High accuracy satellite drag model (HASDM)

The dominant error source in force models used to predict low-perigee satellite trajectories is atmospheric drag. Errors in operational thermospheric density models cause significant errors in predicted satellite positions, since these models do not account for dynamic changes in atmospheric drag for orbit predictions. The Air Force Space Battlelab’s High Accuracy Satellite Drag Model (HASDM) estimates and predicts (out three days) a dynamically varying global density field. HASDM includes the Dynamic Calibration Atmosphere (DCA) algorithm that solves for the phases and amplitudes of the diurnal and semidiurnal variations of thermospheric density near real-time from the observed drag effects on a set of Low Earth Orbit (LEO) calibration satellites. The density correction is expressed as a function of latitude, local solar time and altitude. In HASDM, a time series prediction filter relates the extreme ultraviolet (EUV) energy index E_10.7 and the geomagnetic storm index a_p, to the DCA density correction parameters. The E_10.7 index is generated by the SOLAR2000 model, the first full spectrum model of solar irradiance. The estimated and predicted density fields will be used operationally to significantly improve the accuracy of predicted trajectories for all low-perigee satellites.     

The Emergence of Life

The Rosetta observations have greatly advanced our knowledge of the cometary nucleus and its immediate environment. However, constraints on the mission (both planned and unplanned), the only partially successful Philae lander, and other instrumental issues have inevitably resulted in open questions. Surprising results from the many successful Rosetta observations have also opened new questions, unimagined when Rosetta was first planned. We discuss these and introduce several mission concepts that might address these issues. It is apparent that a sample return mission as originally conceived in the 1980s during the genesis of Rosetta would provide many answers but it is arguable whether it is technically feasible even with today’s technology and knowledge. Less ambitious mission concepts are described to address the suggested main outstanding scientific goals.

     

The GOES-16 Spacecraft Science Magnetometer

Space Science Reviews - The Modular Multispectral Imaging Array (MMIA) is a suite of optical sensors mounted on an external platform of the European Space Agency’s Columbus Module on the...     

Heating and acceleration of charged particles during magnetic dipolarizations

In this paper, we analyzed the thermal and energy characteristics of the plasma components observed during the magnetic dipolarizations in the near tail by the Cluster satellites. It was previously found that the first dipolarization the ratio of proton and electron temperatures (T _p/T _e) was ~6–7. At the time of the observation of the first dipolarization front T _p/T _e decreases by up to ~3–4. The minimum value T _p/T _e (~2.0) is observed behind the front during the turbulent dipolarization phase. Decreases in T _p/T _e observed at this time are associated with an increase in T _e, whereas the proton temperature either decreases or remains unchanged. Decreases of the value T _p/T _e during the magnetic dipolarizations coincide with increase in wave activity in the wide frequency band up to electron gyrofrequency f _ce. High-frequency modes can resonantly interact with electrons causing their heating. The acceleration of ions with different masses up to energies of several hundred kiloelectron-volts is also observed during dipolarizations. In this case, the index of the energy spectrum decreases (a fraction of energetic ions increases) during the enhancement of low-frequency electromagnetic fluctuations at frequencies that correspond to the gyrofrequency of this ion component. Thus, we can conclude that the processes of the interaction between waves and particles play an important role in increasing the energy of plasma particles during magnetic dipolarizations.     

Remnant magnetic fields of Mars and their interaction with the solar wind

This work presents a review of studies of the Martian magnetic fields during the early Soviet missions to Mars in 1971–1974, which never approached Mars by closer than 1000 km before the experiment with the Magnetometer/Electronic Reflectometer (MAG/ER) on board the Mars Global Surveyor spacecraft, which could descend to altitudes of 80–100 km. At present, the experiment with the magnetometer (MAG) onboard the American MAVEN spacecraft adds new data, but the map of distribution of remnant magnetic fields of Mars and the picture of their interaction with the solar wind are already formed and, at its core, obviously, will not be revised. Thus, it would be very instructive to consider the following in detail: (a) what is already known regarding the features and distribution of remnant magnetic fields on Mars; (b) how they control the interaction of solar wind with a weakly magnetized planet (Mars); and (c) what is its distinction from another nonmagnetized planet (Venus).     

The InSight Mars Lander and Its Effect on the Subsurface Thermal Environment

The 2018 InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) Mission has the mission goal of providing insitu data for the first measurement of the geothermal heat flow of Mars. The Heat Flow and Physical Properties Package (HP³) will take thermal conductivity and thermal gradient measurements to approximately 5 m depth. By necessity, this measurement will be made within a few meters of the lander. This means that thermal perturbations from the lander will modify local surface and subsurface temperature measurements. For HP³’s sensitive thermal gradient measurements, this spacecraft influence will be important to model and parameterize. Here we present a basic 3D model of thermal effects of the lander on its surroundings. Though lander perturbations significantly alter subsurface temperatures, a successful thermal gradient measurement will be possible in all thermal conditions by proper (\(>3~\mbox{m}\) depth) placement of the heat flow probe.     

The Juno Radiation Monitoring (RM) Investigation

The Radiation Monitoring Investigation of the Juno Mission will actively retrieve and analyze the noise signatures from penetrating radiation in the images of Juno’s star cameras and science instruments at Jupiter. The investigation’s objective is to profile Jupiter’s \(>10\mbox{-MeV}\) electron environment in regions of the Jovian magnetosphere which today are still largely unexplored. This paper discusses the primary instruments on Juno which contribute to the investigation’s data suite, the measurements of camera noise from penetrating particles, spectral sensitivities and measurement ranges of the instruments, calibrations performed prior to Juno’s first science orbit, and how the measurements may be used to infer the external relativistic electron environment.     

The Ultraviolet Spectrograph on NASA’s Juno Mission

The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS.     

On the Ballistic Efficiency of Bicalibre Aerial Vehicles with Prevailing Coast Phase

The advantages of the bicalibre configuration of the volumetric packaging in comparison with the single-calibre one are shown within the framework of the concept of ballistic efficiency (BE) enhancement of the aerial vehicles (AV) with prevailing coast phase. The rational range of booster and coaster calibre ratios of bicalibre aerial vehicles for both solid propellant jet engines and combined propulsion units are defined.