JAXA/Akatsuki – ESA/JAXA BepiColombo coordination during Venus flybys in Oct. 2020 and Aug. 2021

Updated 8 August 2020 – International collaboration on Venus observations are under discussion during the flybys of BepiColombo (ESA-JAXA), on its way to Mercury. The collaborative observations have been planned between BepiColombo and the operating Venus orbiter, Akatsuki (JAXA), during the cruise and the 2 times of Venus flybys on 2020 October 15 and 2021 August 10, while its details are yet under discussions. This represents unique Venus observation opportunities, perhaps in coming decades, to be coordinated with two spacecraft.

Table 1. Summary of observational conditions during the cruise of BepiColombo. The detailed time and locations are subject to change.*(Updated information on 2020 Aug 08). Click to enlarge.

Figure 1. – Relative locations of the Sun, Venus, Earth, BepiColombo, and Akatsuki on 2020 Aug 28-Sep 2. The +X is assigned to the Sun. Red dots are the locations of BepiColombo and Akatsuki on 2020 Aug 28. Grey curve shows the predicted trajectory of BepiColombo from 2020 Aug 1 to Nov 1. Green arrow indicates the direction of the Earth. Whole-disk observation from BepiColombo and disk-resolved observation from Akatsuki and Earth are planned. Click to enlarge.


Figure 2. – Overview of trajectories of BepiColombo and Akatsuki as seen from the north of the solar system. +X is assigned to the Sun. Red dots are the locations of BepiColombo and Akatsuki at the time of the closest approach (CA) of BepiColombo (2020 Oct 15). Green arrow indicates the direction of the Earth.[Figure 3 Visualized viewing geometries of Venus as seen from BepiColombo (left), Akatsuki (middle) and the Earth (right) at the time of 1st flyby on 2020 Oct 15. The distance is from the center of Venus, green dots are the sub-observer points, and yellow dots are sub-solar points. Click to enlarge.


Figure 3 – Visualized viewing geometries of Venus as seen from BepiColombo (left), Akatsuki (middle) and the Earth (right) at the time of 1stflyby on 2020 Oct 15. The background is the LIR images (Kouyama et al. 2017). The distance is from the center of Venus, green dots are the sub-observer points, and yellow dots are sub-solar points. Click to enlarge.


Figure 4 – Visualized viewing geometries of Venus as seen from BepiColombo (left), Akatsuki (unplanned, so empty middle) and the Earth (right) at the time of 2nd flyby on 2021 Aug 10. The distance is from the center of Venus, green dots are the sub-observer points, and yellow dots are sub-solar points. Akatsuki’s mission extension beyond Apr 2021 is not yet determined at the time of this update (2020 Aug 8). Click to enlarge.


We gladly share this news to worldwide ground-based Venus observers for better coordination among observers, and encourage Venus observers to use this chance to achieve their own scientific goals on Venus studies under collaboration with corresponding instrumental teams of BepiColombo and Akatsuki. Details of 1st Venus flyby can be found from the ESA page (https://www.cosmos.esa.int/web/bepicolombo-flyby/venus1flyby). We also support the call for amateur astronomers (http://pvol2.ehu.eus/bc/Venus/).


l. to r. : Flyby coordination team members Jörn Helbert, Yeon Joo Lee, Pedro Machado, Thomas Widemann, Valeria Mangano. DPS-EPSC conference, Geneva, 19 Sep. 2019.

Visualizing widget for planning coordinated Venus observations:
WINDOWS ver. (https://akatsuki.matsue-ct.jp/sites/default/files/info/BSV_widget_WIN.zip)

WINDOWS manual and example images (https://akatsuki.matsue-ct.jp/sites/default/files/info/README_WIN.pdf)

LINUX ver. (https://akatsuki.matsue-ct.jp/sites/default/files/info/BSV_widget_LIN.tar.gz)
LINUX manual and example images (https://akatsuki.matsue-ct.jp/sites/default/files/info/README_LIN.pdf)

Related websites:

ESA BepiColombo Venus 1st flyby (https://www.cosmos.esa.int/web/bepicolombo-flyby/venus1flyby)
ISAS/JAXA Akatsuki ground-based supporting site (https://akatsuki.matsue-ct.jp/?q=node/20)
Venus BepiColombo amateur coordination campaign (PVOL by Europlanet) (http://pvol2.ehu.eus/bc/Venus/)

Contact information
Venus Working group in the BepiColombo team
Chair: Valeria Mangano, INAF-IAPS Roma, Italy (valeria.mangano@inaf.it)
Guest scientist: Kandis Lea Jessup, SWRI Boulder, CO, USA (kandilea@boulder.swri.edu)
Guest scientist: Yeon Joo Lee, Technische Universität Berlin, Germany (y.j.lee@astro.physik.tu-berlin.de)

Coordination with Akatsuki
Masataka Imai (masataka@ep.sci.hokudai.ac.jp)

Amateur astronomy support
Itziar Garate-Lopez (itziar.garate@ehu.eus)

Instrument contacts
MERTIS: Jorn Helbert (co-PI, Joern.Helbert@dlr.de)
PHEBUS: Eric Quemerais (PI, eric.quemerais@latmos.ipsl.fr)
UVI: Takao M. Sato (sato.takao@do-johodai.ac.jp)
LIR: Makoto Taguchi (PI, taguchi@rikkyo.ac.jp)

Other links:

ESA BepiColombo : Venus Takes Center Stage in October 2020 Observation Campaign – Sep. 2019

EPSC-DPS press release – Sep 2019

JAXA Akatsuki ground-based observations : information from Akatsuki team