Mercury return: Japan, Europe launching spacecraft to planet closest to sun

BepiColombo marks 3rd mission to solar system's smallest planet

Artist’s impression of the BepiColombo spacecraft in cruise configuration, with Mercury in the background. On its 7.2 year journey BepiColombo will fly by Earth once, Venus twice and Mercury six times before entering into orbit. (Image: spacecraft: ESA/ATG medialab; Mercury: NASA/JPL)

Hi Mercury, it’s been a while. Almost four years after the last mission to the planet closest to the sun –intentionally-- crashed into the planet’s surface, Europe and Japan are preparing to launch BepiColombo, a two-part spacecraft to orbit Mercury.

NASA’s Mariner 10 spacecraft was the first to flyby and capture close images of Mercury in 1974. More than 30 years later, NASA launched Messenger, the first spacecraft to successfully orbit and map Mercury’s surface. That mission ended in 2015.

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BepiColombo is a joint mission between the European Space Agency (ESA) and the Japan Space Exploration Agency, known as JAXA. The spacecraft is slated to launch Oct. 19 at 9:45 p.m. ET from the French Guiana on the European workhorse rocket Ariane 5. Watch the launch live here.

The spacecraft actually has two orbiters, one from each space agency. ESA’s Mercury Planetary Orbiter has instruments designed to study the planet’s interior, composition and magnetic field. JAXA’s Mercury Magnetospheric Orbiter, nicknamed Mio, will study the planet’s magnetic field and Mercury’s atmosphere.

Mio means waterway or fairway in Japanese and is a fitting name for the spacecraft.

"Markers called mio-tsukushi were posted to guide boats sailing at rivers and sea," according to the JAXA website. "In traditional Japanese poetry, mio-tsukushi interchangeably means working hard without giving up. This describes the diligent and tenacious spirit of the MMO project team who never ceases to challenge."

After launch, the combo spacecraft will first make flybys for Earth, Venus and the sun as it picks up speed before making the first flyby of Mercury in 2021.

What challenges will BepiColombo face?

Mercury is the fastest planet in our solar system; it whips around the sun every 88 days. Compared to Earth’s 365-day orbit, that’s very fast. However, one day on Mercury takes 59 Earth days because of its slow rotation.

Mercury is the closest planet to the sun, but not the hottest. Because of its its proximity to the sun, it's difficult to observe with ground telescopes and hard to reach via spacecraft.

To reach its destination the spacecraft will use a trajectory theory created by the Italian astrophysicist BeiColombo is named after. Dr. Giuseppe "Bepi" Colombo suggested a mission could reach Mercury by using a gravity-assist swing-by of Venus. The spacecraft will make several of these flybys.

To insure BepiColombo is ready for the seven-year voyage, it's equipped with a solar-electric propulsion system. It will be protected from the sun by a shield-like structure called known as MOSIF.

In this handout from NASA, Mercury is seen from the Messenger spacecraft January 14, 2008. (Photo by NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington via Getty Images)



Will the mission find life?
It’s unlikely. No evidence has been found to indicate any life yet on the small planet. According to NASA, it’s not a great life-supporting candidate. The daytime temperatures can reach 800 degrees and then drop to negative 290 degrees at night.

Also, the atmosphere is very thin. Any atoms on Mercury’s surface don’t stand a chance against solar wind.


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