Explanation: What it would look like to approach planet Earth? Such an event was recorded visually in great detail by ESA's and JAXA's robotic BepiColombo spacecraft last month as it swung back past Earth on its journey in to the planet Mercury. Earth can be seen rotating on approach as it comes out from behind the spacecraft's high-gain antenna in this nearly 10-hour time-lapse video. The Earth is so bright that no background stars are visible. Launched in 2018, the robotic BepiColombo used the gravity of Earth to adjust its course, the first of nine planetary flybys over the next seven years -- but the only one involving Earth. Scheduled to enter orbit in 2025, BepiColombo will take images and data of the surface and magnetic field of Mercury in an effort to better understand the early evolution of our Solar System and its innermost planet.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
<<The launch and cruise configuration of BepiColombo MCS (Mercury Composite Spacecraft) will not allow full operability of all instruments onboard. In fact, on-board the European spacecraft MPO few instruments are obstructed by the MTM (+Z axis) and will not be able to operate. Nevertheless, all the other instruments not requiring pointing or with apertures in the other directions will be switched on. Thanks to MORE, also operative since the beginning of the mission, the real spacecraft trajectory will be tracked also during the Earth flyby, thus collecting data to possibly better model the spacecraft orbit and improve the orbit determination codes, and maybe add some knowledge on the ‘Earth flyby anomaly’. For reference information, please read "Rosetta Navigation at its First Earth Flyby".
ISA, the spring accelerometer, MERMAG, the two fluxgate magnetometers, on the boom
MERTIS, the IR spectrometer and radiometer,
MGNS, the suite of gamma ray and neutron monitors
PHEBUS, the suite of UV spectrometers
SERENA, the suite of ion and neutral particles sensors (only the ion sensors)
SIXS, the X-ray and high energy particle detectors
BERM, the radiation monitor
MCAM (CMS), the three cameras located on the MTM module, with the goal to monitor the spacecraft appendages and try to image the Earth, the Moon, Venus and Mercury during the flybys. MORE, the radio science experiment
The Earth flyby is an opportunity to operate the above instruments of the BepiColombo spacecraft, mainly for calibrations purposes. The geometry of the flyby offers a very close approach to Earth surface (i.e., <13.000 km), while the Moon will stay rather far away from the spacecraft (i.e., >300.000 km) in the opposite direction. The Earth-Moon system is often observed by planetary missions cruising through the Solar System as it offers opportunities to operate the instruments towards targets, which are better known than the main objective of the missions itself. Nonetheless, those calibration observations may sometimes result in new scientific discoveries, as it already happened in the past.
In the present case, both MERTIS and PHEBUS will observe the Moon before and after the closest approach (CA).
MERTIS will obtain the first hyperspectral data of the Moon in the thermal infrared from space. Apart from using this for validating the calibration of the instrument, it will also provide an interesting new science dataset for the lunar science community and a baseline for the comparison with the future Mercury datasets.
PHEBUS will also observe the Moon, in two time slots after the CA with the purpose of checking the absolute calibration of its FUV channel and characterize the pixel to pixel sensitivity of the two detectors (flatfield correction). These data will be compared to previous observations of the Moon in the UV range.
The magnetometer MERMAG, will continue sampling the environment, as it is doing since the beginning of the mission, and it will provide measurements of the interplanetary magnetic field in the solar wind, as well as measurements of the Earth magnetosphere, from the crossing of the bowshock until the exit at about 20 hours later CA.
Ionised particle detectors like the PICAM and MIPA sensors of SERENA package, as well as the SIXS sensors with X rays and particle detectors, will complement the above measurements by sampling the high energy proton and electron population and X-ray spectrum within the FOV of the detectors shortly outside and inside the magnetosphere. In particular, SERENA PICAM and MIPA will also cross calibrate with each other by mean of the known populations and energies known to be present in the different regions, i.e. upstream Solar wind and Magnetosheath (where H+ and He+ ions are in the energy range of the instrument), and Plasmasheet (where O+ are potentially detected); but will be switched off when passing through the radiation belts to avoid the highly energetic particles.
The ongoing ISA accelerometer measurements, which also started since the beginning of the mission, will hopefully add information on the magnetospheric boundary crossings by trying to detect the variation of the charged drag (on MCS) due to abrupt change of particle density.
Finally, the neutron and gamma-ray measurements of MGNS during Earth flyby should also contribute to the investigation of interaction between solar wind and Earth environment, as well as studies of spacecraft neutron and gamma-ray background upon its passage through the Earth's radiation belts.
In addition to the MPO spacecraft, also some instruments onboard the Japanese spacecraft Mio will operate, though partially obstructed during cruise phase by the sunshield MOSIF. They are: the plasma particle sensors MPPE-MSA, MEA, MIA HEP-ele and ENA, the magnetometer MGF, and the magnetic waves sensor PWI.>>
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
My favorite part about this was that they thought it was a near-Earth asteroid:
On April 13, 2020, the Near-Earth Object candidate C14VXL1, reported by the
Catalina Sky Survey, was posted to the Near-Earth Object Confirmation Page.
Follow-up observations from four distinct observing sites, precovery on
April 12, 2020, from Pan-STARRS2, and two isolated tracklets from April 10
and 11 from Northolt Branch Observatory resulted in the designation and
publication of Near-Earth Object 2020 GL2, published in MPEC 2020-G96.
P. Birtwistle subsequently noted that the object is the BepiColombo
spacecraft. Therefore, the designation 2020 GL2 is being deleted and will be
listed as omitted.
Congrats to P. Birtwistle!
"No avian society ever develops space travel because it's impossible to focus on calculus when you could be outside flying." -Randall Munroe
Earth Flyby of BepiColombo
though admittedly short! A lot more than my Grandparents got to see! 
