Spacecraft bound for Mercury begins 'tricky' arrival

The ESA/JAXA BepiColombo mission completed a flyby closer than planned to Mercury, beginning its monthslong, high-risk approach to the planet on Thursday. The spacecraft, carrying European and Japanese probes, traveled more than 10 billion kilometers to study Mercury, which is only slightly bigger than the moon. The mission manager at ESA, Santa Martinez, described the arrival as "most operationally challenging planetary arrival sequences ever attempted." The spacecraft had to execute a series of nine flybys to speed up, slow down, and perfect its trajectory. The two probes, attached to each other, separated from the transfer module at a speed of 40 centimeters per second, leaving them relatively close despite the vastness of space. The separation took place autonomously, as there was about a 30-minute delay between checks and commands from Earth.

• The spacecraft autonomously cut the four mechanical struts connecting the orbiters to the module.
• The separation took place at a speed of 40 centimeters per second.
• The signal confirming the operation's success reached the control center in Darmstadt, Germany, nearly two hours later.

The BepiColombo mission is set to come into Mercury's orbit on Nov. 21. The next tricky phase will occur on Dec. 9 and 10 when the two probes separate into their respective orbits. ESA's Mercury Planetary Orbiter (MPO) will study Mercury with unprecedented precision, passing just 480 km from its surface, while the Japanese Mercury Magnetospheric Orbiter (Mio) will focus on its space environment and magnetic field, following an elliptical orbit that will carry it as far as 11,000 km away. Mercury is the least studied of the four rocky, innermost planets in our solar system, which include Venus, Earth, and Mars. NASA's Mariner 10 was the first probe to capture a close picture of its lunar-looking surface in 1974, and the MESSENGER probe then orbited the planet in 2011. BepiColombo, with its 16 instruments and budget of 1.7 billion euros, is expected to bring unprecedented views of Mercury and open a new chapter in our understanding of the solar system.

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