NASA Signs onto Europe's Mercury Mission

Whether it's new evidence of ancient water sources or a much thicker atmosphere way back when, the Red Planet seems to be claiming most of the headlines these days. However, an announcement Thursday from NASA shows that the space agency hasn't completely forgotten about the runt of the family - Mercury.

NASA is teaming up with the European Space Agency (ESA) in a mission to explore the solar system's innermost planet, as evidenced in the signing of a Memorandum of Understanding for cooperation on the project by NASA Administrator Charles Bolden in Rome on Thursday. Joining him was the Italian Space Agency's (ASI) President Enrico Saggese.

Led by the ESA, the mission, named BepiColombo, was first proposed in 1993, but wasn't officially approved for funding until 2000. Currently under construction, it will consist of two separate orbiters once complete: the Mercury Planetary Orbiter (MPO) to map the planet, and the Mercury Magnetospheric Orbiter (MMO) to investigate its magnetosphere.

Thus far, only NASA's Mariner 10 and Messenger have visited Mercury, the first of which provided the first-ever close-up images of the planet as it flew past three times between 1974 and 1975. Once it arrives in 2022, BepiColombo will offer new insight into the formation and history of the planet, according to the ESA.

Specifically, the orbiters are being designed to gather information on the planet's composition, geophysics, atmosphere and magnetosphere.

Furthermore, due to its location and nature, the scientists behind the project argue that, besides marking the most in-depth look yet at Mercury, the study will offer a better look into the formation and history of the inner planets in general, including Earth.

The project is not without its major challenges, however.

At this point, most of the ESA's previous interplanetary missions have been to relatively cold parts of the solar system. For this reason, designing space crafts that can survive the heat of Mercury's orbit and observe the planet despite the brightness of the Sun at such close proximity represents a new challenge for engineers. In addition, they have to ensure that the orbiters won't be sucked in by the Sun's gravity, which is much stronger around Mercury than it is on Earth.

And finally, there is the problem of just getting the orbiters there, which requires them to lose a lot of energy in order to "fall" toward the planet from Earth.

At this point, several launch methods have been extensively studied, the ESA reports, leading to the selected method that includes the spacecrafts using the gravity of Earth, Venus and Mercury in combination with the thrust provided by solar-electric propulsion.

During the voyage to Mercury, the two orbiters and a transfer module that contains electric propulsion and traditional chemical rocket units, will form one single composite spacecraft.

Then, when it finally approaches Mercury, the transfer module will be separated and the composite spacecraft will use rocket engines and a technique called "weak stability boundary capture" to bring it into polar orbit around the planet, with the MMO and the MPO separating once they reach their separate obits.

At this point, scientists plan to leave the spacecrafts in place for a minimum of one Earth year with the possibility of an extension.