wind interactions was detected. By origin MU69 appears consistent with pebble cloud collapse followed by a low velocity merger of its two lobes., 43 pages, 8 figure

The flight operations of the Cyclone Global Navigation Satellite System (CYGNSS), a constellation of eight microsatellites built and operated by Southwest Research Institute (SwRI), designed to improve the intensity forecasts of Tropical Cyclones, has seen a litany of changes to its concept of operations, software, processes, and personnel. In this paper, we detail how the operations team responded to several challenges such as the reduction in personnel after the Launch and Early Orbit Operations phase, the addition of a downlink antenna in Japan, high-fidelity collection requests during the unusually active 2017 Atlantic hurricane season, and the increased demands of team members from other projects. These pressures forced the CYGNSS operations team to innovate their way to efficient operations. These innovations were enabled by embracing modern open-source tools such as Django, Bokeh, Git, the various libraries available in the Python programming language, and the capabilities that come with all of our operations engineers being competent in software development. The CYGNSS team took the approach of automating the most time-intensive tasks first, which freed up time to carefully design and test more elaborate automation solutions. We utilized the spirit of the Agile Methodology to make incremental improvements to our software suite which further enabled more sophisticated automation. Finally, we chart a path forward to fully closing the automation loop between our mission planning, and real-time Command and Control.

This paper reviews the telemetry downlink and data processing implementation currently in use for the eight spacecraft of the National Aeronautics and Space Administration (NASA) Cyclone Global Navigation Satellite System (CYGNSS) mission (launched December 2016). The NASA CYGNSS mission aims to understand the coupling between ocean surface properties, moist atmospheric thermodynamics, radiation, and convective dynamics in the inner core of Tropical Cyclones (TCs). The mission is comprised of eight microsatellites in Low-Earth Orbit (LEO) at an inclination of 35 degrees. The CYGNSS mission faces unique constraints with respect to telemetry downlink: there are eight satellites to juggle with limited staff (implying unstaffed passes are a necessity), cost constraints limit passes to ∼7 minutes once every two days (implying the downlink must be 100% utilized), and the onboard processor runs at 25 MHz (implying hardware must be utilized to off-load the software). In summary, a microsatellite must downlink the equivalent of 2500 digital photos every two days, using the horsepower of a 2001 Palm Pilot, in less time than it takes to cook a batch of cookies. The ground data processing must then package and deliver the science data cookies to the eager scientists as soon as possible so that it may be used to accurately update forecasting models. The CYGNSS Flight Software (FSW) telemetry downlink implementation is reviewed, including the observed on-orbit advantages, and the lessons learned that could have led to a better implementation. The implementation has now been shown to work well, and was able to avoid the complexity and resource requirements of integrating a third-party Application Programming Interface (API), such as CFDP, into the FSW. In addition to the flight segment implementation, the ground segment data processing of CYGNSS will also be assessed. The ground data processing must be robust: it must handle asynchronous data streams from each microsatellite ground pass, it must handle delivery of science and engineering data to their own unique end-user system, identify any data loss, support ingest of any re-downlinked data, and perform parallel data processing for all eight spacecraft. These implementations are reviewed, noting observed advantages and lessons learned.

The New Horizons encounter with the Pluto system was a historic achievement in planetary exploration. Launched on January 19, 2006, the spacecraft executed its close encounter with Pluto on July 14, 2015, acquiring the first-ever close up data of Pluto, its five known satellites, and the surrounding plasma and particle environment. During its 9½ year cruise, the spacecraft also conducted a flyby of an asteroid in 2006 and a Jupiter gravity assist in 2007 during which over 700 observations of Jupiter, the Galilean satellites, and the plasma and particle environment near Jupiter were acquired. Led by Principal Investigator Alan Stern, New Horizons was the first launch of NASA’s New Frontiers Program and the first mission to Pluto and the Kuiper Belt.

[1] In this paper, we analyze Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) stereo observations of energetic neutral atoms (ENAs) produced from the low altitude emission (LAE) region during the interval 1130–1146 UT on 6 April 2010. Geometrical calculations determine the geophysical locations of pixels at or near the LAE limb and the associated uncertainties. For our event, the two TWINS imagers observed a broad (8.4–9.2 h wide in magnetic local time (MLT)) region of LAEs on the opposing limb, possibly containing an ion boundary near dusk. The most intense LAEs were detected in a narrow range of magnetic latitude (67°–74°) and pitch angle (112°–116°). We implement a simplified thick-target approximation (TTA) to obtain ion spectra from TWINS LAEs and perform a validation study using a conjunction of the TWINS-observed LAE crescents with a simultaneous NOAA 17 polar-orbit pass slightly west of the TWINS LAEs. Since TTA is limited to the brightest portion of LAEs, we apply our analysis for pixels with at least 30% of the peak value. TWINS ion spectra are calculated for individual pixels spanning several hours of MLT. The spectra exhibit a pronounced local time dependence. For more westward MLT (and more equatorward latitude), there is a shift toward spectra that are more energetic and peaked. This spatial dependence is consistent with ion drift theory and previous observations. The peaked LAE-derived ion spectra of 6 April 2010 are notably different than those observed during much weaker disturbances, but are consistent with LAE observations from similar activity levels. These results demonstrate that with proper caution in interpreting the results, TWINS ENA imaging resolves MLT-dependent (and to a limited extent, latitude-dependent) low-altitude ion spectral shape information, simultaneously across a broad range of MLT. This study advances previous results that considered much coarser MLT structure in LAEs and augments previous statistical spectral analysis of in situ data.

The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto's atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto's large moon Charon displays tectonics and evidence for a heterogeneous crustal composition, its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected., 8 pages - Initial Science paper from NASA's New Horizons Pluto Encounter

[1] Stereo energetic neutral atom (ENA) images from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) are analyzed using a simple line-of-sight (LOS) mapping approximation, for two case studies: 6 April 2010 and 29 May 2010. A previous study first reported a global dawn-dusk asymmetry favoring anisotropy on the duskside, observed by TWINS on 6 April. This paper extends and refines the previous analysis, and applies it to ENA data from 29 May, to find a second event containing the dawn-dusk anisotropy asymmetry. Ion pitch angle distributions are retrieved using analytical expressions for anisotropy indices and their associated errors. The analysis is limited to intervals for which TWINS 1 and 2 have similar viewing geometries; i.e., the two spacecraft are at similar magnetic local time (MLT) but different latitudes, to sample two different but overlapping ranges of pitch angle. Application of the method is restricted to portions of the image for which the length of intersection of the LOS with the ENA source distribution is small. For each event, deduced pitch angle anisotropy is higher on the duskside than on the dawnside, a global asymmetry that persists for the hour-long interval of favorable viewing geometry. The anisotropy generally decreases with energy from 1–30 keV. For 6 April the duskside anisotropy spectrum has a local peak at 12 keV, but exhibits an overall decrease over the measured energy range. For 29 May the duskside anisotropy falls monotonically with energy. Finding this previously unreported system-level ring current attribute in two different events demonstrates that the global anisotropy is not a one-time, unique occurrence, and also raises the question of how often and why this new phenomenon occurs. Further work is needed to determine the cause of the dawn-dusk asymmetry in ion anisotropy. It is well known that multiple mechanisms, such as self-consistent adiabatic ion drift, Coulomb collisions and charge exchange, influence the global ion pitch angle distribution. However, the degree to which these multiple mechanisms contribute specifically to the observed dawn-dusk asymmetry will likely require direct comparison between the TWINS observations and simulations of these two events, including self-consistent fields and realistic densities for the plasmasphere and neutral exosphere.

[1] Stereo energetic neutral atom (ENA) images obtained by Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) are analyzed to quantify the latitudinal anisotropy of ring current ENAs, and by implication, the system-level pitch-angle response during a moderate geomagnetic storm on 6 April 2010. During a 15-min interval just after midday, TWINS 1 and 2 were at similar local times but different latitudes, and thus were able to simultaneously sample two different pitch angles from selected locations. The observations show a global dawn-dusk asymmetry in the ring current ENA latitudinal anisotropy, the dusk side being ∼1–2 orders of magnitude more anisotropic than the dawn side. The latitudinal dependence of the ENAs implies a duskside ion distribution that is more equatorial than isotropic; this anisotropy becomes less pronounced with increasing energy. The observed dawn-dusk ENA anisotropy may be caused by ring current ions drifting adiabatically in self-consistently varying electric and (nondipolar) magnetic fields.

[1] Using measurements of the electron density ne found from passive radio wave observations by the IMAGE spacecraft RPI instrument on consecutive passes through the magnetosphere, we calculate the long-term (>1 day) refilling rate of equatorial electron density dne,eq/dt from L = 2 to 9. Our events did not exhibit saturation, probably because our data set did not include a deep solar minimum and because saturation is an unusual occurrence, especially outside of solar minimum. The median rate in cm−3/day can be modeled with log10(dne,eq/dt) = 2.22 − 0.006L − 0.0347L2, while the third quartile rate can be modeled with log10(dne,eq/dt) = 3.39 − 0.353L, and the mean rate can be modeled as log10(dne,eq/dt) = 2.74 − 0.269L. These statistical values are found from the ensemble of all observed rates at each L value, including negative rates (decreases in density due to azimuthal structure or radial motion or for other reasons), in order to characterize the typical behavior. The first quartile rates are usually negative for L 5.8 such as at geostationary orbit (L ∼ 6.8) (at least to L of about 8). These results agree with previous results for ion refilling at geostationary orbit, may agree with previous results at lower L, and are consistent with some trends for ionospheric density.