BepiColombo spacecraft launches quest to survey Mercury
Humans still know very little about Mercury, the planet closest to the Sun. It's hoped the BepiColombo space probe will reveal the planet's secrets. Here is what we do already know about Mercury.
Meet the BepiColombo space probe
The BepiColombo spacecraft is scheduled to start its journey on October 20, 2018. It is a joint project of the European Space Agency (ESA) and the Japanese Space Agency (JAXA). BepiColombo consists of two satellites — the European Mercury Planetary Orbiter (MPO) and the Japanese Mercury Magnetospheric Orbiter (MMO). They will explore Mercury on different orbits starting in early 2026.
Unknown beauty
To date, only two space probes have come close to Mercury. The last one was the successful NASA probe, Messenger. It orbited the planet more than 4,000 times and sent over 250,000 images back to Earth. A planned crash landing in 2015 due to lack of fuel saw the end of the Messenger mission.
Long nights
Mercury probes must be able to withstand a lot. Above all, the extreme temperature differences pose great challenges to engineers and manufacturers here on Earth. Mercury is uninhabitable for another reason — the sun rises there once every 176 Earth days. Yes, you read correctly.
Hot, hot, hot — but no atmosphere
On Mercury it is hot, but not it's as bad as one would expect from a planet so close to the Sun. Its neighbor, Venus, experiences much hotter conditions. The reason: Mercury, in contrast to Venus, has no atmosphere and heat leaves the planet in the form of radiation. Temperatures vary from 430 degrees Celsius (806 degrees Fahrenheit) to minus 180 C.
Unstable and eccentric
Mercury is the smallest planet in our solar system and is closest to the Sun. Its orbit around the Sun is unstable, and is growing larger all the time because Jupiter is slowly pulling Mercury out of its orbit. At some point, this could see Mercury colliding with Earth. But fear not, that won't happen for many millions of years.
Similarities to the moon
The surface of Mercury is scarred and filled with craters like those on our moon. Many meteorites and asteroids have violently smashed into the planet in the past. Some craters are several hundred kilometers in diameter.