The ESA / JAXA mission BepiColombo completed its first flyby on a planet on April 10th. At 06:25 CEST, the spacecraft approached the Earth's surface to within 12,700 kilometers, adjusting its trajectory towards Mercury.
(Press release: ESA, April 2020, photo: ESA / ATG medialab)
Today's maneuver was the first of nine planes to fly past. Together with BepiColombo's solar-electric ion drive, it will help the spacecraft reach its target orbit around Mercury. The next two flybys take place at Venus, after which six more are carried out around Mercury.
During the maneuver, Earth's gravity was used to adjust the spacecraft's trajectory. Active intervention, such as the ignition of the engines, was not necessary for this, but the flyby included 34 critical minutes - shortly after BepiColombo's closest approach to our planet when the spacecraft flew through the shadow of the earth.
“This eclipse was the most delicate part of the maneuver. The spacecraft flew through the shadow of our home planet and was not exposed to direct sunlight for the first time since it was launched, ”said Elsa Montagnon, head of the BepiColombo flight control team at ESA.
In preparation for this planned darkening phase, the responsible persons had fully charged the batteries of the spacecraft and brought all components to operating temperature in advance. During the eclipse itself, between 07:01 and 07:35 CEST, the temperature of the on-board systems was closely monitored.
“It is always very exciting to know that the solar panels are not catching sunlight. When we saw the solar panels start up again to generate electricity, we knew that BepiColombo had finally left the earth's shadow behind and was now ready to continue the interplanetary journey, ”Montagnon continued.
Departure despite Corona
Space operations are never routine at the ESA satellite control center in Darmstadt, but today's flyby had an additional challenge up its sleeve. The maneuver, which had been programmed long in advance and could not be postponed, had to be carried out on site with fewer employees - a result of the measures decided by ESA in the wake of the current coronavirus pandemic. Despite these restrictions, the flyby was successfully completed.
While BepiColombo whizzed past our home planet, most of the scientific instruments on board the ESA Mercury Planetary Orbiter (MPO) - one of the two scientific space probes that are part of this mission - were turned on. In addition, some of the sensors of the second mission component, namely the JAXA magnetospheric orbiter (Mercury Magnetospheric Orbiter, MIO for short), were activated.
Scientists will now use the data collected during the flyby, including photographs of the moon and measurements of the earth's magnetic field, to calibrate the instruments. These will investigate Mercury from 2026 and are intended to help solve the mystery surrounding the creation of this "burned" planet.
"A few months ago, of course, nobody could have guessed under what circumstances today's operation would take place," says Johannes Benkhoff, ESA project scientist for BepiColombo, who followed the maneuver from his home in the Netherlands - like many other scientists from the 16 instrument teams the mission too. These are currently scattered across Europe and Japan.
“We are all delighted that the flyby worked and we had several scientific instruments in operation. Now we are looking forward to the data and its analysis, which will also be very useful for the preparation of the next maneuver: BepiColombo will fly past Venus in October.”
“Japan is very interested in the BepiColombo mission. That is why we are now looking forward to the scientific operations on Venus and Mercury after the successful flyby, ”says Go Murakami, BepiColombo project scientist at JAXA.
Our home viewed from space
The cameras on BepiColombo took a series of pictures of our home planet - on April 9th, before the flyby, and then again today, shortly before the end of the maneuver. The photographs show the earth at a time that is extremely difficult for people in Europe and worldwide.
"These selfies from space fill me with humility. They show our planet, our common home, in a period that for many of us is the most troubling and unsafe we have ever experienced, ”said Günther Hasinger, ESA Director of Science, who also does the maneuver from his home ( in Spain).
“We are scientists who bring spacecraft into space to discover our solar system and explore the universe - so that we can understand at some point how our cosmos was created. But above all, we are people who care about their fellow human beings and deal with this global emergency together. When I look at these pictures, I have to remember how strong and resilient humanity is, what challenges we have already mastered together. I hope that they also bring you a little bit of hope for the future.”
Live stream from April 10th
On April 10, at 5:00 p.m. CEST, watch a live stream on ESA Web TV with ESA mission experts and scientists from some of the instrument teams. They will talk about the flyby and present the data recorded by the different instruments: