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Since the earliest space-based observations of Earth's atmosphere, ultraviolet (UV) airglow has proven a useful resource for remote sensing of the ionosphere and thermosphere. The NASA Ionospheric Connection Explorer (ICON) spacecraft, whose mission is to explore the connections between ionosphere and thermosphere utilizes UV airglow in the typical way: an extreme-UV (EUV) spectrometer uses dayglow between 54 and 88 nm to measure the density of O+, and a far-UV spectrograph uses the O 135.6 nm doublet and N2 Lyman-Birge-Hopfield band dayglow to measure the column ratio of O to N2 in the upper thermosphere. Two EUV emission features, O+ 61.6 and 83.4 nm, are used for the O+ retrieval; however, many other features are captured along the EUV instrument's spectral dimension. In this study, we examine the other dayglow features observed by ICON EUV and demonstrate that it measures a nitrogen feature around 87.8 nm which can be used to observe the neutral thermosphere.

In near-Earth space, variations in thermospheric composition have important implications for thermosphere-ionosphere coupling. The ratio of O to N2 is often measured using far-UV airglow observations. Taking such airglow observations from space, looking below the Earth's limb allows for the total column of O and N2 in the ionosphere to be determined. While these observations have enabled many previous studies, determining the impact of non-migrating tides on thermospheric composition has proved difficult, owing to a small contamination of the signal by recombination of ionospheric O+. New ICON observations of far UV are presented here, and their general characteristics are shown. Using these, along with other observations and a global circulation model we show that during the morning hours and at latitudes away from the peak of the equatorial ionospheric anomaly, the impact of non-migrating tides on thermospheric composition can be observed. During March - April 2020, the column O/N2 ratio was seen to vary by 3 - 4 % of the zonal mean. By comparing the amplitude of the variation observed with that in the model, both the utility of these observations and a pathway to enable future studies is shown.

Breakthrough Listen is the most comprehensive and sensitive search for extraterrestrial intelligence (SETI) to date, employing a collection of international observational facilities including both radio and optical telescopes. During the first three years of the Listen program, thousands of targets have been observed with the Green Bank Telescope (GBT), Parkes Telescope and Automated Planet Finder. At GBT and Parkes, observations have been performed ranging from 700 MHz to 26 GHz, with raw data volumes averaging over 1 PB day−1. A pseudo-real time software spectroscopy suite is used to produce multi-resolution spectrograms amounting to approximately 400 GB h−1 GHz−1 beam−1. For certain targets, raw baseband voltage data is also preserved. Observations with the Automated Planet Finder produce both two-dimensional and one-dimensional high-resolution (R ∼ 105) echelle spectral data. Although the primary purpose of Listen data acquisition is for SETI, a range of secondary science has also been performed with these data, including studies of fast radio bursts. Other current and potential research topics include spectral line studies, searches for certain kinds of dark matter, probes of interstellar scattering, pulsar searches, radio transient searches and investigations of stellar activity. Listen data are also being used in the development of algorithms, including machine-learning approaches to modulation scheme classification and outlier detection, that have wide applicability not just for astronomical research but for a broad range of science and engineering. In this paper, we describe the hardware and software pipeline used for collection, reduction, archival, and public dissemination of Listen data. We describe the data formats and tools, and present Breakthrough Listen Data Release 1.0 (BLDR 1.0), a defined set of publicly available raw and reduced data totaling 1 PB.

Advancing the scientific frontier in the search for life in the universerequires support of searches for both biosignatures and technosignatures. Amodest budgetary increment can expand the search for life in the universe fromprimitive to complex life and from the solar neighborhood to the entire Galaxy.

The vast collecting area of the Square Kilometre Array (SKA), harnessed bysensitive receivers, flexible digital electronics and increased computationalcapacity, could permit the most sensitive and exhaustive search fortechnologically-produced radio emission from advanced extraterrestrialintelligence (SETI) ever performed. For example, SKA1-MID will be capable ofdetecting a source roughly analogous to terrestrial high-power radars (e.g. airroute surveillance or ballistic missile warning radars, EIRP (EIRP = equivalentisotropic radiated power, ~10^17 erg sec^-1) at 10 pc in less than 15 minutes,and with a modest four beam SETI observing system could, in one minute, searchevery star in the primary beam out to ~100 pc for radio emission comparable tothat emitted by the Arecibo Planetary Radar (EIRP ~2 x 10^20 erg sec^-1). Theflexibility of the signal detection systems used for SETI searches with the SKAwill allow new algorithms to be employed that will provide sensitivity to amuch wider variety of signal types than previously searched for. Here we discuss the astrobiological and astrophysical motivations for radioSETI and describe how the technical capabilities of the SKA will explore theradio SETI parameter space. We detail several conceivable SETI experimentalprograms on all components of SKA1, including commensal, primary-user, targetedand survey programs and project the enhancements to them possible with SKA2. Wealso discuss target selection criteria for these programs, and in the case ofcommensal observing, how the varied use cases of other primary observers can beused to full advantage for SETI.