Ariane 5 rocket begins BepiColombo’s journey to Mercury
Europe’s powerful Ariane 5 booster took to the skies on Friday, October 19, to launch BepiColombo on a long journey to Mercury. The joint ESA/JAXA mission is expected to be inserted into Mercurian orbit in December of 2025.
Arianespace used the powerful rocket to send the probe aloft and designation the mission VA245 in the company’s numbering system. The rocket lifted off at exactly 10:45 p.m. local time (9:45 p.m. EDT / 1:45 GMT October 20) from the Ariane Launch Complex No.3 (ELA-3) located in Kourou, French Guiana.
Named after Italian scientist Giuseppe “Bepi” Colombo, the mission consists of European Space Agency’s (ESA) Mercury Planetary Orbiter (MPO) and Mercury Magnetospheric Orbiter (MMO, also known as Mio) developed by Japan Aerospace Exploration Agency (JAXA). The two orbiters are attached to the ESA-built Mercury Transfer Module (MTM), which is carrying them to the planet closest to our Sun.
The launch campaign for the mission commenced almost half a year ago, with the delivery of spacecraft components to French Guiana during four flights aboard a An-124 cargo jetliner. These took place between April 24 and May 9. Additional hardware for the mission was transported by ship.
The next phase of the multi-month preparations for the launch started when the teams finished the integration of MPO with MMO in late August. Fueling operations of the spacecraft began on September 5. On the next day, Ariane 5’s cryogenic main stage (EPC) was unpacked.
The two solid rocket booster were attached to the EPC on September 10. Four days later the engineers erected the launcher’s ESC-A cryogenic upper stage and completed the installation of the vehicle equipment bay. When it comes to the spacecraft itself, it was finally assembled on September 20, when the MPO/MMO stack was integrated with the MTM.
Pre-launch preparations entered the final stage on October 4, when the assembled BepiColombo was installed on Ariane 5’s payload adapter. On October 9, the spacecraft was integrated onto the launch vehicle in the Final Assembly Building (BAF).
Afterward, the teams worked to conduct final inspections of the spacecraft before its encapsulation in the payload fairing (commonly referred to as the nosecone). The fairing was installed on the launch vehicle on October 11 and four days later the launch rehearsal was conducted.
The mission passed the launch readiness review (LRR) on October 17, that cleared the way for flight. With the LRR completed, the Ariane 5 rocket was rolled out to the launch pad the following day and the final countdown for the flight began 11 hours and 23 minutes prior to launch.
During the countdown campaign, checks of the electrical systems were carried out at T-10 hours and 33 minutes. After this was complete, the EPC was ready to be filled with liquid oxygen and hydrogen. This operation began at about the T-minus 4 hours and 38 minutes, while fueling of the ESC-A started some 50 minutes later.
At T-3 hours and 18 minutes, the EPC’s Vulcain 2 engine was chilled down. Some two hours later, engineers performed final checks on connections between the launch vehicle as well as the telemetry, tracking, and command systems. These checks allowed mission controllers to give the green light for the initiation of the synchronized sequence seven minutes before liftoff. During this final pre-launch phase, the tanks were pressurized for flight and the launch vehicle was switched to onboard power mode, leading to the ignition of the EPC.
The EPC stage came to life at T+1 second. Six seconds later, the rocket’s solid boosters were ignited, lifting the rocket off the ground. Ariane 5 then performed a brief vertical ascent before beginning its pitch and roll maneuvers 10 seconds after it had left the pad.
The first phase of the flight lasted until T+2 minutes and 21 seconds when the two solid boosters were jettisoned at approximately 43 miles (70 kilometers) above the ground, leaving the launch vehicle powered by the EPC stage alone.
Almost one minute later the payload fairing was separated and was jettisoned, unveiling the three components of BepiColombo to the space environment. The EPC continued its part of the flight for the next five minutes and 34 seconds, until its separation at T+8 minutes and 43 seconds.
The control over the flight was then assumed by the ESC-A, which ignited its HM7B engine, this marked the start of its job ferrying BepiColombo to space. The spacecraft occurred at 26 minutes and 47 seconds into the flight. Just a few seconds shy after it had left the launch pad far below, the spacecraft separated and was injected into an Earth escape orbit.
BepiColumbo will now begin a seven-year trek toward Mercury. To place it on the right trajectory to this tiny world, it is planned to conduct one fly-by of Earth, two fly-bys of Venus, and six fly-bys of Mercury. BepiColumbo should be inserted into orbit above Mercury on December 5, 2025.
“Following its departure from Earth, the spacecraft will travel nine billion kilometers in seven years, completing nine planetary flybys at a top speed of 60 kilometers per second, all in order to reach the least explored planet of the inner Solar System,” said Paolo Ferri, Head of Mission Operations at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany.
Manufactured by Airbus Defence and Space, MPO weighs some 1.23 metric tons with its measuring approximately: 7.9 x 7.2 x 5.6 feet (2.4 x 2.2 x 1.7 meters). The orbiter features one solar panel and is equipped with 11 scientific instruments, including various spectrometers and imagers. ESA intends to put MPO into a 2.3-hour polar orbit at an altitude of about 298 x 932 miles (480 x 1,500 kilometers) above Mercury’s surface.
MPO is designed to map Mercury by producing measurements of the planet’s surface and interior. If everything goes as planned, the orbiter should make a complete map of Mercury at different wavelengths as well as chart the planet’s mineralogy and elemental composition.
With a mass of around 562 lbs. (255 kilograms), the MMO has dimensions of 5.9 x 3.6 feet (1.8 x 1.1 meters). The orbiter is fitted with five instruments including the Mercury Magnetometer (MMO-MAG) designed to provide a detailed description of Mercury’s magnetosphere and of its interaction with the planetary magnetic field and the solar wind. JAXA plans to insert MMO into a 9.3-hour elliptical polar orbit, at an altitude of 366 x 7,233 miles (590 x 11,640 kilometers).
MMO is slated to focus on performing a detailed study of the magnetic environment of Mercury, the interaction of the solar wind with the planet, and the diverse chemicals present in the exosphere.
“This ambitious project aims to solve all the mysteries about Mercury by bringing the two orbiters to Mercury at the same time. BepiColombo will make the first multilateral and general observations of magnetic fields, the magnetosphere, the interior, and the surface,” said Hajime Hayakawa, BepiColombo Project Manager at JAXA.
The MPO and MMO orbiters are scheduled to conduct a one-year mission at Mercury, with a possible one-year extension.
If successful, BepiColombo will become the third mission to visit Mercury, and the second to enter orbit above it. NASA’s Mariner 10 flew past the planet three times between 1974 and 1975, while NASA’s Messenger spacecraft, orbited the planet from 2011 to 2015.
The Ariane 5 in its ECA configuration that was used to launch BepiColombo is the heavy-lift rocket Arianespace employs for missions to geostationary transfer orbits and usually carries two telecommunications satellite payloads. The 180-foot (54.8-meter) tall ECA is an improved version of the launcher. It is designed to deliver payloads, primarily communications satellites, that weigh up to 10 metric tons.
“With our seventh launch of the year, an Ariane 5 has lofted BepiColombo on a seven-year journey to Mercury, covering nearly nine billion kilometers! We are very proud of our 51st mission for ESA, and the 23rd space exploration mission by Arianespace. Europe’s first mission to the planet closest to the Sun, in partnership with the Japanese space agency JAXA, will enable us to better understand the formation and evolution of planets in the inner Solar System. It carries on the tradition of previous successes for space exploration by ESA, with launches performed by Arianespace, and also heralds the next major scientific mission – the James Webb Space Telescope – to be launched by an Ariane 5 in early 2021,” Stéphane Israël, Chief Executive Officer of Arianespace, stated via a release.
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