The smallest planet in our solar system was captured on Friday by a Japanese European space probe making its closest trip across the globe on its seven-year mission.
The BepiColombo mission made its first flight from Mercury at approximately 7:34 p.m. EDT Friday, passing 124 miles (200 kilometers) from the planet’s surface.
“BepiColombo is now as close as possible to Mercury as it will enter this first of six Mercury flights,” the European Space Agency (ESA) said on Twitter.
During the flight, BepiColombo collects scientific data and images and sends them back to Earth.
The mission will actually put two probes into orbit around Mercury: the ESA-led Mercury Orbiter and the JAXA-led Mercury Magnetic Orbiter, Mio. The orbits will remain stacked in their current configuration with the Hg transport unit until publication in 2025.
Once the Bepicolombo spacecraft approaches Mercury to begin an orbit, the Mercury Transfer Module portion of the spacecraft will separate and the two orbiters will begin to orbit the planet.
Both probes will spend a year collecting data to help scientists better understand the mysterious little planet, such as determining more about the processes unfolding on its surface and its magnetic field. This information could reveal the origin and evolution of the closest planet to the sun.
During Friday’s flight, the spacecraft’s main camera was shielded and unable to take high-resolution images. But two of the spacecraft’s three monitoring cameras will capture images of the planet’s northern and southern hemispheres after a close approach of about 621 miles (1,000 km).
BepiColombo will fly alongside the night side of the planet, so images as you approach closer won’t be able to show much detail.
The mission team expects that the images will show large archaeological craters scattered across the surface of Mercury, like the moon. Researchers can use the images to map Mercury’s surface and learn more about the planet’s composition.
Some instruments will run on both orbits in flight so they can get a first whiff of Mercury’s magnetic field, plasma and particles.
This trip comes just in time on the 101st birth anniversary of Giuseppe “Pepe” Colombo, the Italian scientist and engineer of the namesake for the mission. Colombo’s work helped explain Mercury’s rotation as it orbits the sun and enabled NASA’s Mariner 10 spacecraft to make three flights of Mercury instead of just one using gravity assisted by Venus. He determined that the point at which spacecraft fly above the planets could actually help make future passage possible.
Mariner 10 was the first spacecraft sent to study Mercury, and it successfully completed its three flights in 1974 and 1975. Next, NASA sent its Messenger spacecraft to perform three flights on Mercury in 2008 and 2009, and orbited the planet from 2011 to 2015.
Now, BepiColombo will take on the task of providing scientists with the best information to unravel the planet’s mysteries as the second and most complex orbiting Mercury mission to date.
“We are really looking forward to seeing the first results from measurements taken near the surface of Mercury,” Johannes Benkoff, BepiColombo Project Scientist at the European Space Agency, said in a statement. “When I began working as a project scientist at BepiColombo in January 2008, NASA’s Messenger mission made its first flyby of Mercury. Now it’s our turn. it’s a wonderful feeling!”
Little is known about the history, surface, or atmosphere of Mercury, which is notoriously difficult to study due to its proximity to the Sun. It is the least explored of the four rocky planets of the inner solar system, including Venus, Earth, and Mars. The brightness of the Sun behind Mercury also makes it difficult to observe the small planet from Earth.
The BepiColombo will have to continuously release xenon gas from two of four specially designed engines in order to permanently brake against the massive gravitational force of the sun. Its distance from Earth also makes it difficult to reach – more energy is required to allow BepiColombo to “fall” toward the planet than is required when sending missions to Pluto.
A heat shield and titanium insulation were also applied to the spacecraft to protect it from extreme heat of up to 662°F (350°C).
Instruments on the orbiters will examine the ice inside the planet’s polar craters, why they contain a magnetic field, and the nature of the “cavities” on the planet’s surface.
Mercury is full of mystery for such a small planet, a little bigger than our moon. What scientists do know is that during the day, temperatures can reach as low as 800 degrees Fahrenheit (430 degrees Celsius), but the planet’s thin atmosphere means it can dip to minus 290 degrees Fahrenheit (minus 180 degrees Celsius) at night.
Although Mercury is the closest planet to the Sun about 36 million miles (58 million kilometers) from our star on average, the hottest planet in our solar system is Venus because it has a dense atmosphere. But Mercury is certainly the fastest of the planets, completing one orbit around the sun every 88 days – which is why it was named after the swift-winged messenger of the Roman gods.
If we could stand on the surface of Mercury, the sun would appear three times larger than it appears on Earth, and the sunlight would be blinded because it is seven times brighter.
Mercury’s unusual rotation and elliptical orbit around the sun means that our star appears to rise, set and rise again on some parts of the planet, and a similar phenomenon occurs at sunset.
CNN’s Anusha Rathi and Rob Picheta contributed to this report.
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