( CNN ) After landing a probe on an icy comet and possibly shedding new light on the origins of life on Earth , the European Space Agency ( ESA ) is now looking at scorching-hot Mercury for its next mission . The innermost planet of our solar system orbits so close to the Sun that , in some instances , surface temperature surpasses 400 °C . Areas of the planet without sunlight , on the other hand , can become as cold as -170 °C . No other planet has variations in temperature so severe . The reason for this is the absence of any significant atmosphere , which Mercury is too hot and too small to retain . With a diameter of just over 3,000 miles , it 's just a third larger than the Moon , and smaller than two other moons in the solar system -- Saturn 's Titan and Jupiter 's Ganymede . ESA 's mission to Mercury will tentatively launch on 21 July 2016 , to reach Mercury 's orbit seven and a half years later , in 2024 . The spacecraft is called BepiColombo -- in honor of Italian space pioneer Giuseppe `` Bepi '' Colombo . Mercury is the least studied of the inner planets , but it has many peculiarities . `` Mercury is special , '' said Johannes Benkhoff , the project scientist in charge of the BepiColombo mission , `` It 's the densest planet in our solar system , even denser than Earth - if we consider uncompressed density - and has a magnetic field , like Earth , that no one expected before , so I guess it 's a cool planet to go to . '' There are many challenging aspects to a mission to Mercury , most prominently its proximity to the Sun , with its mighty gravitational pull and intense radiation . The planet 's high orbital velocity of 48 kilometers per second -- compared to Earth 's 30 kilometers per second -- is also an issue . Any probe en route to Mercury must not only cover an average linear distance of 48 million miles , but carefully gauge its velocity so that it can catch the fast planet 's orbit without getting sucked into the Sun 's gravitational well . As a result , only two missions have visited Mercury so far . The first was NASA 's Mariner 10 , launched in 1973 . This was the first spacecraft to use the `` gravitational slingshot '' technique , which uses a planet 's gravity to affect the trajectory and the speed of a spacecraft , saving on fuel and time . Bepi Colombo 's calculations were used to plot Mariner 10 's trip to Mercury , in a maneuver that has been widely used in space exploration ever since . The second mission is still underway : it 's called Messenger and it was launched -- again by NASA -- in 2004 . It is currently orbiting the planet and will continue to study it well into 2015 . Nevertheless , ESA feels that there is enough mystery about Mercury to warrant a third mission . `` Messenger found so many surprising , unexpected results that we have a lot of good reasons to follow-up on what they did , '' Benkhoff told CNN , `` It 's a huge benefit that we have this mission in that stage , because only ten years later we will be at Mercury , follow-up on what Messenger did and get a huge , wonderful exploration of this planet . '' The mission will , once again , use gravity assists to reach its destination : it will first complete a fly-by of Earth , essentially returning to our planet two years after launch . Then it will perform two fly-bys of Venus , before finally heading toward Mercury . Upon arrival , a module called Mercury Planet Orbiter ( MPO ) will separate from the rest of the spacecraft and perform a detailed study of the Mercury system . This module is designed by the Japan Aerospace Exploration Agency , which jointly conducts the mission along with ESA . BepiColombo will help us understand how planets can form so close to their parent star , and will analyze Mercury 's geology and magnetic field . It will also provide further confirmation of Einstein 's general theory of relativity . Mercury 's strange orbital pattern first puzzled physicists in 1845 , when it was discovered that it did not conform to Newton 's theory of gravity . This was later explained by relativity , which revealed that Mercury 's warped orbit was due to curved space and not some unseen object . BepiColombo will be in an optimal position to gather extremely precise data about the planet 's dance around the Sun , offering the ultimate validation to Einstein 's idea . Read more from Make , Create , Innovate : . Are obese crash test dummies to key to preventing road deaths ? Turn your kitchen into an orchestra with this magic device . An end to all airport security lines ?
ESA 's next mission , BepiColombo , will explore the planet closest to the Sun , Mercury . The probe will launch in 2016 and reach Mercury in 2024 . It will endure temperatures of 350 degrees Celsius and observe Mercury from orbit . The data will be used , among other things , to confirm Einstein 's theory of relativity .