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Abstract: In the absence of solar activity, Co-rotating Interaction Regions (CIRs) are a prevailing source of energetic ions observed near 1AU. The combination of observations by near-Earth space observatories and the twin STEREO spacecraft offers an excellent platform for multi-point studies of CIRs. The analysis of CIR events during Carrington rotations 2067–2082 provides evidence that CIR-associated energetic ions frequently show significant differences, particularly at sub-MeV energies. We found discrepancies in the structures observed by different spacecraft which cannot always be attributed to the latitudinal separation or to changes in the coronal hole which generates the high-speed stream. We present several cases where these differences are linked to the presence of Interplanetary Coronal Mass Ejections (ICMEs) or small-scale interplanetary transients in the vicinity of or embedded within the CIR. Evidence of the possible role of ICME-CIR interactions as sources of temporal variations in the CIR-associated ion increases are presented and discussed. [Copyright &y& Elsevier]

Abstract: Since the 1970''s interplanetary electrons in the MeV energy range, of Jovian origin, have been extensively studied from close to the Sun to beyond the Kronian orbit, near the ecliptic. The Ulysses trajectory allowed to study the propagation of these particles, in a wide range of heliographic latitudes. The location of Jupiter with respect to the structure of the heliospheric magnetic field is precisely determined and non-central. This makes Jovian electrons an ideal opportunity for studying the particle propagation parallel and perpendicular to the heliospheric magnetic field. 12 years after its first encounter in February 1992, the Ulysses mission encountered Jupiter for a second time in February 2004 at a distance of 1684 Jovian radii. The first flyby took place at a distance of closest approach of 6 Jupiter radii () and changed the inclination of the Ulysses trajectory so that it would pass above the Sun''s polar regions. During the 2004 encounter, in contrast to 1992, Ulysses did not enter the Jovian magnetosphere but remained upstream of it. In mid 2002, the MeV electron flux started increasing and displaying large short term variations. These features lasted throughout the encounter, making the electron intensities less obviously correlated with the proximity to Jupiter compared with the first Jovian encounter. In previous studies it has been shown that the diffusion coefficient perpendicular to the heliospheric magnetic field in polar direction increased in 1998 during the transition from solar minimum to solar maximum close to the ecliptic plane. Although the distant Ulysses encounter took place during the declining phase of the solar cycle the absence of an intensity variation with latitude indicate an unexpected further increase of . Thus the diffusion coefficients, and in particular perpendicular diffusion in the polar direction, are highly time-dependent. In this paper, we present the corresponding data and discuss the implication for particle propagation in the three-dimensional heliospheric magnetic field. [Copyright &y& Elsevier]

Abstract: Shielding is arguably the main countermeasure for the exposure to cosmic radiation during interplanetary exploratory missions. However, shielding of cosmic rays, both of galactic or solar origin, is problematic, because of the high energy of the charged particles involved and the nuclear fragmentation occurring in shielding materials. Although computer codes can predict the shield performance in space, there is a lack of biological and physical measurements to benchmark the codes. An attractive alternative to passive, bulk material shielding is the use of electromagnetic fields to deflect the charged particles from the spacecraft target. Active shielding concepts based on electrostatic fields, plasma, or magnetic fields have been proposed in the past years, and should be revised based on recent technological improvements. To address these issues, the European Space Agency (ESA) established a Topical Team (TT) in 2002 including European experts in the field of space radiation shielding and superconducting magnets. The TT identified a number of open research questions to be addressed, including development and testing of novel shielding materials, studies on the angular distributions of energetic solar particles, and cooling systems for magnetic lenses in space. A detailed report to the ESA will be published within a few months. A summary of the TT conclusions and recommendations will be discussed in this paper, with emphasis on active shielding using superconducting magnets. [Copyright &y& Elsevier]

Abstract: The Ulysses spacecraft at high heliographic latitudes has detected eight large solar energetic particle events during the recent solar maximum in 2000 and 2001 years. These events are easily identified with famous episodes of the solar activity and the corresponding SEP events near the Earth. Analyzing the absolute intensities of ∼40–100MeV proton time profiles from the Ulysses COSPIN/KET and the GOES detector near Earth we find that for these eight events the intensities vary only within a factor of 2–3 from event to event at high latitudes during the first 30h. In contrast the intensities at Earth differ from one event to another by several orders of magnitude. Thus, the time history during these 30h has only a weak dependence on the relative position of Ulysses to the possible flare location. This implies: (1) a nearly isotropic injection of protons with comparable intensities to high heliolatitudes, and (2) a similar propagation process during the first 30h of the events. We attribute the fact that the decay phases of these events are nearly the same at Ulysses and in the ecliptic rather to cross-field diffusion than to the presence of a shock. [Copyright &y& Elsevier]

Abstract: The in situ measurements of particles and CME transients (IMPACT) investigation on the twin STEREO spacecraft focuses on the solar energetic particle, solar wind and suprathermal electron, and magnetic field measurements needed to address STEREO’s goals. IMPACT will provide regular, identical, in situ multipoint measurements bracketing Earth as each spacecraft separates from it at a rate of ∼22°/yr along Earth’s orbit. Combined with the PLASTIC and SWAVES investigations, IMPACT fills a critical role in the STEREO quest to connect SECCHI’s 3D coronal images to their interplanetary consequences. [Copyright &y& Elsevier]

Abstract: Temporal profiles of energetic ions and electrons observed at 1AU during solar energetic particle events are mainly determined by particle injection features, the observer location relative to the source region at the Sun, and the interplanetary space plasma and field conditions during particle transport. In this work, temporal profiles of 18 solar energetic particle events have been analyzed by fitting a pulse function to them in order to find a set of parameters which can be used to characterize the events. [Copyright &y& Elsevier]

The Ulysses trajectory provides a unique opportunity to study the propagation of MeV electrons in a wide range of heliographic latitudes and during varying conditions in the inner heliosphere. In recent papers we reported Ulysses Kiel Electron Telescope (KET) observations from the Ulysses launch up to the end of the second fast latitude scan in late 2001. While the period until the beginning of 1998 has been consistently described by modulation models taking into account galactic cosmic rays as well as Jovian electrons, the observed electron intensity variation after 1998 needs further investigation. From 1998 onwards KET measures short term electron increases, which were not attributed to solar particle events. When space-probes approached Jupiter in the ecliptic plane such electron intensity increases have been reported and interpreted as a changing magnetic connection from the giant planet to the observer. In spring 2002 Ulysses was at ∼40° N heliographic latitude when KET observed a quiet time electron increase, which showed the same characteristic as the Jovian electron events measured by KET in 1991, when Ulysses was magnetically well connected to Jupiter. This leads to the conclusion that Jovian electron events can unambiguously be observed at heliographic latitudes beyond 40° N. In a Parker-like heliospheric magnetic field, however, there are no field lines connecting Jupiter and Ulysses at >40° N, and therefore, an efficient latitude transport is needed to account for the “high” electron intensities. [Copyright &y& Elsevier]