GOES-R Series X-Ray Sensor (XRS): 1. Design and Pre-Flight Calibration.

The X-Ray Sensor (XRS) has been making full-disk observations of the solar soft X-ray irradiance onboard National Oceanic and Atmospheric Administration's (NOAA) Geostationary Operational Environmental Satellites since 1975. Critical information about solar activity for space weather operations is provided by XRS measurements, such as the classification of solar flare magnitude based on X-ray irradiance level. The GOES-R series of XRS sensors, with the first in the series launched in November 2016, has a completely different instrument design compared to its predecessors, GOES-1 through GOES-15.

Earth's ambipolar electrostatic field and its role in ion escape to space.

Cold plasma of ionospheric origin has recently been found to be a much larger contributor to the magnetosphere of Earth than expected. Numerous competing mechanisms have been postulated to drive ion escape to space, including heating and acceleration by wave-particle interactions and a global electrostatic field between the ionosphere and space (called the ambipolar or polarization field). Observations of heated O ions in the magnetosphere are consistent with resonant wave-particle interactions.

Evidence Against Carbonization of the Thin-Film Filters of the onboard the .

In spite of strict limits on outgassing from organic materials, some spacecraft instruments making long-term measurements of solar extreme ultraviolet (EUV) radiation still suffer significant degradation. While such measures have reduced the rate of degradation, they have not completely eliminated it in some cases. For example, in five years, the aluminum filters used in the (EVE) instruments onboard the (SDO) suffered losses exceeding 40% at 30.

Tidal Effects on the Longitudinal Structures of the Martian Thermosphere and Topside Ionosphere Observed by MAVEN.

Longitudinal structures in the Martian thermosphere and topside ionosphere between 150 and 200 km altitudes are studied using in situ electron and neutral measurements from the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Four time intervals are selected for comparison, during which MAVEN sampled similar local time (9.3-10.

Mars Upper Atmospheric Responses to the 10 September 2017 Solar Flare: A Global, Time-Dependent Simulation.

We report the first global, time-dependent simulation of the Mars upper atmospheric responses to a realistic solar flare event, an X8.2 eruption on 10 September 2017. The Mars Global Ionosphere-Thermosphere Model runs with realistically specified flare irradiance, giving results in reasonably good agreement with the Mars Atmosphere and Volatile EvolutioN spacecraft measurements.

Decoupling Solar Variability and Instrument Trends Using the Multiple Same-Irradiance-Level (MuSIL) Analysis Technique.

The solar spectral irradiance (SSI) dataset is a key record for studying and understanding the energetics and radiation balance in Earth's environment. Understanding the long-term variations of the SSI over timescales of the 11-year solar activity cycle and longer is critical for many Sun-Earth research topics. Satellite measurements of the SSI have been made since the 1970s, most of them in the ultraviolet, but recently also in the visible and near-infrared.

Early MAVEN Deep Dip campaign reveals thermosphere and ionosphere variability.

The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits.

MAVEN observations of the response of Mars to an interplanetary coronal mass ejection.

Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions.