The development of satellite swarm technology offers new possibilities for space studies and comes with new challenges. Among them is the need of knowledge on the swarm topology and attitude, especially in the context of space-borne radio interferometry. This paper presents an algorithm that recovers the absolute swarm attitude autonomously. This algorithm uses the imaging capability of a low frequency radio interferometer that acts as a star-tracker using the main radio sources in the sky. The Lost-In-Space (LIS) mode is presented in this paper. This algorithm is studied through numerical simulations. This concept is applied here to the kilometric wavelength spectral range (30 kHz – 1 MHz) but the technique can be extended to higher frequencies. Images are reconstructed using an iterative Discrete Fourier Transform (DFT) at two frequencies and using source subtractions. Pattern-matching is performed with a voting system implemented on geometrical parameters defined by triangles of sources. The radio sky in the working band is modeled by extrapolating down observation of the sky at 50 MHz. The modeled interferometer corresponds to the NOIRE (Nanosatellite pour un Observatoire Interferométrique Radio dans l’Espace) concept study. The accuracy on the recovered swarm attitude is measured for different levels of noise in the interferometric visibilities. The simulation shows that, the suggested algorithm can achieve an attitude knowledge error lower than 1 arcmin for a swarm scale of 100 km. The requirements in terms of memory and computation capability are discussed as well as the limitations of the technique and the simulation.

Heliophysics data analysis often involves combining diverse science measurements, many of them captured as time series. Although there are now only a few commonly used data file formats, the diversity in mechanisms for automated access to and aggregation of such data holdings can make analysis that requires inter-comparison of data from multiple data providers difficult. The Heliophysics Application Programmer’s Interface (HAPI) is a recently developed standard for accessing distributed time-series data to increase interoperability. The HAPI specification is based on the common elements of existing data services, and it standardizes the two main parts of a data service: the request interface and the response data structures. The interface is based on the REpresentational State Transfer (REST) or RESTful architecture style, and the HAPI specification defines five required REST endpoints. Data are returned via a streaming format that hides file boundaries; the metadata is detailed enough for the content to be scientifically useful, e.g., plotted with appropriate axes layout, units, and labels. Multiple mature HAPI-related open-source projects offer server-side implementation tools and client-side libraries for reading HAPI data in multiple languages (IDL, Java, MATLAB, and Python). Multiple data providers in the US and Europe have added HAPI access alongside their existing interfaces. Based on this experience, data can be served via HAPI with little or no information loss compared to similar existing web interfaces. Finally, HAPI has been recommended as a COSPAR standard for time series data delivery.

The MASER (Measuring, Analysing and Simulating Radio Emissions) project provides a comprehensive infrastructure dedicated to low frequency radio emissions (typically < 50 to 100 MHz). The four main radio sources observed in this frequency are the Earth, the Sun, Jupiter and Saturn. They are observed either from ground (down to 10 MHz) or from space (down to a few kHz). Ground observatories are more sensitive than space observatories and capture high resolution data streams (up to a few TB per day for modern instruments). Conversely, space-borne instruments can observe below the ionospheric cut-off (10 MHz) and can be placed closer to the studied object. Several tools have been developed in the last decade for sharing space physcis data. Data visualization tools developed by the CDPP (http://cdpp.eu, Centre de Données de la Physique des Plasmas, in Toulouse, France) and the University of Iowa (Autoplot, http://autoplot.org) are available to display and analyse space physics time series and spectrograms. A planetary radio emission simulation software is developed in LESIA (ExPRES: Exoplanetary and Planetary Radio Emission Simulator). The VESPA (Virtual European Solar and Planetary Access) provides a search interface that allows to discover data of interest for scientific users, and is based on IVOA standards (astronomical International Virtual Observatory Alliance). The University of Iowa also develops Das2server that allows to distribute data with adjustable temporal resolution. MASER is making use of all these tools and standards to distribute datasets from space and ground radio instruments available from the Observatoire de Paris, the Station de Radioastronomie de Nançay and the CDPP deep archive. These datasets include Cassini/RPWS, STEREO/Waves, WIND/Waves, Ulysses/URAP, ISEE3/SBH, Voyager/PRA, Nançay Decameter Array (Routine, NewRoutine, JunoN), RadioJove archive, swedish Viking mission, Interball/POLRAD… MASER also includes a Python software library for reading raw data. This work is supported by CDPP, CNES, PADC and Europlanet-2020-RI. The Europlanet 2020 Research Infrastructure project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208.

The Europlanet H2020 program started on 1/9/2015 for 4 years. It includes an activity to adapt Virtual Observatory (VO) techniques to Planetary Science data called VESPA. The objective is to facilitate searches in big archives as well as sparse databases, to provide simple data access and on-line visualization, and to allow small data providers to make their data available in an interoperable environment with minimum effort. The VESPA system has been hugely improved during the first three years of Europlanet H2020: the infrastructure has been upgraded to describe data in many fields more accurately; the main user search interface (http://vespa.obspm.fr) has been redesigned to provide more flexibility; alternative ways to access Planetary Science data services from VO tools have been implemented; VO tools are being improved to handle specificities of Solar System data, e.g. measurements in reflected light, coordinate systems, etc. Current steps include the development of a connection between the VO world and GIS tools, and integration of Heliophysics, planetary plasmas, and mineral spectroscopy data to support of the analysis of observations. Existing data services have been updated, and new ones have been designed. The global objective is already overstepped, with 42 services open (including ESA’s PSA) and ~15 more being finalized. A procedure to install data services has been documented, and hands-on sessions are organized twice a year at EGU and EPSC; this is intended to favour the installation of services by individual research teams, e.g. to distribute derived data related to a published study. In complement, regular discussions are held with big data providers, starting with space agencies (IPDA). Common projects with PDS have been engaged, with the goal to connect PDS4 and EPN-TAP based on a local data dictionary. In parallel, a Solar System Interest Group has been established in IVOA; the goal is here to adapt existing astronomy standards to Planetary Science. The Europlanet 2020 Research Infrastructure project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208. [1] Erard et al 2014, Astronomy & Computing 7-8, 71-80. http://arxiv.org/abs/1407.4886

In the frame of the Europlanet-RI-2020 program, the VESPA (Virtual European Solar and Planetary Access) team has developed a metadata dictionary dedicated to data discovery in solar system sciences. The dictionary is called EPNcore and includes metadata for data coverage (temporal, spatial, spectral…), data content (target, measured parameter…), data origin (instrument, publisher…) and data access (format, URL…). In order to interoperate with the NASA/PDS4, the main archive information model in planetary sciences, it is first necessary to implement the EPNcore dictionary into the PDS4 information model. This is done with setting up a Local Data Dictionary (LDD). The second step deals with the mapping between terms already defined in the PDS4 information model and the EPNcore dictionary. We present the EPNcore LDD and a first version of the term mapping, as well as a prototype interface to query PDS4 from the VESPA portal. The Europlanet H2020 Research Infrastructure project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208.

Auroral Kilometric Radiation (AKR) is radio emission that originates in particle acceleration regions along magnetic field lines, coinciding with discrete auroral arcs. Found in both hemispheres, an increase in the amplitude of a particular AKR source denotes the strengthening of parallel electric fields in the auroral zone, while the emission frequency gives insight into source region morphology. AKR viewing geometry is complex due to the confinement of the source regions to nightside local times and the anisotropy of the beaming pattern, so observations are highly dependent on spacecraft viewing position. We present a novel, empirical technique that selects AKR emission from remote radio observations made with the spin-axis aligned antenna of the Wind/WAVES instrument, based on the rapidly varying amplitude of AKR across spacecraft spin timescales. This selection is applied to 30 days of data in 1999, during which the Cassini spacecraft flew close to Earth and recorded AKR for the majority of the period, while the Wind spacecraft completed close to two, precessing petal orbits. We examine the flux density and integrated power, which gives an occurrence distribution with spacecraft local time that is typical of AKR, with an increase in power of around $10^{3}$ Wsr$^{-1}$ between dayside and nightside observations. We also find a statistically significant ($p < 10^{-5}$), previously observed diurnal modulation of the AKR integrated power for the period, further verifying the empirical selection of AKR and showing the promise of its application to larger subsets of Wind/WAVES observations.

The observations from the Juno spacecraft in polar orbit of Jupiter provide for the first time a complete view of Jupiter’s radio emissions from all latitudes. Characterizing the latitudinal distribution of radio emissions’ occurrence and intensity is a useful step for elucidating their origin. Here we analyze for that purpose the first 3 years of observations from the Waves experiment on the Juno spacecraft (mid-2016 to mid-2019). Two prerequisites for the construction of the latitudinal distribution of intensities for each Jovian radio component are (i) to work with absolute flux densities, and (ii) to be able to associate each radio measurement with a specific radio component. Accordingly, we develop a method to convert the Juno/Waves data in flux densities and then we build a catalog of all Jovian radio components over the first 3 years of Juno’s orbital mission. From these, we derive occurrence and intensity distributions versus observer’s latitude and frequency for each component; these will be the basis for future detailed studies and interpretations of each component’s characteristics and origin.

On October 28th 2021 the Sun released a large Coronal Mass Ejection (CME) in Earth’s direction. An X1.0 class solar flare and a rare ground level enhancement (GLE) were observed, along with bright solar radio bursts. Here we examine data from the near-Earth environment to investigate the terrestrial response to this solar event, as a typical example of Sun-Earth interactions. The CME arrival is tracked at $\sim$1 AU from Wind radio observations and the interplanetary magnetic field (IMF) and solar wind dynamic pressure by \textit{in-situ} measurements of OMNI spacecraft. Geomagnetic activity is studied with indices including SYM-H while the auroral response is monitored by remote Wind radio measurements of Auroral Kilometric Radiation (AKR) and SSUSI UV observations. We quantify the timeline for solar wind-magnetosphere coupling via exploration of the dayside reconnection rate and polar cap voltages and address the visibility of AKR sources for a dayside radio observatory.

Reanalyzing Cassini radio observations performed during Jupiter’s flyby of 2000-2001, we study the internal (rotational) versus external (solar wind) control of Jupiter’s radio emissions, from kilometer to decameter wavelengths, and the relations between the different auroral radio components. For that purpose, we build a database of the occurrence of Jovian auroral radio components bKOM, HOM and DAM observed by Cassini, and then frequency-longitude stacked plots of the polarized intensity of these radio components. Comparing the results obtained inbound and outbound, as a function of the Observer’s or Sun’s longitude, we find that HOM & DAM are dominantly rotation-modulated (i.e. emitted from searchlight-like sources fixed in Jovian longitude), whereas bKOM is modulated more strongly by the solar wind than by the rotation (i.e. emitted from sources more active within a given Local Time sector). We propose a simple analytical description of these internal and external modulations and evaluate its main parameters (the amplitude of each control) for HOM+DAM and bKOM. Comparing Cassini and Nançay Decameter Array data, we find that HOM is primarily connected to the decameter emissions originating from the dusk sector of the Jovian magnetosphere. HOM and DAM components form a complex but stable pattern in the frequency-longitude plane, that remains to be modelled. HOM also seems to be related to the so-called ‘lesser arcs’ identified by Voyager. bKOM consists of a main part above ∼40 kHz in antiphase with HOM occurrence, and detached patches below ∼80 kHz in phase with HOM occurrence.

We study 10 years (1995-2004 inclusive) of auroral kilometric radiation (AKR) radio emission data from the Wind spacecraft to examine the link between AKR and terrestrial substorms. We use substorm lists based on parameters including ground magnetometer signatures and geosynchronous particle injections as a basis for superposed epoch analyses of the AKR data. The results for each list show a similar, clear response of the AKR power around substorm onset. For nearly all event lists, the average response shows that the AKR power begins to increase around 20 minutes prior to expansion phase onset, as defined by the respective lists. The analysis of the spectral parameters of AKR bursts show that this increase in power is due to an extension of the source region to higher altitudes, which also precedes expansion phase onset by 20 minutes. Our observations show that the minimum frequency channel that observes AKR at this time, on average, is 60 kHz. AKR visibility is highly sensitive to observing spacecraft location, and the biggest radio response to substorm onset is seen in the 2100 - 0300 hr LT sector.

Das2 describes a collection of cooperating programs originally created to support daily review and analysis activities of the Cassini Radio and Plasma Wave Science (RPWS) investigation. The system proved useful and is now relied on for rapid access to working data sets from many planetary missions including Mars Express and Juno, as well as ground-based radio astronomy results from the Nançay Decameter Array and Long Wave Array 1. As more teams have begun using das2 tools, the need for updates to what was largely an in-house protocol have become apparent. Though Autoplot continues to be the most flexible and commonly used das2 client program, interfacing with other tools would benefit the research community. We will provide an overview of recent updates to the das2 interface definition supporting redundant servers and federated data source catalogs. We will describe a cross site deployment between Southwest Research Institute and the University of Iowa to aid collaboration among ASPERA-3 and MARSIS investigators. We will give an update on the status of new client libraries for NumPy and IDL, as well as das2 stream adapters for HAPI and VOTables. Finally, we will describe how working data sets can be published in-place by registering das2 data sources with a VESPA EPN-TAP service.