This paper describes the design and control concepts of a wall-climbing robot. It has an hexapod configuration and it is able to manoeuvre on vertical surfaces carrying high payloads. Configuration and leg design criteria specific for climbing tasks are discussed. The controller architecture showing decentralised parallel control and hard real-time performance is outlined. New stability criteria for wall locomotion are introduced and a climbing gait using force distribution shows the working of our control scheme for wall gait generation. We call this four phase discontinuous sawing gait. This prototype is an example of a climber specifically tailored for industrial applications.

The first orbit of Solar Orbiter provided comprehensive measurements of six corotating interaction regions (CIRs) within 1 au. Five of these CIRs were also observed by ACE at 1 au, allowing for comparisons of the suprathermal ion intensities and spectra at different radial distances. Only subtle modulations of the 4He spectral slopes are observed between Solar Orbiter and ACE. Additionally, the radial gradients of 226−320 keV/nuc 4He ion intensities between Solar Orbiter and ACE are similar to that of 1.53 MeV H reported by Van Hollebeke et al. (1978, J. Geophys. Res., 83, A10). These observations provide a new addition to the study of the radial dependence of CIR-associated suprathermal ions in the inner heliosphere.

After decades of observations of solar energetic particles (SEP) from space-based observatories, relevant questions on particle injection, transport, and acceleration remain open. To address these scientific topics, accurate measurements of the particle properties in the inner heliosphere are needed. In this paper we describe the Energetic Particle Detector (EPD), an instrument suite that is part of the scientific payload aboard the Solar Orbiter mission. Solar Orbiter will approach the Sun as close as 0.28 au and will provide extra-ecliptic measurements beyond ∼ 30 • heliographic latitude during the later stages of the mission. The EPD will measure electrons, protons, and heavy ions with high temporal resolution over a wide energy range, from suprathermal energies up to several hundreds of megaelectronvolts/nucleons. For this purpose, EPD is composed of four units: the SupraThermal Electrons and Protons (STEP), the Electron Proton Telescope (EPT), the Suprathermal Ion Spectrograph (SIS), and the High-Energy Telescope (HET) plus the Instrument Control Unit (ICU) that serves as power and data interface with the spacecraft. The low-energy population of electrons and ions will be covered by STEP and EPT, while the high-energy range will be measured by HET. Elemental and isotopic ion composition measurements will be performed by SIS and HET, allowing full particle identification from a few kiloelectronvolts up to several hundreds of megaelectronvolts/nucleons. Angular information will be provided by the separate look directions from different sensor heads, on the ecliptic plane along the Parker spiral magnetic field both forward and backwards, and out of the ecliptic plane observing both northern and southern hemispheres. The unparalleled observations of EPD will provide key insights into long-open and crucial questions about the processes that govern energetic particles in the inner heliosphere.

Aims. We present observations of the first coronal mass ejection (CME) observed by the Solar Orbiter spacecraft on April 19, 2020 and the associated Forbush decrease (FD) measured by the High Energy Telescope (HET). This CME is a multi-spacecraft event that was also seen near Earth the following day. Methods. We highlight the capabilities of the HET for observing small short-term variations of the galactic cosmic ray count rate using its single detector counters. We applied the analytical ForbMod model to the FD measurements to reproduce the Forbush decrease at both locations. Input parameters for the model were derived from both in situ and remote-sensing observations of the CME. Results. The very slow (∼350 km s−1) stealth CME caused an FD with an amplitude of 3% in the low-energy cosmic ray measurements at HET and 2% in a comparable channel of the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on board the Lunar Reconnaissance Orbiter, as well as a 1% decrease in neutron monitor measurements. Significant differences are observed in the expansion behavior of the CME at different locations, which may be related to influence of the following high speed solar wind stream. Under certain assumptions, ForbMod is able to reproduce the observed FDs in low-energy cosmic ray measurements from HET as well as CRaTER, however, with the same input parameters, the results do not agree with the FD amplitudes at higher energies measured by neutron monitors on Earth. We study these discrepancies and provide possible explanations. Conclusions. This study highlights the notion that the novel measurements of Solar Orbiter can be coordinated with observations from other spacecraft to improve our understanding of space weather in the inner heliosphere. Multi-spacecraft observations combined with data-based modeling are also essential for understanding the propagation and evolution of CMEs, in addition to their space weather impacts.

Context. Solar Orbiter, launched in February 2020, started its cruise phase in June 2020, in coincidence with its first perihelion at 0.51 au from the Sun. The in situ instruments onboard, including the Energetic Particle Detector (EPD), operate continuously during the cruise phase enabling the observation of solar energetic particles. Aims. In situ measurements of the first near-relativistic solar electron events observed in July 2020 by EPD are analyzed and the solar origins and the conditions for the interplanetary transport of these particles investigated. Methods. Electron observations from keV energies to the near-relativistic range were combined with the detection of type III radio bursts and extreme ultraviolet (EUV) observations from multiple spacecraft in order to identify the solar origin of the electron events. Electron anisotropies and timing as well as the plasma and magnetic field environment were evaluated to characterize the interplanetary transport conditions. Results. All electron events were clearly associated with type III radio bursts. EUV jets were also found in association with all of them except one. A diversity of time profiles and pitch-angle distributions was observed. Different source locations and different magnetic connectivity and transport conditions were likely involved. The July 11 event was also detected by Wind, separated 107 degrees in longitude from Solar Orbiter. For the July 22 event, the Suprathermal Electron and Proton (STEP) sensor of EPD allowed for us to not only resolve multiple electron injections at low energies, but it also provided an exceptionally high pitch-angle resolution of a very anisotropic beam. This, together with radio observations of local Langmuir waves suggest a very good magnetic connection during the July 22 event. This scenario is challenged by a high-frequency occultation of the type III radio burst and a nominally non-direct connection to the source; therefore, magnetic connectivity requires further investigation.