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# BepiColombo’s Cruise Phase: Unique Opportunity for Synergistic Observations

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The investigation of multi-spacecraft coordinated observations during the cruise phase of BepiColombo (ESA/JAXA) are reported, with a particular emphasis on the recently launched missions, Solar Orbiter (ESA/NASA) and Parker Solar Probe (NASA). Despite some payload constraints, many instruments onboard BepiColombo are operating during its cruise phase simultaneously covering a wide range of heliocentric distances (0.28 AU–0.5 AU). Hence, the various spacecraft configurations and the combined in-situ and remote sensing measurements from the different spacecraft, offer unique opportunities for BepiColombo to be part of these unprecedented multipoint synergistic observations and for potential scientific studies in the inner heliosphere, even before its orbit insertion around Mercury in December 2025. The main goal of this report is to present the coordinated observation opportunities during the cruise phase of BepiColombo (excluding the planetary flybys). We summarize the identified science topics, the operational instruments, the method we have used to identify the windows of opportunity and discuss the planning of joint observations in the future.
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BepiColombos Cruise Phase: Unique
Opportunity for Synergistic
Observations
1
*, V. Génot
2
, S. Aizawa
2
, A. Milillo
3
, J. Zender
4
, G. Murakami
5
, J. Benkhoff
4
,
I. Zouganelis
6
, T. Alberti
3
, N. André
2
, Z. Bebesi
7
, F. Califano
8
, A. P. Dimmock
9
, M. Dosa
7
,
C. P. Escoubet
4
, L. Griton
2
,G.C.Ho
10
, T. S. Horbury
11
, K. Iwai
12
, M. Janvier
13
, E. Kilpua
14
,
B. Lavraud
2
,15
7
, Y. Miyoshi
12
, D. Müller
4
, R. F. Pinto
2
,16
, A. P. Rouillard
2
,
J. M. Raines
17
, N. Raoua
10
, F. Sahraoui
1
, B. Sánchez-Cano
18
, D. Shiota
19
, R. Vainio
20
and
A. Walsh
6
1
Laboratoire de Physique des Plasmas (LPP), CNRS, École Polytechnique, Institut Polytechnique de Paris, Observatoire de Paris,
Sorbonne Université, Université Paris Saclay, Palaiseau, France,
2
CNRS, UPS, CNES, Institut de Recherche en Astrophysique et
Planétologie (IRAP), Université de Toulouse, Toulouse, France,
3
INAF, Institute for space astrophysics and planetology (IAPS),
Rome, Italy,
4
European Space Agency, ESTEC, Noordwijk, Netherlands,
5
Japan Aerospace Exploration Agency, Institute of
Space and Astronautical Science, Sagamihara, Japan,
6
European Space Agency (ESA), European Space Astronomy Centre
7
Wigner Research Centre for Physics, Budapest, Hungary,
8
Dipartimento di Fisica E. Fermi, Universitá di
Pisa, Pisa, Italy,
9
Swedish Institute of Space Physics (IRF), Uppsala, Sweden,
10
Johns Hopkins University Applied Physics
Laboratory, Laurel, MD, United States,
11
Blackett Laboratory, Imperial College, London, United Kingdom,
12
Institute for Space-
Earth Environment Research, Nagoya University, Nagoya, Japan,
13
CNRS, IAS, Université Paris-Saclay, Gif-sur-Yvette, France,
14
Department of Physics, University of Helsinki, Helsinki, Finland,
15
CNRS, Laboratoire dastrophysique de Bordeaux, University
Bordeaux, Pessac, France,
16
Département dAstrophysique/AIM, CEA/IRFU, CNRS/INSU, University Paris-Saclay, University de
Paris, Gif-sur-Yvette, France,
17
Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor,
MI, United States,
18
School of Physics and Astronomy, University of Leicester, Leicester, United Kingdom,
19
National Institute of
Information and Communications Technology, Koganei, Japan,
20
Department of Physics and Astronomy, University of Turku,
Turku, Finland
The investigation of multi-spacecraft coordinated observations during the cruise phase of
BepiColombo (ESA/JAXA) are reported, with a particular emphasis on the recently
launched missions, Solar Orbiter (ESA/NASA) and Parker Solar Probe (NASA). Despite
some payload constraints, many instruments onboard BepiColombo are operating during
its cruise phase simultaneously covering a wide range of heliocentric distances (0.28
AU0.5 AU). Hence, the various spacecraft congurations and the combined in-situ and
remote sensing measurements from the different spacecraft, offer unique opportunities for
BepiColombo to be part of these unprecedented multipoint synergistic observations and
for potential scientic studies in the inner heliosphere, even before its orbit insertion around
Mercury in December 2025. The main goal of this report is to present the coordinated
observation opportunities during the cruise phase of BepiColombo (excluding the
planetary ybys). We summarize the identied science topics, the operational
instruments, the method we have used to identify the windows of opportunity and
discuss the planning of joint observations in the future.
Keywords: solar wind, multi-spacecraft measurements, inner heliosphere, spacecraft mission, coordinated
measurements
Edited by:
Rudolf A. Treumann,
Ludwig Maximilian University of
Munich, Germany
Reviewed by:
Daniel Heyner,
Technische Universitat Braunschweig,
Germany
Alexander Kozyrev,
Space Research Institute (RAS),
Russia
*Correspondence:
Specialty section:
Space Physics,
a section of the journal
Frontiers in Astronomy and Space
Sciences
Accepted: 30 August 2021
Published: 14 September 2021
Citation:
Hadid LZ, Génot V, Aizawa S, Milillo A,
Zender J, Murakami G, Benkhoff J,
Zouganelis I, Alberti T, André N,
Bebesi Z, Califano F, Dimmock AP,
Dosa M, Escoubet CP, Griton L,
Ho GC, Horbury TS, Iwai K, Janvier M,
Kilpua E, Lavraud B, Madar A,
Miyoshi Y, Müller D, Pinto RF,
Rouillard AP, Raines J M, RaouaN,
Sahraoui F, Sánchez-Cano B,
Shiota D, Vainio R and Walsh A (2021)
BepiColombos Cruise Phase: Unique
Opportunity for
Synergistic Observations.
Front. Astron. Space Sci. 8:718024.
doi: 10.3389/fspas.2021.718024
Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 7180241
BRIEF RESEARCH REPORT
published: 14 September 2021
doi: 10.3389/fspas.2021.718024
1 INTRODUCTION
A new era of coordinated observations in the inner heliosphere
has begun with the launch of NASAs Parker Solar Probe (PSP,
Fox et al., 2016) in August 2018, followed by the ESA-JAXA
BepiColombo spacecraft mission in October 2018 (Benkhoff
et al., 2021), and by ESA-NASAs Solar Orbiter (Müller et al.,
2020) in February 2020. Until the end of the cruise phase of
BepiColombo (November 30, 2025), these three spacecraft will be
traveling simultaneously in the inner heliosphere covering
different heliocentric distances (Velli et al., 2020):
BepiColombos elliptical orbit will cover distances from about
1.2 Astronomical Unit (AU) to 0.31 AU, while Solar Orbiter
from 1.02 to 0.28 AU, and Parker Solar Probe from about 0.7 to
0.04 AU. Together with these missions, previous (and future)
spacecraft provide continuous in situ and remote sensing
measurements in our Solar System (as shown in Figure 1): at
Venus 0.7 AU (Akatsuki, also known as the Venus Climate
Orbiter), around Earth, including the L1 Lagrange point 1AU
(e.g., SOHO, ACE, Wind, Cluster, THEMIS, and MMS), at Mars
1.5 AU (e.g., MAVEN, Mars Express, Mars Odyssey), and at
Jupiter 5 AU (e.g., JUNO). In addition many Sun-observing
including, SOHO, Hinode, Solar Dynamics Observatory,
PROBA-2, and STEREO-A monitor the Sun with various
instrumentations. The exceptional and complementary in-situ
and remote sensing payloads on-board these different satellites,
together with ground based measurements, will give the
opportunity to perform unprecedented multi-point
measurements of the solar wind plasma and the Sun. Hence
allowing the community to address different fundamental
physical processes in the solar wind, such as turbulence, the
generation, acceleration, and transport of solar energetic particles
(SEPs), and the characterization of large scale heliospheric
structures such as Interplanetary Coronal Mass Ejections
(ICMEs).
During the cruise phase, the BepiColombo spacecraft is in a
so-called stackedconguration: the Mercury Magnetospheric
Orbiter (MMO/Mio) is inside the Sunshield and Interface
Structure (MOSIF) which is attached to the Mercury Planetary
Orbiter (MPO). MPO, MOSIF, and Mio are all connected to the
Mercury Transfer Module (MTM) (Mangano et al., 2021).
Therefore, unlike some MPO instruments that are fully
operational during cruise, all the instruments onboard Mio are
shielded by MOSIF and not all of them can be scientically
operational (i.e., limited eld of view, undeployed instruments). It
is only after entering Mercurys orbit in December 2025, that all
the instruments will be fully deployed and operational at full
capacity. Nevertheless, despite some operational and
instrumental constraints, science operations could be
performed during cruise in coordination with other spacecraft
missions. Moreover, since long term planning is required for at
least BepiColombo and Solar Orbiter (9 months and 6 months in
advance respectively), a close coordination between
BepiColombo, Solar Orbiter, and PSP teams was necessary
(Velli et al., 2020). In this context, the BepiColombo
Coordinated Observations Working Group (BC-CoObs WG)
was initiated in November 2019. The BC-CoObs WG
consisted of the project scientist and deputy project scientist of
BepiColombo, along with instruments Principal Investigators
(PIs) and members from BepiColombo, Solar Orbiter and PSP
teams and researchers from the planetary and heliophysics
community. The main goal of the BC-CoObs WG was to
identify the science opportunities during the cruise phase of
BepiColombo from September 1, 2020 till November 30, 2025,
excluding the planetary ybys. In order to achieve this goal, we
have dened three main tasks: 1) to specify the different science
FIGURE 1 | Examples of operational missions covering different heliocentric distances in our Solar System.
Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 7180242
Hadid et al. BepiColombos Coordinated Observations During Cruise
topics that are related to the multi-spacecraft observations, 2) to
report the potential operational instruments on-board
BepiColombo, and 3) to identify the potential windows of
opportunities of BepiColombo in coordination with all the
operational spacecraft, by selecting the most interesting
spacecraft congurations.
In the following sections, we summarize the operational
instruments on board BepiColombo, the science topics that
can be addressed during cruise, and some operation
constraints. Then, we describe the method and the tool that
we used to identify the different windows of opportunity. Finally,
we discuss the planning of the joint observations and present
some specic examples.
2 OPERATIONAL INSTRUMENTS, SCIENCE
TOPICS, AND CONSTRAINTS
The only ofcial instrument onboard BepiColombo that was
originally planned to be operating during cruise was the
Mercury Orbiter Radio science Experiment (MORE, Iess et al.,
2021) during superior solar conjunctions. Nevertheless, the
beginning of the cruise phase has revealed that other
instruments on board Mio and MPO could be operating as well
and exploited for scientic studies. In fact, some of the instruments
on-board MPO will be continuously operating during cruise,
except for the Electric Propulsion (EP) periods, such as the
BepiColombo Radiation Monitor (BERM), the Magnetometer
(MPO-MAG, Glassmeier et al., 2010;Heyner et al., 2021), the
Mercury Gamma-ray and Neutron Spectrometer (MGNS,
Mitrofanov et al., 2010), the Italian Spring Accelerometer (ISA,
Iafolla et al., 2021) and MORE. In table 1,wesummarizeallthe
operational instruments during the cruise phase, excluding the
planetary ybys periods [more details regarding the planetary
ybys periods and the pointing of the different instruments can
be found in Mangano et al. (2021)]. A detailed description about
the combined in situ and remote sensing instruments on-board
Solar Orbiter and Parker Solar Probe can be found in Velli et al.
(2020) and Müller et al. (2020).
Despite the limited science operations, interesting science studies
can be performed. During the cruise phase of BepiColombo, at least
from September 2020 until December 2025, the Sun will be
TABLE 1 | Operational instruments during the cruise phase (excluding the periods of the planetary ybys).
Consortium and reference Instrument and information Targer Sensitivity
MMO/Mio
MPPE (Mercury Plasma Particles Experiment). Saito
et al. (2021)
MEA1 and MEA2 (Mercury Electron Analyzer),
reduced FOV
Low energy electrons 3 eV26 keV
HEP-e (High Energetic Particleselectrons), reduced FOV High energy electrons 30700 keV
Kobayashi et al. (2020) MDM (Mercury Dust Monitor), reduced FOV Impact momentum and dust
particles direction
MPO
SERENA (Search for Exospheric Relling and Emitted
Natural Abundances). Orsini et al. (2021)
MIPA (Miniature Ion Precipitation Analyser), reduced FOV Low energy ions 15 eV15 keV
PICAM (Planetary Ion CAMera), reduced FOV Low energy ions 10 eV3keV
SIXS (Solar Intensity X-ray and particles Spectrometer).
Huovelin et al. (2020)
SIXS-X, partially in the MOSIF shadow. It could face the
Sun on request during specic periods
Solar X-ray 120 keV
SIXS-P, hot distributions can be detected High energy protons 0.3330 MeV
High energy electrons 50 keV3 MeV
MPO-MAG, fully operational B-eld (nominal mode) DC16 Hz
B-eld (reduced mode) DC1Hz
Quémerais et al. (2020) PHEBUS (Probing of Hermean Exosphere by Ultraviolet
Spectroscopy): can be operated
Far-Extreme UV 55330 nm
Hiesinger et al. (2020) MERTIS (MErcury Radiometer and Thermal Infrared
Spectrometer), fully operational
BERM, fully operational High energy protons 1200 MeV
High energy electrons 0.310 MeV
MORE, fully operational Radio emissions X-band and Ka-
band
MGNS, fully operational Gamma-rays 300 keV10 MeV
Neutron ux 1 eV10 MeV
ISA, fully operational Non-gravitational acceleration
vector
3.10
5
10
1
Hz
Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 7180243
Hadid et al. BepiColombos Coordinated Observations During Cruise
approaching Solar maximum (predicted in July 2025). The joint
measurements with BepiColombo, Solar Orbiter, and Parker Solar
Probe including other operational spacecraft in the interplanetary
space, will allow a better understanding of the evolution of the solar
wind plasma and its large scale three-dimensional distribution under
different conditions of the solar activity using both remote sening
and in-situ meaurements. An extensive discussion on the science
investigations during the cruise phase of BepiColombo can be found
in Mangano et al. (2021).Briey, the main science topics can be
grouped into seven cases: 1) Solar wind turbulence properties (e.g.,
Tu and Marsch, 1995;Bruno and Carbone, 2013;Sahraoui et al.,
2020). They include studies of the scaling properties (e.g., Alberti
et al., 2020), characterization of the wave modes propagation (e.g.,
Howes et al., 2012), high order statistics, and intermittency (e.g.,
Bruno et al., 2001), and their evolution with heliocentric distances. 2)
Solar wind structures. These include the study of the properties and
radial evolution of small scale structures, such as discontinuities,
including reconnection exhausts (e.g., Gosling et al., 2005), magnetic
holes (e.g., Turner et al., 1977;Volwerk et al., 2020;Karlsson et al.,
2021), interplanetary shocks and of large scale heliospheric
structures, such as transient events [e.g., ICMEs, ux ropes
(Kilpua et al., 2017)], and the Co-rotating Interaction Regions
(CIRs, Richardson, 2018) which are compressive regions formed
in the background magnetic eld where high-speed wind runs into
the slower wind ahead (e.g. Pizzo, 1980;Gosling and Pizzo, 1999).
Moreover, the large scale properties of the solar wind (electron
number density and velocity) could be done by combining ground-
based interplanetary scintillation observations (IPS) observations
(e.g., Iwai et al., 2019), heliospheric imaging (e.g., Harrison et al.,
2018) and global magnetohydrodynamic (MHD) simulations and
models such as SUSANOO (e.g., Shiota et al., 2014), IPS-ENLIL (e.g.,
Odstrcil, 2003;Jackson et al., 2015), or EUHFORIA (e.g., Pomoell
and Poedts, 2018). The solar wind plasma parameters measured
onboard one of the spacecraft can also be propagated with the help of
a simple 1D MHD model such as Heliopropa (http://heliopropa.
irap.omp.eu) to another planet, comet, or spacecraft in order to
provide a virtual solar wind monitor and predict the properties of the
solar wind in another heliospheric location. 3) Solar Energetic
Particles (SEPs). The study of their generation, acceleration and
transport processes and their ux-time proles at different locations
in the solar wind (e.g., Miroshnichenko, 2018). Moreover,
combining in situ SEP data with type-II radio burst data, and
global MHD simulations may provide information regarding the
structure of the background interplanetary magnetic elds and the
propagation of ICMEs. 4) Dust and Comets. The characterization of
the dust distribution in the inner Solar System (e.g., Grün et al., 1980)
and the analysis of the cometary composition such as the hydrogen
coma at Lyman-αin Extreme Ultraviolet Violet (EUV) (e.g., Bertaux
et al., 1995). Even though this depends on the passage of the comets
in the eld of view of BepiColombosEUVspectrometer(PHEBUS),
at least one observation of comet 2P/Encke would be possible by the
end of November 2023 as it arrives at a distance of 0.6 AU from
BepiColombo. 5) Solar Corona. Measurements of the density
uctuations of the solar corona down to a few solar radii (e.g.,
Miyamoto et al., 2014) will be possible using radio measurements
from the Mercury Orbiter Radio-science Experiment (MORE). 6)
High frequency electromagnetic radiation. These include the
detection of Gamma-Ray Bursts (GRBs) and their localization, in
particular the gamma-rays that originate from solar ares, and
monitoring the local radiation background of the spacecraft due
to bombardment by energetic particles of Galactic Cosmic Rays. Last
but not least, 7) General relativity test could be performed during
superior solar conjunctions (e.g., Bertotti et al., 1993;Iess et al., 2021).
Two major constraints had to be taken into account for the
planning of the joint observations with BepiColombo. The rst one is
related to the Electric Propulsion periods during which no
instruments operations can be performed, and the second one is
related to the science downlink rate, as BepiColombo moves away
from Earth. As one can see from Figure 2, in periods with a distance
between BepiColombo and Earth larger than 1.2 AU the data
downlink rate gets very low (<0.3 kbps), not even allowing the
instrumentsbackground operations. Therefore, we assume that all
in-situ instruments can operate in background mode when the
distance Bepi-Earth is less than 0.7 AU (data downlink rate >6kbps).
3 METHODS
In order to identify the potential windows of opportunities, we have
focused our investigation on ve different spacecraft geometries and
used the Centre de Données de la Physique des Plasmas (CDPP)
tools, in particular the Automated Multi-Dataset Analysis (AMDA)
tool. In the following subsections, we give a short overview of AMDA
and describe the different spacecraft congurations.
3.1 AMDA Tool
AMDA is an online database and analysis tool (http://amda.cdpp.
eu/) developed for 15 years by the CDPP (http://www.cdpp.eu/).
It gathers a large variety of plasma data from space missions and
ground instruments together with simulations and models. It also
offers a dedicated work space to all registered users where plot
layouts, data mining conditions, and event lists can be stored and
reused. Hundreds of user accounts have been provided over the
years from space physics students to senior researchers. Several
papers describe the basics of AMDA and its various applications
in heliophysics and planetary sciences (Génot et al., 2021, and
references herein). Registration is done by sending an mail to
FIGURE 2 | Distance of BepiColombo from Earth in AU (left axis, in blue)
and the science downlink rate (right axis, in black) as a function of time during
cruise. The Electric Propulsion (EP) periods are highlighted in red lines.
Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 7180244
Hadid et al. BepiColombos Coordinated Observations During Cruise
amda@irap.omp.eu, and a public access (with no workspace) is
also available. For the planning activities of the BC-CoObs
Working Group, the choice of using AMDA arose for several
considered objects (spacecraft and planets) in several common
coordinate systems and measurements at several cadences.
Second, it enables to create new parameters from existing data,
to perform conditional search on a large volume of data-set, and
nally, to manage resulting event lists, and so, to produce
catalogues which are relevant to this study.
3.2 Spacecraft Congurations
The investigation of the different windows of opportunity was
done based on ve different geometries, Cone,”“Opposition,
the following spacecraft/bodies: BepiColombo, PSP, Solar
Orbiter, STEREO-A, Venus, Earth, Mars, and Jupiter. Each of
these congurations are dened below in the Heliocentric Earth
Ecliptic (HEE) system, where the Xaxis points towards the Earth
and the Zaxis is perpendicular to the plane of the Earths orbit
around the Sun (positive North). This system is xed with respect
to the Earth-Sun line.
Cone: radial alignments between two or more spacecraft/
bodies, i.e., when they are within a small longitude cone
from the Sun. For the radial alignment we require here the
maximum cone width of 10 ±3 in longitude without putting
any constraints on the latitude assuming that its sufcient
to identify all the events that are radially aligned within a
cone (Figure 3B). The Conegeometry allows mainly to
study the in situ evolution of the same plasma parcel and the
underlying processes as a function of the distance from the
FIGURE 3 | 3DView illustration of the downselected congurations for the rst half of 2021, in the HEE coordinate system: (A) 2021-02-192021-03-08: Parker
Solar Probe and BepiColombo are in a cone geometry and in Quadrature geometry with Solar Orbiter. (B) 2021-03-132021-03-14: BepiColombo and Venus are in a
cone geometry. (C) 2021-03-212021-03-24: Parker Solar Probe is in quadrature geometry with Solar Orbiter and BepiColombo is in quadrature geometry with
STEREO A. (D) 2021-06-012021-07-01: BepiColombo and Solar Orbiter are in cone geometry and in quadrature geometry with STEREO A.
Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 7180245
Hadid et al. BepiColombos Coordinated Observations During Cruise
Sun, such as the properties of the solar wind plasma, and
turbulence as it has been already done using Helios 1 and 2
probes (Schwartz and Marsch, 1983), Ulysses and ACE
(DAmicis et al., 2010) and more recently using PSP and
Solar Orbiter (Telloni et al., 2021), as well as the evolution of
large-scale heliospheric structures (e.g., Gosling and Pizzo,
1999).
Opposition: two or more spacecraft/bodies are oppositely
aligned forming a cone with respect to the Sun. The
difference in longitude (in absolute values) between the
spacecraft is dened as 180 ±10. This geometry is
particularly interesting for periods of superior solar
occultation observations can be performed to observe
remotely the solar corona using both remote sensing
measurements and ground based observations.
Parker: magnetic alignment between two or more bodies,
i.e., when the footpoints of Parker eld lines passing through
the bodies are in a small latitude/longitude region at the so-
called source surface(R
s
), which is an imaginary spherical
surface above the corona. The alignment along the same
spiral eld line would allow to study the evolution of the
solar wind plasma that originate from the same source at
different locations on the eldline(withatimedifference
that corresponds to the travel time of the plasma that
would change over this time). Moreover, it would allow to
analyze unpredictable bursty events (e.g., SEPs) that
originate from the same activeregion on the solar
surface.
For this conguration, the longitude of the Parker eld line at
the source surface (ϕ
s
) has rst to be computed for a given Solar
Wind velocity u
SW
; the formula is given below by:
ϕsϕ(r)+Ω(rRs)/uSW (1)
where ϕ(r) is the spacecraft heliocentric longitude at distance r,
Ω2π/25.38 days, and R
s
2.5R
Sun
. Several values of u
SW
were
used in the range 200800 km/s, to take into account the slow
(200400 km/s), intermediate (400500 km/s) and fast solar wind
(600800 km/s). At the source surface a small region of 3 ×3in
longitude/latitude is considered for the footpoints to be said co-
located. Varying the size of this region impacts the duration of the
magnetic conjunction. The footprint of a given spacecraft at a
given time is dened by its longitude (ϕ
s
) and by its latitude (equal
to the one of the spacecraft as a Parker eld line is inscribed on a
cone of constant latitude). Below the source surface, the Parker
approximation to model the magnetic eld generally fails as the
coronal magnetic eld becomes more complex; rened models
that take into account observed/modeled magnetograms (e.g.,
Potential-Field Source-Surface model Wang et al., 1992) can then
be used. This is what is done, for instance, in the Magnetic
Connectivitytool developed at IRAP
1
to estimate the solar
source location of the solar wind and energetic particles
measured by different spacecraft. Nevertheless the rst order
approach explained above and used in AMDA by the working
group is a quick way to derive times of interest for the coordinated
analysis.
Cone-Parker: the combination of the Cone and Parker
geometries. This conguration is mainly interesting to
study and analyze ICMEs, SEPs, or any other bursty
event that propagates and expands at different longitude
Quadrature: Spacecraft with remote sensing instruments
(e.g., imagers, coronographs) forming an angle of 90 ±10
with the Sun and other spacecraft/planet. For this particular
geometry we only considered BepiColombo, Earth (L1
probes, e.g., Wind, SOHO) and the solar missions: PSP,
Solar Orbiter, and STEREO-A. This conguration is
optimal for observing remotely the structure of the Solar
corona (Lamy et al., 2020) or any transient events that
emanate from the Sun, and linking them to the heliosphere
observed in-situ 90
from the Sun-spacecraft line. An
example would be when Parker Solar Probe is in
quadrature with Solar Orbiter. Close to the Sun, the
remote sensing instruments onboard Solar Orbiter (such
as the Solar Orbiter Heliospheric Imager using Thomson
scattering) would be providing imagery of the plasma lifting
up from the limb and so the solar wind plasma parcel that is,
expected to be encountered by Parker Solar Probe further
away from the Sun at 90
from the Sun-Solar Orbiter line
(Howard et al., 2020). The quadrature geometry and the
combination of the in situ and remote sensing measurement
would allow to observe the global structure of the eruptive
events as they evolve in the interplanetary space and
contribute to the understanding of their initiation at
the Sun.
In a recent study, Davies et al. (2021) could investigate in situ
the propagation of an ICME through the interplanetary medium
as Solar Orbiter, BepiColombo, and Wind spacecraft were
radially aligned, and could observe its global shape and
expansion using the remote observations from STEREO-A as
it was in a quadrature geometry with respect to the Sun-
Earth line.
A detailed description of AMDAs data mining conditions can
be found in the Bepi-CoObs WG AMDA manual (see data
availability statement). It is worth noting that the travel time
of the plasma from one spacecraft to another was not taken into
account when selecting the different events and this should be
taken into account when considering the radial alignment case
studies.
4 WINDOWS OF OPPORTUNITY AND
FUTURE PLANNINGS
Using the AMDA tool and applying the method described in
section 3, the investigation of the joint observations with
BepiColombo by the CoObs WG, has led to 921 windows of
opportunity between September 1st, 2020 and November 30th,
1
http://connect-tool.irap.omp.eu/
Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 7180246
Hadid et al. BepiColombos Coordinated Observations During Cruise
2025. We note that this large number of events is mainly due to
the Parkergeometry condition, that was applied assuming
different ranges of the solar wind speed. The full list of events
is publicly available on AMDA, and will be shared on
BepiColombos Cruise Science study group ESAs website (see
data availability statement). The timetable includes an identier
(ID) for each case study, the starting and ending time of the
observation window, the geometry, the name of the spacecraft or
objects, whether the event coincides with any particular yby of
BepiColombo, Solar Orbiter or PSP, or to an EP period.
Furthermore, for each of the considered objects
(BepiColombo, PSP, Solar Orbiter, STEREO-A, Venus, Earth,
Mars, and Jupiter) we added the minimum, maximum and
average values of the latitude, longitude, and radial distance
from the Sun. We note that movies of Solar Orbiter,
BepiColombo, PSP and STEREO-A trajectories, and the
planning of Solar Orbiters joint observations for July-
December 2021 (and future plans) are available at Solar
Orbiters Science Operation Center website (see data
availability statement).
After identifying all the potential opportunities with the
different conjunctions, a down-selection of the most feasible
and realistic cases was necessary in order to plan and
coordinate well in advance the joint observations, in particular
between the two ESA missions, BepiColombo and Solar Orbiter
teams. The down-selection is based on the following selection
approach: 1) we assume that the BERM instrument is always
operational in the background and not further analyzed, as its
downlink rate is relatively low (38 bps); 2) the EP and instruments
checkout periods are immediately excluded from any analysis; 3)
all the in situ instruments are assumed to be operating in
background mode when the distance BepiColombo-Earth is
less than 0.7 AU. The only question to the teams during these
periods would be related to the spacecraft pointing requirements;
and 4) no events near the ybys periods (closest approach ±
1 week) are down-selected, as the yby operations are
discussed withing the yby working group.
The down-selection step is implemented by a small group
including the Project Scientists of the missions, who discusses
9 months in advance, a 6 months planning period for the
coordinated observations between BepiColombo and Solar
Orbiter - and any other non-ESA missions, taking into
account the constraints as discussed above in the selection
approach (Figure 2). The down-selected opportunities are
then sent by the project scientists to the different instruments
PIs of both missions, who analyze the different periods and
specify for each of them a set of information (a priority level,
a description of the observation, operational mode, pointing
requests, and the expected science downlink rate and volume)
that are then studied and validated by the ESA Mission Operation
Center (MOC). Due to the spacecraft and payload constraints,
only few windows of opportunities could be down-selected. In
fact, for the planning of the year 2021 and the rst half of 2022
(January 1st, 2022June 30, 2022), only 17 events out of 349 could
be requested to MOC. Examples of these joint observations,
plotted using 3DView tool (Génot et al., 2018), are shown in
Figure 3 and listed below:
2021-02-192021-03-08: BepiColombo is in a cone
geometry with PSP and in quadrature geometry with
Solar Orbiter.
2021-03-132021-03-14: BepiColombo and Akatsuki in
solar conjunction.
2021-03-212021-03-24: PSP, BepiColombo, Solar Orbiter,
and STEREO-A are longitudinally distributed around the
Sun. PSP-Solar Orbiter and BepiColombo-STEREO-A are
more or less in quadrature geometry.
2021-06-012021-06-12: BepiColombo is in a cone
geometry with Solar Orbiter and in quadrature geometry
with STEREO-A.
2021-07-012021-08-02: BepiColombo, Solar Orbiter and
Mars are in Cone-Parker geometry. On 2021-07-15
BepiColombo is radially aligned with Solar Orbiter, and
2021-08-142021-08-26: BepiColombo and Solar Orbiter
are magnetically aligned, and STEREO-A in quadrature
geometry.
2021-09-052021-09-25: PSP, Solar Orbiter, and STEREO-
A are in a Cone geometry and BepiColombo is nearby.
2021-10-072021-10-08: BepiColombo, Solar Orbiter, and
STEREO-A are magnetically connected on the same parker
spiral.
2021-10-142021-10-15: BepiColombo, Solar Orbiter, and
STEREO-A are magnetically connected on the same parker
spiral.
with Earth and Solar Orbiter is in a quadrature geometry.
with STEREO-A and Solar Orbiter is in a quadrature
geometry.
with Earth.
2022-06-092022-06-10: BepiColombo is close to Mercury
and radially aligned with PSP, and STEREO-A is in a
CONCLUSION
In this short report we attempt to summarize the extensive
investigationthatwehavedonewithintheBepiColomboCoObs
WG to identify the potential scientic coordinated observations
related to BepiColombo, Solar Orbiter and any other operational
spacecraft mission. Despite some spacecraft and payload constraints,
this work has revealed many interesting science opportunities for in-
situ and remote sensing synergistic observations in the inner
heliosphere even before the orbit insertion of BepiColombo
around Mercury in December 2025. The joint in situ and remote
sensing observations of BepiColombo, Solar Orbiter, Parker Solar
Probe including other space, and ground based observatories, would
allow detailed mapping of the inner heliosphere and to better
understand the solar wind properties, structures and magnetic
eld expansion at different heliocentric distances. Recent studies
of coordinated observations between BepiColombo, Solar Orbiter
andWind(Davies et al., 2021), and Parker Solar Probe and Solar
Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 7180247
Hadid et al. BepiColombos Coordinated Observations During Cruise
Orbiter (Telloni et al., 2021) and additional on-going studies,
highlight the need for careful advance planning to optimize the
scientic return from this unprecedented opportunity of synergistic
observations. At the time of writing this report, regular meetings for
the planing of the future years are being held and the approved
selected events will be made public to the community and will
available on BepiColombos Cruise Science Study Group ESA
cosmos website (see Data Availability Statement).
DATA AVAILABILITY STATEMENT
The SPICE kernels are used for the different missions with the
ofcial data sources as given below. The kernels are regularly
updated at the ofcial sources and in orbitography services
(including AMDA), for instance when reconstructed kernels
are replacing predicted ones. As a consequence the catalogue
of events as it is presented at the time of publication of the article
may change. However, it has been checked that these possible
changes (shift in start/stop times of some events) are limited, and,
for example, on the same scale as the shift induced by varying the
cone aperture of a few degrees (for Coneconguration), or the
solar wind velocity by a few 10 km/s (for Parkerconguration).
List of the SPICE kernels:
BepiColombo: ESA/ESAC https://doi.org/10.5270/esa-
dwuc9bs
Solar Orbiter: ESA/ESAC https://doi.org/10.5270/esa-kt1577e
Parker Solar Probe: https://sppgway.jhuapl.edu/lpredict_
ephem and https://sppgway.jhuapl.edu/recon_ephem
STEREO-A: https://sohowww.nascom.nasa.gov/solarsoft/
Planets: NASA/NAIF https://naif.jpl.nasa.gov/naif/
The websites of the different tools and movies are:
CDPP: http://www.cdpp.eu/
AMDA: http://amda.cdpp.eu/
3D View: http://3dview.irap.omp.eu/
Magnetic Connectivity: http://connect-tool.irap.omp.eu/
Heliopropa: http://heliopropa.irap.omp.eu
Bepi-CoObs WG Amda manual
Solar Orbiters Science Operation Center: https://issues.
cosmos.esa.int/solarorbiterwiki/display/SOSP/
Solar+Orbiter+SOC+Public
BepiColombo planning - the generated catalogue and the
down-selected list of events are available in:
AMDA: Shared cataloguedirectory http://amda.cdpp.eu/
BepiColombos Cruise Science: https://www.cosmos.esa.int/
web/bepicolombo-yssg-cs
Solar Orbiter planning - the future planning during the cruise
phase of Solar Orbiter is available in:
https://issues.cosmos.esa.int/solarorbiterwiki/display/
SOSP/Cruise+Phase
AUTHOR CONTRIBUTIONS
All the co-authors have contributed in discussing the science
topics, operational instruments and geometries for identifying the
potential coordinated observations. In addition, LH, VG, and SA
have investigated the potential windows of opportunities using
the AMDA tool.
FUNDING
The CDPP is supported by CNRS, CNES, Observatoire de Paris
and Université Paul Sabatier Toulouse, and parts of the
aforementioned tools are currently being developed through
the Sun Planet Interactions Digital Environment on Request
(SPIDER) Virtual Activity of the Europlanet H2024 Research
Infrastucture funded by the European Unions Horizon 2020
research and innovation programme under grant agreement No
871149. B.S.-C. acknowledges support through UK-STFC grants
ST/S000429/1 and ST/V000209/1.
ACKNOWLEDGMENTS
AMDA team thanks all active users who provided very useful
feedback over the years and therefore contributed to enhance the
quality of the system. French co-authors ackowledge the support
of CNES for the BepiColombo, Solar Orbiter, and Parker Solar
Probe missions. This analysis was performed in the frame of the
ESA/JAXA working group: BepiColombos cruise phase
coordinated observations.
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Conict of Interest: The authors declare that the research was conducted in the
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potential conict of interest.
The reviewer DH declared a past co-authorship with several of the authors SA, AM,
JZ, JB, LG, TH, EK, and BS to the handling editor.
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Frontiers in Astronomy and Space Sciences | www.frontiersin.org September 2021 | Volume 8 | Article 71802410
Hadid et al. BepiColombos Coordinated Observations During Cruise
... The most recent heliospheric missions, namely BepiColombo (BC, Benkhoff et al., 2010), Parker Solar Probe (PSP, Fox et al., 2016), and Solar Orbiter (SO, Müller et al., 2020), which are probing in situ and remotely the inner heliosphere along complementary trajectories, has partially overcome this gap, while providing exciting and unprecedented opportunities for coordinated studies, in conjunction with the current near-Earth orbiting fleet, of the complex heliospheric dynamics and structures. Preliminary investigations were carried out by Velli et al. (2020) and Hadid et al. (2021) to identify the useful spacecraft configurations for such synergistic studies and highlight their potential for discovery. Since the first studies relying on these special orbital configurations (Jannet et al., 2021;Telloni et al., 2021a,b;Davies et al., 2021;Weiss et al., 2021;Musset et al., 2021;Möstl et al., 2022;Alberti et al., 2022;Réville et al., 2022), it became immediately clear that multi-point, multi-instrument observations by BC, PSP, and SO represent an exceptional added value in order to successfully address all the scientific goals the three heliospheric missions aim at. ...
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SQUARE2 is the acronym for Spacecraft in QUAdrature for solaR Exploration, and is a mission concept for multi-instrumental two-point observations of the Sun and its environment. It stems from the need to have two probes that are systematically in orbital configurations of interest, such as quadratures or radial alignments, in order to successfully address some science topics that joint measurements by different spacecraft, not specifically designed though to operate in synergy, can only partially solve. This perspective paper describes the mission profile that SQUARE2 should have in order to achieve a better understanding of how the Sun creates and controls the heliosphere. Specifically, the combined use of remote-sensing and in-situ instrumentation aboard the twin SQUARE2 probes would allow the connection of the locally sampled solar-wind plasma flow with its coronal drivers and a proper investigation of solar wind evolution, dynamics, and transient events in the inner heliosphere. The potential impact of SQUARE2 and the science topics covered by such a solar mission are here discussed.
... With the launch of the Parker Solar Probe (PSP; Fox et al., 2016), we now have the opportunity for unprecedented coordinated multi-spacecraft observations, including complementary remote-sensing and in situ observations of the same solar wind and transient structures, as well as in situ measurements over a range of angular separations and radial distances (e.g. Velli et al., 2020;Hadid et al., 2021;Mö stl et al., 2022). There have already been several well-observed slow, streamer blowout CME events in the PSP data that exhibit flux rope morphology in remote-sensing observations (e.g. ...
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We present a comprehensive analysis of the three-dimensional magnetic flux rope structure generated during the Lynch et al. (2019, ApJ 880:97) magnetohydrodynamic (MHD) simulation of a global-scale, 360°-wide streamer blowout coronal mass ejection (CME) eruption. We create both fixed and moving synthetic spacecraft to generate time series of the MHD variables through different regions of the flux rope CME. Our moving spacecraft trajectories are derived from the spatial coordinates of Parker Solar Probe’s past encounters 7 and 9 and future encounter 23. Each synthetic time series through the simulation flux rope ejecta is fit with three different in-situ flux rope models commonly used to characterize the large-scale, coherent magnetic field rotations observed in a significant fraction of interplanetary CMEs (ICMEs). We present each of the in-situ flux rope model fits to the simulation data and discuss the similarities and differences between the model fits and the MHD simulation’s flux rope spatial orientations, field strengths and rotations, expansion profiles, and magnetic flux content. We compare in-situ model properties to those calculated with the MHD data for both classic bipolar and unipolar ICME flux rope configurations as well as more problematic profiles such as those with a significant radial component to the flux rope axis orientation or profiles obtained with large impact parameters. We find general agreement among the in-situ flux rope fitting results for the classic profiles and much more variation among results for the problematic profiles. We also examine the force-free assumption for a subset of the flux rope models and quantify properties of the Lorentz force within MHD ejecta intervals. We conclude that the in-situ flux rope models are generally a decent approximation to the field structure, but all the caveats associated with in-situ flux rope models will still apply (and perhaps moreso) at distances below 30R⊙. We discuss our results in the context of future PSP observations of CMEs in the extended corona.
... [astro-ph.SR] 4 May 2022 2016), we now have the opportunity for unprecedented coordinated multi-spacecraft observations, including complementary remote-sensing and in-situ observations of the same solar wind and transient structures, as well as in-situ measurements over a range of angular separations and radial distances (e.g. Velli et al., 2020;Hadid et al., 2021;Möstl et al., 2022). There have already been several well-observed slow, streamer blowout CME events in the PSP data that exhibit flux rope morphology in remote-sensing observations (e.g. ...
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We present a comprehensive analysis of the three-dimensional magnetic flux rope structure generated during the Lynch et al. (2019) magnetohydrodynamic (MHD) simulation of a global-scale, 360 degree-wide streamer blowout coronal mass ejection (CME) eruption. We create both fixed and moving synthetic spacecraft to generate time series of the MHD variables through different regions of the flux rope CME. Our moving spacecraft trajectories are derived from the spatial coordinates of Parker Solar Probe's past encounters 7 and 9 and future encounter 23. Each synthetic time series through the simulation flux rope ejecta is fit with three different in-situ flux rope models commonly used to characterize the large-scale, coherent magnetic field rotations observed in a significant fraction of interplanetary CMEs (ICMEs). We present each of the in-situ flux rope model fits to the simulation data and discuss the similarities and differences between the model fits and the MHD simulation's flux rope spatial orientations, field strengths and rotations, expansion profiles, and magnetic flux content. We compare in-situ model properties to those calculated with the MHD data for both classic bipolar and unipolar ICME flux rope configurations as well as more problematic profiles such as those with a significant radial component to the flux rope axis orientation or profiles obtained with large impact parameters. We find general agreement among the in-situ flux rope fitting results for the classic profiles and much more variation among results for the problematic profiles. We also examine the force-free assumption for a subset of the flux rope models and quantify properties of the Lorentz force within MHD ejecta intervals. We conclude that the in-situ flux rope models are generally a decent approximation to the field structure, but all the caveats associated with in-situ flux rope models will still apply...
... As to in situ measurements, it is clear that the availability of multi-point observers at different radial distances and heliolongitudes is crucial for analyzing and validating modeling results across the entire inner heliosphere. Given the presence of currently operational spacecraft at six independent locations (i.e., the ones explored in this work), it is important to consider the future opportunities for heliophysics and space weather science via multi-point studies and coordinated observations (e.g., Hadid et al., 2021;Möstl et al., 2022;Velli et al., 2020). In conclusion, the potential for significant progress in heliophysics and space weather science will be realized as future studies increasingly utilize the multi-spacecraft capabilities of the Heliophysics System Observatory. ...
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... As to in-situ measurements, it is clear that the availability of multi-point observers at different radial distances and heliolongitudes is crucial for analysing and validating modelling results across the entire inner heliosphere. Given the presence of currently-operational spacecraft at six independent locations (i.e., the ones explored in this work), it is important to consider the future opportunities for heliophysics and space weather science via multi-point studies and coordinated observations (e.g., Hadid et al., 2021;Möstl et al., 2022;Velli et al., 2020). In conclusion, the potential for significant progress in heliophysics and space weather science will be realised as future studies increasingly utilise the multi-spacecraft capabilities of the Heliophysics System Observatory. ...
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Predictions of coronal mass ejections (CMEs) and solar energetic particles (SEPs) are a central issue in space weather forecasting. In recent years, interest in space weather predictions has expanded to include impacts at other planets beyond Earth as well as spacecraft scattered throughout the heliosphere. In this sense, the scope of space weather science now encompasses the whole heliospheric system, and multi-point measurements of solar transients can provide useful insights and validations for prediction models. In this work, we aim to analyse the whole inner heliospheric context between two eruptive flares that took place in late 2020, i.e. the M4.4 flare of November 29 and the C7.4 flare of December 7. This period is especially interesting because the STEREO-A spacecraft was located ~60{\deg} east of the Sun-Earth line, giving us the opportunity to test the capabilities of "predictions at 360{\deg}" using remote-sensing observations from the Lagrange L1 and L5 points as input. We simulate the CMEs that were ejected during our period of interest and the SEPs accelerated by their shocks using the WSA-Enlil-SEPMOD modelling chain and four sets of input parameters, forming a "mini-ensemble". We validate our results using in-situ observations at six locations, including Earth and Mars. We find that, despite some limitations arising from the models' architecture and assumptions, CMEs and shock-accelerated SEPs can be reasonably studied and forecast in real time at least out to several tens of degrees away from the eruption site using the prediction tools employed here.
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